General Biology 1 Past Paper PDF

GENERAL BIOLOGY 1 OVERVIEW OF SCIENCE Science- systematic study of the structure and behaviour of the natural and physical world through observation and experimentation. Major Branches of Science:...

GENERAL BIOLOGY 1 OVERVIEW OF SCIENCE Science- systematic study of the structure and behaviour of the natural and physical world through observation and experimentation. Major Branches of Science: 1. Social Science (Soft Science) - deals with human behavior, people, and society. - quantitative research - ex. Sociology, Anthropology, Psychology, etc. 2. Mathematics and Logic - numbers and thinking 3. Natural Sciences (Hard Science) - deals with the natural phenomena - qualitative research - Branches: a) Physical Science:  study of matter and energy (e.g., chemistry, physics, astronomy, meteorology, geology, etc.)  deals with nonliving things b) Biological Science  study of living things (e.g., botany, zoology, microbiology, etc.)  deals with living things *interdisciplinary (builds on both life and physical science) 2 Types of Science: 1. Pure Science (Basic Science) - seeking knowledge - the goal is for knowledge sake 2. Applied Science - “technology” - solves real-world problems INTRO TO BIOLOGY Biology- the study of life Branches of Biology: 1. Cytology/Cell Biology - the study of cells 2. Histology - the study of the tissue 3. Embryology/Developmental Biology - the study of the formation and development of organisms in their earliest stages of life ATTRIBUTES OF LIFE 1. GROWTH - Increase in Size (assimilation of nutrients) - assimilated nutrients are delivered to the cells (protoplasm)   Unicellular vs Multicellular Organisms a. Unicellular: growth in size b. Multicellular: growth in size and numbers  Plants vs Animals a. Plant growth is indefinite/unlimited b. Animal growth is definite/limited  Controlled by chemical substances produced a. Chemical Substances called Hormones.  Living vs Nonliving Things a. Living Things: Intussesception - growth is from within - growth by deposition of new materials between existing components of cell walls. b. Nonliving Things: Accretion - growth is accumulated from outside 2. REPRODUCTION - continuation of life - the process by which an organism produces an offspring either sexually or asexually a. Sexual - requires the union of male and female gametes (fertilization) - male gametes: sperm cells - female gametes: egg cell - Types of Fertilization: 1) External Fertilization- the union of sperm cells outside the body of the female organisms (e.g., seashells, starfishes, fishes) 2) Internal fertilization- the union of sperm cells and egg cells inside the body of a female organism (e.g., higher forms of animals and humans) b. Asexual - reproduction without the gametes or sex cells. - one parent organism can reproduce by itself. - Examples: 1) Binary Fission - Splitting of the body of an organism into two identical parts. - Single parent cell doubles its DNA, then divides into two cells. - Usually occurs in bacteria 2) Budding - Growing of bud out of the parent cells or bodies which when detached can grow into another organism that resembles the appearance of the parent. - (e.g., sponges, hydra, and yeast) 3) Fragmentation - Organisms break into two or more fragments that develop into a new individual. 3. METABOLISM - sum of all processes in an organism. a. Catabolism: process of breaking down complex molecules to release energy from chemical bonds. e.g. Digestion b. Anabolism: building up process by which simple molecules are used to from more complex molecules for growth, repair, and reproduction. e.g. Photosynthesis, Hydrolysis, Dehydration Synthesis.  4. HOMEOSTASIS - Homeostatic Response - to keep balance: a) Irritability: ability of an organism to respond to stimuli.  2 Types: a) Internal (hunger, thirst, pain, etc.) b) External (environment, gravity, chemicals, etc.)  Tropism: response of plants.  Taxism: response of animals. b) Adaptability/Adaptation:  adapting to environmental conditions,  leads to evolution. *Regulation - all systems of the human body are working together. 5. NUTRITION - Nutrients give: a) Growth and Development b) Energy c) Maintenance 6. MUTATION - change in genetic make-up of the organism, - change in DNA molecule. - Two Types: a) Somatic Mutation  changes in the autosomal cells (body cells)  ex. failure to produce melanin, Albinism b) Germ Mutation  changes in the sex chromosomes  ex. having an extra chromosome, Abnormality 7. BIOLOGICAL ORGANIZATION - Single-celled organisms: (atoms - molecules - cell organelles - cell inclusions) - Multicellular organisms: (cells - tissues organs - organ system - organism) - Population - Community - Ecosystem - Biosphere 8. MOVEMENT - Animals: Motile - Plants: Stationary; based on their response to stimuli, stem bends towards the sunlight, while roots move towards gravity. 9. LIFE SPAN - Specific lifespan, Definite - controlled by genetic composition (rate of aging) - controlled by external environment (accidents, diseases, etc.) 10. FORM SHAPE - controlled by genetic composition - environmental factors  Key Concepts ✓ Cell is the basic unit of life (smallest unit of a living being) ✓ Several cells make the structure of an entire organism. ✓ Functional Unit of Life, several cells are responsible for proper functioning of an organism as a whole. ✓ The Cell Theory is a unified theory that governs all life forms. The Cell Theory  Robert Hooke (1665) - English Physicist - first discovered the cell  looked at a slice of cork under a microscope and noticed some “pores” or “cells” in it.  compared cells to a honeycomb like structure - named it “Cell” or “Cellulae” in Latin, which means “little rooms.”  Anton van Leeuwenhoek (1674) - Father of Microbiology - first to observe live cells  discovered “protozoa”– a single-celled organism, he called them “animalcules” - perfected the microscope. - first to observe individual cells in blood, semen, feces, pepper, and pond water (as units not cells) - first to see and describe bacteria  GAP or Dark Age - persisted for 150 to 200 years - no further studies on cells - Abiogenesis Theory or Theory of Spontaneous Generation.  Aristotle (384-322 BC)  Greek Philosopher  one of the earliest recorded scholars to articulate the theory.  states that “Life arose from nonliving matter”  persisted into the 17th century  Francesco Redi  presented the first significant evidence refuting the theory by: showing that flies must have access to meat for maggots to develop.  Louis Pasteur  proposed that “life only comes from life”  Swan-Neck Experiment:  the flasks allowed air to enter but prevented the entry of bacterial and fungal spores.  two parts: boiled broth to sterilize flask. when it was cooled, it remained free of contamination. flask was boiled then the neck was broken off, broth became contaminated.  John Needham (1745)  briefly boiled broth infused with plant or animal matter  likely did not boil enogh to kill pre-existing microbes.  Lazzaro Spallanzani  replicated Needham’s experiment by boiling it longer, resulted to uncontaminated flasks.  Robert Brown (1831) - Scottish Botanist - discovered nucleus - Brownian Movement, continuous motion of minute particles in solution.  Felix Dujardin (1835) - French Biologist and Cytologist - discovered protoplasm - Infusoria– microscopic animal life frequently found in infusions of decaying organic materials  1834, he proposed a new group of protozoans called Rhizopada (rootfeet)  Protoplasm (sarcode), in the group Foraminifera, he observed formless life substance that exuded outward through openings in the calcareous shell. - said cells are not hollow but filled with jelly-like fluids.  Matthias Jakob Schleiden (1838) - German Botanist - wrote “Contributions to Phytogenesis” - stated that the different parts of the plant organism are composed of cells.  Theodor Schwann (1839) - German Physiologist - founded modern histology - stated that cells are the basic units of animal structure. - Schwann Cells, forms a sheath surrounding nerve axons and conducted experiments that helped disprove the theory of spontaneous generation  Rudolf Virchow (1855) - German Pathologist - ‘Omnis cellula e cellula’ meaning “every cell stems from another cell.” - stated that all diseases involve changes in normal cells. The ideas of 3 scientists— Schwann, Schleiden, and Virchow, led to the cell theory. Therefore, the 3 Postulates of the Cell Theory are: 1) All living organisms are made up of one or more cells. 2) Cells are the basic units of structure and function of all living things. 3) All cells arise from pre-existing cells. 3 Postulates of Cell Theory 1) All living organisms are made up of one or more cells. states that all living things,whether big or small, simple or complex, are composed of either one or more cells. Unicellular Organism-- organisms that are made up of one cell. ex. Bacteria, Amoeba, Archaea Multicellular Organism-- organisms that are made up of more than one cell. ex. Plants, Animals, Human Body 2) Cells are the basic units of structure and function of all living things. states that all biological processes that occur within an organism cannot occur without the presence of cells. For Unicellular Organisms, the cell is everything, it is the very structure that carries out all biochemical activities to maintain cellular life. For Multicellular Organisms, one cell undergoes division to increase in numbers, leading to the formation of tissues, organs, the organ system, then the whole organism. 3) All cells arise from pre-existing cells.  refers to the process of cell division, whereby one cell divides to produce more than one cell. This is the basis of cellular reproduction either be sexual or asexual, depends on the organism. this implicates the evolution of life on Earth, that all cells on Earth arose from one single cell. Modern Tenets of the Cell Theory 1. All energy flow (metabolism and biochemistry) occur within the cells.  energy released by the cell is converted to ATP (adenosine triphosphate) which can later do work; energy carrier. 2. Cells contain hereditary information (DNA) which is passed from cell to cell during cell division.  DNA (deoxyribonucleic acid) is packed in nucleus in the form of chromosomes.  Hereditary Information is passed when cell division occurs 3. All cells are basically the same in chemical composition.  Hydrogen, Oxygen, Nitrogen, Carbon, Phosphorus, and Sulfur normally make up more than 99% of the mass of living cells, when combined, forms organic molecules. 4. The activity of an organism depends on the total activity of independent cells.  several cells of similar structure and function interconnect to form tissues, then organs, organ system, together they form an organism.  whatever the cell do, determines what an organism does. CELL STRUCTURE AND FUNCTIONS Tree Major Parts of Cell: 1. Cell Membrane 2. Nucleus 3. Cytoplasm a. Organelles b. Inclusion Plasma Membrane Structure:  Fluid Mosaic Model 1972 (Jonathan Singer and Garth Nicholson)  Also called as cell membrane or plasmalemma.  Found in all cells.  It is a selectively permeable membrane. Functions: Maintain the physical integrity of the cell by enclosing the contents of the cell Control the movement of particles e.g. ions or molecules, gases into and out of the cell. It is a barrier that separates a cell from its surrounding environment. Gives shape to the cell. Site for receiving signals. Parts:  Phospholipid Layer − make up the basic structure of a cell membrane. − single phospholipid molecule has two different ends: a head and a tail. → The head end contains a phosphate group and is hydrophilic. This means that it likes or is → attracted to water molecules. → The tail end is made up of two strings of hydrogen and carbon atoms called fatty acid chains. These chains are hydrophobic or do not like tomingle with water molecules.  Proteins: − Are embedded in the cell membrane like tiles in a mosaic or icebergs floating in the fluid phospholipid. − Either partially sunken (peripheral proteins) or totally sunken (integral proteins) in the phospholipid layer. − They act as carriers of large molecules which can’t pass through the lipid part of the membrane. Glycolipids and Glycoproteins: − Found on the extracellular side of a cell membrane. − Act as a glue to attach cells together. − Provides cushioning and protection for the plasma membrane. − For cell recognition. Plant Cell Wall: − The cells of plants, fungi, and some single-celled organisms are protected and supported by a rigid cell wall which lies outside the plasma membrane. Cell walls are made mostly of cellulose except in bacteria and fungi. − Lies outside the plasma membrane. − Plant cell walls are made mostly of cellulose − Peptidoglycan is the chief component in prokaryotic cells Cellulose - complex sugar considered as structural carbohydrate because it is for protection and structure. → The cell wall consists of distinct layers: the primary cell walls and middle lamella. The primary cell wall is the outer layer. It expands as the cell grows. As the plant cell reaches its full size, a secondary cell wall develops inside the primary cell wall Middle lamella is a pectin layer which cements the cell walls of two adjoining cells together. Plasmodesmata (singular: plasmodesma) are microscopic channels which traverse the cell walls enabling transport and communication between cells. Cell Wall of Bacteria − considered as a rigid wall which − encases the cell membrane and − helps secure the shape of the bacteria. − maintains osmotic pressure, − protects the cell from changes in water pressure. ✓ It contains a layer of peptidoglycan, a molecule naturally found only in bacteria. A peptidoglycan cell wall composed of disaccharides and amino acids gives bacteria structural support. Hence, the peptidoglycan layer acts as the cell wall's backbone, offering strength to the cell wall. The cell wall is coated with an external layer of sticky or slimy polysaccharides called a capsule (protects the cell from physical damage). Cytoplasm  Everything in a cell except the nucleus. (The factory area of the cell) 3 Elements: 1. Cytosol is watery matrix where organelles float in 2. Organelles “little organs”; active parts Specialized structures that perform specific jobs in the cell Found only in eukaryotic cells Many are “membrane-bound” (a membrane surrounds the organelle) Machinery of the cell 3. Inclusions is passive nonliving part of the cell Cytoplasmic Organelle Are structures within the cell that carry out specific functions to support the life of the cell These functions include: 1. Bringing in nutrients  2. Removing wastes 3. Generating and releasing energy for the cell to use 4. Making substances that the cell needs 5. Reproducing 6. Ribosomes Smallest organelle NOT surrounded by a membrane Makes proteins according to DNA instructions. Found in all cells o Two Types: 1. Free ribosomes: float free in cytosol 2. Bound ribosomes: attached to rough ER They synthesize proteins such as enzymes, hormones, antibodies, pigments, structural components, and surface receptors. Abundant in cells that synthesize large amounts of protein. Example: pancreas Endoplasmic Reticulum Transport system for materials in cell. o Two Types: 1. Rough ER: covered with ribosomes; site of protein synthesis. 2. Smooth ER: NO ribosomes; it makes hormones & lipids. Factory Part: Conveyor Belts. In muscle cells, a specialized SER called the sarcoplasmic reticulum is responsible for storage of the calcium ions that are needed to trigger the coordinated contractions of the muscle cells. Golgi Apparatus Collect, package, and distribute molecules synthesized at one location in the cell and utilized at another location. Front - cis Back – trans Cisternae – stacked membrane folds Vesicles Are membrane-covered sacs that transport and/or store materials inside the cell and sometimes help these materials cross the cell membrane to enter or exit the cell. They bud from the RER and transport their content elsewhere. o These organelles are also called microbodies. 1. Lysosomes - Suicidal bag of the cell Contain digestive or hydrolytic enzymes(lysozyme) that break down lipid, NA, CHO, protein, wastes and worn-out organelles Destroy pathogens. - A macrophage has engulfed (phagocytized) a potentially pathogenic bacterium and then fuses with a lysosomes within the cell to destroy the pathogen. 2. Peroxisomes - Carry out oxidation reaction that breaks down fatty acid and amino acid Detoxify toxins that enter the body Alcohol is detoxified by peroxisomes in liver cells. Form bile acid, and break down fats. - Breaks down safely H2O2 (damaging to cells) to oxygen and water. - Glyoxisomes (specialized peroxisomes in plants) –break down stored fats to sugars Vacuole Large central vacuole usually in plant cells Many smaller vacuoles in animal cells Storage container for water, food, enzymes, wastes, etc.  Supports cell shape in plants How Does the Endomembrane System Works? Vesicles can bud from the ER and transport their contents elsewhere. The vesicles still need to be sorted, packaged, and tagged so that they wind up in the right place. Sorting, tagging, packaging, and distribution of lipids and proteins takes place in the Golgi apparatus (also called the Golgi body), a series of flattened membranes. The transport vesicles that formed from the ER travel to the cis face, fuse with it, and empty their contents into the lumen of the Golgi apparatus. As the proteins and lipids travel through the Golgi, they undergo further modifications that allow them to be sorted. The most frequent modification is the addition of short chains of sugar molecules. These newly modified proteins and lipids are then tagged with phosphate groups or other small molecules so that they can be routed to their proper destinations. Finally, the modified and tagged proteins are packaged into secretory vesicles that bud from the trans face of the Golgi. While some of these vesicles deposit their contents into other parts of the cell where they will be used, other secretory vesicles fuse with the plasma membrane and release their contents outside the cell. Mitochondria: “Powerhouse” of the cell Site of cellular respiration Converts energy stored in food into energy the cell needs – ATP Have their own DNA o Factory Part: - Power Plant / Electrical Room Chloroplast (Sunlight + Carbon Dioxide + Water →Sugar + Oxygen): Found only in plant cells and algae Contains green pigment, chlorophyll For photosynthesis Changes sunlight (solar energy) into food like glucose (chemical energy) Vacuoles: Large central vacuole usually in plant cells Many smaller vacuoles in animal cells Storage container for water, food, enzymes, wastes, etc. w Supports cell shape in plants Cytoskeleton: Maintains cell shape and anchors organelles Microfilaments o cell movement Microtubules (25 nm dm) o Small hollow tubes o Facilitate cell movement Intermediate filaments (8-12 nm dm) o Stable; maintains shape of the cell Centrioles: Involved in the organization of the mitotic o Centrosome - Two centrioles form near the nucleus - Source of microtubules in animal cells. Cilia short, hair-like structures that moves entire cells (Paramecia) or substances along the outer surface of the cell (cilia of the cells lining the Fallopian tubes that move the ovum toward the uterus, or cilia lining the cells of the respiratory tract that trap particulate matter and move it toward your nostrils) Flagella  long, whip-like structures for locomotion (for example, sperm, Euglena) Nucleus  a highly specialized organelle that serves as the information processing and control center of the cell. Two major functions: 1. It stores the cell's hereditary material, or DNA (maintain the integrity of the genes) 2. It coordinates the cell's activities, which include growth, intermediary metabolism, ribosomes and protein synthesis, and reproduction (cell division). Parts: 1. NUCLEAR MEMBRANE o a double membrane (of phospholipid bilayers) that encloses the entire organelle or constitute the outermost portion of the nucleus o Punctuated with nuclear pores that control the passage of ions, molecules, and RNA between the nucleoplasm and cytoplasm 2. THE NUCLEOLUS o a non-membrane bound structure composed of proteins and nucleic acids o synthesizes ribosomes that make the proteins. 3. CHROMOSOMES o Contains DNA, the hereditary materials o Condensed and visible during cell division o Chromatin threads PROKARYOTIC AND EUKARYOTIC CELL PROKARYOTIC  Cells without true nucleus  Simplest organisms, one-celled organisms e.i. Bacteria 1. Genetic materials are not complexed with proteins 2. Lack a well-defined nucleus 3. Do not have structures surrounded by membranes 4. Few internal structures or lack most of the organelle as mitochondria, plastids, and Golgi apparatus 5. Enzymes for cellular respiration are attached to the plasma membrane 6. Ribosomes are found free in the cytoplasm but some are attached to messenger RNA 7. Circular DNA (plasmid) are coiled up in a region of the cytoplasm called nucleoid, not involved in reproduction PROKARYOTIC EUKARYOTIC Size Small (1-5 micrometers) Larger (10-100 micrometers) Organism Bacteria/archaea Animals, plants, fungi, protists Cell Structure Always unicellular Can be unicellular or multicellular  Are placed in two taxonomic domains: Bacteria Archaea The Structure of Bacteria Extremely small - 1–1.5 μm wide and 2–6 μm long o Occur in three basic shapes:  1. Spherical coccus 2. Rod-shaped bacillus 3. Spiral spirillum (if rigid) or spirochete (if flexible) Parts of the Bacterial Cell Cell Envelope includes: Plasma membrane - lipid bilayer with embedded and peripheral protein o Form internal pouches (mesosomes) Cell wall - made of peptidoglycan, comprised of sugars and amino acids (or small proteins) o acts as an extra layer of protection, o maintains the shape of the cell o prevents dehydration. Glycocalyx - layer of polysaccharides on the outside of the cell wall Capsule – if compact; outermost layer of carbohydrates; well-organized and resistant to removal and protects the cell from physical damage Slime layer - if diffuse o The capsule is sticky and enables the cell to attach to surfaces in its environment. The Structure of Bacteria Cytoplasm - Semifluid solution surrounded by plasma membrane and encased in a rigid cell wall (15- 100nm;provides rigidity) composed of peptidoglycan, and a capsule - Contains water, inorganic and organic molecules, and enzymes. - no distinct interior compartments Nucleoid - is a region that contains the single, circular DNA molecule. - Plasmids are small accessory (extrachromosomal) rings of DNA The Structure of Bacteria Cytoplasm & Appendages - Some prokaryotes have flagella, pili, or fimbriae. Appendages Flagella − Provide motility or are used for locomotion. Fimbriae − small, bristle-like fibers that sprout from the cell surface – − numerous, hair-like structures that are used for attachment to host cells and other surfaces. Sex pili/pili/conjugation pili − rigid tubular structures used to pass DNA from cell to cell EUKARYOTIC CELLS  Cells with true nucleus 1. Genetic material is enclosed in a membrane, the nuclear envelope 2. With a defined nucleus as well as organelles 3. Mitochondria contain respiratory enzymes a. Enzymes of TCA or Kreb’s Cycle reside in the intercristae spaces of mitochondria b. Enzymes for ETS and oxidative phosphorylation are found in the cristae membrane 4. Ribosomes are found in the ER (RER) while some are soluble in the cytoplasm 5. Characterized by compartmentalization by an endomembrane system, and the presence of membrane-bound organelles.  6. Multiple linear chromosomes Domain Eukarya includes: Protists, Fungi, Plants, Animals TISSUES ANIMAL TISSUES Histology - study of tissues Why study histology? − To know between normal and abnormal tissue is the first step in diagnosis and treatment of patients Tissues - are group of cells that are similar in structure and function. And greatest form of a teamwork in body. Note: Skin is the largest tissue because it made up of all the four tissueS type MAJOR GROUPS OF SOMATIC TISSUES 1. Epithelial Tissue 2. Connective Tissue 3. Muscular Tissue 4. Nervous Tissue EPITHELIAL TISSUE - Makes up 3% of your body weight - They don’t move - They don’t send messages - Their cells are all touching one another - Most widely varied in structure and function - Forms the covering of all free body surfaces both external and internal as in the skin and lining of the DT: o One type of epithelium forms the outer layer of the skin o Another type of epithelium lines the air sacs of the lungs - Cells lie on the basement membrane and the cells are held together by intercellular cement. LOCATION OF EPITHELIAL: Covers the body (epidermis) Found on the inside of hollow organs and the outside of all organs Found above a connective tissue layer (epi = above) Lines the cavities, tubes, ducts, and blood vessels inside the body EPITHELIAL ANATOMY Apical surface − upper surface that is free or exposed to the “exterior” Basal surface − attached surface (below) Microvilli − small fingerlike extensions that increase the surface area allowing for more work to be done Cilia-hair − like projections, small hair FUNCTIONS OF EPITHELIAL TISSUE Protects from physical & chemical injury and against microbial infection − provide covering of the body Contains nerve endings which respond to stimuli − comprising the sensory organs of the body Filters, secretes & reabsorbs materials − provide secretory portion in organs as well as in the duct of these organs Secretes fluids to lubricate joints  − provide secretory portion in organs as well as in the duct of these organs Line the cavities of some internal organs as KIDNEY and DIGESTIVE TRACT GENERAL CLASSIFICATION OF EPITHELIAL TISSUES According the arrangement of cells, number of cell layers; o Simple epithelium − epithelial cells are one layer thick o Stratified epithelium − cells are arranged in two or more layer Shape of cells CELL ORGANIZATION (AND BASED ON SHAPE) A. Simple - single layer of cells; typically found where absorption and filtration occur or a single layer of epithelial is needed simple squamous simple cuboidal simple columnar THREE BASIC SHAPE 1. Simple Squamous → like scales, or pancakes (“being squashed like a pancake”) → A single layer of flat cells with scaly appearance → Found in the skin, linings of the body cavity and blood vessels → Permits diffusion or filtration through a semi- permeable membrane 2. Simple Cuboidal → looks like cubes → A single layer of approximately cube-shaped cells → Nucleus of each cell is large and centrally located → For secretion and absorption → Found in the kidney tubule, surface of ovaries, linings of many glands and their ducts. 3. Simple Columnar – longer and look like columns → Simple – one cell thick → Column shaped (long and narrow) → Lines digestive tract where re-absorption & secretion occurs. → Located at base of cells. May be ciliated or non-ciliated; may secrete mucus. (goblet cells) may have microvilli on free surfaces of cells → For lubrication, secretion, absorption, protection, cilia and mucus combine to sweep away foreign substance → Found in the stomach, intestines, digestive glands, gall bladder, upper respiratory tract, uterus Squamous Epithelium − Simple – one cell thick − Forms solid layer of cells which line blood vessels, body cavities and covers organs in body cavities − Stratified – multiple layers − Forms epidermis B. Stratified - with 2 or more layers of cells; common in areas where protection is needed like the skin stratified squamous stratified cuboidal stratified columnar 1. STRATIFIED SQUAMOUS → Have layers of flat squamous cells → For protection → At epidermis, vagina, mouth, esophagus 2. STRATIFIED CUBOIDAL  → A multi-layered arrangement of cells with superficial composed of cuboidal cells → For secretion → At ducts of sweat glands, oil glands and developing epithelium in ovaries and testes 3. STRATIFIED COLUMNAR → Several layers of thin, tall columnar cells, sometimes ciliated → For secretion and movement → In the larynx, part of soft palate, pharynx, ducts of salivary and mammary glands Atypical Epithelium – Confusing Epithelial Tissue Transitional Epithelium − stratified tissue that can’t make up its mind as to whether it is squamous or cuboidal Shape of cells depends upon the amount of stretching (ex: bladder) Surface cells cannot be classified by shape because it changes as tissue is distended Usually no distinct basement membrane Allow for changes in shape At urinary tract Pseudostratified Columnar Epithelium Looks like it has more than one layer because of the position of the nucleus Nuclei are positioned at differing levels Cells narrow in the area without the nucleus Single layer of cells varying in height and shape Nuclei at different heights give false impression of cells being multi-layered All cells in contact in the basement membrane but not all cells reach superficial layer Glandular epithelial tissue Epithelial cells modified to perform secretion For synthesis, storage and secretion of ducts Sweat, mammary, salivary, and thyroid glands TYPES OF EPITHELIAL MEMBRANES Mucous or mucosa– lining of tubes; moistens and protects from enzymes (stomach, trachea, and vagina) Serous or serosa – outside of organs; lubricates (all thoracic, abdominal and pelvic organs) Cutaneous or skin – body surface; protection Synovial – synovial joints; lines and protects synovial cavities (elbow, knee, hip, etc.) EPITHELIAL SECRETION/GLANDS → synthesis and secretion of specialized products; organs composed primarily of such epithelia are called glands. → epithelial ducts carrying secretions to specific sites → form round, saclike acini (also called alveoli) or elongated tubules → Endocrine glands lack ducts; secreted substances are hormones carried throughout the body by the interstitial fluid and blood, with specificity produced by the hormone receptors of target cells. → basic secretory mechanisms: merocrine, releases product which contain protein by exocytosis. Exocrine glands − producing mucus, or similar individual cells called goblet cells, are called mucous glands.producing largely enzymes (proteins) are called serous glands. CONNECTIVE TISSUE - Made up of different types of cells in varying amounts of a nonliving substance around the cells, called the matrix. - Examples of connective tissue include: Bone Cartilage Adipose tissue (fat) Blood - Protects, supports, and binds together other body tissues. For support and connection of the body Serve to bind tissues and organs together Supports and protects the body parts - Cells are embedded in an extensive of large amount of intercellular matrix and are widely separated A. CONNECTIVE TISSUE PROPER 1. LOOSE CONNECTIVE TISSUE − loose, irregular arrangement of fibers, the large amount of ground substance (matrix) and the presence of numerous cells a. AREOLAR − elastic resistant, pliable, contain fibroblast. − Basic supporting substance around organs, muscles, blood vessels and nerves. b. ADIPOSE − Consist of clustered adipocytes (cells specialized for fat storage) − Cells are rounded or polygonal with thin layer of cytoplasm and the nucleus at one side − Specialized areolar tissue for storage of reserve food or fat, protect the body against excessive heat loss. c. RETICULAR − Makes the framework of lymph glands, red bone marrow, spleen, and of delicate branching fibrils 2. DENSE CONNECTIVE TISSUE − compact arrangement of fibers, limited amount ground substance and smaller number of cells. − Provide support and protection, connect muscles to bones (tendon) and bone to bones (ligaments) a. IRREGULAR − Dermis of skin, capsules of many organs, covering sheaths of nerves, tendons, brain, spinal cord and deep covering of muscles b. REGULAR − Tendons, ligaments, aponeuroses B. SPECIALIZED CONNECTIVE TISSUE 1. CARTILAGE  − Has a firm yet elastic matrix called CHONDRIN, a rubbery substance composed of a mixture of protein and polysaccharides. The cells (CHONDROCYTES) are found in randomly scattered spaces (lacunae) in the matrix. a. HYALINE CARTILAGE − Translucent, pearly, blue-white appearance − Known as FETAL SKELETON; most of this will develop into bone and forms major part of embryonic skeleton; aids in the free movement of joints, assist growth of long bones, allow rib cage to move during breathing − Cover joint surfaces, rib ends, especially the costal ribs, present in the nose and tracheal rings. OSSIFICATION- replacement of cartilage into a bone b. ELASTIC CARTILAGE − Contain yellow elastic fibers − Allow stretching, provides support and suspension − Present in the external ears of mammals, Eustachian tubes, epiglottis, larynx c. FIBROUS CARTILAGE OR FIBROCARTILAGE − The most resistant type, made up largely of fibers, fewer cells and less matrix − Found in the Intervertebral disks, fleshy pads between 2. BONES − Make up the framework of the body − Provides protection for delicate organs like the brain, spinal cord, heart and lungs − Has a hard rigid matrix due to the presence of mineral deposits chiefly calcium carbonate − Production of RBC through hematopoiesis Bone Formation: Babies are born with 350 bones, many are composed almost entirely of cartilage. Later the cartilage cells will be replaced by cells that form the bones. (ossification) The SOFT SPOT of a babie’s skull will fuse around age 2, but growth of the skull continues until adulthood. Long bones develop and grow throughout childhood at the centers of ossification (growth plates) Parts of a bone: The haversian canal and the concentric lamellae constitute the haversian system of which there are several in the section of the bone. LACUNAE - little spaces which house the osteocytes OSTEOCYTES - Bone cells CANALICULI - minute canal in the matrix that joint the lacunae with one another and with the Haversian canal. Through this canal, the protoplasmic projections of each bone cell pass. MATRIX - the ground substance where the lacunae and other substances are located LAMELLAE - layer of hard inorganic matrix Concentric layer of matrix surrounding the haversian canal HAVERSIAN CANAL - central canal at the center of the concentric lamellae. each haversian canal transverses the bone longitudinally and serves as the passage of blood vessels and nerves VASCULAR TISSUE - a typical connective tissue because it consists of blood cells surrounded by a nonliving tissue which is the liquid or fluid matrix. It consists of: a. a fluid plasma made up of 90% water and 10% dissolved substances as protein (gamma globulin) , carbohydrates (GLUCOSE, the form of CHO circulated by the blood) , lipids (phospholipids, cholesterol) and inorganic salts as Na, Ca, Mg, K, b. free cells or corpuscles as RBC, WBC and thrombocytes and blood platelets FUNCTION: BLOOD- a circulating or fluid tissue Transport: o Oxygen from the lungs to the cells o Carbon dioxide from the cells to the lungs o Digested food from the intestine to cells o Waste product from the cells to excretory organelles as kidney, liver, and lungs Carry anti bodies for immune defense Prevents blood loss (forms a clot) Establishes correct parentage FUNCTIONS: Hemoglobin carries oxygen, no nucleus, made in bone marrow. WHITE BLOOD CELLS OR LEUCOCYTES Soldiers of the body Much smaller in number, irregularly shaped, larger in size, 5000-9000/cc TYPES OF WBC GRANULOCYTES - With granules in the cytoplasm, nucleus lobulated. BASOPHIL - nucleus with one lobe  - With large granules - Nucleus bent in S-shaped form - 0.5% EOSINOPHILS - NUCLEUS WITH 2 LOBES - With large but fewer granules in the cytoplasm - Identified with eosin dye - 2% NEUTROPHIL - Nucleus with 3 lobes or more joined by threadlike structure - Cytoplasm with fine granules - Identified with neutral dye - 65-75% AGRANULACYTES - Without granules in the cytoplasm LYMPHOCYTES - For defense but not act as phagocytes rather they have an intimate involvement with the immune responses of the animal by producing antibodies - Nonmotile - 20-25% MONOCYTES - Capable of leaving the circulatory system to become phagocytesin tissues - 2-6% RED BLOOD CELLS OR ERYTHROCYTES Transport gases as oxygen and CO2 which is facilitated by hemoglobin HEMOGLOBIN- respiratory pigment which gives RBC red color to the blood when combined with oxygen 5M RBC/mm3 in male M RBC/mm3 for females Produced chiefly in the red bone marrow and an excess supply in often Stored in the spleen BLOOD PLATELETS OR THROMBOCYTES more or less disk-shaped much smaller than red cells without nuclei more than a trillion blood platelets provide substance for blood clotting, thromboplastin Thrombocytes: platelets Platelets adhering to damaged vessel BLOOD RBC (hematocrit) 40% WBC 1% Platelets 1% Plasma 58% MUSCULAR TISSUE  - Muscle tissue is specialized to contract and cause movement. - There are three main types of muscle tissue: TYPES: Skeletal muscle Cardiac muscle Visceral muscle TYPES OF MUSCULAR TISSUE SMOOTH MUSCLE TISSUE OR INVOLUNTARY VISCERAL Composed of cells that are long, slender, and spindle shaped Myofibrils do not exhibit striations hence smooth Can’t be contracted at will like the peristaltic contraction of the visceral organs Found in the walls of the digestive organs as the stomach and small intestine STRIATED, VOLUNTARY OR SKELETAL MUSCLE TISSUE Composed of cells organized into long fibers Appear striated because of the alteration of light and dark bands Under the control of the will With two or more nuclei; such multi-nucleated condition is termed syncytium NERVOUS TISSUE - composed of specialized cells called neurons that receive and send electrical signals in the body. - responds to stimuli and transmits impulses and together with supporting cells, makes up the brain, spinal cord, and nerves. Neuron (nerve cell): Cell body, dendrite, axon. Glial cells support the neuron Types of Neurons SENSORY OR AFFERENT NEURON − conducts impulses from receptors as the skin, sense organ towards the CNS. MOTOR OR EFFERENT NEURON − conducts impulses from the CNS to effectors as muscles glands  SEVERAL − nerve fibers bound together by connective tissues constitute a nerve SENSORY NERVE − made up of sensory neuron MOTOR NERVE − made up of motor neuron MIXED NERVE − made up of both sensory and motor neuron Plant Tissues Tissues Aggregate of similar cells and cell products of common origin and function. Fabric of organs Two Types of Plant Tissues a. Meristematic tissue, diving tissue b. Permanent tissue, non-dividing tissue Overview: Meristematic Tissue - Consist of immature cells and undifferentiated cells at the shoot tips and root tips and are regions of active cell division. Apical meristem- for the increase in length of the plant body Lateral meristem/vascular cambium- found embedded as a single layer in the vascular core of stem and roots; for the increase in girth of the plant body - Are thin-walled and rich in cytoplasm (with small vacuoles) - Differentiate into different kinds of cells that compose the permanent tissues Structural Adaptation Function Cells are small, spherical or polygonal in shape. This allows for close packing of a large number of cells. Vacuoles are very small or completely absent. Vacuoles provide rigidity to cells thus preventing rapid division. Large amount of cytoplasm and large nucleus. The lack or organelles is a feature of an undifferentiated cell. Large amount of nuclear material contains the DNA necessary for division and differentiation. Meristematic tissue- localized regions of cell division. Apical Meristems Primary or transitional - Primary growth o Protoderm- gives rise to epidermis o Ground Meristem- gives rise to ground tissue o Procambium- gives rise to 1-degree vascular tissue Lateral Meristems Vascular cambium- 2 degrees vascular tissue Cork cambium or phellogen- periderm Intercalary Meristems (Found in the nodes of grasses) Cell Division: Mitosis (nuclear division) + Cytokinesis (cytoplasmic division) 1. Interphase(not a part) 2. Prophase 3. Metaphase 4. Anaphase 5. Telophase 6. Cytokinesis Meristematic cells in the growing root-tip of the onion, from a longitudinal section: Shoot Apical Meristem Root Apical Meristem 1. Root cap initials 2. Protoderm 3. Ground meristem 4. Procambium 5. Root cap Lateral Meristems – secondary growth in woody plants Basswood – ro section Basswood – s section 1,2,3-y Permanent Tissues - Simple permanent tissues are made up of cells of the same type 1. Surface tissue 2. Fundamental or ground tissue - Complex permanent tissues are made up of more than one cell type that combine to perform a particular action Vascular tissue – xylem and phloem - They can be categorized into subtypes based on their form, and function of component cells Forms the protective outer covering of young plants and herbaceous adult plants The principal surface tissue of roots, stem and leaves Replaced by the periderm also called corky outer bark, another surface tissue as the plant matures NOTE: The chemicals in trichomes make plants less easily digested by hungry animals and can also show down the growth of fungus on the plant. As such they act as a form of protection for the plant against predation. The Function of Key Structural features of the Epidermis Structure Function Layer of cells covering surface of entire plant. Acts as a barrier to fungi and other microorganisms and pathogens. Layer is thin and transparent. Allow for light to pass through, thereby allowing for photosynthesis in the tissues below. Epidermal tissues have abundant trichomes which are tiny Leaf trichomes trap water in the area above the stomata hairs projecting from surface of epidermis. Trichomes are and prevent water loss. abundant in some plant leaves. Root hairs are elongations of epidermal cells in the root. Root hairs maximize the surface area over which absorption of water from the soil can occur. Epidermal tissues in leaves are covered with a waxy The waxy outer layer on the epidermis prevents water loss cuticle. from leaves. Epidermal tissues contain guard cells containing Guard cells control the opening and closing of the pores chloroplasts. known as stomata thus controlling water loss in plants. Some plant epidermal cells can secrete poisonous or bad- The bitter taste of the substances deters browsing and tasting substances. grazing by animals. Guard cells and Stomata Stoma - pore found in the leaf and stem epidermis that allows for gaseous exchange. - bordered on either side by a pair of specialized cells known as guard cells.  Guard cells - are bean shaped specialized epidermal cells, found mainly on the lower surface of leaves, which are responsible for regulating the size of the stoma opening. Together, the stoma and the guard cells are referred to as stomata. The stomata in the epidermis allow oxygen, carbon dioxide and water vapor to enter and leave the leaf. The guard cells also contain chloroplasts for photosynthesis. Opening and closing of the guard cells is determined by the turgor pressure of the two guard cells. The turgor pressure is controlled by movements of large quantities of ions and sugar into the guard cells. When guard cells take up these solutes, the water potential decreases causing water to flow into the guard cells via osmosis. This leads to an increase in the swelling of the guard cells and the stomatal pores open. Simple Tissues – consisting of one cell type 1. Parenchyma → alive at maturity; → often multifaceted → with primary walls and no secondary walls → With large vacuoles and thin peripheral cytoplasm → Found in the cortex of stem, roots and leaves → Parenchyma cells with chloroplast are called chlorenchyma, are photosynthetic → Parenchyma in the stem and roots serves for storage of nutrients and water Structure and function of parenchyma Structure Function Thin-walled cells. Thin walls allow for close packaging and rapid diffusion between cells. Intercellular spaces are present between cells. Intercellular spaces allow diffusion of gases to occur. Parenchyma cells have large central vacuoles. This allows the cells to store and regulate ions, waste products and water. Also function in providing support. Specialized parenchyma cells also known as This allows them to perform a photosynthetic function and chlorenchyma found in plant leaves contain chloroplasts. responsible for storage of starch. Some parenchyma cells retain the ability to divide. Allows replacement of damaged cells. 2. Collenchyma → Structurally similar to the parenchyma, except for their irregularly thickened primary walls. → Thin-walled but the corners of the cell wall are thickened with cellulose. This tissue gives strength, particularly in growing shoots and leaves due to the thickened corners. The cells are tightly packed and have fewer intercellular spaces. → Important supporting tissue in young plants and in the stems of no woody older plants and in leaves Structure Function Cells are spherical, oval or polygonal in shape with no This allows for close packing to provide structural support. intercellular spaces. Corners of cell wall are thickened, with cellulose and pectin Provides mechanical strength deposits. Cells are thin-walled on most sides. Provides flexibility, allowing plant to bend in the wind. → 3 Cs pertaining to collenchyma: thickened at corners, contain cellulose, and named collenchyma. Collenchyma - thick walled and alive at maturity Sclerenchyma - thick walled and dead at maturity Sclerids or stone cells - cells as long as they are wide Fibers - cells longer than they are wide 3. Sclerenchyma → Simple, permanent tissue. It is the supporting tissue in plants, making the plants hard and stiff. Two types of sclerenchyma cells exist: 1. Sclerenchyma fibers - long and narrow and have thick lignified cell walls. They provide mechanical strength to the plant and allow for the conduction of water. - commonly used as materials for fabrication of ropes (hemp fibers) and textile (pinya) 2. S c l e r e i d s o r s tone cells - specialized sclerenchyma cells with thickened, highly lignified walls with pits running through the walls - They account for toughness of nutshells and the gritty texture of pears and guavas. Structure Function Cells are dead and have lignified secondary cell walls. This provides mechanical strength and structural support. The lignin provides a wire-like strength to prevent from tearing too easily. Sclereids have strong walls which fill nearly the entire Provide the hardness of fruits like pears. These volume of the cell. structure are used to protect other cells.  Endodermis → Cells look like parenchyma cells except for the thickening on their side and end walls → The thickness is due to lignin → Appear as single layer of cells surrounding the vascular tissue core of roots and sometimes of stems → Regulate the uptake of water and nutrients into the plant Complex Tissue Made up of parenchyma cells (the only living component of mature xylem), fibers, xylem vessels and tracheids. Xylem - water conducting tissue; permeates entire plant body Phloem - food conducting tissue; sieve-tube members (no nucleus at maturity, cytoplasm present), companion cells, fibers, parenchyma, and ray cells. Structure Function Long cells Forms effective conducting tubes for water and minerals Dead cells: no cytoplasm No obstruction to water transport Thick, lignified walls Support the plant and are strong enough to resist the suction force of transpiration pull, so they don’t collapse. Pits in cell walls Allow lateral water transport to neighboring cells. Tracheids have tapered ends Improved flexibility of the stem in wind. Vessels elements have open ends Water is transported directly to the next cell. No intercellular spaces Added support for the stem. Living parenchyma cells in between xylem Form vascular rays for water transport to the cortext of the stem Patters of secondary wall thickening Improve flexibility of the stem in wind and allow the stem to stretch as it lengthens. Phloem: Major Cell Types Sieve elements –conducting cells which transport sucrose Parenchyma cells – store food for transport in phloem Companion cells – associated with parenchyma cells and control the activities of sieve tube elements to allow for the transport of sucrose. They play an important role in loading sieve tubes with sucrose produced during photosynthesis. Companion cells and sieve tubes elements are connected via connecting strands of cytoplasm call plasmodesmata. Fibers- unspecialized and supportive cell Complex Tissue Periderm- protective covering; composed of cork and parenchyma Secretory structures- responsible for making latex, resins, nectar, and other substances produced and stored in channels inside the plant body. Secretory Structure Nectar (flowers) from nectaries Oils (peanuts, oranges, citrus) from accumulation of glands and elaioplasts Resins (conifers) from resin canals Lactified (e.g. latex- milkweed, rubber plants, opium poppy) Hydathodes (openings for secretion of water) Digestive glands that shed salt (especial in plants adapted to environments laden with salt) Structure Function Companion Cells Contain large numbers of ribosomes and mitochondria Due to absence of organelles or nuclei in sieve tubes, companion cells perform cellular function of the sieve tube Has many plasmodesmata (intercellular connections) in the Allows transfer of sucrose-containing sap over a large area wall attached to the sieve tube Sieve Tubes Sieve tubes elements are long conducting cells with Form good conducting tubes over long distances. Allows cellulose cell walls transfer over a large area They are living cells with no nucleus or organelles such as Allows for more space to transport sap. It is also why sieve vacuoles or ribosomes elements need companion cells to carry out all cellular functions CELL MODIFICATION Cells are the building blocks of all living things. The human body contains hundreds of different types of cells that each serve a different purpose Cell specialization (or modification or differentiation) - process that occurs after cell division where the newly formed cells are structurally modified so that they can perform their function efficiently and effectively. - help the cell for adaptation and other beneficial functions re-acquired by the cell after cell division. Almost all these cells can perform the activities which are characteristics of living things, but many of them specialize in doing some of these better than other cells do. Each cell has adaptations that allow it to work effectively within living things. Cell differentiation - process by which a cell changes from one cell type to another which allows cell to perform different functions from its previous state. - Complex process that involves large modifications in gene expression Specialized cells - cells with the same set of genes from its parent cell but have different structures and functions. - Those differences arose due to variations on gene expression, a process where information carried by a gene is translated into a more useful product Root hair cell Modified epidermal cell of the roots Have thin cell walls, a large vacuole with lots of mitochondria in the cytoplasm and a long, hair-like projection to increase surface area, which allow for efficient absorption of water and mineral. Unlike any typical plant cells, root hair cells have no chloroplasts. Absorb water and mineral salts by osmosis and active transport The hair-like structure helps to increase the surface area of the root hair cell Hair-like structure long, and narrow helps to penetrate between soil particles in search of water and mineral salts Water is used to increase hydrocastatic pressure inside other cells in the plant to help keep plant rigid Mitochondria is large number in the cytoplasm of the root har cell; helps for more absorption of mineral salts by active transport. NOTE: Active transport will only occur in the presence of energy provided by the mitochondria. The large vacuole enables more water and mineral salts to be stored after being absorbed. Plasmodesmata  → Microscopic channels that pass between cell walls of adjacent plant cells, connect their cytoplasm, and enable materials to be transported from cell to cell. → They traverse cell walls of adjacent plants cell allowing more efficient transport and communication. → Xylem vessels Made up of long cells joined end to end Once a region of the plant has ceased growing, the end walls of these cells are digested away to form a continuous fine tube Cell walls are thickened and impregnated with a substance called lignin, makes the cell wall very strong and impermeable. It is just like a water pipe which is hollow with no living materials in it Transports water and minerals from the roots to other parts of a plant as well as to provide support to the whole plant hence enable a plant to stand erect. Provides support to the whole plant Ex in leaf; helps the leaf to be positioned horizontally on the plant towards the sun Helps the leaf absorb as much light energy as possible to use for photosynthesis Being very narrow helps water to move up the xylem vessel by means of capillary action Guard cells  Specialized plant cell in the epidermis of leaves, stems and other organs that are used to control gas exchange or help to regulate the rate of transpiration by opening and closing the stomata. Cells between a stoma Become turgid and closed when water availability is critically low and the guard cells become flaccid The cell wall in the inner side of the guard cells is thicker than the outer side, helps guard cells to bend outward when they become turgid- results in opening stoma. If the guard cells become flaccid, the guard cells will bend inward- resulting closing of the stoma Red blood cell or Erythrocyte Tiny, disc-like cell (biconcave shape), no nucleus In the cytoplasm of a red blood cell, there is a red pigment called hemoglobin Each red blood cell lives for about four months, after which it breaks down The red hemoglobin changes to a yellow pigment, which is excreted in the bile. Iron from the hemoglobin is stored in the liver RBC are made by the bone marrow of certain bones in the skeleton No nucleus, more hemoglobin can be accommodated (hence more oxygen can be transported); enable the RBC to squeeze through small blood capillaries Has biconcave shape for increasing its surface area thus diffusion of oxygen in and out of the red blood cell becomes easy White Blood Cell or Leukocyte Works to keep the human body free of infection Finds and destroys microbes within the human body, responding to and treating infection Highly mobile and capable of pushing through capillary walls to reach sites of infection Highly flexible, capable of shifting shape as necessary as they move throughout the body They act like phagocytes Muscle Cell Elongated and elastic containing mitochondria in large number; helps muscle tissues to contact and relax Contraction and relaxation of muscle tissues help in mov eme nt L arge numb er of mitoc hondr ia is very important in tissue respiration in the muscle cells NOTE: Energy is required for muscle to contract Cilia  Cilia, hair-like projections or protuberances found at cell surfaces. They are either motile or no-motile. → Motile Cilia – present on a cell’s surface in large numbers and beat in coordinated waves → Non-motile (primary cilia) -occur one per cell; all mammalian cells have a single non-motile primary cilium Functions of Primary Cilia: 1. Mechanoreceptors – where a primary cilium extends from the apical surface of the epithelial cells lining the kidney tubules and monitors the flow of fluid through the tubules 2. Chemoreceptors – detect odors by receptors on the primary cilium of olfactory neurons 3. Photoreceptors – found in sensory organs like eye particularly in the outer segment of the rods in the vertebrate retina and nose Ciliated epithelia include ciliated pseudostratified columnar (respiratory) epithelium and the ciliated simple columnar epithelium of the oviducts The inner core of cilia consists of a cytoskeleton called axoneme similar to the structural arrangement in flagella. Flagella Tail-like projections that protrude from the cell membrane of certain prokaryotic and eukaryotic cells, and functions in locomotion or for the propulsion of single cells A eukaryotic flagellum is a bundle of nine fused pairs of microtubule doublets surrounding two central single microtubule doublets in the center So-called "9+2" structure is characteristic of the core of the eukaryotic flagellum called an axoneme base of a eukaryotic flagellum is a basal body, structurally identical to centrioles Flagellum with 9 + 2 array of microtubules: 9 microtubule doublets surround a single microtubule doublet Pseudopods Temporary, irregular lobes formed by amoebas and some eukaryotic cells They bulge outward to move the cell or engulf prey 3 protozoas with their locomotory organelles- cilia, pseudopod, and flagellum Microvilli (brush border or striated border) → Plasma membrane-covered extensions of the cell surface, increases apical surface area when extended → Their cores are composed of parallel actin microfilament, anchored in a dense mat of filaments in the apical cytoplasm called the terminal web → By interacting with cytoplasmic myosin, the microfilaments can contract, shortening the microvilli  → Commonly found in simple cuboidal epithelium lining the proximal tubules of the kidney → Simple columnar cells of the small intestines, absorbs nutrients from digested food → Cannot absorb nutrients, leads to malnutrition, cramping, and diarrhea → Also found in sensory cells of the inner ear (as stereocilia), in the cells of taste buds and in olfactory receptor cells Stereocilia Not true cilia but very long microvilli Found in the male reproductive tract (epididymis, ductus deferens) Have an absorptive function, and in the internal ear (hair cells of the maculae and organ of corti) where they have a sensory function Neurons Specialized cells that carry messages with the human brain These cells come in an assortment of shape and sizes These cells have extensions called dendrites and axons that bring information into and, release information from, the cell itself Sperm Cells Necessary for human reproduction Made up predominantly of a nucleus Highly mobile as they must move to locate an egg for fertilization to occur Mitochod4ia within the sperm cell, provides the energy that specialized cells of this type require to move at such high rates of speed Have flagella to propel them towards the ovum or egg cell Significance of cell specialization 1. Replacement of old and worn-out cells - most popular stem cells are cells that have potential to divide into almost any cell in the body, sometimes triggered by certain environmental conditions. - New cells from the stem cells will then use to replace any old or worn-out cells, hence maintaining their integrity as tissues or organs 2. Preserve the Genetic Material - DNA serves as the genetic material that contains the necessary information used in growth, reproduction, and normal functioning of individuals. - During transcription, the DNA becomes prone to mutations and the process of cell specialization makes it less susceptible to them, hence preventing further damage in the gene 3. Importance in Cell-To-Cell-Communication - importance in the production of cells that can produce signals that influence the activities of their neighboring cells. As a result, these cells collectively react toward a specific stimulus. - most common ex, neurons or nerve cells in animals; can send impulses to other nerve cells or other types of cells as well 4. Possible Medicinal importance  - At present, scientists are looking into the possible uses of stem cells for treating certain diseases like diabetes and cardiovascular ailments. One of their hypotheses was using stem cells and inducing them to differentiate as replacements for the lost cell in the pancreas and the heart CELL REPRODUCTION/CYCLE Important characteristics to make possible the continuity of life. They reproduce their own kind. They transmit their characteristics to the next generation; They develop from simple structures into functional organisms. CELL REPRODUCTION → One of the important attributes of life. → With cell reproduction through cell division, cells grow and develop, cells increase in number, damaged and worn-out tissues are repaired and replaced. In unicellular organisms, they also increase their kind. → If all is well, in the next minute of our life, 3B cells will die. But 3B new cells will also be created at that same minute. CELL CYCLE → Life history of the cell. → Life span of the cell. → Period from the beginning of one cell division to the next cell division. → It varies from one cell to another. Cell cycle may take minutes, hours, days or even years or the lifetime of the body. CELL CYCLE CONCEPT MAP CELL DIVISION 3 TYPES: 1. binary fission in unicellular organisms, 2. mitosis and  3. meiosis in multi-cellular organisms. Chromosomes in the nucleus contain genetic information that determines the cell’s structure, shape and function. The genetic information is composed of DNA and organized into units called genes. THREE STAGES → Interphase – time between mitotic divisions → M-phase → Cytokinesis INTERPHASE → It is the phase where a cell prepares itself for cell division. Interphase is subdivided into three stages namely: Gap 1 (G1)-> Synthesis (S)-> Gap 2 (G2) MITOSIS → Mitosis is the second stage of cell cycle where actual division of cell into two identical daughter cells occurs. 3 Stages of the Cell Cycle Interphase- the period of cell growth during which the DNA in the nucleus replicates. Mitosis- period during which the nucleus divides with its genetic material. Cytokinesis-period during which the cytoplasm divides into two genetically identical daughter cells as the parent cells 2 TYPES OF CELLS In human chromosomes occur in pairs. 1. Somatic cells/Autosomal or Body cells − carry 23 pairs or 46 chromosomes diploid set or 2n o − undergo mitosis 2. Reproductive cells/Germ cells/Sex cells − carry only one copy of chromosomes and have 23 unpaired chromosomes or haploid set or n − undergo meiosis 2 TYPES OF SEX CHROMOSOMES X chromosomes and  Y chromosomes XY in males; XX in females INTERPHASE → is not part of mitosis → precedes mitosis or a prelude to mitosis (Hence, it has the number 0.) → A resting stage CHROMATIN → is material in a cell nucleus consisting of DNA and protein. → From 18 hrs to 24 hrs (M phase less than 1 hr) STAGES OF INTERPHASE Gap 1(G1 Synthesis Phase (S Phase) Gap 2(G2) INTERPHASE G1 PHASE (G1) the intermediate phase between Mitosis and synthesis phase, where a cell is prepared for DNA replication. The cell size and cell components such as proteins undergo replication at this stage before proceeding to S phase. period of growth, cell organelles, membranes and ribosomes are constructed. Centrioles replicate; represents the first gap between cell division and S phase S PHASE where the cell synthesizes an exact copy of its DNA. This phase ensures that the cell undergoing cell division will obtain an identical daughter cell. G2 PHASE another growth phase for the cell where proteins and other organelles continue to grow and rearrange in preparation for the next stage, which is Mitosis. RNA and protein are also produced.  G1 G2 S PHASE G1 is the first phase of the interphase G2 is the third phase of the interphase S is the second phase of the interphase PROGRESSION Cell proceeds to S phase after G1 Cell proceeds to mitosis after G2 phase Cell proceeds to G2 phase after S phase phase MAJOR EVENT OCCURRING Duplication of cell organelles and Replication of genetic material and Synthesis of proteins and RNA, makes synthesis of proteins, RNA and centrosomes organelles and reorganizes cellular molecular building blocks content ORGANISMS Metabolic changes DNA synthesis Metabolic changes DURATION G1 phase is the longest phase G2 phase is shorter than G1 and S S phase is longer than the G2 phase phases and shorter than the G1 phase G0 PHASE Not all cells undergo mitotic phase. Cells in the G0 phase are not actively preparing to divide. The cell is in a quiescent (inactive) stage that occurs when cells exit the cell cycle. Some cells enter G0 temporarily until an external signal triggers the onset of G1. No more DNA replication or cell division happens at this phase. The cells that never or rarely divide include mature cardiac muscle and nerve cells, and they remain in G0 permanently. MITOSIS → During mitotic phase, there are two sub-stages, Mitosis and Cytokinesis, which result to two identical daughter cells. MITOSIS AND ITS IMPORTANCE → the type of cell division by which a single cell divides in such a way as to produce two genetically identical (2n)"daughter cells“ as the parent cell (2n). → A method by which the body produces new cells for both growth and repair of aging or damaged tissues throughout the body - as opposed to sexual reproduction (where meiosis applies). → In unicellular organisms it is a means for reproduction.  → A disease like cancer happens by an error in mitosis. Uncontrolled mitosis occurs in cancer, where either genes that stop cell division (tumor suppressors) are switched off, or genes that encourage cell division (oncogenes) are overactive. → Mitosis has four stages: prophase, metaphase, anaphase and telophase REMEMBER: Mitosis is responsible for producing the cells necessary for growth and development. Mitosis continuously produced cells necessary for regeneration. Meiosis produces sex cells necessary for reproduction. Recombination in Meiosis is key to a diverse gene pool. MITOTIC PHASE Mitosis Cytokinesis The cell's DNA condenses into chromosomes at this The cytoplasm of the cell divides into two new daughter phase. cells during cytokinesis Stages of Mitosis: Direction and nature of cytokinesis will vary in plants and animals. 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase PROPHASE > METAPHASE > ANAPHASE > TELOPHASE Prophase → It is the early stage of mitosis where the nucleolus disappears and chromatin fibers condense into chromosomes. Spindle fibers are then formed in the cytoplasm and attaches with the chromosomes. → During prophase stage, the cell is preparing for division - the nucleolus disappears, chromosomes are formed  and attached with the spindle fibers formed in the cytoplasm. Metaphase → Chromosomes align at the "metaphase plate" during this phase. Then, microtubules from each spindle poles attach to the chromosomes in preparation for anaphase. → A spindle checkpoint also occurs to ensure that the chromatids separate evenly during anaphase. → The next stage is metaphase where chromosomes align themselves at the metaphase plate and are attached with microtubules from the opposite poles. A spindle checkpoint also occurs to ensure that the chromatids separate evenly during anaphase. Anaphase → It is the stage where separation of chromosomes occur. The kinetochore microtubules pull the chromosomes toward the poles - separating the chromatids - while unattached microtubules push the poles further apart. → Anaphase is mitosis' third stage where chromosomes are separated into chromatids once again. Telophase & Cytokinesis → These are the last stages of mitosis where mitotic spindle is broken down and the nuclear membranes and nucleoli reappear (telophase). The cytoplasm then divides into two new cells during cytokinesis. → The last stages of mitosis is focused on separating the daughter cells. When the chromosomes are now enclosed in nucleoli and nuclear membrane during telophase, cytokinesis then proceed in dividing the cell  into two diploid cells. MEIOSIS → a special type of nuclear division which segregates one copy of each homologous chromosome into each new "gamete". → reduces the number of sets of chromosomes by half, so that when gametic recombination (fertilization) occurs the ploidy of the parents will be reestablished. → Mitosis maintains the cell's original ploidy level (for example, one diploid 2n cell producing two diploid 2n cells; one haploid n cell producing two haploid n cells; etc.). → Happens only in germ cells or sex cells → With 2 divisions (Meiosis I and Meiosis II) → Reduction division, → Meiosis I reduced the ploidy level from 2n to n (reduction), form n or haploid chromosomes. meiosis I, chromosomes in a diploid cell re-segregate, producing four haploid daughter cells. It is this step-in meiosis that generates genetic diversity. → Meiosis II is similar to mitosis. However, there is no "S" phase. The chromatids of each chromosome are no longer identical because of recombination. Meiosis II separates the chromatids producing two daughter cells each with 23 chromosomes (haploid), and each chromosome has only one chromatid. MEIOSIS I PROPHASE I → Chromosomes condense and pair laterally with their homologous chromosomes during prophase I. → A unique feature of this phase is the occurrence of synapsis (the positioning of the chromosomes for crossing over. → Like mitosis, stages of meiosis also follows the prophase, metaphase, anaphase, and telophase stages. In Meiosis I however, prophase I is the pairing of homologous chromosomes. Instead of a single chromosome, homologous pairs dominate the entire stages of meiosis I. It is also in prophase I where synapsis occurs, a feature missing in mitosis. → DNA replication precedes the start of meiosis I. → Homologous chromosomes pair (tetrads or bivalent chromosomes) and swap segments. → Swapping or crossing -over form synapses, a step unique to meiosis. Recombination takes place. They physically associate to exchange materials or parts. → bivalent has two chromosomes and four chromatids, with one chromosome coming from each parent. METAPHASE I → Metaphase I is also where spindle captures chromosome and align them at the metaphase plate.  → Unlike in mitosis, homologue pairs line up at the metaphase plate and microtubules from opposite poles attach to only one chromosome of the homologue pair. → Metaphase I in meiosis I also occurs with the aligning of chromosomes in the metaphase plate, however, instead of single chromosomes lining up, metaphase I has homologous pairs of chromosomes lining up at the plate with microtubules from opposite poles attaching to them. → Bivalents, each composed of two chromosomes (four chromatids) align at the metaphase plate. The orientation is random, with either parental homologue on a side. This means that there is a 50-50 chance for the daughter cells to get either the mother's or father's homologue for each chromosome ANAPHASE I → Chromosomes, at this stage, are pulled to the opposite sides of the poles while keeping the sister chromatids of each chromosome intact. → Each side of the pole now has 3 chromosomes → Pair of homologous chromosome separate moving toward opposite poles. → Each of the daughter cells is now haploid (23 chromosomes), but each chromosome has two chromatids connected at the centromere. TELOPHASE I & CYTOKINESIS → Telophase I prepare the cell for the division into daughter cells (cytokinesis) by forming the nuclear membranes and nucleoli around the chromosomes. → Two haploid cells (n=3) are then produced after cytokinesis. → Cytokinesis occurs as the plasma membrane pinches in forming two cells. Each new cell contains one chromosome from each homologous pair. → Nuclear envelopes may reform around each set of chromosomes, nucleolous reappear. → Cytokinesis is analogous to mitosis where two complete daughter cells form. MEIOSIS II Prophase II → The unpaired chromosomes condense. Metaphase II → The 23 unpaired chromosomes attach to spindle fibers and line up at the metaphase plate. Anaphase II → The centromere divides, and the attached chromatids separate and move towards opposite poles of the cell. Telophase II → Chromosomes uncoil,nuclear envelopes form around the four haploid nuclei. Meiosis now is complete. Cytokinesis → Produces four haploid cells → In meoisis, one diploid cell with 46 chromosomes (zygote) has undergone one round of chromosome replication and two rounds of division to produce four haploid cell, each of which contain one copy of chromosomes. COMPARISON OF MITOSIS AND MEIOSIS MITOSIS MEIOISIS Parental cells are diploid. Parental cells are diploid. Doubled chromosomes appear in late prophase. Doubled chromosomes appear in late prophase. Unpaired chromosomes align at metaphase. Paired homologous chromosomes align at metaphase I then separate at anaphase I Sister chromatid separate at anaphase. Sister chromatid separate at anaphase II Produce two daughter cells that are diploid, genetically Produce four daughter cells that are haploid, not  identical to parent cell. genetically identical to parent cell One division. Two successive nuclear divisions occur, Meiosis I (Reduction) and Meiosis II (Division) CONTROL OF THE CELL CYCLE G0 PHASE → Not all cells adhere to the classic cell cycle pattern in which a newly formed daughter cell immediately enters the preparatory phases of interphase, closely followed by the mitotic phase. Cells in G0 phase are not actively preparing to divide. The cell is in a quiescent (inactive) stage that occurs when cells exit the cell cycle. → Some cells enter G0 temporarily until an external signal triggers the onset of G1. Other cells that never or rarely divide, such as mature cardiac muscle and nerve cells, remain in G0 permanently. Regulation of the Cell Cycle → The cell cycle is controlled by a cyclically operating set of reaction sequences that both trigger and coordinate key events in the cell cycle The cell-cycle control system is driven by a built-in clock that can be adjusted by external stimuli (chemical messages) → Checkpoint - a critical control point in the cell cycle where stop and go-ahead signals can regulate the cell cycle → Animal cells have built-in stop signals that halt the cell cycles and checkpoints until overridden by go-ahead signals. → Three Major checkpoints are found in the G1, G2, and M phases of the cell cycle 1. Regulation of the Cell Cycle by External Events - A lack of HGH can inhibit cell division, resulting in dwarfism, whereas too much HGH can result in gigantism. Crowding of cells can also inhibit cell division. Another factor that can initiate cell division is the size of the cell; as a cell grows, it becomes inefficient due to its decreasing surface-to-volume ratio. The solution to this problem is to divide. 2. Regulation at Internal Checkpoints - It is essential that the daughter cells produced be exact duplicates of the parent cell. Mistakes in the duplication or distribution of the chromosomes lead to mutations that may be passed forward to every new cell produced from an abnormal cell. - To prevent a compromised cell from continuing to divide, there are internal control mechanisms that operate at three main cell cycle checkpoints. - A checkpoint is one of several points in the eukaryotic cell cycle at which the progression of a cell to the next stage in the cycle can be halted until conditions are favorable. These checkpoints occur near the end of G1, at the G2/M transition, and during metaphase. Control Points of the Cell Cycle → The cell cycle is controlled at three checkpoints. The integrity of the DNA is assessed at the G1 checkpoint. Proper chromosome duplication is assessed at the G2 checkpoint. Attachment of each kinetochore to a spindle fiber is assessed at the M checkpoint. The G1 Checkpoint → The G1 checkpoint determines whether all conditions are favorable for cell division to proceed.  → The G1 checkpoint, also called the restriction point (in yeast), is a point at which the cell irreversibly commits to the cell division process. External influences, such as growth factors, play a large role in carrying the cell pass the G1 checkpoint. → In addition to adequate reserves and cell size, there is a check for genomic DNA damage at the G1 checkpoint. A cell that does not meet all the requirements will not be allowed to progress into the S phase. The cell can halt the cycle and attempt to remedy the problematic condition, or the cell