Full Gen Biology PDF

PROKARYOTES VS EUKARYOTES Domains: Bacteria Archaea Eucarya PROKARYOTIC EUKARYOTIC - all in domain Eukaryota / Eucarya Simple, unicellular organisms that do not have a Com...

PROKARYOTES VS EUKARYOTES Domains: Bacteria Archaea Eucarya PROKARYOTIC EUKARYOTIC - all in domain Eukaryota / Eucarya Simple, unicellular organisms that do not have a Complex, cell has a nucleus enclosed by a nucleus and membrane bound organelles membrane Asexual reproduction; binary fission Sexual (meiosis) and asexual (mitosis)reproduction Movement by rigid rotating flagellum Movement by flexible (tails of) cilia or flagella  consists of a single cylinder of protein  contain microtubules and motor proteins subunits (flagellin) that enable complex movements. Circle of double-stranded DNA in nucleoid Linear and organized chromosomes in nucleus Short pieces of circular DNA that replicate NO plasmids independently are plasmids. 70s ribosome (smaller) 80s ribosome (larger type of ribosome) Cell wall has a rigid framework of murein, a All have cell membranes but not all eukaryotic polysaccharide cross-linked by cells have cell walls: Animal cells don’t have. polypeptidoglycan  Pili - for interaction to other bacterial KINGDOM PLANTAE cells; used in infecting cells  Plants  Presence of Cell Wall ARCHAEBACTERIA - all in domain Archaea  Plasmodesmata - channel for molecules  HALOPHILES - salt concentration at from other plant cells least five times greater than that of the  Large Vacuoles - stores wastes ocean.  NO lysosome - Vacuole compensates for  PSYCHROPHILES - reproduces and this grows best at low temperatures, VASCULAR - presence of xylem & phloem typically in the range -10 to 20°C (14 to NON - VASCULAR - no xylem & phloem 68°F).  THERMOPHILES - an optimum growth KINGDOM FUNGI temperature of 50o or more, a  Heterotrophs - consumes other maximum of up to 70oC or more organisms  METHANOGENS - common in  Gets their nutrients from substrate wetlands, ocean environments, digestive tracts of animals KINGDOM ANIMALIA  Very diverse EUBACTERIA  Has all the organelles except chloroplast  Thrive at room temperature  Examples: Propionibacterium acnes KINGDOM PROTISTA (acne); Lactobacillus acidophilus (for  “Garbage kingdom” - organism placed digestion) here if their specific kingdom is undecided  Ex. Amoeba, Paramecium, Euglena Plasmodium CELL SPECIALIZATION  Also known as Cell Differentiation  It is the process by which generic cells change to different types of cells to be able to perform special or specific functions.  From stem cells to specialized cells RED BLOOD CELL (erythrocytes) NERVE CELL or NEURON  It carry oxygen throughout the body  Carry nerve impulses through body Characteristics: Characteristics:  No nucleus - to contain more oxygen  Long, thin axon - carries signal from cell  Biconcave shape - for better transport body to brain  Contains hemoglobin - protein  Branching dendrites - receives outside stimulus WHITE BLOOD CELL (leukocytes)  Myelinated - covered by myelin sheath; for  It play an important role in the immune faster response system; fights diseases & pathogens Characteristics:  Irregular shape - different types  Can produce antibodies and antitoxins > Neutrophils: Kill bacteria, fungi, foreign debris > Monocytes: Clean up damaged cells > Eosinophils: Kill parasites, cancer cells and involved in allergic response > Lymphocytes: Help fight viruses & make antibodies > Basophils: Involved in allergic response MUSCLE CELL SPERM CELL  Facilitate movement Characteristics  Fertilize an egg cell Characteristics:  Elongated and elastic  Long tail to swim for movement  Numerous mitochondria  Numerous mitochondria - give energy to tail for quick movement  Head  Contains acrosome (acrosin enzyme) to break the egg cell membrane and enter  Contains nucleus for father’s DNA EGG CELL GUARD CELL  Carries genetic material  Regulates rate of transpiration  For developing embryo  Protects stomata Characteristics Characteristics  Large and bulky  Cell wall has varying thickness  A chemical change in the membrane prevents fertilization of more than one PHOTOSYNTHETIC CELLS sperm  Produces food through the process of photosynthesis Characteristics  Contains numerous of chloroplasts PLANT TISSUES Tissues - A group of cells that are similar in structure and/or work together to achieve a particular function forms a tissue. Shoot System: flower, leaves, stem Root System: taproot, lateral roots Meristematic – Meristos meaning “dividing” cells; found in the growing areas of plants. Permanent – “non-dividing cells”; composed of matured meristematic tissue MERISTEMATIC TISSUES Apical Meristem Wood - densely packed in heartwood  Apical meristems are responsible for Bark > Living phloem: provides nutrients the primary growth (height) of plants. > Periderm > Cork cambium  Mitosis phases are seen at root tips > Cork  Give rise to permanent tissues which > Cork: Cork cells for protection against will differentiate into specialized cells injuries and microorganisms with certain functions. PERMANENT TISSUES Derivatives of apical meristem (byproducts)  Procambium: gives way to primary Simple Permanent Tissues xylem and phloem  Composed of one kind of cell  Ground meristem: food; storage, photosynthesis Ground tissue  Protoderm: protection o Parenchyma cells - Mostly responsible for photosynthesis and storage of Lateral Meristem food. Thin and flexible cell wall.  Lateral meristems are responsible for o Collenchyma cells - Provides a the secondary growth (girth or furnishing flexible support to immature diameter) of plants. Ex. stems parts of plants. Thin & Thick cell wall. o Sclerenchyma cell – Thick cell walls Vascular cambium  Sclereids strengthen seed o Gives rise to secondary xylem and coats and are responsible for phloem. Secondary xylem gives rise gritty-textured flesh of some to wood. fruits Cork cambium  Fibers are used commercially o Gives rise to cork cells which replaces as components of making epidermis of plants once they rope and flax fibers. mature. o Cork cambium, cork, and phloem make up the bark. Parenchyma Collenchyma Schlerenchyma Dermal Tissue (Epidermis) Phloem o It covers the whole body of non woody and young woody plants o The lower and upper parts of leaves are protected by this Parts:  Cuticle prevents water loss and invasion of disease-causing microorganisms.  Root hairs help in increasing the absorption capacity of roots.  Trichomes are hair-like epidermal outgrowths in leaves and stems that  Phloem is composed of sieve-tube prevent water loss and reflect excess elements that help in the transport of light. nutrients throughout the plant’s body.  Guard cells are specialized structures  Companion cells aid in transportation at the lower epidermis that regulate of nutrients the opening and closing of stomata.  Two-way transport of food and  Stomata are slit-like structures on the nutrients; (1) photosynthesis to roots lower epidermis of leaves which aid in and (2) soil to leaves the exchange of gases between plants and the environment.  Mesophyll region (Photosynthetic cells) Palisade mesophyll - photosynthesis layer Spongy mesophyll - facilitates the exchange of gases through air spaces Complex Permanent tissues  Vascular tissues are the only complex permanent tissues in plants. Xylem  Tracheids are thin and elongated cells where water passes through.  Vessel Elements have perforated plates that allow the transport of water through the vessels.  One way transport of water ANIMAL TISSUES In complex multicellular organisms like animals, cells come in different structures and functions. There are different levels of biochemical organization, and these include the following (lowest to highest): chemical, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem, and biosphere. Tissues refer to groups of cells that are similar in structure and function. The four types of tissues in animals vary significantly in structure and function EPITHELIAL TISSUES  Epithelial tissue or epithelium is a type of animal tissue that forms the inner and outer lining of organs, the covering in surfaces, and the primary glandular tissue of the body. Epithelial Tissue No. of layers and Examples Functions cell shape Simple Squamous - one layer air sacs or alveoli, site of diffusion or - flat, scale-like capillary walls – for exchange of gas exchange substances; secretion Simple Cuboidal - one layer glands and their absorption and - cube shaped ducts, ovaries, and secretion lining of kidney tubules Simple Columnar - one layer walls of the absorption and - elongated or gastrointestinal tract secretion; contains column-shaped and body cavities goblet cells that secrete mucus Pseudostratified columnar - one layer the lining of the absorption and - elongated or respiratory tract secretion; usually column-shaped ciliated; cells have unequal length and position of nucleus forming a false layering of cells Stratified Squamous - more than one the epidermis, lining protection against layer of mouth, abrasion or constant - flat, scale-like esophagus, and exposure to friction - “fake” “layer” vagina Stratified Cuboidal - more than one sweat glands, protection and layer salivary glands, and secretion - cube-shaped mammary glands Stratified Columnar - more than one male urethra and protection and layer ducts of some secretion - elongated or glands column-shaped CONNECTIVE TISSUES Loose connective tissue  The basic components of connective  Matrix contains more cells and lesser tissues vary according to their type fibers than dense connective tissue so (left, extracellular matrix; right, fibers). it is softer.  The different connective tissues vary  Adipose tissue or fat tissue (ex. with the composition of their stomach, mammary gland, skin) extracellular matrices and the types  insulation, storage (of energy since it of cells they consist of. is taken from fats)  All tissues give protection and support Blood  Plasma  Cellular components consist of blood cells.  With fibers that are only visible during clotting because they are made up of soluble proteins  Erythrocytes, Leukocytes, Thrombocytes  transport of substance, immune response, and blood clotting MUSCULAR TISSUE  The types of muscle tissues differ in their general structure but more or less perform the same function, to elicit movement. Bone or osseous tissue  layers of a very hard matrix with calcium salts and collagen fibers  strengthen skin and joints  skull and ribs Cartilage  more flexible matrix than bone; to reduce friction in joints Skeletal muscle  cartilage cells called chondrocytes  Attached to the skeleton or bones  hyaline cartilage: ribs, nose, trachea  Long, cylindrical, striated (with visible  fibro cartilage: spinal cord, knee stripes), and multinucleated (with  elastic cartilage: ear, larynx more than one nucleus)  voluntary Dense connective or dense fibrous tissue  Matrix is predominantly made up of Smooth muscle collagen fibers and has lesser cells.  Found in the walls of hollow organs  This is a fibroblast or a fiber-forming such as intestines, stomach, bladder, cell. blood vessels, and uterus  Tendon and ligament  Made up of nonstriated, uninucleated, and spindle shaped (have pointed ends) cells.  Involuntary Cardiac muscle  Found in the heart  Uninucleated and striated  Has intercalated disks - junctions between muscle fibers that allow for rapid electric transmission  Involuntary NERVOUS TISSUE  Neuron, the basic unit of the nervous system, consists of supporting cells (glial cells) that support, protect, and insulate neurons and conduct electrochemical signals as a form of information. Astrocytes  Located in CNS  Star-shaped cells that support and control the chemical environment around the neurons. These are the most abundant glial cell in the CNS. Microglial cells  Located in CNS  Ovoid cells in the CNS that can transform into a phagocytic macrophage to clean neuronal debris and wastes. Ependymal cells  Located in CNS  Ciliated cells that line the central cavities of the brain and the spinal cord and form a fairly permeable membrane between the cavities with cerebrospinal fluid and the tissues of CNS. Oligodendrocytes  Located in CNS  Responsible for the production of the myelin sheath which is needed for faster conduction of signals Schwann cells  Located in PNS  They surround all the nerve fibers and produce myelin sheath similar to the oligodendrocytes. CELL MODIFICATION General Biology | Quarter 1 STEREOCILIA - Non-motile modified microvilli Adaptation or changes acquired by the cell - Actin-based protrusions on auditory and after the cell division that aids the cell in various vestibular sensory cells for hearing and beneficial ways. balance. Convert stimuli to electrical signals - Ex. ears (cochlea), male reproductive part CILIA (vas deferens and epididymis) - Hair-like structures extending from the cell surface. - Locomotion and mechanoreception. - Organisms that possess cilia are known as ciliates. Use cilia for feeding & movement. TYPES OF CILIA Non-motile or Primary cilia (sensory) - Sensory cellular antenna that coordinates cellular signaling pathways. - Ex. photoreceptors of retina, for urine flow of tubular epithelial kidney cells Motile (movement) - Clearing the mucus and dust out of the lungs - Ex. Upper respiratory tract, Bronchi, Oviducts (fallopian tube), Inner ear Epididymis - Stores sperm and facilitates their maturation, enabling motility and fertilizing capability before ejaculation. Vas Deferens - Transports mature sperm from the epididymis to the urethra during ejaculation PSEUDOPODS - ”False feet” - Temporary extension of the cytoplasm - For movement and ingestion of particles during phagocytosis - Allow cells like amoebas and white blood FLAGELLA cells to move and capture food - Long whip-like structures for locomotion - Allows cell to swim from one location to another by rotating a rigid filament - Ex. Spermatozoa or Sperm VILLI or MICROVILLI - Small, slender, finger-like projections - Increases surface area to increase absorption of nutrients - Ex. lumen of small intestine - absorbs nutrients and minerals from digested food and completes most digestion CELL CYCLE AND CELL DIVISIONS Any sexually reproducing multicellular Introduction to Cell Cycle organism begins as a single -celled entity.  Cell cycle describes how cells grow, It then relies on cellular events to produce develop, and reproduce. more cells, the early stage of which is shown  Involves different phases that constitute in the blastula. a series of preparations for a cell to divide to produce new cells. THE GENETIC MATERIAL OF CELLS DNA Molecule THREE STAGES OF CELL CYCLE  Almost every cell in our bodies has genetic material in the form of deoxyribonucleic acid (DNA)  The primary genetic material of living organisms, stores genetic info in the sequences of its nucleotides  Most biological traits are coded for by the DNA. INTERPHASE Histones Gap 1  Positively charged histone proteins aid  Growth of cytoplasm and doubling of in DNA packaging. organelles z  Produce proteins, enzymes, nutrients, Chromatin and energy  Interphase DNA is found in the form of  Highest rate of protein synthesis chromatin, a complex of DNA and  Movement of centrioles of the proteins. centrosomes away to await and assist  Dispersed inside the intact cell nucleus the events of mitosis during interphase. S Phase Chromosomes  This stage is named so because it is  DNA in interphase in form of chromatin when the cell synthesizes a copy of its condenses during mitosis DNA in a very notable process called  Each chromosome is made up of two DNA replication. sister chromatids  Humans have 46 individual (or 23 pairs of) chromosomes Gap 2 CELL CYCLE CONTROL SYSTEM  Continued growth, further maturation To ensure that they replicate all their DNA and and the production of materials that organelles, and divide in an orderly manner, are necessary for cell division eukaryotic cells possess a complex network of  Protein synthesis but not at the rate regulatory proteins similar to that of the G1 phase Cyclins MITOSIS OR MEIOSIS  Regulatory proteins whose  The M phase in eukaryotic organisms concentrations rise and fall at specific involves either one of two processes times during the eukaryotic cell cycle  Division of nucleus and genetic material o Sex cells or gametes undergo meiosis and produce varied cells o Somatic cells or non-sex cells undergo mitosis and produce identical cells CYTOKINESIS  marked by the formation of a cleavage furrow in animal cells; cell plate in plants  Division of cytoplasm Kinase  Can only occur once the genetic  Enzymes that catalyze the material is properly distributed to the phosphorylation of a protein resulting daughter cells in a change affecting that protein’s function o Phosphorylation = turning ON o Dephosphorylation = turning OFF Cyclin-dependent kinase (CDK) o Cdk1 o Cdk2 o Cdk4 o Cdk6 CELL CYCLE CHECKPOINTS G1-to-S Checkpoint (Restriction point) Cyclin-Cdk Complexes  Is there any damage in the cell’s DNA?  Is the cell large enough with all the necessary energy reserves and doubled organelles? G2-to-M Checkpoint  Are the environmental conditions favorable for cell division to take place?  Is the DNA properly replicated?  Is there a presence of DNA damage? M (metaphase) Checkpoint  Are the spindles properly attached?  All the sister chromatids correctly attached to the spindle microtubule? MITOSIS Mitosis refers to how a cell divides to produce PHASES OF MITOSIS new cells. Only somatic cells (also known as body cells) undergo mitosis. THE ROLE OF MITOSIS IN THE CELL CYCLE  It allows the cell to divide and produce new cells. A cell will only begin mitosis if the conditions PROPHASE are correct and favorable for cell division.  The nucleolus - Cell cycle checkpoints check for errors. disintegrates. - The synthesis phase involves the  The chromatin duplication of the cell’s DNA. condenses into chromosomes.  The mitotic spindle starts to form. METAPHASE Prometaphase  Nuclear membrane dissolve  Proteins (cohesin) attach to the centromeres creating the kinetochores.  Microtubules attach at the kinetochores and the chromosomes Haploid and Diploid cells begin moving  The human genome has 23 pairs of chromosomes for a total of 46 chromosomes in each cell.  23 is the haploid number whereas 46 is the diploid number.  Haploid is n while diploid is 2n.  The number of sets of chromosomes that a cell or an organism has is known as ploidy.  All human body cells are diploid except gametes which are haploid. Metaphase  Microtubules of the mitotic spindle attach and interact with the kinetochores of the chromosomes.  The chromosomes align at the center of the cell, in the metaphase plate. ANAPHASE Early Anaphase  The mitotic spindle pulls and separates the sister chromatids apart.  The chromatids, now called daughter chromatids, are then pulled toward the opposite poles. Late Anaphase  Chromosomes have almost reached their respective poles  Cell membrane begins to pinch at the center. TELOPHASE and CYTOKINESIS  Daughter chromatids decondense. o In animals, the boundary of the new cells is known as the cleavage furrow. o In plants, it is known as the cell plate. Cytokinesis After telophase, cytokinesis will divide the cell into two.  Cytokinesis is not a phase of mitosis but is closely related to it.  Recall from the previous lesson that each of the two daughter cells will inherit a nucleus, similar genetic material, organelles, and more. TIPS  In Prophase, the cell’s genetic material resembles Polka dots or strings.  In Metaphase, the chromosomes Migrate to the Middle of the cell.  In Anaphase, the chromosomes move Away from each other.  In Telophase, the parent cell starts to form Two new cells. MEIOSIS General Biology | Quarter 1 Week 7 Like mitosis, meiosis also refers to how cells divide to produce new cells. Sex cells or gametes are produced from meiotic division. Very closely tied with the process of sexual reproduction. Meiosis is the M phase that leads to the production of either sperm cells or egg cells. PROMETAPHASE I MEIOTIC DIVISION - further chromosomal condensation - further disintegration of nuclear envelope - meiotic spindle formation METAPHASE I - Alignment of the homologous chromosomes at metaphase plate - Facilitates reduction in chromosome number - Production of functional sex cells or ANAPHASE I gametes - Separation of homologous pairs - Reduction in the chromosome number - Two rounds: meiosis I and meiosis II. Meiosis II TELOPHASE I and CYTOKINESIS immediately takes place after meiosis I, so - Chromosomes reach opposite poles. only the latter is preceded by the - Cytoplasm divides duplication of genetic material - Allows restoration of original chromosome MEIOSIS II number during fertilization - EQUATIONAL division because there is no - Involves two rounds of cytokinesis which will further reduction of the chromosome ultimately produce four daughter cells with number in daughter cells a reduced chromosome number. PROPHASE II - Preceded by an interkinesis, chromosomes decondense - A new spindle forms around chromosomes MEIOSIS I - REDUCTIONAL division because it reduces PROMETAPHASE II the number of sets of chromosomes from - Disintegration of nuclear envelope two to one METAPHASE II - Alignment of the duplicated metaphase II chromosomes at the metaphase plate ANAPHASE II - Centromeres divide - Separation of sister chromatids PROPHASE I - Chromosome condensation, synapsis, TELOPHASE II crossing over - Formation of daughter cells - Nuclear envelope breaks down - A nuclear envelope forms around each set of chromosomes - Cytoplasm divides - MITOSIS AND MEIOSIS DIFFERENCE CHANGES IN # OF CHROMOSOME Syndromes Nondisjunction - uneven distribution of chromo. Synapsis involves the pairing of the members of homologous chromosomes so as to allow them to undergo crossing over and to segregate them. Crossing over refers to the exchange of segments between non-sister chromatids of homologous chromosomes. Ultimately, this enhances the genetic diversity of species. Importance: - facilitates genetic recombination Down Syndrome or Trisomy 21 - enhances genetic variation - Extra chromosome 21 - increases chances of survival - Some physical characteristics of the down Number of chromosomes of daughter cells syndrome include the following: protruding tongue, small stature, and a short neck, eyes that slant upward. Klinefelter Syndrome - Extra X chromosome - Typically have small testes - May have low muscle tone and problems with coordination - Wide hips, breast development, narrow shoulders, poor hair growth Cri du chat syndrome - Chromosome 5 is missing - Mitosis maintains an identical set of genetic - High-pitched cry sounds like cat material in the daughter cells whereas - Small head size, low birth meiosis reduces this amount and introduces weight, and weak muscle tone new combinations. These have different - Widely set eyes, low-set ears, a small jaw, consequences and applications as a result. and a rounded face. MEIOSIS I and MEIOSIS II DIFFERENCE Turner’s syndrome - Synapsis occurs only in meiosis I. - All X chromosomes is missing - Crossing over occurs only in meiosis I. - Below average in height and they - Tetrads line up and separate into individual experience early loss of ovarian function homologous chromosomes in meiosis I. - Sister chromatids line up and separate into individual chromosomes in meiosis II. - Meiosis I and II are also different in terms of the segregating elements. Meiosis I entails the separation of the members of the homologous chromosomes, whereas meiosis II involves the separation of the sister chromatids DEFINITION OF TERMS: Centrosome Kinetochore - The structure that organizes microtubules in - A protein complex located at the animal cells, consisting of two centrioles. It centromere serves as the main microtubule-organizing - Where microtubular spindle fibers attach to center (MTOC) and plays a critical role in pull the chromatids apart during cell the formation of the spindle apparatus division. during cell division. Centromere Centriole - The region of a chromosome where two - A cylindrical structure made of nine sister chromatids are held together, and microtubules arranged in a circle and where the spindle fibers attach during found in animal cells mitosis and meiosis. - Important for the formation of spindle fibers Chromatid during cell division. - One of the two identical halves of a Spindle/ mitotic fibre duplicated chromosome, connected by - Microtubule fibers that form during cell the centromere. Sister chromatids separate division and attach to the chromosomes during mitosis or meiosis. - Responsible for separating the Telomere chromosomes by pulling sister chromatids to - The protective, repetitive DNA sequences opposite poles of the cell. found at the ends of chromosomes They prevent chromosomes from deteriorating or fusing with neighboring chromosomes and are involved in the aging process. CELL MEMBRANE - The presence of double bonds in fatty General Biology | Quarter 1 Week 8 acids helps maintain membrane fluidity. Present in all cells (animal, plant, bacterial) with the primary function of protection. - With no membrane, organelles become exposed to the outside environment that may be toxic; cell therefore becomes non-functional and life ceases to exist Cholesterol - Only present in animal cells; may be good or bad - Affects and regulates membrane compaction and expansion at different temperatures - Warm temp: Restrains movement of phospholipids. Since heat expands the spaces between phospholipids Fluid Mosaic Model - Cool temp: Maintains the fluidity by - Static in structure but neither rigid nor static preventing tight packing that may break in structure but is highly flexible and can down the lipids change its shape and composition through time. Phytosterol - Structure is composed of diverse protein - Only synthesized in plants molecules embedded in a mosaic-like - Helps plants maintain temperature In harsh fashion in the fluid phospholipid bilayer. environments - Lowers bad cholesterol- Used in plant Components of the cell membrane based oils which are healthier but more Phospholipid pricey due to it being harder to extract - Made of two layers of lipids with hydrophilic head and hydrophobic tail Functions of cell membrane - Most abundant lipids in membranes, an 1. Define the boundaries and act as amphipathic molecule permeability barriers - As barrier: To keep desirable substances in the cell and keep undesirable substances out. Ex. Keeps stomach acid in check by the sphincter to prevent leakage - As permeability barrier: Hydrophobic core prevents transport of ions and polar molecules - Selectively permeable - only allows - Contains fatty acid component (carboxylic certain substances into cells while acid); long chain of hydrocarbons keeping others out. Size and the - Contains saturated (single bonds ONLY) chemical nature of the molecules are fatty acid determiners of the permeability - Unsaturated (double bonds) fatty acids that cause bend in hydrophobic tail chain - The individual lipid molecules are able to move in their own monolayer.  4. Contain the protein molecules that act as receptors to detect extracellular signals - Proteins in the cell membranes of neurons contain embedded molecules that interpret signals from neurotransmitters and other signaling molecules. - When these molecules bind to the receptors, they initiate a series of biochemical reactions inside the neuron. - Ex. Caffeine that keeps you awake and Adenosine that makes you sleepy 5. Membrane proteins - Diverse proteins are associated with the plasma membrane, and they are functionally classified. Molecules that are free to move across the Transport proteins membrane (Permeable) - Classified into channel or carrier proteins - LIPIDS, ALCOHOL - NON-POLAR molecules - fully distributed charge - SMALL molecules - O2, N2, CO2, H2O Molecules that require energy expenditure (Impermeable) - POLAR molecules - contain negative and positive charges - LARGE molecules - Glucose, amino acids, nucleic acids, proteins 2. Site for biochemical functions - This includes photosynthesis (both light dependent and light independent) and cellular respiration in mitochondria membrane 3. Provide mechanisms for cell-to-cell contact and communication Adhesion proteins - Cells in multicellular organisms are in - Fasten adjacent cells together in animal contact with other cells tissues. - Cell junctions in skin cells that allow cells to adhere to each other for communication Recognition proteins - Preventing unregulated flux of fluid or - Help in recognition when the body is being leakage of urine in urinary bladder invaded by pathogens so that the - Plasmodesma that connects 2 plant cells necessary immune response may be triggered eg. glycoprotein Receptor proteins - Have certain shapes that allow only specific molecules to bind to them. CELL TRANSPORT MECHANISM General Biology | Quarter 1 Week 8 FACILITATED DIFFUSION - Diffusion through membrane aided by Describes the movement of molecules across transport proteins (channel and carrier the cell membrane (ACTIVE or PASSIVE) proteins) Protein channels - To accommodate different molecules; membrane becomes semi-permeable ex. Aquaporin for water PASSIVE TRANSPORT - High to low concentration; along the concentration gradient - No energy required SIMPLE DIFFUSION - “Moves with the flow” since there is net diffusion caused by uneven distribution of molecules Protein transporters/ carriers - Net diffusion happens to reach equilibrium - They hold onto their passengers and where there is equal number of molecules change shape in a way that shuttles them on each side across the membrane. - Intrinsic energy: from internal thermal/kinetic energy which allow molecules to move even without ATP - Selective permeability is still applied Rule in DIffusion: - In the absence of other forces, a substance will diffuse from where it is more concentrated to where it is less concentrated - Any substance will diffuse down its OSMOSIS concentration gradient. No work must be - Diffusion of water through the cell done to make it happen. membrane Examples: - Net movement of - Homogeneous solution: juice powder in water molecules to water or blood in ocean area with more - Fetus and mother: nutrients, antibodies, solute and less vitamins of mother to fetus; CO2 of fetus to water mother making mother fatigued - Lungs: Respiratory system; alveoli where gas Cell Tonicity exchange occurs Each dye molecule wanders randomly , but there will be net movement of the dye molecules across the membrane to the side that began as pure water. - Hypotonic for plant cells since they contain large vacuole that can store a lot of water Isotonic BULK TRANSPORT - Equal solute, equal water; concentration of - For large molecules water in the solution is the same as the concentration of water inside the cell. Types of ENDOCYTOSIS Hypotonic Phagocytosis - Less solute, more water; water enters a cell - Cell engulfs large particles or even by osmosis, causing the cell to swell and other cells, often seen in immune cells burst (CYTOLYSIS - disruption of cell) like macrophages Hypertonic Pinocytosis - Less water, more solute; water leaves a cell - Involves the uptake of small particles by osmosis, causing the cell to shrink and fluids, often referred to as "cell (PLASMOLYSIS - shrinkage of protoplasm in drinking" plant cell) Receptor-mediated endocytosis - Selective form of endocytosis where cells internalize specific molecules based on receptor recognition, allowing for efficient uptake of needed substances. Isotonic Hypotonic Hypertonic ACTIVE TRANSPORT - Energy (ATP) is required - Against the concentration gradient (low to high concentration) EXOCYTOSIS - Cells expel materials in vesicles that TYPES OF TRANSPORTERS/ CARRIERS fuse with the plasma membrane, releasing their contents outside the cell. - Uniporters – move one molecule at a time Ex. Sodium-Potassium pump - Symporters – move two molecules in the same direction Ex. Na+/glucose - Antiporters – move two molecules in opposite directions ENZYMES General Biology | Quarter 1 Week 8 Monomers - Small, foundational units in biomolecules that can join together to form larger molecules known as polymers. - Enzyme/substrate complex: transient formation that occurs when a substrate binds to the active site of an enzyme. It brings the substrate into close proximity to the enzyme, allowing for the necessary chemical interactions to take place. - Enzyme/product complex: forms after a substrate is converted into products. This temporary complex stabilizes the transition state during the reaction, allowing the products to be released. Lock and key - Model that describes enzyme specificity, where the enzyme (the "lock") has an active site perfectly shaped to fit a specific substrate (the "key") allowing it to catalyze Metabolism a reaction. - The sum of all the chemical activities taking place in a organism Induced fit > Catabolism (exergonic) - Model that describes how an enzyme - Breakdown of larger molecules into smaller changes shape upon substrate binding, ones, releasing energy in the process. allowing for a better fit between the two. - Enzymes facilitate these chemical reactions, helping to convert complex Enzyme Examples: substances into simpler forms which can then be used for energy production. Ex. carbohydrates to glucose > Anabolism (endergonic) - Build complex materials from simpler ones - Enzymes help synthesize complex molecules such as proteins, nucleic acids, and polysaccharides from their monomeric units Enzyme - Substances (proteins) that catalyze chemical reactions - Act as a catalyst: speeds up chemical reactions by decreasing the activation energy - Active site: A specific region on an enzyme where substrate molecules bind. It typically consists of a pocket or groove formed by the arrangement of amino acids - Substrate: The reactant molecule that an enzyme acts upon FACTORS AFFECTING ENZYME ACTIVITY General Biology | Quarter 1 Week 8 Enzyme concentration Several factors can affect enzymatic activity affecting its efficiency in catalyzing metabolic processes Temperature - Each enzyme has its own specific optimal temperature - When exposed to optimal temperature, the - Enzyme concentration increases, rate of rate of reaction is the fastest reaction also increases given there is - Majority of human enzymes have optimal enough substrate temperatures from 37C to 38C - More chances of enzymes colliding with - Low temp: enzymes become inactive, substrates unfunctional, or slow - Limiting factor - variable that slows down - High temp: enzyme bonds breakdown or the reaction rate denature and the active site changes shape to the point where substrate no Inhibitors longer fits; - Inhibitors can bind to the enzyme slowing - At high fever, body kills pathogens and down or stopping the functionality or denatures the enzymes present in chemical activity of the enzyme bacterial cells - Allosteric site (regulatory site) - specific region separate from the active site where pH Level allosteric effectors/regulators can bind. - Very active at optimal level of pH Binding causes a conformational change in - If exposed beyond optimal - disruption of the enzyme's structure. bonds that affect structure - Competitive inhibitor - Tries to compete with - Each part of our body has different pH the substrate levels - Non-competitive inhibitor - Molecule binds to allosteric site and inactivates enzyme by changing the shape of active site Activators - Allosteric activators - Molecules that bind at allosteric site, causing a conformational change that enhances the protein's activity. Substrate concentration - With more substrate, there is a higher rate of reaction until it reaches maximum point - Higher chance of collision between enzyme and substrate - After reaching maximum point, enzyme becomes saturated and rate of reaction becomes constant