1st Grading Biology PDF

Principles of Cell Theory: Father of Pathology 1. All living things are made up of cells. “omnis cellula e cellula” 2. Cell is the basic unit of life. Observed cancer cells with the early cases of 3. Cells came fr...

Principles of Cell Theory: Father of Pathology 1. All living things are made up of cells. “omnis cellula e cellula” 2. Cell is the basic unit of life. Observed cancer cells with the early cases of 3. Cells came from pre-existing cells. leukemia. Cell Theory 1859, Louis Pasteur ❖ Most accepted and recognized concept in Pasteurization of food to prolong shelf like wine Science. Contributed to prove that Virchow’s concept of ❖ Major evolution in the microscope technology. cells developing from pre-existing cells is true. ❖ Study on the concepts of living organisms and “Swan-neck” flask experiment disproved their environment. spontaneous generation. ❖ Contributed on the study of medicine, human His work was the ground of bacteriology. disease and microbiology. Cell Structure and Functions Three tenents of cell theory: Protection a) Theodor Schwann and Matthias Schleiden Plasma Membrane - Cell theory: All living things are made up of ○ Controls what goes in and out of the cell cells. (molecules, ions, and gases) b) Rudolf Virchow ○ HOMEOSTASIS - Found out about cell division ❖ Tenet of the cell theory argues against life on Earth evolving from abiotic factors. (Cells came from pre- existing cells.) 1665, Robert Hooke Author of Micrographia “Small Drawings” Member of the Royal Society Coined the term “CELL” - “CELLULA” small room Compound microscope with a magnification of ○ Composition: phospholipid bilayer and 30x to examine an oak tree bark (cork) embedded proteins 1674, Anton Van Leeuwenhoek ○ 3 Basic parts: Charged Phosphate Group, Father of Microbiology Glycerol, 2 Fatty Acid Chains Microscope with a magnification of 300x ○ Phospholipid Bilayer Named protozoa/bacteria “ANIMALCULES” ─ Head - glycerol and phosphate group Discovered that they are “MOTILE” and reported “Hydrophilic” - ability to mix well, to the Royal Society that motility is a quality of dissolve, or to be attracted to water. life. ─ Tails - Fatty acids Credited for making the first observations of red “Hydrophobic” - lacking an affinity for blood cell and sperm cells. water. First evidence against SPONTANEOUS GENERATION. 1827-1833, Robert Brown Pollen grains in water jiggled around called “Brownian motion” Discovered the nucleus. 1838, Matthias Jakob Schleiden German biologist who studied different species of plants. Membrane Structure Co-founder of Theodore Schwann in the cell theory. Author of “Contributions of Phytogenesis” Recognized the importance of nucleus (1831, discovered by Robert Brown). Free cell formation 1839, Theodore Schwann Zoologist German biologist who founded the modern Cell Wall histology. ○ A rigid layer that provides protection, rigid Contributed to the germ theory of alcoholic support, and shape to the cell fermentation. ○ Plants, algae, fungi, and bacteria Cell is the basic unit of animal structure. Schwann cells Coined the term metabolism Existing cells 1855, Rudolf Virchow German physician and political activist ○ Plant and algae - polysaccharide cellulose  ○ Fungi - chitin ○ Bacteria – peptidoglycan ○ DNA – Nucleiod Region Cytoplasm ○ It surrounds all the internal cell structures on both prokaryotes and eukaryotes. ○ Chromosome - the DNA molecule packed into thread-like structures ○ Cytosol - the fluid portion of the cytoplasm Cytoplasm - Organelles = Cytosol Genetic Control Nucleus ○ Stores the cell’s hereditary material, or DNA ○ Nuclear Envelope - encloses the DNA and ○ Coordinates cell’s activities (growth, separate it from the cytoplasm metabolism, protein synthesis, and ○ Nuclear Pore - regulate cellular reproduction) transportation between the nucleus and Anatomy of the Nucleus cytoplasm ○ Nucleolus - organelle within the nucleus that manufactures Ribosomal RNAs Endomembrane System Endoplasmic Reticulum ○ Network of hollow membrane tubules that facilitate the manufacture and transport of essential molecules for the cell ○ Connects nuclear envelope & cell membranes ○ DNA - Genes - Histones - Chromatin - Chromosomes - Nuclear Envelope - Nuclear Pores - Nucleolus - Ribosomes ○ DNA - holds the blueprint for all living organisms ─ Sugar ○ Cisternae - series of flattened, stacked ─ Phosphate groups pouches ─ Nitrogen bases ○ Lumen - the inside space of a tubular structure ○ Vesicles - store and transport materials with the cell Category: ○ Genes - specific sequence present on a start Storage of DNA which encodes for specific proteins. Transport Secretory ○ Histone - basic protein that helps condense ○ Rough ER DNA into chromatin ─ contains ribosomes, pancreas, plasma cells, WBC ○ Smooth ER ─ The site of lipid metabolism ─ Stores Calcium ions ─ Breaks down of alcohol and drugs live, ovary, and testes ○ Chromatin - the dense string-like fiber within a chromosome consisting of DNA and protein  Golgi Apparatus Energy-Processing Organelles ○ Is responsible for tansporting, modifying, and Mitochondria packaging proteins and lipids into vesicles for ○ Generate chemical energy in the form of ATP delivery to targeted destinations ○ Contain ribosomes and DNA Chloroplasts ○ Cis face - receiver ○ Types of plastids which help plants convert ○ Trans face - transporter solar to chemical energy ○ Cisternae and lumen ○ Contain ribosomes and DNA ○ plants Parts of Chloroplast Vacuole ○ Fluid-filled sacs for storage surrounded by a membrane called TONOPLAST ○ Sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes Support, Movement, and Intercellular Communication Centrosome and Centriole ○ Bundle of microtubules (9 triplets microtubules) ○ Mitotic spindle fiber Lysosome ○ Contains lysozyme and other digestive enzymes ○ Break down food, bacteria, and worn out cell parts ○ Apoptosis, autolysis and phagocytosis ○ Self-digestion or self-eating Peroxisome ○ Where Hydrogen Peroxide is both generated and broken down ○ Lipid catabolism Cilia and Flagellum ○ Allow the cell to move (9+2 pattern)  Cell Surfaces and Junctions ○ Form extracellular connections between adjacent cells ○ Eukaryotes flagellum ─ Movement: whiplike manner ─ Composed of the protein tubulin ○ Bacterial flagellum ─ Movement: rotates in a clockwise or counterclockwise direction ─ Contains the protein flagellin ○ Cilia - shorter and numerous ○ Plant Cells ─ Plasmodesmata - allows intercellular communication between plant cells Cytoskeleton ○ Provides mechanical support ○ Microtubules, Intermediate Filaments, and Microfilaments ○ Animal Cells ─ Tight Junctions - plasma membrane stitches to the cell ─ Adhesion Junctions - joining the acting filament in the neighbor cell ─ Gap Junction - linkage of the two adjacent ○ Intermediate Filaments - resist mechanical cell stress PLANT CELL vs ANIMAL CELL ○ Microtubules ─ Mitotic spindle fiber ─ Cilia ─ Flagellum ─ Cell transport COMMON TO PLANT AND ANIMAL CELL: Mitochondria PROKARYOTIC AND EUKARYOTIC CELLS: Modern Cell Theory Multicellular organisms depend on the total ○ Microfilaments - internal cell movement activity of every cell. “All living organisms are made of cells” Cell is the basic unit of life Energy flow occurs within cells  Cell contains hereditary information passed on to the next cell. All cells in similar species have the same basic composition. 6 Kingdoms of taxonomy of life: Eubacteria Archae Organ Protista A distinct structure made up of different tissues Fungi that have a specific function. Plantae Animalia Prokaryotic Cells - UNICELLULAR, do not have concrete structure. - Ancestor organism - Lived before eukaryotic cells lived - Not complex compared to eukaryotic cells Organ System - Kingdom monea (2 domain) A collection of organs that carry out specific Kingdoms under Prokaryotic cells: functions within an organism a. Bacteria b. Archaea Eukaryotic Cells - UNICELLULAR OR MULTICELLULAR, have concrete structure. Kingdoms under Eukaryotic cells: a. Protists b. Plants Organism c. Animals A living thing that carries out all of life’s d. Fungi functions. Similarities between Prokaryotes and Eukaryotes 1. In both types of cells, DNA exists that relates to genes. 2. Both the cells have ribosomes which is responsible for the production of protein according to instructions from the genes. 3. Both has Cytoplasm (storage/container for all organelles). 4. Cell Membrane/Plasma Membrane - regulates the Different tissues in our body entrance and exit of materials inside a cell. Epithelial Tissues Generally functions for homeostasis. Characterized by closely-joined cells with tight 5. Most Prokaryotic Cells have cell wall but only some junctions. in Eukaryotic Cell. When it comes to Animal Cell, Seen outside the body as coverings or as linings there is no cell wall present. of organs and cavities. Function and involve parts of the body Differences between Prokaryotes and Eukaryotes Prokaryotic Cells Eukaryotic Cells No membrane - bound With membrane - bound organelles organelles Plant cells have Types of Epithelial Tissues CHOROPLASTS ✓ Cuboidal No Nucleus Have Nucleus ▪ Single layer of cells that are approximately as tall as they are wide with spherical and centrally placed nuclei. HISTOLOGY ▪ These cells offer secretary, absorptive, or Branch of biology that deals with tissues. excretory funtions. Cell Basic unit of life. Mostly seen in the: ─ Surface of ovaries Tissue ─ Renal tubule walls - located in our urinary A group of specialized cells that work together system. for a particular function.  ─ Internal walls of the seminiferous tubules Non-Keratenized Keratenized of the male testes Oral Cavity Skin ─ Pancreas Pharynx ▪ Stratum basale ─ Salivary gland Esophagus ▪ Stratum spinosum ─ Parts of the eye Distal ureters ▪ Stratum granulosum ─ Follicles the thyroid Vagina ▪ Stratum lucidun ▪ The function of the excretory system is to External female genitalia ▪ Stratum corneum eliminate waste and filter the blood. Keratin in our body/skin: ✓ Simple Columnar ❖ S. Basale - continuously divide by mitosis to give ▪ Single layer of brick-shaped cells; for rise to kertinocytes. secretion and active absorption. ❖ S. Spinosum - partly responsible for the skin’s ▪ The height of cells exceeds the width of the strength and flexibility. ovoid nuclei. ❖ S. Granulosum - help to form a waterproof barrier ▪ The nucleus are located in the basement that functions to prevent fluid loss from the body. membrane and the shape of the nucleus is ❖ S. Lucidum - lowers the effects of friction in the oval or oblong. skin, especially in regions like the soles of feet and palms of hands. ❖ S. Corneum - topmost, non-living, cellular layer of the epidermis. Mostly seen in the (Digestive System) ─ Stomach ─ Small Intestine ─ Large Intestine ─ Upper Cervix ✓ Simple Squamous Epithelium ▪ Single layer of plate-like cells; for exchange of material through diffusion. ▪ Secretes lubricating substance, allows diffusion and filtration. ✓ Pseudo-Stratified Columnar ▪ Single layer of cells; may just look stacked because of varying height; usually lined with cilia. ▪ Secretes mucus which is moved with cilia. ▪ The Cilia is located in the Trachea Example: (Circulatory and Respiratory System) ─ Blood and lymphatic vessels ─ Air sacs of lungs ─ Lining of the heart ✓ Stratified Squamous ▪ Multilayered and regenerates quickly; for protection against abrasion. Mostly seen in the: ─ Trachea ─ Most of the Respiratory Tract (Ciliated) Connective Tissue Connects, separates and supports all other types of tissues in the body. Blood, Connective Tissue Proper, Cartilage, Bone Function and involve parts of the body Adipose Mostly seen in the: Tissues ─ Esophagus ─ Mouth ─ Vagina ─ Integumentary System ─ Urethra ✓ Connective Tissue Proper Mostly seen in the: ▪ Dense Irregular Connective Tissue ─ Made up of type I collagen fiber ▫ Red bone marrow ─ Found in high concentrations in body parts ▫ Lymph nodes ▫ Spleen where support is needed to prevent the effects of forces that pull in multiple ✓ Specialized Connective Tissue ▪ Blood directions. ─ This is for making the skin resistant to ─ Specialized connective tissue within the circulatory system. tearing. ─ It is used for preventing scratches. ─ Made up of plasma (fluid portion) Three major parts: Mostly seen in the: ▫ Erythrocytes (Red Blood Cells) ▫ Dermis of the skin → They carry oxygen to deliver in our ▫ Glandular tissue body and carbon dioxide to ▫ Walls of the organs eliminate during exhalation. ▫ Whites of the eyes → The lack of iron in the red blood ▪ Dense Regular Connective Tissue cells leads to Iron Deficiency and ─ Made up of type I collagen fiber peeling of skin in the lips. ─ Found in areas of the body where large → Hemoglobin - pigment that gives amounts of tensile strength are required. red. ▫ Leukocytes (White Blood Cells) → Helps in fighting infections, disease, bacterias and viruses. Defense. ▫ Thrombocytes (Blood Platelets) → Responsible for the blood clotting. Mostly seen in the: → These are your body’s natural ▫ Ligaments bandage to stop bleeding. ▫ Tendons ▪ Bone ▪ Loose Connective Tissue ─ Mineralized connective tissue made by ─ AKA areolar connective tissue bone-forming cells called osteoblasts ─ Most common type of connective tissue which deposit collagen. ─ Holds organs in place ─ Serve as a storage site for calcium and phosphate, alongside its weight bearing and protection functions. Mostly seen in the: ▫ Lamina propria of the alimentary and respiratory tracts ─ Osteoblasts - responsible for bone forming. ▫ Mucous membranes of reproductive ─ Osteocytes - when osteoblasts formed. It and urinary tracts is for the cells in our bone ▫ Glands ─ Osteoclasts - damage the bone. ▫ Mesentery ▪ Cartilage ▫ Dermis of the skin ─ Functions as cushion between bones ▪ Reticular Connective Tissue ─ (rib cage, ear nose, bronchial tubes, ─ Produced by modified fibroblasts called intervertebral discs) reticular cells. ─ Reticular meshes filter lymph and provide a microenvironment for the passage and attachment of white blood cells Different Kinds of Cartilage  ▫ Hyaline - nose, ribs, larynx and trachea ─ Found in middle layer (tunica media) of the consist of Hyaline cartilage wall of most blood vessels; and ▫ Elastic - also known as the yellow ─ The muscular part of the wall of the digesting fibrocartilage. Mostly seen in the ears. tract ▫ Fibrocartilage - mostly seen in the ─ Uterus intervertebral discs or spinal column. ▪ Adipose Tissue ─ Energy-storing connective tissue. ─ Consists of adipocytes, cells filled with lipids. ─ It also cushions and insulates the body. Nerve Tissue Composed of nerve cells called neurons and glial cells that function as support cells. Transmit information throughout the body in the form of electrical signals or nerve impulses Neuron (cell body, dendrites, the axon, and axon Different Kinds of Adipose Tissue terminals) ▫ Subcutaneous Fat - located in the deepest layer of the skin. ▫ Visceral Fat - mostly seen inside the belly, liver and the intestine. ▫ Breast Tissue - it is part of our mammary gland. Composed of the milk PARTS OF THE NEURON gland. Muscle Tissue Composed of long cells called muscle fibers that allows the body to move voluntary or involuntary. Skeletal, Cardiac, Smooth Neuroglial Cells ▪ Cells of the nervous system that are not involved in the conduction of nervous Properties: impulses ◦ Excitability ▪ Small than neurons, and do not have axons or ◦ Contractibility dendrites ◦ Extensibility CELL CYCLE ◦ Elasticity Different Muscular Tissue ○ Skeletal Muscle ─ Which move bones and other structures. ─ Multi-nucleated; striated; voluntary movements ─ Attached to the skeleton IINTERPHASE - preparatory phase Gap 1/G1 Phase The cell organelles are being prepared. The ○ Cardiac Muscle organelles are being duplicated or multiplied ─ Forms the muscular wall of the heart except the DNA. Rapid growth. ─ One nucleus; striated; involuntary ─ Walls of the heart ○ Smooth Muscle Synthesis/S Phase ─ The only tissue in the body that has the ability Replication of the DNA. to contract and therefore move the other Development of the Centrosome or Centrioles. parts of the body. ─ One nucleus; not striated; involuntary Growth 2/Gap 2/G2 Phase Prepared cell to enter the division. Assemble the 4. TELOPHASE microtubules. The nucleus and nuclear membrane are already formed. There is no spindle fiber here. Every nucleus consists of single chromatin or 1 sister chromatin. KARYOKINESIS - division of nucleus What is MITOSIS? A type of cell division in which the nucleus of the cell divides into two. Consists of 2 sets of chromosomes. CYTOKINESIS - division of the cytoplasm First step in cytokinesis is the formation of the cytokinesis plate. Nucleus divide. What is the function of MITOSIS? The major purpose of mitosis is for growth, development, repair and asexual reproduction. Different Phases in Mitosis 1. PROPHASE The chromosomes are very evident here. The nucleus and nuclear membrane disappear or dissolve. The development of the spindle fiber. 2. METAPHASE The chromosome is already in the middle or center part Can we stop Mitosis? of the cell. The spindle fiber is already holding the ─ Yes we can stop Mitosis especially when the chromosomes. Metaphase plate is a plane or region in person have cancer cells. the center of the cell. How to stop Mitosis? ─ We can stop this by using chemotherapy or radiation therapy. 3. ANAPHASE Detachment of the 2 chromosome. Smaller spindle fiber. Science Connection: Skin Grafting or Skin Transplantation  ❖ Hair Color ❖ Skin Tone ❖ Blood Type ❖ Hair Whorl ❖ Handedness Humans have 46 chromosomes. That is how many chromosomes most body cells in our body have. Social Integration: History The bombing had killed an estimated 140,000 people in Hiroshima, and a further 74,000 in Nagasaki. In the years that followed, many of the survivors would face leukemia, cancer, or other terrible side effects from the radiation. But there are some human cells that don’t have 46 chromosomes. Human sperm cells and egg cells have 23 chromosomes. MITOSIS makes identical body cells like your skin cells and stomach cells. Requires one parent. Why the number difference? If the sperm cell has 23 chromosomes and an egg cell has 23 chromosomes, when they come together that makes 46 chromosomes. Process during PMAT: That will allow a newly formed fertilized egg to develop into a human. MEIOSIS is what we call a reduction division because you MEIOSIS have a starting cell that has 46 chromosomes and your The production of sex cells in preparation for ending cells -- the sperm and egg cells --- have only has sexual reproduction. 26 chromosomes. Requires two parents Starter cell could be primary spermatocyte (in It is a process that contributes to genetic variety. males) or primary oocyte (in female) Meiosis does not make body cells. It makes Gametes are sperm and egg cells. sperm and egg cells; otherwise known as What happens before meiosis can start? gametes (sex cells). INTERPHASE happens before meiosis is going to start. “Meion” - to make small ✓ Growth Bumababa yung chormosomes once na nag- ✓ DNA Replication undergo na siya ng cell division ✓ Cell Functions The number of chromosomes of a species The starting cell has 46 chromosomes, and you have to remains the same from the same from one duplicate those chromosomes in interphase before generation to the next thus reducing the meiosis starts. That basically means you’re duplicating chromosomes number of germ cells by half your DNA, since chromosomes are made of DNA and during meiosis. protein. Haploid We tend to count chromosomes by the number of Inherited Traits centromeres present, ❖ Eye Color Centromere Part of chromosome where sister chromatids are held together. Because of this, in meiosis, you put numbers after the When the 46 chromosomes duplicate, we still say there phases to indicate whether you’re in the first division or are 46 chromosomes because the sister chromatids are the second division. still attached and we’re counting by centromeres. MEIOSIS I Prophase I “pro”, this actually means “before” Homologous chromosomes pair (synapsis) Chromatids Exchange of genetic material occur between Strands of replicated chromosome homologous chromosomes (crossing over) So 46 chromosomes here, they replicate in interphase, It comes before all the other stages start. This is where the chromosomes are going to condense and thicken. Chromosomes starts to coil and shorten. Spindle fibers originate from the centrioles on either side of the cell. Nuclear Envelope disintegrates. and you still have 46 chromosomes in this picture. They are going to line up with their homologous pairs. But you went from 46 to 92 chromatids. Homologous Chromosomes - The chromosomes are approximately the same size and they contain the same types of genes in the same locations. Synapsis. Meiosis is a reduction division; you’re going from 46 chromosomes to 23. Which means you actually divide twice. In Meiosis, you’re going to divide twice and therefore do PMAT twice.  Crossing Over - when the chromosomes are lined up in homologous pairs, they have a way that they can transfer their genetic information and exchange it between each other. Exchange of genetic material occur between homologous chromosomes CYTOKINESIS It involves the division of the cytoplasm to produce two individual daughter cells. Recombinant Chromosomes - which can eventually contribute to the variety that siblings can have even when they have the same parents. Interphase I - The DNA in the cell is copied resulting in two Metaphase I identical full sets of chromosomes M is standing for “middle” Meiosis I Paired chromosomes are going to be align along - Anaphase I: the pair of chromosomes are then the center of the cell. (metaphase plate) pulled apart by the meiotic spindle, which pulls These chromosomes in pairs are attached to one chromosome to one pole of the cell and the spindle fiber. other chromosome to the opposite pole. Metaphase Plate - center of the cell - Telophase: the single-cell pinches in the middle to form two separate daughter cells - MEIOSIS II Prophase II It is not going to be as eventful as it was in prophase I because they are not going to have Anaphase I homologous pairs of chromosomes. They also Think of A for “away” not going to have the process called crossing- The Homologous chromosomes (separate) are over. going to be pulled away by the spindle fibers. The Nuclear membrane disintegrates. The chromosomes move toward opposite poles New spindle fibers are formed around the of the cell by the spindle fibers. chromosomes Lumiliit na yung Spindle fibers You have your chromosomes and the spindles Telophase I T stands for “two” starting to form like in prophase I. Chromosomes reach opposite poles (cleavage furrow) The nuclear envelope is formed around the chromosome. The chromosomes uncoil and become less dense. Cleavage Furrow - opposite poles End with telophase I, where you have two newly Metaphase II found formed nuclei and it becomes obvious that The chromosomes are going to line up in the you are going to end meiosis 1 with two new middle. (metaphase plate) This time, they are in cells. a single file line. They are not in pairs like. Attached to their centromeres to the spindle fiber.  - Telophase II: at each pole of the cell, a full set of chromosomes gather together. Four haploid daughter cells are produced called gametes Chronological Activities during Meiosis I and II 1. Chromosomes condense. 2. Chromosomes pair up. 3. Homologous chromosomes line up at the equator. Anaphase II 4. Chromosomes pulled apart. This time, it is the chromatids that are getting 5. Cell pinches in the middle forming 2 daugther pulled away by the spindle fibers. cells. Each chromosome into two sister chromatids. 6. Chromosomes condense AGAIN into visible X- The chromatids move to opposite poles. shaped structures. (chromosomes) 7. Chromosomes line up at the equator. 8. Sister chromatids pulled apart. 9. Cell pinches in the middle forming 4 granddaughter cells. 10. Gametes are formed. Main Difference Between MEIOSIS I and MEIOSIS II: Meiosis I - two separate daughter cells Telophase II Meiosis II The spindle fibers pull the chromosomes apart. - Four haploid daughter cells The newly separated chromosomes travel to the opposite ends of their cells. Meiosis in males produces sperm cells and in females, it This separation guarantees diversity of the newly produces egg cells. Because of independent assortment formed gametes. and also crossing over, you’re going to have variety. Nuclei reforming and the 2 cells are each going to divide so you can see that the 4 cells are going to be formed. For example, in a male the four sperms cells that are produced each time, they are all different from each other. They are also different from the starting cell because the starting cell had 46 chromosomes and the CYTOKINESIS will follow to completely split the ending cells only have 23. cytoplasm. Identical to cytokinesis I. involving the second cytoplasm division, resulting in the formation of two individual daughter cells. A reason why two siblings with the same parents can look different from each other. MITOSIS vs MEIOSIS Meiosis II - Prophase II: the membrane around the nucleus in each daughter cell dissolves away releasing the chromosomes - Metaphase II: the chromosomes (pair of sister chromatids) line up end-to-end along the equator of the cell - Anaphase II: the sister chromatids are pulled to opposite poles due to the action of the meiotic spindle Meiosis Organism Diploid No# Haploid # Chicken 78 39  Rat 42 21 Starfish 36 18 Elephant78 56 28 Role of Meiosis in Gametogenesis The process by which, gametes, or germ cells, are produces in an organism Formation of gametes “genesis” = formation Meiosis in FEMALES ❖ Oogenesis - the processes of formation of Female gametes (egg cell) Oogenesis What would happen if MEIOSIS suddenly stops? Pre-Natal Antral Pre- When a cell can receive too many or too few ovulatory chromosomes in the separation which contributes to some genetic disorders. ❖ Oogenesis takes place in the outermost ovary Mutations in Gametes/Genetic Disorders layers. Down Syndrome ❖ Oogenesis starts with an oogonium-like germ cell Trisomy 21 - The most common type of Down and undergoes mitosis. syndrome, trisomy 21, occurs when a developing ❖ Pre-natal, Antral, Pre-ovulatory baby has three copies of chromosome 21 in every ❖ Menstruation and Ovulation cell instead of typical two copies. Short neck Small ears Small hands and feet Delays in speech and language development Attention problem Klinefelter Syndrome Meiosis in MALE Klinefelter syndrome is a common genetic condition ❖ Spermatogenesis - the processes of formation of where male is born with an extra X chromosomes. Male gametes (sperm cell) Typically, male has one X and one Y chromosome. 1) Meiosis, during which the number of Being born with a smaller penis chromosomes in the cell is reduced to half or 23 Having abnormal body proportions chromosomes each; Experiencing increased breast tissue 2) Meiosis II, during which each haploid cell forms Having weaker bones or more fractures spermatids; and 3) Spermiogenesis, during which each spermatid develops into a sperm cell with a head and tail. ❖ Within the male reproductive organs, the testes. ❖ In order to create the haploid gamete, a cell undergoes the process of meiosis in which the genome is replicated and divided twice to produce four haploid gametes. Turner Syndrome Turner syndrome is a genetic disorder affecting girls and women. The cause of Turner syndrome is a completely or partially missing X chromosome. Broad chest Unusually short, wide neck or webbed neck Grow more slowly than their peers Have delayed puberty and lack of growth spurts, resulting in an average adult height of 4 feet, 8 inches. Don’t experience breast development May not have menstrual periods. Significance of MEIOSIS Meiosis is important because it ensures that all organisms produced via sexual reproduction contain the correct number of chromosomes. Meiosis also produces genetic variation by way of the process of recombination. To keep the chromosomal number constant To keep species character constant Formation of diversity Evolution Formation of gametes and reproduction