BIOLOGY 1 - REVIEWER.pdf

GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion INTRODUCTION Antonie Van Leeuwenhoek (1632 - 1723) was...

GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion INTRODUCTION Antonie Van Leeuwenhoek (1632 - 1723) was a Dutch naturalist who was the first to study Biology means the study of life. It came magnified cells. He observed microscopic from the Greek words, bios meaning “life” and moving things and called them animacules, logos meaning “study”. There are three major meaning "little animals." divisions of biological sciences namely: Robert Brown (1773 - 1858) was a Scottish Microbiology botanist and microscopist. He was the one who Botany discovered the cell nucleus and distinguished Zoology Gymnosperms (naked seeds) and Angiosperms (covered seeds). Biological Hierarchy Matthias Jakob Schleiden (1804 - 1881) was a Atoms → Molecule → Cell → Tissue → Organ German botanist who immensely studied plant → Body System → Organism → Population → cells, particularly Elodea Leaf. Stated that “All Community → Ecosystem → Biosphere plants are made of one or more cells” - 1838. Current Beliefs about the Origin of Life Theodor Schwann (1818 - 1910) was an English inventor and industrialist who immensely Divine Creation studied animal cells, particularly Cheek Cells. Spontaneous Origin Stated that “All animals are made of one or more Panspermia cells” - 1839. Characteristics of Life Rudolf Carl Virchow (1821 - 1902) was a German pathologist who proposed a third tenet 1. Displays Organization in cell theory stating that “All cells arise from 2. Made of One or More Cells pre-existing cells through cell division”. a. Unicellular (Prokaryotes) b. Multicellular (Eukaryotes) Foundation of Biology - Cell Theory 3. Reproduces 4. Development 5. Adaptations Evolve Overtime THE POSTULATES OF CELL THEORY 6. Responds to Stimuli 7. Homeostasis 1. All organisms are composed of one or 8. Requires Energy more cells. The first cell to exist - PROTOBIONT – Schleiden and Schwann 2. Cells are the smallest and basic units of HISTORY OF CELL structure and function in organisms. – Schleiden and Schwann Robert Hooke (1635 - 1703) was an English scientist who discovered cells in 1665 by 3. All cells arise only from previously observing a thin slice of cork under a existing cells (through cell division). microscope. – Virchow 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 1  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion MICROSCOPES Zacharias Jansen was the one who invented the microscope in the late 1600s. Microscope - allows us to see things that are too small to be seen by the naked eye. Micrograph - image produced by a microscope. Magnification - measure of an optical instrument. Resolution - clarity of an image. Types of Microscopes CELL ORGANELLES Light Compact Microscope (LCM) - Small, portable optical - “Little organs” that are present inside the microscopes that use light to cells. magnify objects. - each has a distinct structure and Electron Microscopes (EMS) function in all cell types. - Uses a beam of electrons to - a part that is not bound by a membrane image samples. will not be considered an organelle. Scanning Electron Structure is an arrangement or Microscope (SEM) organization of parts to form an organ, - Produces system, or living thing. high-resolution images Function is the activity, role, value, or of a sample’s surface. purpose of a part, activity, or trait of an - 100 000x magnification organism. Transmission Electron Note: Structure and Function are Microscope (TEM) interdependent with each other. - Provides detailed images of a sample’s TYPES OF ORGANELLES BY FUNCTION internal structure. - 200 000x magnification PROTECTION Plasma Membrane - regulates the passage of materials into and out of the cell. It separates the interior and exterior of the cell. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 2  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Cell Wall - a rigid layer in plants, algae, Ribosomes - minuscule structures fungi, and bacteria. The outermost layer consisting of small and large subunits of of a cell (except animal cells) gives proteins and RNA molecules. Site for protection, rigid support, and shape to protein synthesis; Some are free-floating the cell. and some are attached to the ER. Initially separated into two parts, they ○ Plants - plasmodesmata merge upon receiving the command to ○ Fungi - chitin protein synthesis. After merging, they ○ Bacteria - peptidoglycan can modify and link amino acids to produce proteins. Cytoplasm - fills the space between the nucleus and cell membrane. Composed Golgi Apparatus - layered stacks of of cytosol, and the cell organelles membrane-enclosed spaces. Process, (excluding the nucleus). sort, and deliver proteins. Temporarily stores proteins. Have enzymes that further modify proteins. GENETIC CONTROL Lysosomes - formed from the Golgi Nucleus - stores genetic information Apparatus. Responsible for intracellular (DNA). It directs all activity of the cell. digestion using its digestive enzymes. In Controls the other cell parts or charge of destroying the cell when it organelles. Houses the nucleolus, a undergoes programmed cell death. region that assembles proteins. Vesicles - aids in transporting materials Genetic Materials: that an organism needs to survive and recycle waste materials. It also delivers DNA - Genetic Information materials produced by different RNA - It carries DNA organelles outside the cell. Also absorbs and destroys toxic substances. MANUFACTURING, STORAGE, Endomembrane System DISTRIBUTION, AND BREAKDOWN The endomembrane system is a network of organelles that work together to Endoplasmic Reticulum (ER) - an produce, modify, package, and transport interconnected network of thin and proteins and lipids within a cell. The process folded membranes. Divided into two begins with protein synthesis on the ribosomes parts, namely: attached to the rough endoplasmic reticulum (ER). These proteins are then folded, modified, ○ Smooth ER - production of and packaged into vesicles that bud off from the lipids, breaking down of alcohol ER. The vesicles travel to the Golgi apparatus and drugs. It doesn’t contain (cis-Golgi network receives and trans-Golgi ribosomes which makes it exports), where the proteins are further smooth. processed and sorted. ○ Rough ER - forms proteins by joining amino acids together (protein synthesis). More hardworking than Smooth ER. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 3  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Finally, the proteins are packaged into Plastids - main sites of photosynthesis new vesicles and transported to their final in eukaryotic cells. A well-known plastid destinations within or outside the cell. is the chloroplast. Contains disc-like Lysosomes, another organelle within the structures called thylakoids, which in endomembrane system, are responsible for turn, contain photosynthetic pigment breaking down cellular waste and debris. This called chlorophyll. collaborative process ensures the efficient and accurate production and distribution of essential Types of Plastids: cellular components. ○ Etioplast Vacuoles - fluid-filled sacs for storage of ○ Chromoplast water, food molecules, toxins, and ○ Chloroplast enzymes. Plant cells contain a larger ○ Leucoplast vacuole compared to animal cells ○ Amyloplast because plants are stationary which ○ Elioplast makes them unable to find and drink ○ Proteinoplast water, hence they need to have a large water reserve. Note: Different pigments in plants are caused by different plastids. Peroxisomes - Exist as small vesicles around the cell and contain digestive and oxidative enzymes. They digest STRUCTURAL SUPPORT, toxic materials and, if they find oxidative MOVEMENT, AND COMMUNICATION substances, they engulf and convert them into useful substances. Centrosome & Centrioles Encompasses metabolic processes, particularly lipid metabolism and ○ Centrosome - contains two detoxification. centrioles. Serves as the main microtubule organizing center. Lysosomes vs Peroxisomes ○ Centrioles - cylinder-shaped organelles made of triple-nine Peroxisomes contain digestive and microtubules arranged in a ring. oxidative enzymes while lysosomes only contain digestive enzymes. Cilia & Flagella ○ Cilia - allows cells to move like ENERGY PROCESSING an oar. It looks like little hairs with motion similar to oars in a Mitochondria - bean-shaped and have rowing team. It moves the two membranes. The inner membrane mucus substances that trap has many folds (cristae) that process foreign microorganisms and cellular respiration like converting food particles that might be harmful into adenosine triphosphate (ATP); to our bodies. mitochondria have their own ribosomes and DNA. Mitochondria are genetically hereditary. ATP - the energy currency of the cell. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 4  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion ○ Flagella - are whiplike or tail-like organelles that allow the cell to swim. It occurs in bacteria, archaea, and eukaryotes. The only cell with a flagella in the human body is the sperm cell. Cytoskeleton Three Types of Cytoskeleton ○ Microtubule: Maintenance of cell shape, transportation of molecules and organelles, cellular movement, and cell wall synthesis. Rigid rod-like. ○ Intermediate Filament: Structural support and cell-to-cell junction. Semi-flexible. ○ Microfilament: Cytokinesis, cell shape maintenance, cellular transportation, and contraction. Flexible. Organelles are Classified into Three Categories Based on the Presence and Absence of Membranes. Organelles without Membrane: Cell Wall, Ribosomes, and Cytoskeleton. Present both in the prokaryotic cell and the eukaryotic cell. Single Membrane-Bound Organelles: Vacuole, Lysosome, Golgi Apparatus, and Endoplasmic Reticulum. Present only in a eukaryotic cell. Double Membrane-Bound Organelles: Nucleus, Mitochondria, and Chloroplast. Present only in eukaryotic cells. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 5  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion PROCARYOTIC AND EUKARYOTIC CELLS Prokaryote Organelles: Capsule – a sticky outer layer that provides protection. Cell Wall – confers rigidity and shape to the cell. Plasma Membrane – a permeability barrier. Plasmid – genetic material. Nucleoid – DNA-containing region in the cytoplasm. Eukaryotic Cells Cytoplasm – a region where chromosomes, ribosomes, and Eukaryotes are organisms with cells inclusions are found. having the three following components: Ribosome – site for protein synthesis. Pilus (Pili) – hair-like appendages that Cell Membrane function in adhesion. Cytoplasm Flagellum – facilitates movement. Nucleus Fimbriae – reproductive organ. Eukaryotes include all living organisms Example of Prokaryotes other than the eubacteria and archaebacteria. Mycoplasma 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 6  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Genetic Materials DNA (Deoxyribonucleic Acid): The primary genetic material in most organisms. It's a double-stranded molecule shaped like a twisted ladder. RNA (Ribonucleic Acid): A single-stranded molecule involved in protein synthesis. It's often referred to as the "messenger" between DNA and protein-making machinery in the cell. Ribosomes Prokaryotic ribosomes are bacterial ribosomes that are small (70S) while eukaryotic ribosomes are large ribosomes (80S). Prokaryotic ribosomes occur free in the cytoplasm while most eukaryotic ribosomes are membrane-bound. Reproduction ANIMAL TISSUE Tissue is a group of cells that have a similar structure and that function together as a unit. The human body is made up of 210 different types of cells. These are groups of cells with a common origin to perform a specific function in the multicellular animal body. A collection of similar cells that perform specific functions is called tissue. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 7  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Epithelial Tissues are widespread throughout the body. They form the covering of all body surfaces, line body cavities, and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception. Usually found on: ○ The epidermis ○ The lining of the intestines ○ The lining of the respiratory tract ○ The lining of the abdominal cavity ○ The sweat glands Classification of Epithelial Tissues 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 8  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Connective Tissues bind structures together, provide support for organs, store fat, transport substances, protect against disease, and assist in tissue repair. They are characterized by an abundance of intercellular matrix with relatively few cells. While connective tissue cells can reproduce, they do so at a slower rate than epithelial cells. Most connective tissues have a good blood supply, but some do not. ○ Loose CT: This type of tissue has a loose arrangement of fibers and cells within a gel-like ground substance. It provides support and cushioning to organs. Examples include areolar tissue (found under the skin) and adipose tissue (fat storage). ○ Dense CT: This tissue has a dense arrangement of collagen fibers, making it strong and resistant to stretching. It includes regular (tendons and ligaments) and irregular (dermis of the skin) connective tissues. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 9  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Muscular Tissues are another important type of tissue in the human body that is responsible for movement, stability, and generating force. ○ Skeletal MT: Skeletal muscle tissue is attached to bones by tendons and is under voluntary control. It is responsible for voluntary movements such as walking, running, lifting weights, and facial expressions. ○ Smooth MT: Smooth muscle tissue is found in the walls of internal organs, blood vessels, and other structures. Smooth muscle contractions are involuntary and slow, enabling various functions like regulating the diameter of blood vessels, pushing food through the digestive tract, and facilitating urination. Propels substances. ○ Cardiac MT: Cardiac muscle tissue is found in the heart. It is striated like skeletal muscle but is also branched and interconnected by specialized junctions called intercalated discs. The cardiac muscle is responsible for involuntary contractions of the heart, which pumps blood throughout the circulatory system. Nervous Tissues are found in the brain, spinal cord, and nerves. It is responsible for coordinating and controlling many body activities. It stimulates muscle ○ Cartilage contraction, creates an awareness of the environment, and plays a major role Fibro - lest flexible in emotions, memory, and reasoning. To Hyaline - flexible do all these things, cells in nervous Elastic - most flexible tissue need to be able to communicate with each other by way of electrical nerve impulses. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 10  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion The cells in nervous tissue that generate and conduct impulses are called neurons or nerve cells. These cells have three principal parts: the dendrites, the cell body, and one axon. Dendrites: Receive signals from other neurons. Cell body: Contains the nucleus and other organelles. Apical Modification: Modifications Axon: Sends signals to other neurons found on the apical surface of epithelial or target cells. cells. ○ Cilia (Cillum): These are hair-like projections in the apical surface of columnar epithelial cells. They move in a sweeping motion. Two Types Primary Cilia - commonly found on mammalian cells. It signals and detects stimuli (sensory CELL MODIFICATION functions). Motile Cilia - moves in Are specialized or modifications a coordinated manner. It re-acquired by the cell after cell division that moves substance. help the cell in different beneficial ways. ○ Flagella (Flagellum): Used in Types of Cell Modification locomotion. They move in a wavelike (undulating) motion. Apical Modification Lateral Modification Basal Modification 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 11  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Cilia and flagella are cell organelles ○ Pseudopods/Pseudopodia: that are structurally similar but different in Pseudopods are temporary length and function. Cilia are shorter and extensions of the cytoplasm more numerous than flagella. used for locomotion and feeling. It is also used to capture prey. Fun Fact: Pseudo means “false” and Pods means “feet”. Hence, Pseudopods are also called “false feet” ○ Villi and Microvilli: Villi are finger-like projections arising from some organs' epithelial layer. Microvilli are minuscule ○ ECM: It is a huge network of protrusions from the cellular proteins and other molecules that surround, support, and give membrane. They are thicker structure to cells and tissues in than cilia and increase the a body. The extracellular matrix surface area for absorption. helps to attach cells to and As the surface area communicate with adjacent increases the absorption cells. level also increases. Fun Fact: Small Intestines absorb nutrients, while the large intestine absorbs water. Lateral Modification: Modifications between apical and basal surfaces. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 12  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Cell Junctions: Cell junctions are intercellular connections between the plasma membranes of adjacent cells of animal tissues. ○ Tight Junctions: Regulates the movement of water and solutes between epithelial layers. It seals the cells to prevent leakage. Usually found on intestinal walls and kidneys. It also helps transfer nutrients from one cell to another. (Seal) ○ Adhering Junctions: Connects the cytoskeleton (actin microfilaments) of two adjacent cells. Maintains cell-to-cell connection. They form in organs where tissues must stretch. (Mechanical Attachment) ○ Gap Junctions: Connect the cytoplasm of two adjacent cells. It allows adjacent cells to communicate and allows the passage of small water-soluble ions and molecules. (Communication/Messenger) ○ Desmosomes: Connect the cytoskeleton (intermediate filaments) of two adjacent cells. CELL CYCLE It is present in tissues that experience mechanical stress. Cell Division vs Cell Cycle (Structure of the Cell) Cell Division Basal Modification: Modifications found on the basal surface of the cell. ○ A way to produce new individuals ○ Hemidesmosomes: Forms a ○ For growth and development bridge between the epithelial ○ Production of gametes cells and the extracellular matrix ○ Repair of tissues or organs of another tissue. It contributes ○ Prokaryotes - Binary Fission to the attachment of epithelial ○ Eukaryotes - Cell Cycle cells to the underlying basement membrane. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 13  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Cell Cycle Condensed: Long thin chromatin strands into compact chromosomes. ○ Series of events that involve cell Telomere: Tips of a chromosome. growth and cell division. Ploidy Levels - number of chromosomes in cell. Two Parts: Haploid (n): Cells are those that have Interphase (Growth) only a single set of chromosomes. M Phase (Mitosis & Diploid (2n): Cells have two sets of Meiosis) chromosomes Terminologies Two Types of Division DNA: Molecule that carries genetic information (development, growth, & 1. Mitotic/Equational Division: It is reproduction) primarily for growth, repair, and asexual Chromosomes: Made of two sister reproduction. It involves a single division chromatids. process, resulting in two daughter cells Chromatids: These are joined at the that are genetically identical to the centromere; Half of a chromosome. parent cell; 2n = 2n. Chromatin: Unravel condensed structure of DNA to form chromosomes. 2. Meiotic/Reductional Division: It is specifically for the formation of gametes (sperm or egg cells) for sexual reproduction. It involves two divisions, resulting in four genetically different daughter cells (gametes), each with half the number of chromosomes as the parent cell; 2n = n. Homologous Pairs Zygote Formation - Mitosis Sex Cells Development - Meiosis 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 14  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Cell Cycle M PHASE (MITOSIS) 1. Interphase - DNA is copied Mitosis: This type of cell division produces two 2. Cell Division (M Phase) - DNA is split identical cells with the same number of 3. Cytokinesis - The parent cell is divided chromosomes; All body cells are diploid (2n). 1. Prophase - 2n INTERPHASE a. The chromosomes coil up The resting stage between cell division; (condense) and become visible. is longer than the M phase. b. The nuclear membrane breaks down so that the mitotic spindle 1. Gap 1 - the cell grows and copies all cell can reach the center of the cell. contents except DNA. c. The mitotic spindle attaches to the chromosomes. Checkpoints: d. The nucleoli break down and become invisible. a. Signals tell the cells to divide. b. Cells must have plenty of 2. Metaphase (MIDDLE) - 2n nutrients. c. The DNA must be in good a. Cells organize the condition. Cells must be large chromosomes by lining them up enough to divide. in the middle of the mitotic 2. Synthesis - the cell synthesizes a spindle complete copy of the DNA in its nucleus. b. At the metaphase checkpoint, It also duplicates a cells make sure that all the microtubule-organizing structure called chromosomes are attached to the centrosome. The centrosomes help the mitotic spindle. separate DNA during the M phase. c. Cells can’t continue through mitosis unless they pass the 3. Gap 2 - duplication of organelles; metaphase checkpoint. protein synthesis; preparation of cell division. 3. Anaphase (AWAY) - 4n Checkpoints: a. During anaphase, the replicated chromosomes are separated so a. The DNA isn’t damaged. that each sister chromatid goes b. The cell copied all the to opposite sides of the cell. chromosomes. b. The identical sister chromatids c. Signals tell the cell to proceed are separated carefully to into mitosis. ensure that each new cell will get one. APOPTOSIS - cell death or suicide. c. After the sister chromatids are separated from each other, they’re again called chromosomes. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 15  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion 4. Telophase - 4n a. The chromosomes uncoil (decondense) and become invisible. b. The nuclear membrane reforms. c. The mitotic spindle breaks down. d. The nucleoli reform and become visible. CYTOKINESIS - 2n During cytokinesis, the cell membrane pinches in at the cell equator, forming a cleft called the cleavage furrow; Membrane separates to produce two daughter cells; The cell now reverts to interphase. M PHASE (MEIOSIS) Meiosis: The making of gametes; Type of cell division reduces chromosomes’ number by half; All sex cells are haploid (n); The four daughter cells are not genetically identical; Has two stages (a) Meiosis Ⅰ - reductional division. (b) Meiosis ⅠⅠ - equational/mitotic-like division; Has an equal number of Father and Mother chromosomes. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 16  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Meiosis I 05. Diakinesis: Chromosomes continue to condense and become more visible. 1. Prophase I - 2n The nuclear envelope breaks down. The nucleolus disappear; Completely a. The nuclear envelope breaks separate from each other and regain down. their individual identity. b. Chromosomes condense and homologous pairs come together. c. Crossing over occurs, where genetic material is exchanged between homologous chromosomes. d. It is separated into 5 subphases: 01. Leptotene: Chromosomes become visible as long, thin threads. The nuclear envelope remains intact. 02. Zygotene: Homologous chromosomes begin to pair up, a process called synapsis. The paired homologous chromosomes are called bivalents or tetrads. 03. Pachytene: Chromosomes thicken and become more visible. Crossing over occurs, where genetic material is exchanged between homologous chromosomes. 04. Diplotene: Homologous chromosomes begin to separate, but they remain 2. Metaphase I - 2n connected at points called chiasmata. These chiasmata are the sites of a. Homologous pairs line up at the crossing over. equator of the cell. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 17  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion 3. Anaphase I - 2n 8. Telophase II - 2n a. Homologous chromosomes are a. Nuclear envelopes form around separated and move to opposite the separated chromatids. poles. b. Chromosomes decondenses. c. The nucleolus starts 4. Telophase I - 2n reappearing. a. Nuclear envelopes form around the separated chromosomes, CYTOKINESIS II - n and nucleolus starts to reappear Divides the cell into four haploid daughter cells. CYTOKINESIS I - n Divides the cell into two daughter cells INTERKINESIS INTERPHASE II Interkinesis or interphase II is a period of rest that cells of some species enter during meiosis between meiosis I and meiosis II. Meiosis II 5. Prophase II - n a. Chromosomes condense and become short and compact. b. The nuclear membrane and nucleolus start to vanish. 6. Metaphase II - n a. Chromosomes line up at the equator of the cell forming the metaphase plate. 7. Anaphase II - 2n a. Sister chromatids are separated and move to opposite poles due to the contraction of spindle fibers. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 18  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Importance of Haploid Gametes 1. Spermatogonia Proliferation n (egg) + n (sperm) = 2n (zygote) Spermatogonia are undifferentiated germ cells. If the sex cells didn’t have ½ the amount They undergo mitotic division to produce more spermatogonia. of chromosomes, what would happen when the Some of these spermatogonia sperm and egg made a zygote? differentiate into primary spermatocytes. 46 chr’s + 46 chr’s = 92 chr’s buang gwa mo eh! 2. Primary Spermatocyte Formation Spermatogenesis is the process of sperm cell production, occurring in the seminiferous tubules Primary spermatocytes are the largest type of spermatocyte. of the testes. It involves several stages, starting They are formed from from spermatogonia and culminating in the spermatogonia. maturation of sperm cells. They are diploid, meaning they have 46 chromosomes. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 19  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion 3. Meiosis I 7. Sperm Maturation Primary spermatocytes undergo Mature sperm cells are released meiosis I, a type of cell division into the lumen of the that reduces the chromosome seminiferous tubules. number by half. They are then transported to the This results in two secondary epididymis for storage and spermatocytes, each with 23 further maturation. chromosomes. In the epididymis, sperm cells During meiosis I, genetic acquire the ability to fertilize an recombination occurs, allowing egg. for genetic variation in sperm cells. Oogenesis is the process of egg cell (ovum) production in females. It occurs in the ovaries 4. Secondary Spermatocyte Formation and is a complex process involving meiosis and Secondary spermatocytes are cellular differentiation. smaller than primary spermatocytes. 1. Oogonia They are haploid, meaning they have 23 chromosomes. These are the primordial germ cells that differentiate into 5. Meiosis II oocytes. They are diploid and undergo Secondary spermatocytes mitotic division to increase their undergo meiosis II, a second round of cell division. number. This results in four spermatids, each with 23 chromosomes. 2. Primary Oocyte 6. Spermiogenesis A primary oocyte is formed from an oogonium that has entered Spermatids undergo a series of transformations to become meiosis I. mature sperm cells. It remains arrested in the first This process is called meiotic division until puberty. spermiogenesis. During spermiogenesis, the 3. First Meiotic Division spermatid develops a head, midpiece, and tail. At puberty, a primary oocyte The head contains the nucleus, which houses the genetic resumes meiosis I, resulting in a material. secondary oocyte and a first The midpiece contains polar body. mitochondria, which provide The first polar body is a small, energy for the sperm cell. non-functional cell. The tail, or flagellum, allows the sperm cell to move. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 20  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion 4. Secondary Oocyte The secondary oocyte is the larger cell produced from meiosis I. It is haploid and can be ovulated. 5. Polar Body The first polar body is a small, non-functional cell produced along with the secondary oocyte. 6. Second Meiotic Division If the secondary oocyte is fertilized, it completes meiosis II, producing a mature ovum and a second polar body. The second polar body is also non-functional. 7. Ovum The ovum is the mature egg cell. It is haploid and can be fertilized by a sperm cell. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 21  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion CANCER CHROMOSOMAL ABNORMALITIES Cancer is a disease that involves Aside from cancer, there are also other uncontrolled growth and spread of abnormal disorders or diseases associated with the cell cells in the body. This can occur in various body cycle. Separation of chromosomes is crucial parts when the cell cycle process breaks down, because it will ensure the chromosomes’ causing abnormal or damaged cells to multiply number’s integrity after the division. and form tumors. This occurs when a damaged cell fails to undergo apoptosis; MITOSIS. Euploidy: It’s term used to describe when an organism has the correct number of chromosomes for its species. This is the normal NORMAL CELLS CANCER CELLS state for most individuals. Normal cells only grow Grow in the absence of when they receive signals telling them to signals grow Ignore signals that Can undergo apoptosis normally tell cells to stop dividing or to die Stop growing when they encounter other cells, Invade into nearby and most normal cells areas and spread to do not move around the other areas of the body body The immune system normally eliminates Hide from the immune damaged or abnormal system. cells Accumulate multiple Have normal changes in their chromosome count (23 chromosomes, such as pairs) duplications and deletions of chromosome parts. Some cancer cells Numerical Aberrations make energy from Rely on nutrients for nutrients in a different Occurs when an individual has an growth way than most normal cells. This lets cancer abnormal number of chromosomes. This can cells grow more quickly. happen when chromosomes are gained (extra copies) or lost (missing copies) during cell Tell blood vessels to division. Oxygen, nutrients, and grow toward tumors other substances are which supply tumors received from blood with oxygen and Aneuploidy: It is a condition where an vessels nutrients and remove individual has an abnormal number of waste products from tumors. chromosomes. This occurs when a cell has either an extra chromosome or is missing a chromosome. It's a common type of chromosomal abnormality. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 22  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Triploidy Syndrome: Description: Occurs when an individual has an extra complete set of chromosomes. Symptoms: Often fatal before or shortly after birth, but can include physical abnormalities and developmental delays. TRIGGERWARNING! T ^ T Turner Syndrome: SYNDROMES Description: Occurs in females who have only one X chromosome or part of Down Syndrome (Trisomy 21): an X chromosome. Symptoms: Short stature, infertility, Description: Individuals with Down heart defects. syndrome have an extra copy of chromosome 21. Symptoms: Intellectual disability, delayed development, distinctive facial features, increased risk of certain health problems. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 23  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Cri du Chat Syndrome (Monosomy 5): Klinefelter Syndrome (XXY Males): Description: Caused by a deletion on Description: Occurs in males who have chromosome 5. an extra X chromosome. Symptoms: Distinctive cat-like cry, Symptoms: Tall stature, infertility, intellectual disability, delayed learning difficulties. development. Patau Syndrome (Trisomy 13): Angelman Syndrome: Description: Occurs when an individual has an extra copy of chromosome 13. Description: Caused by a deletion on Symptoms: Intellectual disability, cleft chromosome 15. lip and palate, heart defects. Symptoms: Intellectual disability, seizures, happy demeanor. Pallister Killian Syndrome: Edward’s Syndrome (Trisomy 18): Description: Caused by a duplication of Description: Occurs when an individual the small arm of chromosome 12. has an extra copy of chromosome 18. Symptoms: Intellectual disability, Symptoms: Intellectual disability, heart delayed development, distinctive facial defects, clenched fists. features. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 24  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Burkitt’s Lymphoma: Description: A type of non-Hodgkin lymphoma, a cancer of the lymphatic system; Translocation of chromosome 8. Associated with: Epstein-Barr virus. TRANSPORT MECHANISM Transport mechanisms are essential for various biological processes, including nutrient Walker-Warburg Syndrome: uptake, waste removal, and maintaining cellular homeostasis. These mechanisms can be Description: A rare genetic disorder categorized into two main types: Passive that affects the brain, spinal cord, and Transport and ActiveTransport. muscles; Inversion of chromosome 9. Symptoms: Intellectual disability, seizures, muscle weakness. PASSIVE TRANSPORT Passive transport occurs without the expenditure of cellular energy. It relies on the natural movement of molecules from areas of higher concentration to areas of lower concentration. Simple Diffusion Molecules move from a point of greater Four Ring Syndrome: concentration to less concentration to attain equilibrium (equal distribution). Description: A rare chromosomal abnormality where four rings of chromosome material are fused together. Symptoms: Can vary widely, but may include intellectual disability, heart defects, and facial abnormalities (cleft palate). 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 25  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Facilitated Diffusion: Larger or charged Water Potential: Describes the molecules require the assistance of membrane movement of water molecules as they proteins to cross the membrane. This is done undergo osmosis. through channels or carriers. Three Types of Solution: Ion Channels: Selective pores that allow specific ions to pass through the Isotonic: A solution with the same membrane. These can be gated by solute concentration as the cell. Cells in voltage, ligands, or mechanical stimuli. an isotonic solution neither gain nor lose Carrier Proteins: Bind to specific water; Iso = same. molecules and undergo conformational Hypertonic: A solution with a higher changes to transport them across the solute concentration than the cell. Cells membrane. Examples include glucose in a hypertonic solution lose water and transporters and amino acid shrink (crenation); hyper = more transporters. Hypotonic: A solution with a lower solute concentration than the cell. Cells in a hypotonic solution gain water and may burst (hemolysis); hypo = less. Osmosis: The movement of water through a membrane from an area of low solute concentration to an area of high solute concentration is essential for maintaining cell volume and pressure. Osmosis depends on the solute concentration in the solution. Simple Diffusion: High Concentration → Low Concentration Facilitated Diffusion: Low Concentration → High Concentrattion Osmosis: Low Solute Con. → High Solute Con. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 26  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion ACTIVE TRANSPORT BULK OR VESICULAR TRANSPORT Active transport requires the For larger molecules or substances, expenditure of cellular energy, usually in the cells use bulk or vesicular transport form of ATP, to move molecules against their mechanisms: concentration gradient. Endocytosis: Cells engulf substances by Primary Active Transport: Directly uses ATP to forming a vesicle around them, which then transport molecules. pinches off from the cell membrane and enters the cell. This is used for: Example: Phagocytosis: Cell engulfs large solid Sodium-potassium pump: Pumps particles (e.g., bacteria, cell debris) by sodium ions out of the cell and forming a phagosome, which fuses with potassium ions into the cell, maintaining a lysosome for digestion; cell eating. the cell's resting membrane potential. Pinocytosis: Cell engulfs small fluid droplets by forming a pinocytic vesicle. This is used for uptake of nutrients and extracellular fluid; cell drinking. Receptor-mediated Endocytosis: A specific type of endocytosis where a specific molecule binds to a receptor on the cell surface, triggering the formation of a vesicle and internalization of the molecule. This is used for selective uptake of specific substances, such as hormones, growth factors, and antibodies. Exocytosis: Vesicles inside the cell fuse with the cell membrane, releasing their contents into the extracellular space. This is used for: Secretion: Release of hormones, neurotransmitters, and enzymes. 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 27  GENERAL BIOLOGY 1 REVIEWER Darwin P. Eleccion Cell Signaling: Communication between cells. Cell-matrix Interactions: Adhesion and migration. Waste Removal: Excretion of cellular waste products. Factors Affecting Transport Several factors influence the rate of transport: Concentration Gradient: The difference in concentration between two areas. Temperature: Higher temperatures increase the kinetic energy of molecules, increasing the rate of diffusion. Surface Area: A larger surface area increases the rate of diffusion. TAPOS NA GID TENKYU LORD! Membrane Permeability: The ability of molecules to pass through the membrane. This is influenced by the lipid composition and the presence of membrane proteins. Membrane Proteins: The availability and function of specific membrane proteins can facilitate or inhibit transport. FIN. “There are times when I'm lying in my bed How I bellow and cry from this stupid gate And my eyes are like windshields on a rainy day Almost rubbed-down, swelling As I keep on dipping my face in these cold hands of mine Heaven knows how embittered I am” ADDING MY FACE PARA MADALA PRINT!! – Heaven Knows by Orange and Lemons 12 STEM - ST. MARIA GORETTI BATCH 2024-2025 28