NMAT Biology 1 Cell Biology PDF

NMAT REVIEW (BIOLOGY) CELLULAR BIOLOGY INTRODUCTION TO CELLS (DNA) is located, usually in the form of Cell is the basic unit of a living body. a circular chromosome. It makes all the tissues of an organism. - Plasmids: are...

NMAT REVIEW (BIOLOGY) CELLULAR BIOLOGY INTRODUCTION TO CELLS (DNA) is located, usually in the form of Cell is the basic unit of a living body. a circular chromosome. It makes all the tissues of an organism. - Plasmids: are small, circular pieces of Cell has three (3) main parts: DNA that are separate from the o DNA: Genetic material chromosome and often contain genes that o Cytoplasm: Fluid matrix confer specific traits, such as antibiotic o Cell membrane resistance. - Flagella: Flagella are long, whip-like MICROSCOPE structures that protrude from the cell and Light Microscope are used for locomotion. - Use visible light - Pili: thin, hair-like structures that - Commonly used in a live specimen protrude from the cell and are used for - Resolution (200 nm) attachment to surfaces and other cells. - Magnification (Max: 1000x) - Fimbria: shorter and more numerous Electron Microscope than flagella, another type of bacterial Scanning electron microscope (SEM) surface structure that is used for - Used beam of electrons attachment. - Dead specimens - Resolution (1-10nm) Eukaryotes: an organism (single or - Requires metal coating (gold) multicellular) that contains a nucleus and other - Requires a vacuum environment (limited membrane-bound organelles. samples) Basic Parts: - Topography: 3-Dimensional - Nucleus: large, membrane-bound Transmission electron microscope (TEM) organelle that contains the cell's genetic - Used beam of electrons material (DNA) and is responsible for - Dead specimens controlling gene expression and cell - Resolution (1-10nm) division. - Requires a vacuum environment (limited o Nucleolus: a dense region within samples) the nucleus that is involved in - Internal structures: 2-Dimensional synthesizing ribosomal RNA and assembling ribosomes. CELLS COMPONENTS AND o Chromatin: a mixture of DNA ORGANELLES and proteins. Prokaryotes: a single-celled organism that lacks o DNA: the genetic material of the a nucleus and membrane-bound organelles. cell Basic Parts: - Mitochondria: responsible for energy - Cell membrane: a thin layer of lipids production through aerobic respiration. and proteins that encloses the cell and They generate ATP (adenosine regulates the passage of molecules into triphosphate), the main energy currency and out of the cell. of the cell. - Cell Wall: protects the cell membrane - Endoplasmic reticulum: a network of and provides structural support for the membranous tubes and sacs that are cell. involved in protein and lipid synthesis, as - Cytoplasm: a gel-like substance that fills well as the detoxification of drugs and the cell and contains enzymes, other harmful substances. ribosomes, and other molecular - Golgi Apparatus: a stack of flattened compounds. membranes that receive and modify - Nucleoid: The nucleoid is a region proteins and lipids from the ER, sort within the cell where the genetic material Tenten’s Academy Online Review Center NMAT REVIEW (BIOLOGY) CELLULAR BIOLOGY them into vesicles, and send them to their - Large Vacuoles: large, membrane- final destination. bound sacs that store water, nutrients, - Vesicles: transport molecules between and waste products. different parts of the cell, as well as to the plasma membrane for secretion outside THE CELL CYCLE the cell. The cell cycle is a series of events that occur - Lysosomes: contain digestive enzymes in a eukaryotic cell leading to its division and that break down macromolecules such as duplication. The cell cycle is regulated by a proteins, nucleic acids, and lipids. complex network of molecular events, - Peroxisomes: contain enzymes that are including checkpoint controls, cyclins, and involved in breaking down fatty acids cyclin-dependent kinases. and other metabolic processes. Four main phases: - Plasma membrane: a thin layer of lipids G1 phase: cell growth and proteins that encloses the cell and S phase: DNA replication regulates the passage of molecules into G2 phase: Protein synthesis and out of the cell. M phase: Cell division (Mitosis) - Cytoskeleton: a network of protein fibers that provide structural support and G1 Phase help the cell maintain its shape. It also The cell grows and prepares for DNA plays a role in cell movement and synthesis in the S phase. The duration of the division. G1 phase varies among different cell types o Microtubules – the thickest and can be influenced by various internal and components of the cytoskeleton external factors, such as growth factors, and are made up of the protein nutrient availability, and DNA damage. tubulin. Cell growth and metabolic activity: o Intermediate filaments – made Accumulate nutrients and synthesize up of various proteins, such as materials. This phase is crucial for the cell's keratin, vimentin, and lamin, and preparation for DNA synthesis in the S phase, are found in different cell types, Checkpoint control mechanisms: such as skin cells and muscle Restriction point (R point) - This is a cells. checkpoint that determines whether the cell o Microfilaments – thinnest has sufficient resources and growth signals to components of the cytoskeleton proceed to the S phase. and are made up of protein actin. Organelles only in ANIMAL CELLS S Phase - Centrioles: paired barrel-shaped The S phase, also known as the synthesis organelles located in the cytoplasm of phase, is the second phase of the cell cycle. animal cells near the nuclear envelope. During this phase, the cell replicates its DNA Centrioles play a role in organizing and synthesizes histones, the proteins that microtubules that serve as the cell's package DNA into chromosomes. skeletal system. They help determine the Checkpoint control mechanisms: locations of the nucleus and other DNA damage checkpoint: This checkpoint organelles within the cell. ensures that the DNA is intact and can be Organelles only in PLANT CELLS replicated without errors. If DNA damage is - Chlorophyll: carries out photosynthesis, detected, checkpoint proteins such as p53 can the process by which plants convert light activate signaling pathways that halt the cell energy into chemical energy. cycle and initiate DNA repair mechanisms. - Cell Wall: a rigid layer that surrounds the cell membrane and provides support and protection to the cell. Tenten’s Academy Online Review Center NMAT REVIEW (BIOLOGY) CELLULAR BIOLOGY G2 Phase Meiosis: a type of cell division in sexually During this phase, the cell completes its reproducing organisms that reduces the number preparations for cell division, including the of chromosomes in gametes synthesis of microtubules and other During meiosis, a diploid cell, which has two components of the mitotic spindle. sets of chromosomes (one from each parent), Checkpoint control mechanisms: undergoes two rounds of cell division, G2/M checkpoint: This checkpoint ensures resulting in the formation of four haploid that the cell has completed all necessary cells. preparations for mitosis before proceeding to Meiosis is a complex process that involves cell division. It is regulated by proteins such two rounds of cell division, called meiosis I as cyclin B and the CDK1 complex, which and meiosis II. activate signaling pathways that initiate Meiosis I mitosis. o Prophase I: synapsis, crossing over, and formation of the tetrad o Metaphase I: alignment of tetrads on M Phase the metaphase plate The M phase, or mitotic phase, is the final o Anaphase I: separation of stage of the cell cycle. homologous chromosomes Two main events: o Telophase I: formation of two o Mitosis: the process by which the haploid daughter cells nucleus divides into two identical Meiosis II daughter nuclei, o Prophase II: spindle apparatus forms o Cytokinesis: the physical separation and attaches to chromosomes of the two daughter cells. o Metaphase II: chromosomes align at the metaphase plate o Anaphase II: sister chromatids Mitosis (PMAT) separate and move to opposite poles 1. Prophase: Chromosomes condense and o Telophase II: formation of four become visible, and the nuclear envelope haploid daughter cells breaks down. The mitotic spindle begins to form, with microtubules extending SPECIALIZED CELLS from the centrosomes to the Specialized cells are cells that have chromosomes. developed unique structures and functions 2. Metaphase: Chromosomes line up at the that allow them to carry out specific tasks in equator of the cell, with their centromeres the human body. aligned on the metaphase plate. The There are many types of specialized cells in spindle fibers attach to the kinetochores the human body: on each chromosome. - Nerve cells (Neurons): Transmits 3. Anaphase: The spindle fibers pull the electrical and chemical signals sister chromatids apart, and each throughout the body. chromatid is pulled towards opposite - Muscle cells (Myocytes): Body poles of the cell. movement. 4. Telophase: Chromosomes reach the - Red Blood cells (Erythrocytes): poles of the cell and begin to decondense. Transportation of oxygen and nutrients. The nuclear envelope reforms around - White Blood cells (Leukocytes): each set of chromosomes, and the spindle immune response fibers begin to break down. - Epithelial cells: Absorption, protection, secretion, and sensory activities. Tenten’s Academy Online Review Center NMAT REVIEW (BIOLOGY) CELLULAR BIOLOGY - Bone cells (Osteocytes): Maintain the energy for the plant, stored as starch, or used for structure and function of the bone. the synthesis of other organic compounds. - Fat cells (Adipocytes): Stores energy in the form of fat. Chemosynthesis - Reproductive cells (Gametes): Give Chemosynthesis is a process by which certain rise to offspring through sexual bacteria and other microorganisms obtain reproduction. energy for their metabolism by converting inorganic molecules into organic compounds. CELLULAR PROCESSES Unlike photosynthesis, which uses light Cellular processes regulated the energy to drive the process, chemosynthesis characteristics of life. relies on the energy derived from chemical The cell is a system that conducts a variety of reactions. functions associated to maintain life. Chemosynthetic organisms are typically Basic cellular processes include: found in environments where sunlight is scarce or completely absent, such as deep-sea Photosynthesis hydrothermal vents, volcanic hot springs, and the process by which green plants, algae, and some cave systems. These organisms are some bacteria convert light energy from the capable of utilizing various inorganic Sun into chemical energy in the form of substances, such as hydrogen sulfide, glucose (a type of sugar). methane, ammonia, and iron, as sources of It is a vital process for life on Earth as it is energy. responsible for producing oxygen and For example: organic compounds, which serve as a source Chemosynthetic bacteria use the chemical- of energy for organisms that cannot perform rich fluids spewing from the vents to produce photosynthesis. organic molecules. They do this by oxidizing The process of photosynthesis takes place hydrogen sulfide (H2S), or other compounds primarily in the chloroplasts, specialized present in the vent fluid. The energy released organelles found in the cells of green plants during these oxidation reactions is used to and algae. Chloroplasts contain a green convert carbon dioxide (CO2) into organic pigment called chlorophyll, which absorbs compounds, such as sugars. light energy. Photosynthesis has two main stages: Respiration o the light-dependent reactions Cellular respiration is the process by which o light-independent reactions (Calvin cells break down organic molecules, such as cycle) glucose, to generate energy in the form of Light-dependent reactions: ATP (adenosine triphosphate). chlorophyll captures light energy, which is then Cellular respiration has three main stages: used to generate high-energy molecules like ATP o Glycolysis (adenosine triphosphate) and NADPH o Krebs cycle (nicotinamide adenine dinucleotide phosphate). o Oxidative phosphorylation These energy-rich molecules are utilized in the (including the electron transport next stage. chain). Light-independent reactions (Calvin cycle): Glycolysis: This is the initial step of cellular ATP and NADPH produced in the light- respiration and takes place in the cytoplasm of the dependent reactions are used to convert carbon cell. During glycolysis, a molecule of glucose is dioxide (CO2) into glucose. This process broken down into two molecules of pyruvate. involves a series of chemical reactions that take This process produces a small amount of ATP and place in the stroma of the chloroplasts. The NADH (nicotinamide adenine dinucleotide). glucose produced can be used as a source of Tenten’s Academy Online Review Center NMAT REVIEW (BIOLOGY) CELLULAR BIOLOGY Krebs cycle: After glycolysis, the pyruvate - a specialized form of cell division that molecules are transported into the mitochondria, occurs in reproductive cells (gametes) where the Krebs cycle occurs. Each pyruvate is and is involved in sexual reproduction. further broken down, releasing carbon dioxide as - It consists of two successive divisions, a byproduct. This cycle generates additional called meiosis I and meiosis II. NADH and FADH2 (flavin adenine - Meiosis I involve the pairing of dinucleotide). homologous chromosomes and their Oxidative phosphorylation: The final stage exchange of genetic material in a process takes place in the inner mitochondrial membrane called crossing over. The resulting (Cristae). The NADH and FADH2 molecules daughter cells are genetically distinct produced in the previous stages donate their from the parent cell and have half the electrons to the electron transport chain. As the number of chromosomes. electrons pass through a series of protein - Meiosis II is similar to mitosis and complexes, their energy is gradually released. results in the separation of sister This energy is used to pump protons (H+) across chromatids, producing four haploid the membrane, creating a proton gradient. The daughter cells (gametes) with unique flow of protons back through ATP synthase combinations of genetic material. generates ATP through a process called chemiosmosis. At the end of the electron Cell Differentiation transport chain, oxygen acts as the final electron Cell differentiation refers to the process by acceptor, combining with protons to form water. which unspecialized or less specialized cells become specialized and acquire distinct Cell Division structures and functions. During Cell division is the process by which a single development, cells differentiate to give rise to parent cell divides into two or more daughter the various cell types that make up the tissues cells. There are two primary types of cell and organs of an organism. division: mitosis (autosomes) and meiosis Cell differentiation is regulated by a (gametes). combination of intrinsic genetic programs Mitosis and extracellular signals. - the process by which somatic cells (non- The process of differentiation involves reproductive cells) divide to produce two changes in gene expression, resulting in the genetically identical daughter cells. activation or repression of specific sets of - It consists of several stages: prophase, genes that determine cell fate and function. metaphase, anaphase, and telophase. The specific cues and mechanisms involved - Prophase: the DNA in the cell's nucleus in cell differentiation vary depending on the condenses into visible chromosomes, and organism and the particular cell type. the nuclear membrane starts to break However, common processes that contribute down. to differentiation include cell signaling, cell- - Metaphase: the chromosomes line up at cell interactions, changes in gene expression, the center of the cell. epigenetic modifications, and cellular - Anaphase: the separation of sister movements. chromatids, which are pulled to opposite The process of cell differentiation involves a ends of the cell by spindle fibers. series of steps that lead to the specialization - Telophase: two new nuclei form around of cells into distinct cell types: the separated chromosomes, and the cell o Specification undergoes cytokinesis, dividing into two o Determination daughter cells. Each daughter cell o Differentiation receives an identical set of chromosomes. o Maturation Meiosis Tenten’s Academy Online Review Center NMAT REVIEW (BIOLOGY) CELLULAR BIOLOGY - Specification: During early the body, but they cannot give rise to the development, cells become specified to extraembryonic tissues required for follow specific developmental pathways. embryonic development. For examples: This occurs through the activation of Embryonic stem cells (derived from the specific genes and the establishment of inner cell mass of a developing embryo) cell fate. At this stage, cells are still and induced pluripotent stem cells relatively flexible in their potential (generated from adult cells that have outcomes. been reprogrammed to a pluripotent - Determination: Determination is a state) commitment step where cells become - Multipotent or unipotent cells: committed to a particular developmental Multipotent cells have a more limited fate. It involves irreversible changes in range of developmental options gene expression patterns that restrict the compared to pluripotent cells. They can cell's future potential and establish its differentiate into a specific subset of fate. related cell types within a particular - Differentiation: Once determined, cells tissue or organ. For example, begin to differentiate, acquiring Multipotent cells include blood stem specialized structures and functions. This cells giving rise to different blood cell involves changes in gene expression that types. Unipotent cells, on the other hand, result in the production of specific can only differentiate into a single cell proteins and the development of distinct type such as an Epidermal stem cell cellular characteristics. Differentiation (regenerate skin). often involves cell shape changes, changes in organelle composition, and Practice Questions: the development of specialized cellular structures. 1. Proteins are responsible for nearly every - Maturation: Maturation refers to the task of cellular life, including cell shape final stages of differentiation, where cells and inner organization, product reach their fully functional state. This can manufacture and waste cleanup, and involve further morphological changes, routine maintenance. What organelles acquisition of specific cell surface synthesize protein? markers, and the development of a. Ribosomes specialized organelles or cellular b. Endoplasmic reticulum processes that enable the cell to perform c. Nucleus its specific function. d. Nucleolus Cell Potency: the cell's ability to differentiate 2. Which type of microscopy uses a beam of into other cell types. electrons to produce high-resolution - Totipotent cells: Totipotent cells have images of the external surfaces of a the highest level of potency and can give biological sample? rise to all cell types in an organism, a. Light microscopy including both embryonic and b. Fluorescence microscopy extraembryonic tissues. In humans, the c. Transmission electron microscopy only totipotent cells are the cells of the d. Scanning electron microscopy early embryo up to the eight-cell stage 3. As humans excrete waste from the body (Zygote), where each cell has the through sweat, urine, feces etc. The cells potential to develop into a complete present within the body also have their organism. metabolic waste and excrete it through - Pluripotent cells: Pluripotent cells can many processes. Which of the following is differentiate into almost all cell types of responsible for breaking down waste materials in cells? Tenten’s Academy Online Review Center NMAT REVIEW (BIOLOGY) CELLULAR BIOLOGY a. Ribosomes 10. The phase of the cell cycle where the cell b. Lysosome grows, carries out its normal functions, c. Golgi apparatus and prepares for DNA replication is: d. Mitochondria a. G1 phase 4. The process by which cells engulf and take b. S phase in particles or substances from their c. G2 phase surroundings is called: d. M phase a. Osmosis 11. Which type of cells are responsible for b. Diffusion producing antibodies in the immune c. Endocytosis system? d. Exocytosis a. T cells 5. Prokaryotes are single-celled organisms b. B cells that are capable of moving from one place c. Basophils to another. All are surface structures of d. Neutrophils prokaryotes needed for movement except: 12. Diabetes is a chronic (long-lasting) health a. Cilia condition that affects how your body turns b. Fimbria food into energy. Your body breaks down c. Flagella most of the food you eat into sugar d. None of the above (glucose) and releases it into your 6. The cell cycle is a series of events that bloodstream. When your blood sugar goes occur in a cell leading to its division and up, this organ is signaled to release insulin. duplication. Which is the correct sequence a. Liver of phases in the cell cycle? b. Gallbladder a. G1 → S → G2 → M c. Appendix b. G2 → M → G1 → S d. Pancreas c. S → G1 → M → G2 13. Which type of cells in the bones are d. M → G1 → S → G2 responsible for breaking down and 7. The phase of the cell cycle where DNA remodeling bone tissue? replication occurs is: a. Osteoblast a. G1 phase b. Osteoclast b. S phase c. Osteocytes c. G2 phase d. Osteogenic stem cells d. M phase 14. The hydrochloric acid in the gastric 8. Cell cycle checkpoints are surveillance juice breaks down the food and the mechanisms that monitor the order, digestive enzymes split up the proteins. integrity, and fidelity of the major events What cells in the stomach is responsible in of the cell cycle. Which of the following is secreting HCl? responsible for regulating the cell cycle? a. Chief cells a. Cyclins b. Mucous secreting cells b. Helicase c. Neuroendocrine cells c. DNA polymerase d. Parietal cells d. Primers 15. Fibrinogen is a soluble protein in the 9. The protein complex responsible for plasma that is broken down to fibrin by the separating sister chromatids during cell enzyme thrombin to facilitate blood division is called: clotting. In which organ does fibrinogen a. Spindle fiber produced and synthesized? b. Cyclin a. Liver c. Kinetochore b. Bone Marrow d. Centromere c. Lungs d. Blood Tenten’s Academy Online Review Center NMAT REVIEW (BIOLOGY) CELLULAR BIOLOGY 16. Which process involves the breakdown of glucose in the absence of oxygen, resulting in the production of lactic acid or ethanol? a. Fermentation b. Glycolysis c. Aerobic respiration d. Photosynthesis 17. Which process involves the rearrangement of genetic material during the formation of gametes? a. Mitosis b. Meiosis c. Apoptosis d. DNA synthesis 18. What process occurs when a cell engulfs large particles or other cells by forming membrane-bound vesicles? a. Phagocytosis b. Exocytosis c. Trogocytosis d. Pinocytosis 19. Insulin secreted by the beta cells of the pancreas travels via the bloodstream and influences the activity of somatic cells. The type of cell-to-cell communication is: a. Autocrine b. Endocrine c. Paracrine d. Contact dependent 20. Which cellular process involves the synthesis of RNA molecules using DNA as a template? a. Replication b. Transcription c. Translation d. Extraction Answer Key: 1. A 11. B 2. D 12. D 3. B 13. B 4. C 14. D 5. B 15. A 6. A 16. A 7. B 17. B 8. A 18. A 9. A 19. B 10. A 20. B Tenten’s Academy Online Review Center