Cell Structure Chapter 3 Review PDF

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8/21/24 Cell Structure Generalized Cell Organelles: specialized structures in cells that perform specific functions Example: nucleus, mitochondria, ribosomes Cytoplasm: jelly-like substance that holds organelles Cell membrane: also termed the plasma membrane a structure that encloses the cytoplasm Figure 3.1 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 2 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 3 2 3 Functions of the Cell Cell Membrane Smallest units of life The cell membrane, or plasma membrane, is the outermost component of a cell. Cell metabolism and energy use It forms a boundary between material in inside the cell and Synthesis of molecules the outside. Communication Materials inside the cell are intracellular and those Reproduction and inheritance outside are extracellular. It acts as a selective barrier. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 4 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 5 4 5 Cell Membrane Structure Phospholipid Structure The fluid-mosaic model is the model used to describe A phospholipid molecule has a polar head region that is the cell membrane structure. hydrophilic and a nonpolar tail region that is hydrophobic. The membrane contains phospholipids, cholesterol, The polar region is exposed to water around the proteins, and carbohydrates. membrane. Phospholipids form a bilayer. The nonpolar region is facing the interior of the membrane. Phospholipids contain 2 regions: polar and nonpolar. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 6 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7 6 7 1  8/21/24 The Cell Membrane Movement through the Cell Membrane The cell membrane has selective permeability, which allows only certain substances to pass in and out of the cell. Substances such as enzymes, glycogen, and potassium are found in higher concentrations inside the cell. Substances such as sodium, calcium, and chloride are found in higher concentrations outside the cell. Figure 3.2a Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 8 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 9 8 9 Cell Membrane Passage 1 Cell Membrane Passage 2 Some substances, like O2 and CO2, can pass directly Some substances require carrier molecules to transport through the cell membrane’s phospholipid bilayer. them across the cell membrane, such as glucose. Some substances must pass through transmembrane Some substances require a vesicular transport across the protein channels, such as Na+ through its channels. membrane. The route of transport through the membrane depends on The vesicle must fuse with the cell membrane for the size, shape, and charge of the substance. transport. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 10 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 11 10 11 Active Transport and Passive Transport 1 Active Transport and Passive Transport 2 Passive membrane transport does not require the cell to Passive membrane transport mechanisms include expend energy. diffusion, osmosis, and facilitated diffusion. Active membrane transport does require the cell to Active membrane transport mechanisms include active expend energy, usually in the form of ATP. transport, secondary active transport, endocytosis, and exocytosis. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 12 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 13 12 13 2  8/21/24 Diffusion 1 Concentration Gradient Diffusion generally involves movement of substances in a A concentration gradient is the difference in the solution down a concentration gradient. concentration of a solute in a solvent between two points A solution is generally composed of two major parts, divided by the distance between the two points. solutes and the solvent. The concentration gradient is said to be steeper when the Solutes are substances dissolved in a predominant liquid concentration difference is large and/or the distance is or gas, which is called the solvent. small. Solutes, such as ions or molecules, tend to move from an area of higher concentration of a solute to an area of lower concentration of that same solute in solution. This movement from high concentration to a low concentration is diffusion. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 14 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 15 14 15 Diffusion 2 Osmosis 1 Osmosis is the diffusion of water (a solvent) across a selectively permeable membrane from a region of higher water concentration to one of lower water concentration. Osmosis exerts a pressure, termed osmotic pressure, which is the force required to prevent movement of water across cell membrane Figure 3.3 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 16 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 17 16 17 Osmosis 2 Osmotic Pressure and the Cell Osmotic pressure depends on the difference of solution concentrations inside a cell relative to outside the cell. A cell may be placed in solutions that are either hypotonic, isotonic, or hypertonic compared to the cell cytoplasm. Figure 3.4 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 18 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 19 18 19 3  8/21/24 Hypotonic Isotonic A hypotonic solution has a lower concentration of solutes A cell immersed in an isotonic solution has the same and a higher concentration of water relative to the solute concentrations inside and outside the cell. cytoplasm of the cell. The cell will neither shrink nor swell. The solution has less tone, or osmotic pressure, than the cell. Water moves by osmosis into the cell, causing it to swell. If the cell swells enough, it can rupture, a process called lysis. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 20 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 21 20 21 Hypertonic Red Blood Cell Changes in Differing Solutions The cytoplasm of a cell in a hypertonic solution has a lower solute concentration and higher water concentration than the surrounding solution. Water moves by osmosis from the cell into the hypertonic solution, resulting in cell shrinkage, or crenation. David M. Phillips/Science Source Figure 3.5 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 22 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 23 22 23 Facilitated Diffusion 1 Facilitated Diffusion 2 Lipid soluble substances such as oxygen, carbon dioxide, Facilitated diffusion is a carrier-mediated transport and steroids can diffuse directly through the phospholipid process that moves substances across the cell membrane bilayer. from an area of higher concentration to an area of lower concentration of that substance. Water-soluble substances, such as ions, can diffuse across the cell membrane only by passing through cell Because movement is with the concentration gradient, membrane channels or through carrier molecules. metabolic energy in the form of ATP is not required. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 24 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 25 24 25 4  8/21/24 Diffusion through the Cell Membrane Leak and Gated Channels 1 Two classes of cell membrane channels include leak channels and gated channels. Leak channels constantly allow ions to pass through. Gated channels limit the movement of ions across the membrane by opening and closing. Figure 3.6 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 26 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 27 26 27 Leak and Gated Channels 2 Carrier Molecules 1 Carrier molecules are proteins within the cell membrane involved in facilitated diffusion. Move water soluble molecules or ions across the membrane. They exhibit specificity; only specific molecules are transported by the carriers. Figure 3.7 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 28 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 29 28 29 Carrier Molecules 2 Active Transport Active transport is a carrier-mediated process, requiring ATP, that moves substances across the cell membrane from regions of lower concentration to those of higher concentration against a concentration gradient. Active transport processes accumulate necessary substances on one side of the cell membrane at concentrations many times greater than those on the other side. Figure 3.8 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 30 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 31 30 31 5  8/21/24 Sodium-Potassium Pump 1 Sodium-Potassium Pump 2 A major example of active transport is the action of the sodium-potassium pump present in cell membranes. The sodium-potassium pump moves Na+ out of cells and K+ into cells. The result is a higher concentration of Na+ outside cells and a higher concentration of K+ inside cells. Figure 3.9 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 32 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 33 32 33 Secondary Active Transport 1 Secondary Active Transport 2 Secondary active transport uses the energy provided by a In cotransport, the diffusing substance moves in the same concentration gradient established by the active transport direction as the initial active transported substance. of one substance, such as Na+ to transport other substances. In countertransport, the diffusing substance moves in a direction opposite to that of the initial active transported No additional energy is required above the energy substance. provided by the initial active transport pump. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 34 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 35 34 35 Secondary Active Transport 3 Endocytosis Endocytosis is a process that that brings materials into cell using vesicles. Receptor-mediated endocytosis occurs when a specific substance binds to the receptor molecule and is transported into the cell. Phagocytosis is often used for endocytosis when solid particles are ingested. Pinocytosis has much smaller vesicles formed, and they contain liquid rather than solid particles. Figure 3.10 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 36 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 37 36 37 6  8/21/24 Receptor-Mediated Endocytosis Exocytosis 1 Exocytosis involves the use of membrane-bound sacs called secretory vesicles that accumulate materials for release from the cell. The vesicles move to the cell membrane and fuse, ultimately releasing the material by exocytosis. Examples of exocytosis are the secretion of digestive enzymes. Figure 3.11 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 38 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 39 38 39 Exocytosis 2 General Cell Structure The interior of a cell is composed of the cytoplasm, which a jelly-like fluid that surrounds the organelles. Organelles are specialized structures that perform certain functions. Organelles include the nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, mitochondria, cytoskeleton, centrioles, cilia, flagella, and microvilli. (b) ©Dr. Birgit H. Satir Figure 3.12 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 40 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 41 40 41 Generalized Cell 2 Cell Nucleus 1 The nucleus is a large organelle usually located near the center of the cell. The nucleus is bounded by a nuclear envelope, which consists of outer and inner membranes with a narrow space between them. The nuclear membrane contains nuclear pores, through which materials can pass into or out of the nucleus. Figure 3.1 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 42 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 43 42 43 7  8/21/24 Cell Nucleus 2 Cell Nucleus 3 The nuclei of human cells contain 23 pairs of Within the nucleus are Nucleoli, which are diffuse bodies chromosomes which consist of DNA and proteins. with no surrounding membrane. that are found within the nucleus During most of a cell’s life, the chromosomes are loosely coiled and collectively called chromatin. There are usually one to several nucleoli within the nucleus. When a cell prepares to divide, the chromosomes become tightly coiled and are visible when viewed with a The subunits of ribosomes, a type of cytoplasmic microscope. organelle, are formed within a nucleolus. These ribosomal components exit the nucleus through nuclear pores. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 44 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 45 44 45 Cell Nucleus 4 Chromosome Structure (b,c) Don W. Fawcett/Science Source Figure 3.13 Figure 3.14 Access the text alternative for slide images. Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 46 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 47 46 47 Ribosomes Ribosome Production Ribosome components are produced in the nucleolus. Ribosomes are the organelles where proteins are produced. Ribosomes may be attached to other organelles, such as the endoplasmic reticulum. Ribosomes that are not attached to any other organelle are called free ribosomes. Figure 3.15 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 48 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 49 48 49 8  8/21/24 Endoplasmic Reticulum 1 Endoplasmic Reticulum 2 The endoplasmic reticulum (ER) is a series of membranes forming sacs and tubules that extends from the outer nuclear membrane into the cytoplasm. The rough ER is involved in protein synthesis and is rough due to attached ribosomes. The smooth ER has no attached ribosomes and is a site for lipid synthesis, cellular detoxification, and it stores calcium ions in skeletal muscle cells. Figure 3.16a Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 50 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 51 50 51 Golgi Apparatus 1 Golgi Apparatus 2 The Golgi apparatus, also called the Golgi complex, consists of closely packed stacks of curved, membrane- bound sacs. It collects, modifies, packages, and distributes proteins and lipids manufactured by the ER. The Golgi apparatus forms vesicles, some of which are secretory vesicles, lysosomes, and other vesicles. (b) Biophoto Associates/Science Source Figure 3.17 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 52 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 53 52 53 Lysosomes Lysosome Action Lysosomes are membrane-bound vesicles formed from the Golgi apparatus. They contain a variety of enzymes that function as intracellular digestive systems. Vesicles formed by endocytosis may fuse with lysosomes in order to breakdown materials in the endocytotic vesicles. One example is white blood cells phagocytizing bacteria. Figure 3.18 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 54 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 55 54 55 9  8/21/24 Peroxisomes Mitochondria 1 Peroxisomes are small, membrane-bound vesicles Mitochondria (singular mitochondrion) are small organelles containing enzymes that break down fatty acids, amino responsible for producing considerable amounts of ATP by acids, and hydrogen peroxide (H2O2). aerobic (with O2) metabolism. Hydrogen peroxide is a by-product of fatty acid and amino They have inner and outer membranes separated by a acid breakdown and can be toxic to a cell. space. The enzymes in peroxisomes break down hydrogen. The outer membranes have a smooth contour, but the inner membranes have numerous folds, called cristae, which project into the interior of the mitochondria. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 56 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 57 56 57 Mitochondria 2 A Mitochondrion The material within the inner membrane is the mitochondrial matrix and contains enzymes and mitochondrial DNA (mtDNA). Cells with a large energy requirement have more mitochondria than cells that require less energy. (b) EM Research Services, Newcastle University Figure 3.19 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 58 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 59 58 59 The Cytoskeleton 2 Microtubules The cytoskeleton gives internal framework to the cell. Microtubules are hollow structures formed from protein subunits. It consists of protein structures that support the cell, hold organelles in place, and enable the cell to change shape. The microtubules perform a variety of roles, including helping to support the cytoplasm of cells, assisting in cell These protein structures are microtubules, division, and forming essential components of certain microfilaments, and intermediate filaments. organelles, such as cilia and flagella. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 60 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 61 60 61 10  8/21/24 Microfilaments Intermediate Filaments Microfilaments are small fibrils formed from protein Intermediate filaments are fibrils formed from protein subunits that structurally support the cytoplasm, subunits that are smaller in diameter than microtubules but determining cell shape. larger in diameter than microfilaments. Some microfilaments are involved with cell movement. They provide mechanical support to the cell. Microfilaments in muscle cells enable the cells to shorten, A specific type of intermediate filament is keratin, a protein or contract. associated with skin cells. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 62 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 63 62 63 The Cytoskeleton 1 Centrioles The centrosome is a specialized area of cytoplasm close to the nucleus where microtubule formation occurs. It contains two centrioles, which are normally oriented perpendicular to each other. Each centriole is a small, cylindrical organelle composed of microtubules. The centriole is involved in the process of mitosis. (b) ©Don W. Fawcett/Science Source Figure 3.20 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 64 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 65 64 65 Centriole Cilia Cilia project from the surface of certain cells. They are responsible for the movement of materials over the top of cells, such as mucus. Cilia are cylindrical structures that extend from the cell and are composed of microtubules. (b) Biology Media/Science Source Figure 3.21 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 66 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 67 66 67 11  8/21/24 Flagella Microvilli Flagella have a structure similar to that of cilia but are Microvilli are specialized extensions of the cell membrane much longer, and they usually occur only one per cell. that are supported by microfilaments. Sperm cells each have one flagellum, which propels the They do not actively move as cilia and flagella do. sperm cell. Microvilli are numerous on cells that have them and they increase the surface area of those cells. They are abundant on the surface of cells that line the intestine, kidney, and other areas in which absorption is an important function. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 68 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 69 68 69 Whole Cell Activity DNA 1 A cell’s characteristics are determine by the type of DNA contains the information that directs protein proteins produced. synthesis; a process called gene expression. The proteins produced are in turn determined by the A DNA molecule consists of nucleotides joined together genetic information in the nucleus. to form two nucleotide strands. Information in DNA provides the cell with a code for its The two strands are connected and resemble a ladder that cellular processes. is twisted around its long axis. Each nucleotide consists of a 5-carbon sugar, a phosphate group, and a nitrogenous base. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 70 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 71 70 71 DNA 2 Gene Expression Each nucleotide on one DNA strand has a specific Gene expression, which is protein synthesis, involves bonding pattern to another nucleotide on the opposite transcription and translation. strand. Transcription involves copying DNA into messenger A gene is a sequence of nucleotides that provides a RNA. chemical set of instructions for making a specific protein. Translation involves messenger RNA being used to produce a protein. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 72 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 73 72 73 12  8/21/24 Overview of Gene Expression Transcription 1 Transcription takes place in the nucleus of the cell. DNA determines the structure of mRNA through transcription. During transcription, the double strands of a DNA segment separate, and DNA nucleotides of the gene pair with RNA nucleotides that form the mRNA. Figure 3.22 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 74 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 75 74 75 Transcription 2 Transcription 3 DNA contains one of the following organic bases: thymine, DNA nucleotides pair only with specific RNA nucleotides. adenine, cytosine, or guanine. DNA’s thymine pairs with RNA’s adenine. Messenger RNA (mRNA) contains uracil, adenine, DNA’s adenine pairs with RNA’s uracil. cytosine, or guanine. DNA’s cytosine pairs with RNA’s guanine DNA’s guanine pairs with RNA’s cytosine. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 76 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 77 76 77 Transcription 4 Translation 1 Translation occurs in the cell cytoplasm after mRNA has exited the nucleus through the nuclear pores. The mRNA attaches to a ribosome. Codons (3 nucleotide bases) on the mRNA are read by anticodons (3 nucleotide bases) on transfer RNA (tRNA). Figure 3.23 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 78 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 79 78 79 13  8/21/24 Translation 2 The Cell Cycle 1 Transfer RNA transports specific amino acids from the During growth and development, cell division occurs to cytoplasm to the ribosome-mRNA complex and initiates increase the number of cells or replace damaged or dying formation of the polypeptide chain. ones. The process continues until the entire polypeptide is This cell division involves a cell cycle. completely formed. The cell cycle includes two major phases: a nondividing phase, called interphase, and a cell dividing phase, termed mitosis. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 80 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 81 80 81 The Cell Cycle 2 The Cell Cycle 3 A cell spends most of its life cycle in interphase which is divided into three phases: G1 phase, during which the cell carries out normal metabolic activity S phase, during which the DNA is replicated; and G2 phase, during which the cell prepares to divide. At the end of interphase, a cell has two complete sets of genetic material Figure 3.24 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 82 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 83 82 83 Cell Genetic Content Mitosis Each human cell (except sperm and egg) contains 23 Mitosis involves formation of 2 daughter cells from a single pairs of chromosomes, a total of 46. parent cell. The sperm and egg contain 23 chromosomes total. Mitosis is divided into four phases: prophase, metaphase, anaphase, and telophase. One pair of chromosomes are the sex chromosomes, which consist of two X chromosomes if the person is a female or an X and Y chromosome if the person is a male. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 84 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 85 84 85 14  8/21/24 Prophase Metaphase During prophase the chromatin condenses to form visible During metaphase, the chromosomes align near the chromosomes. center of the cell. Microtubules, termed spindle fibers, form to assist in The movement of the chromosomes is regulated by the breaking the centromere between the chromatids and attached spindle fibers. move the chromosomes to opposite sides of the cell. The nuclear membrane dissolves. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 86 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 87 86 87 Anaphase Telophase At the beginning of anaphase, the chromatids separate During telophase, the chromosomes in each of the and each chromatid is called a chromosome. daughter cells become organized to form two separate nuclei, one in each newly formed daughter cell. Each of the two sets of 46 chromosomes is moved by the spindle fibers toward the centriole at one of the poles of The chromosomes begin to unravel and resemble the the cell. genetic material during interphase. At the end of anaphase, each set of chromosomes has Following telophase, cytoplasm division is completed, and reached an opposite pole of the cell, and the cytoplasm two separate daughter cells are produced. begins to divide. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 88 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 89 88 89 The Cell Cycle Tumors Tumors are abnormal proliferations of cells. They are due to problems occurring in the cell cycle. Some tumors are benign and some are malignant (cancer). Malignant tumors can spread by a process, termed metastasis. Ed Reschke/Photolibrary/Getty Images Figure 3.25 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 90 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 91 90 91 15