Unit 1 What is Biology Unit 2 Ecology

Unit 1: What is Biology? Unit 2: Ecology Unit 3: The Life of a Cell Unit 4: Genetics Unit 5: Change Through Time Unit 6: Viruses, Bacteria, Protists, and Fungi Unit 7: Plants Unit 8: Invertebrates Unit 9: Vertebrates Unit 10: The Human Body

Unit 1: What is Biology? Chapter 1: Biology: The Study of Life Unit 2: Ecology Chapter 2: Principles of Ecology Chapter 3: Communities and Biomes Chapter 4: Population Biology Chapter 5: Biological Diversity and Conservation Unit 3: The Life of a Cell Chapter 6: The Chemistry of Life Chapter 7: A View of the Cell Chapter 8: Cellular Transport and the Cell Cycle Chapter 9: Energy in a Cell

Unit 4: Genetics Chapter 10: Mendel and Meiosis Chapter 11: DNA and Genes Chapter 12: Patterns of Heredity and Human Genetics Chapter 13: Genetic Technology Unit 5: Change Through Time Chapter 14: The History of Life Chapter 15: Theory of Evolution Chapter 16: Primate Evolution Chapter 17: Organizing Life’s Diversity

Unit 6: Viruses, Bacteria, Protists, and Fungi Chapter 18: Viruses and Bacteria Chapter 19: Protists Chapter 20: Fungi Unit 7: Plants Chapter 21: Chapter 22: Chapter 23: Chapter 24: What Is a Plant? The Diversity of Plants Plant Structure and Function Reproduction in Plants

Unit 8: Invertebrates Chapter 25: What Is an Animal? Chapter 26: Sponges, Cnidarians, Flatworms, and Roundworms Chapter 27: Mollusks and Segmented Worms Chapter 28: Arthropods Chapter 29: Echinoderms and Invertebrate Chordates

Unit 9: Vertebrates Chapter 30: Fishes and Amphibians Chapter 31: Reptiles and Birds Chapter 32: Mammals Chapter 33: Animal Behavior Unit 10: The Human Body Chapter 34: Protection, Support, and Locomotion Chapter 35: The Digestive and Endocrine Systems Chapter 36: The Nervous System Chapter 37: Respiration, Circulation, and Excretion Chapter 38: Reproduction and Development Chapter 39: Immunity from Disease

The Life of a Cell The Chemistry of Life A View of the Cellular Transport and the Cell Cycle Energy in a Cell

Chapter 8 Cellular Transport and the Cell Cycle 8. 1: Cellular Transport 8. 1: Section Check 8. 2: Cell Growth and Reproduction 8. 2: Section Check 8. 3: Control of the Cell Cycle 8. 3: Section Check Chapter 8 Summary Chapter 8 Assessment

What You’ll Learn You will discover how molecules are transported across the plasma membrane. You will sequence the stages of cell division. You will identify the relationship between the cell cycle and cancer.

Section Objectives: • Explain how the processes of diffusion, passive transport, and active transport occur and why they are important to cells. • Predict the effect of a hypotonic, hypertonic, or isotonic solution on a cell.

Osmosis: Diffusion of Water • Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. • In a cell, water always moves to reach an equal concentration on both sides of the membrane.

Osmosis: Diffusion of Water • The diffusion of water across a selectively permeable membrane is called osmosis. • Regulating the water flow through the plasma membrane is an important factor in maintaining homeostasis within a cell.

What controls osmosis? • Unequal distribution of particles, called a concentration gradient, is one factor that controls osmosis. Before Osmosis Selectively permeable membrane After Osmosis Water molecule Sugar molecule

Cells in an isotonic solution H 2 O Water Molecule Dissolved Molecule • Most cells whether in multicellular or unicellular organisms, are subject to osmosis because they are surrounded by water solutions.

Cells in an isotonic solution • In an isotonic solution, the concentration of dissolved substances in the solution is the same as the concentration of dissolved substances inside the cell. H 2 O Water Molecule Dissolved Molecule

Cells in an isotonic solution • In an isotonic solution, water molecules move into and out of the cell at the same rate, and cells retain their normal shape. H 2 O Water Molecule Dissolved Molecule

Cells in an isotonic solution • A plant cell has its normal shape and pressure in an isotonic solution.

Cells in a hypotonic solution • In a hypotonic solution, water enters a cell by osmosis, causing the cell to swell. H 2 O Water Molecule Dissolved Molecule

Cells in a hypotonic solution • Plant cells swell beyond their normal size as pressure increases.

Cells in a hypertonic solution • In a hypertonic solution, water leaves a cell by osmosis, causing the cell to shrink. H 2 O Water Molecule Dissolved Molecule

Cells in a hypertonic solution • Plant cells lose pressure as the plasma membrane shrinks away from the cell wall.

Passive Transport • When a cell uses no energy to move particles across a membrane passive transport occurs. Plasma membrane Concentration gradient

Passive Transport by proteins • Passive transport of materials across the membrane using transport proteins is called facilitated diffusion. Channel proteins Plasma membrane Concentration gradient

Passive Transport by proteins • Some transport proteins, called channel proteins, form channels that allow specific molecules to flow through. Channel proteins Plasma membrane Concentration gradient

Passive transport by proteins • The movement is with the concentration gradient, and requires no energy input from the cell. Carrier proteins Concentration gradient Plasma membrane Step 1 Step 2

Passive transport by proteins • Carrier proteins change shape to allow a substance to pass through the plasma membrane. Carrier proteins Concentration gradient Plasma membrane Step 1 Step 2

Passive transport by proteins • In facilitated diffusion by carrier protein, the movement is with the concentration gradient and requires no energy input from the cell. Carrier proteins Concentration gradient Plasma membrane Step 1 Step 2

Active Transport • Movement of materials through a membrane against a concentration gradient is called active transport and requires energy from the cell. Carrier proteins Plasma membrane Concentration gradient Cellular energy Step 1 Step 2

How active transport occurs • In active transport, a transport protein called a carrier protein first binds with a particle of the substance to be transported. Carrier proteins Plasma membrane Concentration gradient Cellular energy Step 1 Step 2

How active transport occurs Click image to view movie.

How active transport occurs • Each type of carrier protein has a shape that fits a specific molecule or ion. Carrier proteins Plasma membrane Concentration gradient Cellular energy Step 1 Step 2

How active transport occurs • When the proper molecule binds with the protein, chemical energy allows the cell to change the shape of the carrier protein so that the particle to be moved is released on the other side of the membrane. Carrier proteins Plasma membrane Concentration gradient Cellular energy Step 1 Step 2

How active transport occurs • Once the particle is released, the protein’s original shape is restored. • Active transport allows particle movement into or out of a cell against a concentration gradient. Carrier proteins Plasma membrane Concentration gradient Cellular energy Step 1 Step 2

How active transport occurs Click image to view movie.

Transport of Large Particles • Endocytosis is a process by which a cell surrounds and takes in material from its environment. Nucleus Wastes Digestion Endocytosis Exocytosis

Transport of Large Particles • The material is engulfed and enclosed by a portion of the cell’s plasma membrane. Nucleus Wastes Digestion Endocytosis Exocytosis

Transport of Large Particles • The resulting vacuole with its contents moves to the inside of the cell. Nucleus Wastes Digestion Endocytosis Exocytosis

Transport of Large Particles • Exocytosis is the expulsion or secretion of materials from a cell. Nucleus Wastes Digestion Endocytosis Exocytosis

Transport of Large Particles • Endocytosis and exocytosis both move masses of material and both require energy. Nucleus Wastes Digestion Endocytosis Exocytosis

Question 1 The diffusion of water across a selectively permeable membrane is called _____. A. active transport CA: Biology/Life Sciences 1 a Selectively permeable membrane Water molecule Sugar molecule B. endocytosis

Question 1 The diffusion of water across a selectively permeable membrane is called _____. C. exocytosis CA: Biology/Life Sciences 1 a Selectively permeable membrane D. osmosis Water molecule Sugar molecule

The answer is D, osmosis. Regulating the water flow through the plasma membrane is an important factor in maintaining homeostasis within the cell. CA: Biology/Life Sciences 1 a Before osmosis Selectively permeable membrane After osmosis Water molecule Sugar molecule

Question 2 What is the expected result of having an animal cell in a hypertonic solution? A. The cell shrivels up. B. The plasma membrane shrinks away from the cell wall. C. The cell swells up. D. The cell retains its normal shape. CA: Biology/Life Sciences 1 a

The answer is A. In a hypertonic solution, cells experience osmosis of water out of the cell. Animal cells shrivel because of decreased pressure in the cells. H 2 O Water molecule Sugar molecule CA: Biology/Life Sciences 1 a

Question 3 A grocer mists the celery display with water to keep it looking fresh. What type of solution is the celery now in? A. isotonic B. hypotonic C. hypertonic D. exotonic CA: Biology/Life Sciences 1 a, 1 j

The answer is B. Plant cells contain a rigid cell wall and do not burst even in a hypotonic solution. CA: Biology/Life Sciences 1 a, 1 j

Question 4 Transport of materials across the plasma membrane that does not require energy from the cell but does use transport proteins is called _____. Channel proteins A. osmosis B. simple diffusion CA: Biology/Life Sciences 1 a Plasma membrane Concentration gradient

Question 4 Transport of materials across the plasma membrane that does not require energy from the cell but does use transport proteins is called _____. C. facilitated diffusion D. active transport CA: Biology/Life Sciences 1 a Channel proteins Plasma membrane Concentration gradient

The answer is C. Facilitated diffusion is a type of passive transport and requires no energy from the cell. Channel proteins Plasma membrane CA: Biology/Life Sciences 1 a Concentration gradient

Section Objectives • Sequence the events of the cell cycle. • Relate the function of a cell to its organization in tissues, organs, and organ systems.

Cell Size Limitations • The cells that make up a multicellular organism come in a wide variety of sizes and shapes. • Considering this wide range of cells sizes, why then can’t most organisms be just one giant cell?

Diffusion limits cell size • Although diffusion is a fast and efficient process over short distances, it becomes slow and inefficient as the distances become larger. • Because of the slow rate of diffusion, organisms can’t be just one giant-sized cell.

DNA limits cell size • The cell cannot survive unless there is enough DNA to support the protein needs of the cell. • In many large cells, more than one nucleus is present. • Large amounts of DNA in many nuclei ensure that cell activities are carried out quickly and efficiently.

Surface area-to-volume ratio 4 mm 1 mm 2 mm 1 mm mm 2 Surface area = 6 Volume = 1 mm 3 4 mm 2 mm 4 mm Surface area = 24 mm 2 Volume = 8 mm 3 • As a cell’s size increases, its volume increases much faster than its surface area.

Surface area-to-volume ratio 4 mm 1 mm 2 mm 1 mm mm 2 Surface area = 6 Volume = 1 mm 3 4 mm 2 mm 4 mm Surface area = 24 mm 2 Volume = 8 mm 3 • If cell size doubled, the cell would require eight times more nutrients and would have eight times more waste to excrete.

Surface area-to-volume ratio 4 mm 1 mm 2 mm 1 mm mm 2 Surface area = 6 Volume = 1 mm 3 4 mm 2 mm 4 mm Surface area = 24 mm 2 Volume = 8 mm 3 • The surface area, however, would increase by a factor of only four.

Surface area-to-volume ratio 4 mm 1 mm 2 mm 1 mm mm 2 Surface area = 6 Volume = 1 mm 3 4 mm 2 mm Surface area = 24 mm 2 Volume = 8 mm 3 • The cell would either starve to death or be poisoned from the buildup of waste products. 4 mm

Cell Reproduction • Cell division is the process by which new cells are produced from one cell. • Cell division results in two cells that are identical to the original, parent cell.

The discovery of chromosomes • Structures, which contain DNA and become darkly colored when stained, are called chromosomes. • Chromosomes are the carriers of the genetic material that is copied and passed from generation to generation of cells. • Accurate transmission of chromosomes during cell division is critical.

The structure of eukaryotic chromosomes Centromere Sister chromatids Supercoil within chromosome Continued coiling within supercoil Histone H 1 Nucleosome DNA

The Cell Cycle • The cell cycle is the sequence of growth and division of a cell. • The majority of a cell’s life is spent in the growth period known as interphase. Interphase

The Cell Cycle • Following interphase, a cell enters its period of nuclear division called mitosis. • Following mitosis, the cytoplasm divides, separating the two daughter Mitosis cells.

Interphase: A Busy Time • Interphase, the busiest phase of the cell cycle, is divided into three parts. Interphase DNA synthesis and replication Rapid growth and metabolic activity Centrioles replicate; cell prepares for division

Interphase: A Busy Time • During the first part, the cell grows and protein production is high. Interphase Rapid growth and metabolic activity

Interphase: A Busy Time • In the next part of interphase, the cell copies its chromosomes. Interphase DNA synthesis and replication

Interphase: A Busy Time • After the chromosomes have been duplicated, the cell enters another shorter growth period in which mitochondria and other organelles are manufactured and cell parts needed for cell division are assembled. Interphase Centrioles replicate; cell prepares for division

The Phases of Mitosis • The four phases of mitosis are prophase, metaphase, and telophase.

Prophase: The first phase of mitosis • During prophase, the chromatin coils to form visible chromosomes. Spindle fibers Disappearing nuclear envelope Doubled chromosome

Prophase: The first phase of mitosis • The two halves of the doubled structure are called sister chromatids. Sister chromatids

Prophase: The first phase of mitosis • Sister chromatids are held together by a structure called a centromere, which plays a role in chromosome movement during mitosis. Centromere

Metaphase: The second stage of mitosis • During metaphase, the chromosomes move to the equator of the spindle. Centromere Sister chromatids

Anaphase: The third phase of mitosis • During anaphase, the centromeres split and the sister chromatids are pulled apart to opposite poles of the cell.

Telophase: The fourth phase of mitosis • During telophase, two distinct daughter cells are formed. The cells separate as the cell cycle proceeds into the next interphase. Nuclear envelope reappears Two daughter cells are formed

Cytokinesis • Following telophase, the cell’s cytoplasm divides in a process called cytokinesis. • Cytokinesis differs between plants and animals. • Toward the end of telophase in animal cells, the plasma membrane pinches in along the equator.

Cytokinesis • Plant cells have a rigid cell wall, so the plasma membrane does not pinch in. • A structure known as the cell plate is laid down across the cell’s equator. • A cell membrane forms around each cell, and new cell walls form on each side of the cell plate until separation is complete.

Results of Mitosis • When mitosis is complete, unicellular organisms remain as single cells. • In multicellular organisms, cell growth and reproduction result in groups of cells that work together as tissue to perform a specific function.

Results of Mitosis • Tissues organize in various combinations to form organs that perform more complex roles within the organism. • Multiple organs that work together form an organ system.

Results of Mitosis Click image to view movie.

Question 1 The stringy structures in the cell nucleus that contain DNA are _____. A. centromeres B. chromosomes C. genes D. chlorophylls CA: Biology/Life Sciences 2 a

The answer is B. Chromosomes are the carriers of the genetic material of the cell. A gene is a segment of DNA that controls the production of a protein. CA: Biology/Life Sciences 2 a

Question 2 Look at the diagram and identify the stage of mitosis that is depicted. Centromere Sister chromatids A. prophase C. anaphase B. metaphase D. telophase CA: Biology/Life Sciences 5 a

The answer is B. Metaphase is the short second phase of mitosis, during which the chromosomes begin to line up on the equator of the spindle. Centromere Sister chromatids CA: Biology/Life Sciences 5 a

Question 3 What is the process by which a cell's cytoplasm divides? A. cytokinesis B. telekinesis C. meiosis D. mitosis CA: Biology/Life Sciences 5 a

The answer is A. Cytokinesis follows telophase and allows the two new cells to separate. CA: Biology/Life Sciences 5 a

Question 4 In multicellular organisms, groups of cells that work together to perform a specific function are called _____. A. organ systems B. organs C. tissues D. cell cycles CA: Biology/Life Sciences 9 a

The answer is C. Tissues organize to form organs, which work with other organs to form organ systems. CA: Biology/Life Sciences 9 a

Section Objectives • Describe the role of enzymes in the regulation of the cell cycle. • Distinguish between the events of a normal cell cycle and the abnormal events that result in cancer. • Identify ways to potentially reduce the risk of cancer.

Normal Control of the Cell Cycle Proteins and enzymes control the cell cycle • The cell cycle is controlled by proteins called cyclins and a set of enzymes that attach to the cyclin and become activated. • Occasionally, cells lose control of the cell cycle.

Normal Control of the Cell Cycle • This uncontrolled dividing of cells can result from the failure to produce certain enzymes, the overproduction of enzymes, or the production of other enzymes at the wrong time. • Cancer is a malignant growth resulting from uncontrolled cell division.

Normal Control of the Cell Cycle • Enzyme production is directed by genes located on the chromosomes. • A gene is a segment of DNA that controls the production of a protein.

Cancer: A mistake in the Cell Cycle • Currently, scientists consider cancer to be a result of changes in one or more of the genes that produce substances that are involved in controlling the cell cycle. • Cancerous cells form masses of tissue called tumors that deprive normal cells of nutrients.

Cancer: A mistake in the Cell Cycle • In later stages, cancer cells enter the circulatory system and spread throughout the body, a process called metastasis, forming new tumors that disrupt the function of organs, organ systems, and ultimately, the organism.

The causes of cancer • The causes of cancer are difficult to pinpoint because both genetic and environmental factors are involved.

The causes of cancer • Environmental factors, such as cigarette smoke, air and water pollution, and exposure to ultraviolet radiation from the sun, are all known to damage the genes that control the cell cycle.

The causes of cancer • Cancer may also be caused by viral infections that damage the genes.

Cancer prevention • Physicians and dietary experts agree that diets low in fat and high in fiber content can reduce the risk of many kinds of cancer. • Vitamins and minerals may also help prevent cancer.

Cancer prevention • In addition to diet, other healthy choices such as daily exercise and not using tobacco also are known to reduce the risk of cancer.

Question 1 Explain cancer in terms of cell growth. Answer Cancer is a malignant growth resulting from uncontrolled cell division. The loss of control may be caused by environmental factors or changes in enzyme production that result from defective or changed genetic material. Cancerous cells form masses of tissue called tumors that deprive normal cells of nutrients. CA: Biology/Life Sciences 9 a

Question 2 A(n) _____ is a segment of DNA that controls the production of a protein. A. gene B. cyclin C. enzyme D. chromosome CA: Biology/Life Sciences 4 a-4 f

The answer is A. Genes control the production of proteins. Scientists think that cancer results from changes in one or more of the genes that produce substances controlling the cell cycle. CA: Biology/Life Sciences 4 a-4 f

Question 3 Which of the following is thought to reduce the risk of developing cancer? A. increase dietary fat B. increase dietary fiber C. decrease dietary fiber D. decrease dietary minerals CA: Biology/Life Sciences 9 a

The answer is B. Health professionals believe that diets low in fat and high in fiber content can reduce the risk of many types of cancer. CA: Biology/Life Sciences 9 a

Cellular Transport • Osmosis is the diffusion of water through a selectively permeable membrane. • Passive transport moves a substance with the concentration gradient and requires no energy from the cell.

Cellular Transport • Active transport moves materials against the concentration gradient and requires energy to overcome the flow of materials opposite the concentration gradient. • Large particles may enter a cell by endocytosis and leave by exocytosis.

Cell Growth and Reproduction • Cell size is limited largely by the diffusion rate of materials into and out of the cell, the amount of DNA available to program the cell’s metabolism, and the cell’s surface area-to-volume ratio. • The life cycle of a cell is divided into two general periods: a period of active growth and metabolism known as interphase, and a period that leads to cell division known as mitosis.

Cell Growth and Reproduction • Mitosis is divided into four phases: prophase, metaphase, and telophase. • The cells of most multicellular organisms are organized into tissues, organs, and organ systems.

Control of the Cell Cycle • The cell cycle is controlled by key enzymes that are produced at specific points in the cell cycle. • Cancer is caused by genetic and environmental factors that change the genes that control the cell cycle.

Question 1 Which of the following is a factor that controls osmosis? A. prophase B. concentration gradient C. conditioning D. carrier proteins CA: Biology/Life Sciences 1 a

The answer is B. Osmosis is the diffusion of water across a selectively permeable membrane. Concentration gradients, unequal distributions of particles, result in water diffusing to the side of the membrane where the water concentration is lower. CA: Biology/Life Sciences 1 a

Question 2 Predict the result of placing a fresh stalk of celery in a jar of salt water. Answer Salt water would be a hypertonic solution for the celery. Water will leave the cells by osmosis. As a result, the cells will lose pressure as the plasma membrane shrinks away from the cell wall and the celery will probably wilt. CA: Biology/Life Sciences 1 a, 1 j

Question 3 Magnification of a plant cell reveals centromeres that have split and sister chromatids being pulled to opposite poles of the cell. This cell is in which phase of mitosis? A. prophase B. metaphase C. anaphase D. telophase CA: Biology/Life Sciences 5 a

The answer is C. The separation of sister chromatids marks the beginning of anaphase, and the final phase, telophase, begins as the chromatids reach the opposite poles of the cell. CA: Biology/Life Sciences 5 a

Question 4 Which phase of mitosis is depicted in this diagram? Spindle Fibers Doubled chromosome Disappearing nuclear envelope A. prophase C. anaphase B. metaphase D. telophase CA: Biology/Life Sciences 5 a

The answer is A. Prophase is the first and longest phase of mitosis, during which the long, stringy chromatin coils up into visible chromosomes. Sister chromatids have formed, but are not yet lined up along the equator of the spindle. Spindle Fibers Doubled chromosome CA: Biology/Life Sciences 5 a Disappearing nuclear envelope

Question 5 What is the term used for the period of the cell cycle represented by the red arrow in this graph? A. prophase B. metaphase C. centrophase D. interphase DNA synthesis and replication Centrioles replicate; cell prepares for division Rapid growth and metabolic activity Mitosis Cytokinesis CA: Biology/Life Sciences 5 a

The answer is D. Most of the time spent in the cell cycle is in interphase. Interphase CA: Biology/Life Sciences 5 a

Question 6 The structure depicted in this diagram forms during prophase of mitosis. During metaphase, doubled chromosomes will become attached to this by their centromeres. What is this structure? A. spindle B. centriole C. chromatid D. chromatin CA: Biology/Life Sciences 2 a Microtubule

The answer is A. This cage like structure is a spindle, consisting of thin fibers made of microtubules. The chromosomes will become attached to the spindle fibers by their centromeres, and will be pulled to the midline of the spindle. Microtubule CA: Biology/Life Sciences 2 a

Question 7 What is the level of organization that is missing in this diagram? Cell (muscle cell) ? Organ (stomach) Organ System (digestive tissue) A. mass C. tissue B. cluster D. cycle CA: Biology/Life Sciences 9 a Organism (Florida Panther)

The answer is C. In multicellular organisms, groups of cells that work together are tissues. Tissues are formed from different types of cells that are coded for by different parts of the original cell's genetic material. Tissue Cell (muscle cell) (muscle tissue) CA: Biology/Life Sciences 9 a Organ (stomach) Organ System (digestive tissue) Organism (Florida Panther)

Question 8 Which structure represents a cell in prophase of mitosis? A B C A. A C. C B. B D. D CA: Biology/Life Sciences 5 a D

The answer is C. The chromosomes have doubled but are still contained within the nucleus. C CA: Biology/Life Sciences 5 a

Photo Credits • Digital Stock • KS Studios/Bob Mullenix • Alton Biggs

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