Cell Growth And Division Chapter 10 Cell Growth And Division

I. Cell Growth 10-1 Cell Growth A. Limits to Cell Growth 1. DNA Overload DNA provides instructions for proteins, the bigger the cell  the more protein needed b. Protein Synthesis (making of protein) at ribosomes could not keep up with demands of the cell 2. Exchanging Materials a. Very fast and efficient over short distances; very slow and sluggish over long distances

3.Ratio of Surface Area to Volume (Page 275) a. As cell size increases, the amount of space it takes up on the inside (volume) increases much faster than the surface area (outside surface) b. Important for molecule transport

B. Cell Division 1. Before cell becomes too large  cell will divide forming two daughter cells = Cell Division 2. Cell replicates all DNA before division

C. Cell Division & Reproduction 1. Asexual Reproduction -production of genetically identical offspring from a single parent *Single Celled Bacteria splitting into two cells *Small Bud growing off a Hydra breaking off -Advantages *only parent needed -Disadvantages *No Genetic Diversity genetically the same – no differences = less chance for evolving over time

2. Sexual Reproduction -Offspring produced from inheriting DNA from each parent. (two reproductive cells fusing together) *Most plants & animals as well as some single-celled organisms -Advantages *Genetic Diversity different from parent = better chance of evolving over time -Disadvantages *need two parents

10-2 The Process of Cell Division II. Chromosomes Tightly bundled packages of DNA 1. Make it possible to separate DNA precisely *Prokaryotes  in cytoplasm, single, circular DNA chromosome *Eukaryotes  more DNA than Prokaryotes, in nucleus 2. Composed of loosely coiled DNA and protein (histones) = Chromatin that condenses into chromosomes

3. Carries genetic information from generation to generation 4. Consists two identical “sister” chromatids. Sister chromatids *attached at an area called the centromere. 5. # of chromosomes is specific to the organism a. Fruit flies = chromosomes 8 b. Humans = chromosomes 46 Centromere 6. Only visible prior to and during cell division

III. Cell Cycle A. The cell grows, prepares for division and divides to form two identical daughter cells B. Prokaryotic Cell Cycle 1. asexual reproduction known as Binary Fission 2. DNA molecules attach to opposite ends of cell membrane 3. fibers form & cell pinches in and divides cytoplasm 4. resulting in two genetically identical cells

Page 281 M Phase

C. Eukaryotic Cell Cycle Interphase (majority of cell cycle) - G1 = Gap 1  cellular growth - S = Synthesis  DNA replicates - G2 = Gap 2  prepares for cell division

2. M Phase = Mitosis + Cytokinesis a. Mitosis (Page 282-283) *Prophase Spindle forming -Longest phase of mitosis -Chromatin coils up and becomes visible chromosomes -Nucleus begins to disappear -Centrioles separate forming spindle fibers and move to opposite ends Chromosomes (paired chromatids)

*Metaphase -Centromere of each chromosome attaches to the spindle fibers -Chromosomes line up across the middle of the cell Spindle Centriole

*Anaphase -Centromeres split causing sister chromatids to separate becoming individual chromosomes Individual chromosomes -Ends when chromosome movement stops at poles

*Telophase -Chromosomes are at opposite ends of the cell and begin to uncoil -Nucleus reappears -Spindle fibers break down -Easiest way to recognize telophase is because of “Cleavage Furrow” Cleavage Furrow

(aka = Cytoplasmic Division) b. Cytokinesis - Division of cytoplasm *Animal cells – cell membrane pinches from outside in *Plant cells – cell plate grows from inside cytoplasm out to the cell wall and becomes part of the cell wall (page 284) 4. The new daughter cells carry out the same cellular functions as the parent cell

10-3 Regulating the Cell Cycle IV. Cell Cycle Regulators A. Cyclin: Protein that regulates cell cycle in eukaryotes 1. Two Types: a. Internal Regulators -Protein that monitors internal events and timing ex. Can’t start mitosis until chromosomes have been replicated ex. Prevents cell from entering one phase until the previous is completed

b. External Regulators -Proteins that respond to events outside the cell -Direct cells to speed up or slow down cell cycle -Growth factors – stimulate cell growth during wound healing -Neighboring cells inhibit growth so one cell won’t “disrupt” another c. Apoptosis -process of programmed cell death -key role in development of tissues & organs

Wound Healing Assay

B. Uncontrolled Cell Growth 1. One result of uncontrolled growth of the cell = CANCER a. Cancer cells form masses of tissue = Tumor b. Cancer cells migrate through circulatory system = Metastasis c. Cancer cells absorb nutrients needed by other cells, block nerve connections, & prevent organs from functioning properly d. Caused by defect in genes that regulate cell growth/division, environmental factors, enzymes changes in production, diet, cigarettes, water/air pollution, viruses, radiation, UV light

3. Treatment Surgery Radiation Chemotherapy

B. unspecialized cells from which differentiated cells develop V. Stem Cells A. Totipotent  to develop into any type of cell in the body- in zygote B. unspecialized cells from which differentiated cells develop C. Found in: -Adult Stem Cells  in some tissue like blood & skin, bone marrow, hair follicles (multipotent) *only used for replacing cells in the tissue they were found -Embryonic Stem Cells  more versatile = can produce every cell type in the body (pluripotent)

10–1 As a cell increases in size, which of the following increases most rapidly? A. surface area B. volume

10–1 If an imaginary cube-shaped cell has a length of 6 cm, its ratio of surface area to volume is A. 1 : 1. B. 6 : 1. C. 36 : 1. D. 1 : 6.

10–1 The process by which a cell divides into two new daughter cells is called A. cell growth. B. cell division. C. DNA replication. D. cell multiplication.

10–1 When one cell divides in two, what happens to the surface area to volume ratios in the new cells? A. There is no change in the amount of material exchanged. B. Each new cell can exchange more material than the original cell. C. Each new cell can exchange less material than the original cell. D. The two new cells cannot be compared to the original cell.

10–1 When a growing cell undergoes cell division, each new cell gets A. half the DNA from the original cell. B. twice as much DNA as the original cell. C. a random sample of the DNA in the original cell. D. a full copy of all the DNA in the original cell.

10-2 The series of events that cells go through as they grow and divide is called A. the cell cycle. B. mitosis. C. interphase. D. cytokinesis.

10-2 The phase of mitosis during which the chromosomes line up across the center of the cell is A. prophase. B. metaphase. C. anaphase. D. telophase.

10-2 Cytokinesis usually occurs A. at the same time as telophase. B. after telophase. C. during interphase. D. during anaphase

10-2 DNA replication takes place during the A. S phase of the cell cycle. B. G1 phase of the cell cycle. C. G2 phase of the cell cycle. D. M phase of the cell cycle.

10-2 During mitosis, “sister” chromatids separate from one another during A. telophase. B. interphase. C. anaphase. D. metaphase.

10-3 The cell cycle is believed to be controlled by proteins called A. spindles. B. cyclins. C. regulators. D. centrosomes.

10-3 Proteins that respond to events inside the cell are called A. internal regulators. B. external regulators. C. cyclins. D. growth factors.

10-3 Once a multicellular organism reaches adult size, the cells in its body A. stop dividing. B. grow and divide at different rates, depending on the type. C. have the same life span between cell divisions. D. undergo cell division randomly.

10-3 One effect of an internal regulator is that a cell will not begin mitosis until A. it becomes too large. B. the cell’s growth is stimulated. C. it is in physical contact with other cells. D. all its chromosomes have been replicated.

10-3 One factor common to almost all cancer cells is A. a lack of cyclin. B. a defect in gene p53. C. exposure to tobacco smoke. D. exposure to radiation.