Chapter 9 Cellular Reproduction

Cell Size Does size matter (for cells)? If yes, why? Surface area to volume – Transport waste out, nutrients in, communicate – More surface area/lower volume = fast/efficient – Be small

Visualize Surface Area

The Cell Cycle A cell’s life from birth to reproduction – Note: “parent” cell becomes 1 of 2 daughter cells

Stages of the Cell Cycle G 1 : 1 st phase after division, grow S: copy DNA (2 sets now) G 2 : prep for division, reproduce organelles, etc. M Phase: – mitosis occurs, nucleus splits – cytokinesis splits cell in 2, 1 nucleus per cell

The M Phase Mitosis consists of 4 parts following G2 – Prophase Form chromosomes, fragment nucleus, form/attach spindle fibers, centrioles/centrosomes migrate to poles – Metaphase Attached spindle fibers move chromosomes (bound sister chromatids) to middle of cell, line them up – Anaphase Centromeres split, sister chromatids pulled by spindle fiber to separate cell poles – Telophase Opposite of prophase

Cytokinesis In Animal Cells – Microfilament ring shrinks to “pinch” the cell in 2 In Plant Cells – A new membrane and cell wall, called the cell plate, forms down the center of the cell Why don’t plants and animals use the same method?

Mitosis in action

Cell Cycle Regulation Many molecules involved (cyclin/CDK) Ensure controlled growth and reproduction

Checkpoints During the phases of interphase and during mitosis there are points the process can be shut down The ultimate shutdown can occur in G1, in cells that never reproduce (called G0)

Why so careful about Division? Uncontrolled cell growth can occur Cells multiply, but don’t do their jobs – Crowd out and damage tissue Such cells that spread (metastasize) are called cancer

How does cancer start? Several genes prevent cancerous growth – Mutations can damage these genes – They all must be damaged to get cancer The environment can cause mutations Inherited mutations can exist

Apoptosis Programmed cell death (self destruct) – Cell breaks into small compartmental pieces

Stem Cells Can be any type of cell when they grow up Unspecialized cells in: – Early embryos (controversial) – Partly in various adult tissues (bone marrow) Cellular Reproduction

CDQ 1 1.A 2.B 3.C 4.D A. interphase B. prophase C. metaphase D. telophase Which is the first phase of mitosis? Chapter Diagnostic Questions

CDQ 2 1.A 2.B 3.C 4.D Chapter Diagnostic Questions A. interphase B. metaphase C. anaphase D. telophase During what phase do the sister chromatids line up in the middle of the cell?

CDQ 3 1.A 2.B 3.C 4.D Chapter Diagnostic Questions A. cytokinesis B. interphase C. apoptosis D. mitosis Which is not a phase of the cell cycle?

FQ 7 1.A 2.B 3.C 4.D What are the “key and ignition” that start the various activities in the cell cycle? A. chromatin and chromosomes B. cyclin and CDKs C. microtubules and spindle fibers D. protein and ribosomes 9.3 Formative Questions

FQ 8 1.A 2.B 3.C 4.D Which of these cancer-causing substances or agents is impossible to avoid completely? A. chemicals such as asbestos B. food and drinks that the FDA warns may contain carcinogens C. tobacco and second-hand smoke D. ultraviolet radiation from the Sun 9.3 Formative Questions

FQ 9 1.A 2.B 3.C 4.D 9.3 Formative Questions What is the term for the programmed death of cells that are damaged beyond repair or have harmful changes in their DNA? A. apoptosis B. carcinogens C. cytokinesis D. mitosis

FQ 10 1.A 2.B 3.C 4.D 9.3 Formative Questions Which cells are not locked into becoming one particular kind of cell and are capable of developing into specialized tissues? A. apoptotic cells B. cancer cells C. prokaryotic cells D. stem cells

CAQ 1 1.A 2.B 3.C 4.D This cell has completed what stage of mitosis? A. anaphase B. interphase C. metaphase D. telophase Chapter Assessment Questions

CAQ 2 1.A 2.B 3.C 4.D What term is used to describe programmed cell death? A. apoptosis B. anaphase C. necrosis D. cyclins Chapter Assessment Questions

CAQ 3 1.A 2.B 3.C 4.D What is the role of cyclins in a cell? A. to control the movement of microtubules B. to signal for the cell to divide C. to stimulate the breakdown of the nuclear membrane D. to cause the nucleolus to disappear Chapter Assessment Questions

STP 1 1.A 2.B 3.C Which cell has the lowest ratio of surface area to volume? A B C Standardized Test Practice

STP 2 1.A 2.B 3.C 4.D Standardized Test Practice At what stage of interphase does the cell take inventory and make sure it is ready for the division of its nucleus? A. G 1 B. S C. G 2 D. M

STP 3 1.A 2.B 3.C 4.D Standardized Test Practice Which occurs in plant cells but not animal cells during the cell cycle? A. formation of a cell plate B. formation of microtubules C. formation of a cleavage furrow at the equator of the cell D. movement of chromosomes to the poles of the cell

STP 4 1.A 2.B Standardized Test Practice Multiple changes in DNA are required to change an abnormal cell into a cancer cell. A. true B. false

STP 5 1.A 2.B 3.C 4.D Standardized Test Practice Which is not a condition that can result in cancer? A. a failure in the control mechanisms that regulate the cell cycle B. a failure in the repair systems that fix changes or damage to DNA C. a failure of the spindle fibers to move chromosomes during mitosis D. mutations or changes in segments of DNA that control protein production