Top Banner
Cell Reproduct ion
34

Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

Jan 18, 2016

Download

Documents

Lisa Walker
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

Cell Reproduct

ion

Page 2: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

I. Cell Growth

Why do cells divide rather than grow into 1 giant cell?

A. DNA “Overload”

1. A cell’s nucleus contains DNA which has all the information needed for a cell to function

Page 3: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

2. As a cell increases in size, it doesn’t make copies of the cell.

3. There is not enough DNA to support a large cell.

Page 4: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

B. Exchanging materials such as oxygen and water through diffusion becomes harder as the cell gets larger.

Page 5: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

C. Surface area- to- volume ratio:

1. As a cell’s size increases, it’s volume increases much faster than it’s surface area

Page 6: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

2. If a cell became too big, it’s surface area would be too small to allow certain things to enter and leave the cell.

Page 7: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

D. Before it becomes too large, a cell will divide to form 2 “daughter” cells in a process called cell division.

-Cell division is for growth, repair, and maintenance.

Page 8: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

II. The Cell CycleThe cell cycle: sequence of

growth and division of a cell, consisting of 4 main phases:

A. Gap 1 (or G1) phase: cell grows, new proteins are made

Page 9: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

B. Synthesis (or S) phase: DNA is copied

C. Gap 2 (or G2) phase: cell gets ready for M phase

D. M phase: when mitosis, or division of the cell nucleus, occurs

Page 10: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

G1, S, and G2 are also

called INTERPHAS

E

cell cycle

Page 11: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

III. Mitosis

Mitosis- divided into 4 phasesA. Prophase

1. Stringy chromatin coil into visible chromosomes

Page 12: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

2. Nuclear membrane and nucleolus disappear

3. Centrioles move to opposite ends and a spindle fibers forms between them

Page 13: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.
Page 14: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

B. Metaphase

1. Chromosomes attach to the spindle fibers by their centromeres

Page 15: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

2. The spindle fibers push and pull the chromosomes to the middle, or equator, of the cell

Page 16: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

C. Anaphase1. Centromeres split2. Chromosomes split

apart and move to opposite ends of the cell

Page 17: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

D. Telophase

1.Chromosomes unwind

2. Nuclear membrane forms around each new nucleus

Page 18: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

3. Nucleolus reappears4. Plasma membrane

begins to separate 2 new nuclei

Page 19: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

E. Cytokinesis: division of the cytoplasm

1. In animal cells, the plasma membrane pinches inward along the equator (cleavage furrow) until the cell is pinched into 2 new cells.

Page 20: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

2. In plant cells, a cell plate forms at the equator, forming 2 new cells.

Page 21: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

F. Results of Mitosis: 1. Production of 2 new cells

with chromosomes identical to the original parent cell.

G. Enzymes control the cell cycle. Failure to respond to the signals that regulate growth can result in cancer, or the uncontrolled dividing of cells.

Mitosis

Page 22: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

IV. Meiosis*Mitosis produces 2 exact

copies of “body” cellsA. In meiosis, sex cells are

producedB. Body cells are diploid which

means they have 2 of each chromosome, or a pair of each chromosomes.

{1 from mom, 1 from dad}

Page 23: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

• The number of chromosomes in a cell depends on what kind of organism it is.

- Ex. Humans have 46 chromosomes, or 23

pairs.

Page 24: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

1. Homologous chromosomes: chromosomes containing same information–One from mother & 1 from father; represented as 2n

Page 25: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

2. Haploid cells contain only 1 chromosome of a homologous pair. They are called sex cells or gametes (sperm and egg).

a. Represented as n.•Humans: n= 23•Fruit flies: n= 4

Page 26: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

*Gametes (haploid sex cells) fuse during sexual reproduction to form a diploid zygote.

*Meiosis is the process of forming haploid cells from diploid cells. It has 2 main parts:

Page 27: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

C. Meiosis I:

1. Chromosomes have replicated during interphase

2. Matching (or homologous chromosomes) move together, forming a tetrad. One chromosome is from mom and one is from dad. A tetrad is composed of 2 chromosomes each made up by 2 chromatids so has a total of 4 chromatids.

Page 28: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

3. Nucleoli and nuclear membrane disappears.

4. Spindle fibers forms.5. Tetrads line up at

equator.6. The homologous

chromosomes separate and move to opposite ends.

Page 29: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

7. Cell divides into 2 daughter cells- each still contains a double-stranded chromosome.

8. Divided into:Prophase IMetaphase IAnaphase ITelophase I

Page 30: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

D. Meiosis II1. Chromosomes line up at

equator.2. Centromere splits, and

sister chromatids separate.

Page 31: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

3. Each cell separates into 2 daughter cells, so now there are 4 cells, each with a single-stranded chromosome.

4. Divided into Pro II, Meta II, Ana II, Telo II

Meiosis

Page 32: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.
Page 33: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.
Page 34: Cell Reproduction. I. Cell Growth Why do cells divide rather than grow into 1 giant cell? A.DNA “Overload” 1. A cell’s nucleus contains DNA which has.

E. During spermatogenesis, 4 haploid sperm are produced. During oogenesis, 1 haploid egg is produced and 3 polar bodies are produced.

F. Meiosis is sometimes called reduction division and is important because it provides for genetic variation.