UNIT IIIChapter 10

Cell Growth & Division

I. Chemical Pathways

Cell Growth and Division

A. Limits to Cell Growth (two main reasons why cells divide)

1. DNA “Overload”

b. Creates “information crisis” (too much Cell, too little DNA!)

a. The larger the cell gets, the bigger the demand on its DNA (DNA found in the nucleus of the cell)

2. Exchanging Materials

a. Rate of exchange of materials (food, water, wastes depends on the surface area of the cell)b. Rate at which food and oxygen are used up depends on cell’s volume

c. Ratio of surface area to volume- when cell grows, volume increases faster than it’s surface area.

What would the volume of a cell be if each side measured 4 cm?

3. Cell Division- to solve the problem of small surface area to volume, a cell divides into two daughter cells

a. Cell replicates (copies) it’s DNA before divisionb. Rates vary from 30 minutes (bacteria) to many decades

II. Cell Division

A. Chromosomes- genetic information carried on chromosomes

1. Before cell division each chromosome is replicated (copied)

2. Each chromosome consists of two identical “sister” chromatids

3. Each pair of chromosomes attached to area called centromere

B. The Cell Cycle- Series of events that cells go through as they grow and divide

1. Consists of 4 phases (M, {interphase-G1, S, and G2 }) a. M phase (mitosis)-

division of cell nucleus and cytokinesis

b. G1 phase (gap)-periods of growth and activityc. S phase (synthesis)- DNA synthesized (duplicated)

d. G2 phase (gap)- Organelles produced.

C. Mitosis- Division of Cell Nucleus and Cytokinesis. Divided into 4 phases

1. Prophase- First and longest phase.

• Chromosomes become visible

• Centrioles separate and migrate to opposite sides of nucleus

•Chromosomes attach to spindle fibers.

•Nuclear membrane breaks down

2. Metaphase- Chromosomes line up across the center of the cell

3. Anaphase-

•Centromeres that join chromatids separate.

•Sister chromatids separate

•Chromosomes moves to opposite poles

4. Telophase-

•Condensed chromosome begin to disperse

•Nuclear envelope re-forms around cluster of chromosomes

•Nucleolus becomes visible

5. Interphase : not part of mitosis• “Normal cell life” • Cell division does not occur.• Chromotids (DNA) copy

themselves to make a full chromosome.

D. Cytokinesis- division of cytoplasm following mitosis

1. Animal cells- cell membrane drawn inward until cytoplasm is pinched into two nearly equal parts

2. Plant cells- cell plate forms midway between divided nuclei. Gradually develops into separating membrane. Eventually cell wall begins to appear.

Mitosis Review

III. Regulating the Cell Cycle

A. Controls on Cell Division

1. Protein called cyclin regulates the timing of the cell cycle in eukaryotic cells

2. Cells will grow in petri dish until they come into contact with other cells. Cell growth turned “on” and “off”

3. Two main types of regulatory proteins

a. Internal regulator- respond to events inside the cell. (e.g. Cell will not enter mitosis until all chromosomes replicated.

b. External regulator- respond to events outside the cell. (e.g. Wound healing and embryonic development.) can also prevent excessive cell growth

B. Uncontrolled Cell Growth

1. Cancer- do not respond to signals that regulate growth of most cells. Form masses called tumors

2. Don’t respond to external growth regulators. Some may be genetic.

Spread of cancer cells in breast cancer

Check out the streaming videos available in the “Streaming Video” folder. They are a great way to review the material!

Chapter 10

Cell Growth & Division

As a cell becomes larger, its

a. volume increases faster than its surface area.

b. surface area increases faster than its volume.

c. volume increases, but its surface area stays the same.

d. surface area stays the same, but its volume increases.

As a cell becomes larger, its

a. volume increases faster than its surface area.

b. surface area increases faster than its volume.

c. volume increases, but its surface area stays the same.

d. surface area stays the same, but its volume increases.

As a cell grows, it

a. places more demands on its DNA.

b. uses up food and oxygen more quickly.

c. has more trouble moving enough materials across its cell membrane.

d. all of the above

As a cell grows, it

a. places more demands on its DNA.

b. uses up food and oxygen more quickly.

c. has more trouble moving enough materials across its cell membrane.

d. all of the above

If the length of a cell increases 10 times, its volume increases about

a. 5 times.

b. 10 times.

c. 100 times.

d. 1000 times.

If the length of a cell increases 10 times, its volume increases about

a. 5 times.

b. 10 times.

c. 100 times.

d. 1000 times.

The speed with which wastes are produced by a cell depends on the cell's

a. ratio of surface area to volume.

b. environment.

c. volume.

d. surface area.

The speed with which wastes are produced by a cell depends on the cell's

a. ratio of surface area to volume.

b. environment.

c. volume.

d. surface area.

Unlike small cells, large cells have more trouble

a. dividing.

b. producing daughter cells.

c. moving needed materials in and waste products out.

d. making copies of their DNA.

Unlike small cells, large cells have more trouble

a. dividing.

b. producing daughter cells.

c. moving needed materials in and waste products out.

d. making copies of their DNA.

When during the cell cycle are chromosomes visible?

a. only during interphase

b. only when they are being replicated

c. only during cell division

d. only during the G1 phase

When during the cell cycle are chromosomes visible?

a. only during interphase

b. only when they are being replicated

c. only during cell division

d. only during the G1 phase

When during the cell cycle is a cell's DNA replicated?

a. G1 phase

b. G2 phase

c. S phase

d. M phase

When during the cell cycle is a cell's DNA replicated?

a. G1 phase

b. G2 phase

c. S phase

d. M phase

Which event occurs during interphase?

a. The cell grows.

b. Centrioles appear.

c. Spindle fibers begin to form.

d. Centromeres divide.

Which event occurs during interphase?

a. The cell grows.

b. Centrioles appear.

c. Spindle fibers begin to form.

d. Centromeres divide.

Cell division is represented in Figure 10-1 by the letter

a. A.

b. B.

c. C.

d. D.

Cell division is represented in Figure 10-1 by the letter

a. A.

b. B.

c. C.

d. D.

The cell cycle is the

a. series of events that cells go through as they grow and divide.

b. period of time between the birth and the death of a cell.

c. time from prophase until cytokinesis.

d. time it takes for one cell to undergo mitosis.

The cell cycle is the

a. series of events that cells go through as they grow and divide.

b. period of time between the birth and the death of a cell.

c. time from prophase until cytokinesis.

d. time it takes for one cell to undergo mitosis.

The structure labeled A in Figure above is called the _____________.

a. centromere.

b. centriole.

c. sister chromatid.

d. spindle.

The structure labeled A in Figure above is called the _____________.

a. centromere.

b. centriole.

c. sister chromatid.

d. spindle.

The structures labeled B in Figure above are called

a. centromeres.

b. centrioles.

c. sister chromatids.

d. spindles.

The structures labeled B in Figure above are called

a. centromeres.

b. centrioles.

c. sister chromatids.

d. spindles.

The first phase of mitosis is called

a. prophase.

b. anaphase.

c. metaphase.

d. interphase.

The first phase of mitosis is called

a. prophase.

b. anaphase.

c. metaphase.

d. interphase.

During which phase of mitosis do the chromosomes line up along the middle of the dividing cell?

a. prophase

b. telophase

c. metaphase

d. anaphase

During which phase of mitosis do the chromosomes line up along the middle of the dividing cell?

a. prophase

b. telophase

c. metaphase

d. anaphase

Which of the following represents the phases of mitosis in their proper sequence?

a. prophase, metaphase, anaphase, telophase

b. interphase, prophase, metaphase, anaphase, telophase

c. interphase, prophase, metaphase, telophase

d. prophase, metaphase, anaphase, telophase, cytokinesis

Which of the following represents the phases of mitosis in their proper sequence?

a. prophase, metaphase, anaphase, telophase

b. interphase, prophase, metaphase, anaphase, telophase

c. interphase, prophase, metaphase, telophase

d. prophase, metaphase, anaphase, telophase, cytokinesis

What is the role of the spindle during mitosis?

a. It helps separate the chromosomes.

b. It breaks down the nuclear membrane.

c. It duplicates the DNA.

d. It divides the cell in half.

What is the role of the spindle during mitosis?

a. It helps separate the chromosomes.

b. It breaks down the nuclear membrane.

c. It duplicates the DNA.

d. It divides the cell in half.

One difference between cell division in plant cells and in animal cells is that plant cells have

a. centrioles.

b. centromeres.

c. a cell plate.

d. chromatin.

One difference between cell division in plant cells and in animal cells is that plant cells have

a. centrioles.

b. centromeres.

c. a cell plate.

d. chromatin.

During normal mitotic cell division, a parent cell having four chromosomes will produce two daughter cells, each containing

a. two chromosomes.

b. four chromosomes.

c. eight chromosomes.

d. sixteen chromosomes.

During normal mitotic cell division, a parent cell having four chromosomes will produce two daughter cells, each containing

a. two chromosomes.

b. four chromosomes.

c. eight chromosomes.

d. sixteen chromosomes.

Cancer is a disorder in which some cells have lost the ability to control their

a. size.

b. spindle fibers.

c. growth rate.

d. surface area.

Cancer is a disorder in which some cells have lost the ability to control their

a. size.

b. spindle fibers.

c. growth rate.

d. surface area.

Cancer cells form masses of cells called

a. tumors.

b. cyclins.

c. growth factors.

d. p53.

Cancer cells form masses of cells called

a. tumors.

b. cyclins.

c. growth factors.

d. p53.

(j)

(a) (b) (d)

(g)

(c)

(f)

(h)

(i)

(e)

What is the name of structure (f)?

Centrioles

(j)

(a) (b) (d)

(g)

(c)

(f)

(h)

(i)

(e)

What phase is represented by letter (a)?

Interphase

(j)

(a) (b) (d)

(g)

(c)

(f)

(h)

(i)

(e)

What phase is represented by letter (j)?

anaphase

(j)

(a) (b) (d)

(g)

(c)

(f)

(h)

(i)

(e)

What are structures (c) called?

Spindle fibers

(j)

(a) (b) (d)

(g)

(c)

(f)

(h)

(i)

(e)

What phase is represented by letter (d)

metaphase

(j)

(a) (b) (d)

(g)

(c)

(f)

(h)

(i)

(e)

What phase is represented by letter (g)

telophase

(j)

(a) (b) (d)

(g)

(c)

(f)

(h)

(i)

(e)

What phase is represented by letter (b)?

Prophase