10.1 Pre-Read Questions1.Name 2 limitations to cell growth.

2.How does DNA limit cell growth?

3.Why is the ratio of surface area to volume important?

4.Describe the process of cell division.

Ch 10: Cell Growth and Division

10.1: Cell Growth

Cells

Does not continue to grow bigger

Cells just continue to produce more cells

Limits to Cell Growth 2 main reasons

1.Larger a cell becomes, the more demands the cell places on its DNA

Limits to Cell Growth 2 main reasons

2. Cell has more trouble moving enough nutrients and wastes in and out of cell

Reason #1 DNA “overload”

DNA = information that controls a cell’s function

if cells grow, DNA does not make extra copies

DNA would not be able to serve the needs of the cell

Reason #2: Exchanging Materials

how fast materials leave or enter the cell depends on surface area

food and oxygen depend on cell volume

Ratio of Surface Area to Volume

as surface area increases, its volume increases at a faster rate

Ratio of Surface Area to Volume

Consequence = cells have a more difficult time to move needed materials in and waste products out

Cell Division

how cells reproduce

one cell divides into 2 new cells daughter cells

Cell Division

before cell division - cell copies DNA

Each daughter cell gets own copy of DNA

10.2A

12 / 5 / 06

2 Stages

1.Mitosis = division of the cell nucleus

2.Cytokinesis = division of the cytoplasm

Mitosis

asexual source of new cells

Chromosomes carries the genetic information

consists of DNA cells have specific number of chromosomes

Chromosome not visible until cell division

replicated before cell division

chromosomes change form to chromatids

Chromatids Separate from each other and go into daughter cells

attached at a centromere located near the middle of the chromatids

Centromere

Chromatid

Cell Cycle

cell reproduction forms two daughter cells

in between period = interphase

Cell Cycle: 4 phases consists of 4 phases

M phase = mitosis and cytokinesis

S phase = chromosome replication (S = synthesis)

G1 and G2 (G = gap) -- growth and activity

Interphase

3 of the 4 phases occurG1 S phaseG2

G1 Phase

cell growing

increase in size and synthesize new proteins and organelles

S Phase

chromosome replication

proteins synthesized

G2 Phase

DNA replication complete at beginning

shortest phase

G2 Phase

organelles produced

prepare for cell division

10.2 Post Read Questions1.Describe the 2 stages of cell division.

2.Draw a chromosome and label and describe its parts.

3.What are the different phases of interphase? Describe each one.

4. What is the cell cycle?

10.2 B

12 / 06 / 06

QuickTime™ and aCinepak decompressor

are needed to see this picture.

Interphase

In between periods of cell division Cell growth and DNA replication occur

Prophase

first and longest phase (50%-60%)

chromosome becomes visible centrioles take position on opposite sides of nucleus at the centrosome

Prophase

Centrioles lie in centrosome so they can organize the spindle

Spindle = fanlike microtubule structure that helps separate the chromosomes

Prophase end = chromosomes coil and nuclear envelope break down

Metaphase

lasts only a few minutes

chromosomes line up across the center of the cell

Metaphase (cont) microtubules connect the centromere of each chromosome to the two poles of the spindle

Anaphase centromeres that join the sister chromatids split into individual chromosomes and are moved apart to opposite poles

Telophase chromosomes become dense material

spindle breaks apart nucleolus appears

Cytokinesis Division of cytoplasm usually occurs the same time as telophase

Animal Cell = cell membrane draw inward and pinched off

Plant cell = cell plate forms midway between the 2 nuclei; cell wall appears

I P M A TNTERPHASE

ROPHASE

ETAPHASE

NAPHASE

ELOPHASE

A

B

C

D

E Put the pictures in

order

ANSWER

D

C

E

A

B

Ch 10 Review Questions (Cont)

1. What is cytokinesis? When does it occur?

2. Compare how cytokinesis works between animal and plant cells.

3. Describe metaphase. 4. Describe anaphase.5. If you were to look at a picture

of telophase and anaphase, how can you distinguish the difference between the two?

10.3

12 / 7 / 06

Review: Cell Cycle

Preparing for Cell Division INTERPHASE

G1 S G2

Review: Cell Cycle Steps of Cell Division

Mitosis Prophase Metaphase Anaphase Telophase / Cytokinesis

Look at Figure 10.7 Observe what is going on

What is happening in each step?

Cyclin

protein regulates the timing of the cell cycle in eukaryotic cells

Regulatory Proteins Two types1.Internal Regulators2.External Regulators

Internal Regulators proteins that respond to events inside the cell

signals cell cycle to continue ONLY WHEN OTHER THINGS ARE COMPLETE

External Regulator proteins that respond to events outside the cell

direct cells to speed up or slow down the cell cycle

example: growth regulators

Uncontrolled Cell Growth Cancer

body loses ability to control growth

does not respond to the regulator proteins

result = large masses of cells

Tumorsmasses of cells damages the surrounding tissues

cells break off and spread throughout the body

Cause of cancer brought on by smoking tobacco

radiation exposure viral infection etc

10.3 Review Questions1.Why is it important for cells

to have regulated cell growth?2.What is the purpose of the

protein cyclin?3.Compare and contrast internal

regulators and external regulators.

4.What is cancer? What causes cancer?