The Cell Cycle and Cell Division Part Two: Cell Cycle Regulation

Question 1

Evidence for cytoplasmic signals

Answer 1

Molecules (proteins) present in the cytoplasm seem to regulate the progress of a cell through the cell cycle

Transplanted a protein only found in cells going through mitosis into a cell in interphase, caused a mitotic spindle to form.

Discovered by Tim Hunt won 2001 nobel prize

Question 2

Cyclins

Answer 2

Regulate the timing of the cell cycle in eukaryotic cells

Amount fluctuates during steps of cycle

Question 3

Internal regulators

Answer 3

Direct the progression of the cell cycle but will physically pause division if the cell is not ready
Allow the cell cycle to proceed only if certain events hav occurred within the cell itself

EX: some wont let cell enter mitosis unless its chromosomes have replicated

Question 4

External regulators

Answer 4

Proteins that respond to what’s going on outside of the cell
Direct cells to speed up or slow down

A group of external regulators is made up of growth factors, growth factors stimulate growth and division of the cell, important during embryonic development and wound healing

Other external regulatory proteins on the surface of neighboring cells slow down or stop cell cycles, prevents excessive cell growth and keeps body tissues from disrupting one another

Question 5

Apoptosis

Answer 5

Programmed cell death
Key in the development of tissues and organs
Cells that do not die from damage, die from apoptosis

Cell and its chromatin shrink, the cell’s membranes break off, neighboring cells clean up the cells remains

The cells between a mouse’s toes undergo apoptosis during a late stage of development

Question 6

Cancer

Answer 6

An uncontrolled growth of abnormal cells
Some cancer cells neither density-dependent inhibition nor anchorage dependance, others do not produce cyclins
or a defect in gene 53, which plays a role in the G1 checkpoint

Question 7

Cancer cells

Answer 7

Do not respond normally to the body’s control mechanisms

Two types: malignant and benign

Question 8

Malignant tumours

Answer 8

Can spread throughout the body where they may form new tumors (metastasis)

1) Tumor grows from a single cancer cell
2) Cancer cells invade neighboring tissue
3) Cancer cells spread through lymph and blood vessels to neighboring tissue
4) Small percentage of cells may survive and a new tumor somewhere else in the body

Question 9

Benign Tumors

Answer 9

Benign tumors are noncancerous growths in the body. Unlike cancerous tumors, they don’t spread (metastasize) to other parts of the body

Question 10

What makes tumors dangerous

Answer 10

Cancer invades, destroys, and takes nutrients away from other tissues, disrupting proper function of organs

Question 11

Radiation and chemotherapy

Answer 11

Radiation disrupts cancer cells by making cell have trouble replicating DNA, chemotherapy cills cells