Regulating The Cell

Question 1

Regulatory proteins: cyclins

Answer 1

Internal

• events inside the cell
• allow cell to continue only when certain conditions are met
• S phase (metaphase)

Internal regulators are proteins that react to changes within a cell. For example: The fact that a normal cell will not enter mitosis until its entire DNA has been replicated is regulated by a protein within the cell. This protein is an internal regulator. Mitosis is the biological term for the division of a mother cell into two daughter cells.

Question 2

Regulatory proteins: external

Answer 2

• events outside the cell
• don’t respond to cell cycle

-Growth factors: wound healing, space relations (t phase)

External regulators are also proteins, but they react to stimuli from outside the cell. They direct cells to either speed or slow the cell cycle based upon outside conditions. For example, one protein reacts to molecules on the outside of a neighboring cell. This helps make certain that cells stop dividing when overcrowded

Question 3

Apoptosis

Answer 3

Programmed cell death

• shaped organisms: too little webbed feet
• too much: Parkinson’s disease

Question 4

Cancer

Answer 4

Uncontrolled cell growth

-tumors, benign, malignant

Causes

• defects to genes controlling cell division
• tobacco, radiation, infections

Treatments: surgery, radiation, chemical compounds

Question 5

restriction point

Answer 5

G1 checkpoint) a point in the animal cell cycle at which the cell becomes “committed” to the cell cycle, which is determined by external factors and signals

Question 6

Spindle checkpoint

Answer 6

(M checkpoint) prevents separation of the duplicated chromosomes until each chromosome is properly attached to the spindle apparatus

Question 7

G2 checkpoint:

Answer 7

ensures all of the chromosomes have been replicated and that the replicated DNA is not damaged