Oral biology - Cell cycle

Question 1

Definition of cell proliferation

Answer 1

An increase in the number of cells; as a result of cell growth and cell division

Question 2

Definition of Growth factors

Answer 2

Polypeptides that control animal cell growth and differentiation

Question 3

Definition of Transcription factor

Answer 3

a protein that regulates the activity of RNA polymerase

Question 4

Definition of cell signalling

Answer 4

phosphorylation of residues

Question 5

How cell divides?

Answer 5

A cell reproduces by preforming an orderly sequence pf events in which it duplicates its content and then divides in two

Question 6

Mitosis is followed by what?

Answer 6

In most cases followed by cytokinesis

Question 7

Cell division in eukaryotic cells: What occurs during G1 phase?

Answer 7

This is one of the longest phases.

A cell has one centrosome consisting of two centrioles.

Question 8

Cell division in eukaryotic cells: What occurs during S phase?

Answer 8

S phase is completed within 8 hours.

Transition, centrosomes duplicate. Daughter centrioles arise from each centriole

Question 9

Cell division in eukaryotic cells: What occurs at the end of G2 phase?

Answer 9

G2 phase completes in about 4 hours.

The centrosomes complete duplication and each centriole is fully assembled

Question 10

Cell division in eukaryotic cells: What occurs in G0 phase?

Answer 10

Some cells stop dividing occasionally and leave G1 phase and enter the G0 where cells are metabolically active, however there is no appropriate extracellular signals that allows for re-entry to the cell cycle

Question 11

What is the shortest phase of cell cycle?

Answer 11

Mitotic phase

Question 12

Define mitosis

Answer 12

Its a division of the nucleus of a eukaryotic cell, involving condensation of DNA into visible chromosomes and separation of the duplicated chromosomes to form two identical sets.

Question 13

What are the phases of mitosis?

Answer 13

• Interphase
• Prophase/Prometaphase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis

Question 14

What happens at interphase?

Answer 14

The nucleus and the nuclear envelope are distinct and the chromosomes are in the from of threadlike chromatin

Question 15

What happens at prophase and prometaphase?

Answer 15

The chromosomes appear condensed, and the nuclear envelope is not apparent

Question 16

What happens at metaphase?

Answer 16

Thick,coiled chromosomes. Each lined up at the equator.

Question 17

What happens at anaphase?

Answer 17

The sister chromatids are separated to form two daughter chromosomes. Each pulled towards the pole

Question 18

What happens at telophase?

Answer 18

The chromosomes are at the poles and begin to decondense.

A new nuclear envelope is reforming. The cytoplasm may be dividing

Question 19

What happens at cytokinesis?

Answer 19

The cytoplasm is divided into two by contractiole ring - creating two daughter cells, each with one nucleus

Question 20

Control of cell cycle depend on?

Answer 20

• Timer
• Events in correct order
• Events takes place once per cycle
• On/Off switch trigger events in complete and irreversible fashion
• Robustness
• Adaptability

Question 21

What are cyclin dependent kinase (Cdk) controlled by?

Answer 21

Cyclins

Question 22

What do Cdk need for protein kinase activity?

Answer 22

Cyclins

Question 23

What does cyclin undergo during cell cycle?

Answer 23

Cycle of synthesis

Question 24

How many cyclin-Cdk controllers are there?

Answer 24

4

Question 25

What are the cyclin-cdk controllers?

Answer 25

• G1/S-cyclins bind at end G1: commit cell to DNA replication
• S-cyclins bind Cdks during S phase initiate DNA replication
• M-cyclins promote events of mitosis
• G1 cyclins promote passage through restriction point

Question 26

Points to remember for cell cycle control systems..

Answer 26

• Cyclin does not activate the Cdk but directs it
• Different proteins phosphorylated
• Accessibility