Unit 2- Mitosis Basics

Question 1

What is a karyotype?

Answer 1

A display of all the homologous chromosomes of a species in order of largest to smallest

Question 2

What are the several features of a karyotype? What does it show? 4

Answer 2

• different species have different number of chromosomes and all members of the same species have the same number
• each chromosome has a characteristic shape, size and banding pattern
• chromosomes come in homologous pairs
• one pair of homologous chromosomes is different in males and females ( the sex chromosomes) which in humans are homologous for women and non-homologous for men

Question 3

What is another name for non-sex chromosomes

Answer 3

Autosomes

Question 4

Why do we have 2 homologous chromosomes?

Answer 4

We inherit one chromosome from each parent

- so we each have a maternal and paternal homologous chromosome

Question 5

What is an ideogram?

Answer 5

A rod diagram of a chromosome usually with a gene or 2 marked on

Question 6

When can chromosomes be seen?

Answer 6

During cell division when they coil

Question 7

Definition of homologous chromosomes:

Answer 7

2 chromosomes of the same size and shape, one originating from each parent, they contain the same genes but different alleles

Question 8

What is mitosis for?

Answer 8

• growth
• replacement
• repair
• asexual reproduction
• artificial cloning

Question 9

What stages make up interphase?

Answer 9

G1: Where the cell grows back to original size, proteins are synthesised and organelles are replicated
S1: DNA and histones are replicated
G2: spindle proteins are synthesised

Question 10

What occurs in mitosis?

Answer 10

The nucleus divides to make 2 nuclei with identical copies of DNA
PMAT

Question 11

What occurs in cytokinesis?

Answer 11

Division of cytoplasm to form 2 daughter cells each with a nucleus

Question 12

How frequently is the cell cycle monitored to ensure no bad divisions?

Answer 12

At the G1, G2 and Mitosis phase

Question 13

When are cells allowed to go beyond the G1 phase?

Answer 13

• when there is a need for more cells, signalled by growth hormones

Question 14

What must be checked before a cell can pass the G2 phase?

Answer 14

The DNA must be checked to see if it has been replicated correctly with the correct number of chromosomes

Question 15

When can the M phase be passed?

Answer 15

Only when mitosis has been completely successful and there are 2 identical nuclei

Question 16

What happens if a checkpoint fails in the control of cell division?? And what can cause this?

Answer 16

• mutations or viral infections

- failure or checkpoints can result in uncontrolled division which leads to cancer