REPRODUCTION AT THE CELLULAR LEVEL

Question 1

Autosomes

Answer 1

are the 22 pairs of chromosomes that control traits unrelated to gender.

Question 2

Sex chromosomes

Answer 2

are the 1 pair that contains the genes that do control gender.

Question 3

diploid

Answer 3

(body cells) that have 46 (2n) paired chromosomes are called

Question 4

haploid

Answer 4

(sex cells) that have only 23 (n) unpaired chromosomes are called

Question 5

The cell cycle 5

Answer 5

Interphase

– cell doubles its organelles; cell grows
in size

– DNA replication occurs

– proteins needed for division are synthesized

– nuclear division Cytokinesis

– cytoplasmic division

Question 6

major checkpoints 3

Answer 6

G1, if passed, the cell is committed to divide.
G2 cycle pauses to verify DNA replication.
M cycle pauses to verify spindle assembly and chromosome attachment.

Question 7

Chromosomes that are dividing are made up of two identical parts called__________

Answer 7

sister chromatids.

Question 8

centromere

Answer 8

where the sister chromatids are held together at a region

Question 9

Mitosis occurs in body cells.

There are four phases.

Answer 9

Prophase Metaphase Anaphase Telophase

Question 10

PROPHASE

Answer 10

1
Chromosomes condense and become visible.
The nuclear envelope fragments.
The nucleolus disappears.
Centrosomes move to opposite poles.
Spindle fibers appear and attach to the centromeres.

Question 11

MITOSIS: METAPHASE

Answer 11

2
Chromosomes line up at the middle of the cell (equator).
Spindle becomes fully-formed.

Question 12

MITOSIS: ANAPHASE

Answer 12

3

Sister chromatids separate at the centromeres and move towards the poles.

Question 13

MITOSIS: TELOPHASE AND CYTOKINESIS

Answer 13

4
Chromosomes arrive at the poles.
Chromosomes become indistinct chromatin again.
Nucleoli reappear.
Spindle disappears.
Nuclear envelope reassembles.
Two daughter cells are formed by a ring of actin filaments (cleavage furrow).

Question 14

Meiosis occurs

Answer 14

in sex cells

Question 15

Prophase I

Answer 15

1

Homologous chromosomes pair (synapsis); crossing- over occurs, in which there is exchange of genetic information.

Question 16

Metaphase I

Answer 16

2

Homologous pairs line up at the equator.

Question 17

Anaphase I

Answer 17

3

Homologous chromosomes separate and move toward opposite poles

Question 18

Telophase I

Answer 18

4

Two daughter cells result, each with 23 duplicated chromosomes.

Question 19

Prophase II

Answer 19

5

Chromosomes condense again.

Question 20

Metaphase II

Answer 20

6

Chromosomes align at the equator.

Question 21

Anaphase II

Answer 21

7

Sister chromatids separate to opposite poles.

Question 22

Telophase II

Answer 22

8

Four daughter cells result, each with 23 unduplicated chromosomes.

Question 23

MITOSIS VS. MEIOSIS differences

Answer 23

MITOSIS
Growth and repair of cells Occurs in body cells
1 division
Results in 2 diploid, genetically identical cells
MEIOSIS
Formation of gametes Occurs in sex cells
2 divisions
Results in 4 haploid, genetically different cells

Question 24

Monosomy

Answer 24

cell has only 1 copy of a chromosome e.g., Turner syndrome (only 1 X chromosome)

Question 25

Trisomy

Answer 25

cell has 3 copies of a chromosome

e.g., Down syndrome (3 copies of chromosome 21)