BIO CH 1: Part 2 : Meiosis

Question 1

___- (aka sex cells) specialized haploid cells produced by meiosis and involved in sexual reproduction.

Answer 1

Gametes

Question 2

Match female and male for the following,
Sperm
Eggs

Answer 2

Male

Female

Question 3

Humans have __ chromosomes arranged in __ pairs.

Answer 3

46

23

Question 4

Each pair of chromosomes has ___ sets of DNA (diploid). The sets of DNA come from?

Answer 4

2

One set from mother and one set from father.

Question 5

___ means having two copies of each chromosome.

Answer 5

Diploid

Question 6

___ ____- pair of chromosomes that have the same gene sequence; one coming from each parent.

Answer 6

Homologous pair.

Question 7

____- a cell that contains exactly half the cells normal set of genetic material.

Answer 7

Haploid.

Question 8

Human gametes contain __ chromosomes.

Answer 8

23

Question 9

How are gametes produced?

- through a process of …

Answer 9

Cell division called meiosis. Meiosis consists of 2 divisions: meiosis I and meiosis II.

Question 10

What stage is before meiosis I?

Answer 10

Interphase (cell grows, DNA is replicated, … Identical to mitosis)

Question 11

In prophase I…

Answer 11

DNA coils to form chromosomes, spindle fibers and spindle form, homologous chromosomes pair up tightly through synapsis into units called tetrads.

Question 12

Why aren’t we clones of our parents?

Answer 12

2^23 Combinations➡ many possibilities➡random fertilization.

Question 13

___ ____ -when non-sister chromatids are do tightly packed in a tetrad, that a piece of the chromosomes actually break off and genetic material is exchanged.

Answer 13

Cross-over

Question 14

CROSS PVER

• __-__ crossovers occur per chromosome pair.
• allows for … To occur on a chromosome.

Answer 14

• 2-3

- New combination of genes

Question 15

Metaphase I

Answer 15

• spindle fibers attach to centromeres.

- tetrads (chromosome pairs) line up at the cells equator.

Question 16

Anaphase I

Answer 16

• tetrads break apart

- one chromosome moves to each pole.

Question 17

Telophase I

Answer 17

• spindle breaks down

- chromosome uncoils

Question 18

Cytokinesis I

Answer 18

• cytoplasm divides yielding two cells.

- each new cell is haploid (only one member of the homologous pairs in each cell.

Question 19

Prophase II

Answer 19

• spindle fibers form in each cell.

- spindle fibers attach to chromosomes.

Question 20

Metaphase II

Answer 20

-chromosomes line up at the equator. ( not in pairs this time)

Question 21

Anaphase II

Answer 21

Centromeres on each chromosome split and sister chromatids are pulled opposite poles, in each cell.

Question 22

Telophase II

Answer 22

• spindle Breaks down

- nuclei reform

Question 23

Cytokinesis II

Answer 23

• Cytoplasm divides
• 4 new haploid cells results therefore, each has half the amount of genetic material of the original parent cell.
• these cells with further modification become gametes.

Question 24

• In males _ cells become sperm.
• In females of some species (mammals) _ cell becomes the egg, the other three are called __ __ and are absorbed by the body.

Answer 24

4
1
Polar bodies

Question 25

GENETIC RECOMBINATION

How many kinds of genetically differ sperm or eggs can be produced?

Answer 25

2^ haploids

Humans 2^23

Question 26

How many sperm and egg production depend on …

Answer 26

• the # of chromosomes the parent has ( how many homologous pair line up in metaphase)
• when crossing over is included the combos are endless.

Question 27

Mendel’s laws

1. __ : homologous chromosomes separate in meiosis I.
2. __: each homologous pair lines up randomly and independently of other homologous pairs in maya phase I.

Answer 27

Law of segregation

Law of independent assortment

Question 28

Meiosis is important because …
1n =
2n =

Answer 28

You split the chromosomes in half.
Haploid
Diploid.