Ch:9 Meiosis

Question 1

What occurs during prophase 1 of meiosis?

Answer 1

1. Homologous chromosomes align in such a fashion that their genes match up. This is where crossing over occurs. (alleles between the 2 chromosomes mix resulting in hybrids with genes from each)
2. Synapsis or pairing of homologous chromosomes

Question 2

Crossing over allows for ______ to occur.

Answer 2

Variation

Question 3

The visible evidence of a crossover is a _______.

Answer 3

Chiasmata ( where homologous non-sister chromatids exchange their genetic material via crossover)

Question 4

The ___(farther/closer)___ the distance between the two genes the greater possibility of a cross over and recombination between them.

Answer 4

The farther the two genes are from each other the greater chance of crossing over and recombination between them

Question 5

What is the difference between anaphase in mitosis and anaphase 1 in meiosis?

Answer 5

Mitosis anaphase: sister chromatids are separated

Meiosis anaphase 1: Homologous chromosomes separate

* Not sister chromatids but separation homologues*
“A HUGE POINT TO REMEMBER”

Question 6

What occurs during Telophase 1 of meiosis?

Answer 6

Two haploid cells form, two chromatids (sister) still make up a chromosome

Question 7

What is the #1 function of meiosis 2?

Answer 7

The #1 function is to separate the two sister chromatids

Question 8

What occurs during metaphase II of meiosis?

Answer 8

Double stranded chromosomes become attached to the spindle, each chromosome is aligned at spindle equator

Question 9

What occurs during anaphase II of meiosis?

Answer 9

Each chromosome splits; sister chromatids are now chromosomes in their own right and migrate to opposite poles

Question 10

What occurs during telophase II of meiosis?

Answer 10

4 daughter nuclei form; after cytokinesis each gamete has a haploid number of chromosomes

Question 11

What are the 3 main differences between mitosis and meiosis?

Answer 11

Mitosis:

• produced clones… 2 daughter cells are made
• No synapsis, no crossing over
• produces cells for growth

Meiosis:

• produces variation… occurs only in germ cells (egg and sperm), where we halve chromosome #
• Synapsis and crossing over occur in prophase 1
• produces gametes

Question 12

Synaptonemal complex will form during _________.

Answer 12

Prophase 1 of meiosis

Synaptonemal complex is a protein that provides the structural framework for crossing over to occur. It aids in stabilization for proper chromosomal alignment during prophase 1

Question 13

Chromosomes are photographed when most condensed in ________ for a karyotype.

Answer 13

Metaphase

during prophase chromosomes condense but further condense in metaphase which is when they are the most condensed

Question 14

Meiosis will give rise to _________, while fertilization gives rise to a _________.

Answer 14

Meiosis gives rise to __gametes__, while fertilization gives rise to a __zygote__.

Question 15

Fertilization is also called ________.

Answer 15

syngamy

Question 16

How many chromosomes and chromatids are present during each of the following phases of mitosis?

A. Prophase
B. Metaphase
C. Anaphase
D. Telophase

Answer 16

Prophase: 46 chromosomes and 92 chromatids

Metaphase: 46 chromosomes and 92 chromatids

Anaphase: 92 chromosomes and 92 chromatids

Telophase: 92 chromosomes and 92 chromatids

Question 17

How many chromosomes and chromatids are present during each of the following phases of meiosis I?

A. Prophase I
B. Metaphase I 
C. Anaphase I
D. Telophase I
E. End of Meiosis I

Answer 17

Prophase: 46 chromosomes and 92 chromatids

Metaphase: 46 chromosomes and 92 chromatids

Anaphase: 46 chromosomes and 92 chromatids

Telophase: 46 chromosomes and 92 chromatids

End of Meiosis I: 23 chromosomes and 46 chromatids

(PMAT for meiosis I all have 46 chromosomes and 92 chromatids)

Question 18

How many chromosomes and chromatids are present during each of the following phases of meiosis II?

A. Prophase II 
B. Metaphase II
C. Anaphase II
D. Telophase II
E. End of Meiosis II

Answer 18

Prophase: 23 chromosomes and 92 chromatids

Metaphase: 23 chromosomes and 92 chromatids

Anaphase: 46 chromosomes and 46 chromatids

Telophase: 46 chromosomes and 46 chromatids

End of Meiosis II: 23 chromosomes and 23 chromatids

Question 19

What is the definition of spermatogenesis and where does it occur?

Answer 19

Formation of sperm and occurs in the seminiferous tubules of testis

Question 20

Label the following as 2N (diploid) or just N (haploid):

Primary spermatocyte:
Secondary spermatocyte:
Spermatids

Answer 20

Primary spermatocyte: 2N (diploid)

Secondary spermatocyte and the spermatid are both haploid (N)

Question 21

The head of a sperm cells is referred to as the _______.

Answer 21

acrosome

Question 22

The acrosome contains __________ enzymes which can break down the zona pellucid (outer membrane of ova), allowing for syngamy (fertilization)

Answer 22

hyaluronidase

Question 23

A primary oocyte is __haploid/diploid__ but a secondary oocyte is __haploid/diploid__.

Answer 23

Primary oocyte = 2N (diploid)

Secondary oocyte = haploid (N)

Question 24

When will a secondary oocyte resume meiosis II?

Answer 24

Only if a sperm fertilizes the secondary oocyte will it resume meiosis II

Question 25

The functional maturation of the sperm is termed ________.

Answer 25

capacitation