Chapter 27: Sperm and semen, Meiosis

Question 1

What is spermatogenesis?

Answer 1

the process of sperm production. It occurs in the seminiferous tubules and involves three principle events

Question 2

What are the three principle events of spermatogenesis?

Answer 2

1. Division and remodeling of a relatively large germ cell into four small, mobile cells with flagella
2. reduction of the chromosome number by one half
3. a shuffling of these genes so that each chromosome of the sperm carries a new gene combination that didnt exist in the chromosome of the parents

This ensures genetic variety in the offspring

Question 3

What is meiosis?

Answer 3

The genetic recombination and reduction in chromosome number are achieved through meiosis, which produces four daughter cells that subsequently differentiate into sperm

Question 4

What are the two types of cell division?

Answer 4

meiosis and mitosis

Question 5

what is mitosis?

Answer 5

the basis for division of single celled fertilized egg, growth of an embryo, and all postnatal growth and tissue repair. Essential it is the splitting of a cell with a distribution of chromosomes that results in two genetically identical daughter cells. It consists of four stages.

Question 6

What are the four stages of mitosis?

Answer 6

prophase
metaphase
anaphase
telophase

Question 7

What does it mean for a parent cell to be diploid?

Answer 7

it has two sets of chromosomes

Question 8

What does it mean for a daughter cell to be haploid in meiosis?

Answer 8

with 23 unpaired chromosomes

Question 9

How do chromosomes differ in mitosis vs meiosis?

Answer 9

in mitosis the chromosomes don’t change their genetic makeup. In an early stage of meiosis, however, the chromosomes of each homologous pair join and exchange portions of their DNA.

This creates new combinations of genes, so the chromosomes we pass to our offspring aren’t the same ones that we inherited from our parents

Question 10

How many daughter cells do parent cells produce in mitosis vs meiosis?

Answer 10

In mitosis parent cells produce two daughter cells while in meiosis they produce 4.

Question 11

What happens in prophase I?

Answer 11

pairs of homologous chromosomes line up side by side and form tetrads (chromatids).

They line up side by side with similar chromosomes provided by the opposing parent (mom and dad)

Question 12

What happens during the process called crossing-over in prophase I?

Answer 12

When the paternal and maternal chromosomes exchange segments of DNA. This creates new combinations of genes and thus contributes to genetic variety in the offspring.

Question 13

What happens after the crossing over process?

Answer 13

the chromosomes line up at the midline of the cells in metaphase then they separate at anaphase I, and the cell divides in two at telophase I.

Question 14

Whats different in meiosis during anaphase I?

Answer 14

It looks like mitosis but there important difference is that the centromeres don’t divide and the chromatids don’t separate from each other at anaphase I.

at this point each homologous chromosome parts company with its twin.