Sexual Reproduction

What are the 2 key process of sexual reproduction?

1.formation of haploid cells
2.2 sex cells joining to form fertilized cell (zygote)

What are gametes?

Sex cells that contain genetic information from parents

What is meiosis?

Process through which haploid gametes are formed

What is the difference between mitosis and meiosis?

in mitosis, # of chromosomes stays the same, but in meiosis # is cut in half

What does the combination of 2 gametes result in?

complete set of chromosomes

What does the combination of 2 gametes result in?

Complete set of chromosomes

What forms homologous chromosomes?

Complete set of DNA from each parent

How many haploid gametes does meiosis produce

4

What is gametogenesis?

formation of sex cells: 2 types in humans

What happens in prophase 1?

Homologous chromosomes come together

How many sister chromatids are in each chromosome?

2 sister chromatids (one chromosome from each parent)

How many chromatids form a tetrad?

4

Where does the crossing over between homologous chromosomes occur?

Prophase 1

Where do intertwined chromosomes break off and reattach at?

the chiasmata

What happens in metaphase 1?

tetrads migrate towards center off cell

what is the difference between metaphase 1 in meiosis and mitosis?

in mitosis there are only sister chromatids lining up in the cetre, whereas in meiosis, the tetrads are lining up to the center of the cell

What happens in anaphase 1?

homologous chromosomes move to opposite poles of the cell as the spindle fibers shorten

Will both chromosomes from each homologous pair be in each new daughter cell?

no, only one to make the new daughter cell genetically unique

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

in mitosis, the sister chromatids are being pulled apart, but in anaphase we are splitting up the homologous chromosomes

What happens in telophase 1?

nuclear membrane reforms, spindle fibers dissolve cells begins to divide

How many duplicated copies of chromosomes are made at this point

1

During telophase 1, are cells haploid or diploid? why or why not?

They are haploid, because the cell does not have one copy of the mom, and one copy of the dad. Each cell has 2 copies of mom, and 2 copies of the dad, causing them to be haploid.

During prophase 2 how many chromosomes and sister chromatids are in each haploid cell?

1 chromosome and 2 sister chromatids

During prophase 2, are the sister chromatids genetically identical? why or why not

they are not genetically identical, due to the crossing over in prophase 1

What happens in prophase 2

nuclear membrane dissolves, centrioles move to opposite poles, and spindle fibers reform

What happens in metaphase 2?

1 chromosome moves to the center of cell

In metaphase 2, what is the chromosome made of?

2 sister chromatids

What happens in anaphase 2?

sister chromatids separate and move to the opposite poles of the cell

What is the difference between anaphase 1, and anaphase 2?

in anaphase 1, the homologous chromosomes move to opposite poles of the cell, but in anaphase 2, the sister chromatids move to the opposite poles of the cell

Will the sister chromatids be identical in anaphase? Why or why not?

They will not be identical due to the genetic exchange that occurred while crossing over

What happens in telophase 2?

Nuclear membrane reforms, DNA relaxes into chromatin, and spindle fibers dissolve

How many haploid daughter cells will be created after cytokinesis?

4

Why are the haploid cells unique?

Due to the crossing over in prophase, and the meeting in the center in metaphase

When does synapsis occur?

prophase 1