Meiosis

Question 1

What’s Meiosis?

Answer 1

Process by which sex cells( Gametes) are formed

Question 2

What’s Reduction Division?

Answer 2

Daughter cells must have HALF the chromosomes of parents—-(2n—->n)

Question 3

What is Recombination?

Answer 3

• Offspring are genetically distinct from each parent (diversity)

Question 4

Phrophase 1

Answer 4

• Nuclear membrane dissolves
• Centrioles split and move to the poles
• Spindle fibres form
• Homologous chromosomes pair up

Question 5

What are Sex Chromosomes?

Answer 5

• In humans we have 23 pairs of chromosomes
  First 22 are Autosomes(Body cells)
  23rd pair are sex chromosomes
• Males XY
• Females XX

Question 6

Homologous Chromosomes?

Answer 6

• Chromosomes that are similar in shape,size, and arrangements of genes

Question 7

What’s a tetrad?

Answer 7

A pair of homologous chromosomes is called a tetrad because of 4 chromatids

Question 8

What’s Synapsis?

Answer 8

It’s a pairing of Homologous chromosomes

Question 9

What’s crossing over?

Answer 9

Recombination-produces a combination of chromosomes with genes from two different parents

Question 10

Metaphase 1

Answer 10

• Spindle Fibers attach to the centromere
• One pole attaches to the pair of homologous chromosomes
• Chromosomes line up as homologous pairs (One on each side of the equatorial plate)

Question 11

Anaphase 1

Answer 11

• Homologous Chromosomes move towards opposite poles
• Called Segregation

Question 12

Telophase 1

Answer 12

• Not all cells go through telophase 1
• Cytokinesis begins
• Replicated chromosomes must be pulled apart
• At this point cells are non-identical and have half the chromosome number

Question 13

What’s Meiosis ||- Equatorial Divison

Answer 13

• Cells proceed directly into another round of meiosis
• Similar to the stages of meiosis |

Question 14

Prophase ||

Answer 14

• Nuclear membrane dissolves
• Centrioles move to opposite poles and spindle fibers form

Question 15

Metaphase ||

Answer 15

• Chromosomes line up along the equatorial plate

Question 16

Anaphase ||

Answer 16

• Sister Chromatids seperate

Question 17

Telophase ||

Answer 17

Nuclear membrane forms

Question 18

Cytokinesis

Answer 18

Forms four non-identical cells

Question 19

Meiosis |

Answer 19

• Reduction Division
• Chromosome number is reduced by half

Question 20

Meiosis ||

Answer 20

• Equatorial Division
• Similar to mitosis as centromeres on sister chromatids seperate
• Chromosome number is unchanged

Question 21

What’s the formation of male Gametes?

Answer 21

• The formation of male gametes is called spermatogenesis
• Males make billions of sperm a day

Question 22

What’s the formation of female Gametes?

Answer 22

The formation is a process called oogenesis
- occurs in ovaries
- Each round produces, 1 egg cell, 2 or 3 polar bodies which die
- Parthenogenesis is where one polar body fertilizes the mother’s egg making clones

Question 23

What are the sources of Genetic Variation?

Answer 23

. Crossing over (recombination)
- Reshuffle genes
- Contributes to evolution

. Sexual Reproduction
- Chromosomes assort independently during meiosis
- Fertilization

Question 24

Karyotype meaning?

Answer 24

A picture of chromosomes arranged in homologous pairs according to size and structure.

Question 25

Preparing a Karyotype?

Answer 25

- Dividing cells are withdrawn - Cells are arrested in metaphase - Cells are stained and examined - A photograph is taken, chromosomes are arranged in homologous pairs - Pairs are placed in descending order, sex chromosomes are last

Question 26

What is Nondisjunction (Not seperating)?

Answer 26

- occurs when two homologous chromosomes move to the same pole during Anaphase in meiosis

Question 27

What’s one way to diagnose genetic disorders?

Answer 27

- Blood tests from the Mother

Question 28

Autosomal- Down syndrome (Trisomy- 21)

Answer 28

- 47 chromosomes - Associated with mental retardation - Risks go up with Maternal age

Question 29

Klinefelter syndrome- Sex chromosomes (XXY)

Answer 29

- Extra 23rd chromosomes - Appears male at birth because of Y chromosome - sterile due to hormonal imbalances

Question 30

Turner’s syndrome- (XO)

Answer 30

- Monosomic Disorder - Females have single X chromosomes - Sterile because of hormone imbalance

Question 31

Patau Syndrome ( Trisomy 13)

Answer 31

- 3 copies of chromosomes 13 - Babies have severe defects - Limited life expectancy - Non-Functioning eyes

Question 32

Edward syndrome (Trisomy 18)

Answer 32

- 3 copies of chromosomes 18 - Results in severe deficits - Limited life expectancy of 10 weeks

Question 33

What are Mutations?

Answer 33

Mutation are changes in the DNA sequence of an organism - Mutation are important for evolution and contribute to variation - mutations can sometimes lead to problems like genetic defects and cancer

Question 34

What are chromosomal Mutations?

Answer 34

Can have deletion or duplication of parts of chromosomes Are less harmful than trisomy or monosomy

Question 35

Where do you inherit Mitochondrial DNA

Answer 35

- Is inherited from your Mother Only

Question 36

In plants

Answer 36

- Diploid(2n)- Sporophyte -Haploid (1n)- Gametophyte

Question 37

Anytime you replicate a cell exactly it is…

Answer 37

Mitosis

Question 38

Anytime you see a reduction in chromosomes numbers it is….

Answer 38

Meiosis