AP Bio Ch.13 - Meiosis

good luck

Heredity / interhertiance

Heredity / interhertiance

transmission of traits from one generation to another

What is genetics

the study of heredity and variation

*What are genes

Hereditary units of DNA (Units of inheritable traits)

What is the genome

All of the genes composed together

*** What is the point of meiosis

To make sperm and egg cells that might be used in sexual reproduction

What are gametes

Cells that are used by plants and animals to pass on their genetic info

What is the corresponding location for each gene called?

Locus

What are locus

The corresponding location at which each specific gene can be found

In asexual reproduction, what causes variation in family lines?

Mutations

What is karyotyping?

The matching up of pairs of chromosomes from longest to shortest.

What are the pairs of chromosomes used in karyotyping called?

Homologous chromosomes OR pairs of autosomes

(should know both probably!)

How many homologous pairs of chromosomes would a male have?

22 (Males have XY sex chromosome pair— NOT homologous)

How many homologous pairs of chromosomes would a female have?

23 (Females have XX sex chromosome pair— HOMOLOGOUS!! all 23 chromosomes are homologous)

Does the sperm or egg dictate gender of offspring?

SpermW

What are the two categories of chromosomes?

Autosomes and sex chromosomes

What are autosomes?

The chromosomes that are not the sex chromosomes :] easy enough

XY: male or female

male

XX: male or female

female

Is the sperm X or Y

Either X or Y

Is the egg X or Y

ALWAYS Y

*What does haploid mean

cells with a single set of chromosomes (not homologous pairs)

*What does diploid mean

Both sets of chromosomes; have to be homologous.

If a cell is haploid, you can immediately assume…

Meiosis is happening

What are the only haploid cells in the human body?

sperm and egg cells— GAMETES

When does the life cycle start?

when the egg meets the sperm and is fertilized

What process reduces the number of chromosome sets from diploid to haploid?

meiosis

How many cell divisions in meiosis? names?

2: meiosis I and meiosis II

How many daughter cells are produced in meiosis

4

what stage is the longest in meiosis?

Prophase I

What happens in prophase I? (6)

1. chromosomes condense

2. Homologous chromosomes form tetrads

3. Crossing over

4. centrosome movement towards poles

5. Spindle formation

6. nuclear envelope breakdown

How many chromosomes in 1 tetrad?

2

how many chromatids in 1 tetrad?

4

What is the point of crossing over?

to make unique gametes— genetic diveristyyy

How do you remember how many chromatids are in one tetrad??

Tertris = tetra = each piece in tetris is 4 blocks = tetra = four = tetrad

What are the only cells that do meiosis?

Germ line cells

Does meiosis make zygotes

no

What happens during metaphase I

tetrads align on the metaphase plate

What happens during anaphase I

sister chromatids move towards poles— REMAIN ATTACHED

what happens during telophase I and cytokinesis 1 (3)

1. each cell will have sister chromatids

2. cytokinesis

3. chromosomes might unwind (depends on organism)

In meiosis, what happens after telophase I and cytokinesis I?

Meiosis II!

What happens in Meiosis II?

The same thing as mitosis, except for crossing over. isn’t mitosis bc cells are haploid

*What makes meiosis unique? (5)

1. Synapses

2. crossing over

3. chiasmata

4. tetrads

5. Sisters stay attached

What 3 mechanisms contribute to genetic variation

1. independent assortment

2. crossing mover

   1. random fertilization

**What is random assortment of chromosomes

The random orientation of the homologous pairs at metaphase I

*What formula is used to figure out how many possible combinations of assortments there are?

What does the variable represent?

2ⁿ

n = haploids