2 of each kind of chromosome

2n

(total # of chromosomes)

one of each kind of chromosome

n

(1/2 the chromosome #)

How many pairs of chromosomes do humans have?

What is the diploid chromosome number for humans?

What is the haploid chromosome number for humans?

Germ Cell

a type of cell that goes through meiosis to make gametes

Sex cells

egg and sperm

The uniting of male and female gametes

How many chromosomes are in a human germ cell?

How many chromosomes are in a human gamete?

Meiosis occurs in _____ phases, and mitosis occurs in ____ phases.

2

1

• Chromosomes coil up
• Nuclear envelope breaks down
• Centrioles form
• Spindle fibers form
• Homologous chromosomes form tetrads
• Crossing Over occurs

Tetrad

Pair of homologous chromosomes that come together during prophase I of meiosis

• Homologous chromosomes exchange portions of their chromatids
• 2 to 3 cross overs for each pair of chromosomes
• New genetic combinations

Pairs of chromosomes line up in middle

Pairs of chromosomes separate and move to opposite poles

• Chromosomes uncoil
• Nuclear envelope reforms
• Centrioles break down
• Spindle fibers break down 

At the beginning of meiosis a human germ cell has ____ chromosomes, the chromosomes are _______ and the cell is ____.

46

duplicated

diploid

At the end of meiosis I in a human germ cell, there are ____ chromosomes in the cell, the chromosomes are _______ and the cell is _______.

23

duplicated

haploid

Because the cells at the end of meiosis I have the right chromosome number (1/2 of what is started with), but the chromosomes are duplicated so there is double the amount of DNA.

Prophase II

• Chromosomes coil up
• Nuclear envelope braks down
• Centrioles form
• Spindle fibers form 

Metaphase II

Chromosomes line up in a single file straight line in the center of the cell

Anaphase II

• Centromere splits and sister chromatids separate and move to opposite poles.
• Each chromatid is now called a chromosome

• Chromosomes uncoil
• Nuclear envelope reforms
• Centrioles break down
• Spindle fibers break down 

In a human gamete produced at the end of telophase II, there are ___ chromosomes in the cell, the chromosomes are _______, and the cell is _______.

23

unduplicated

haploid

1. Crossing Over
2. How the pairs line up in metaphase I
3. What sperm meets what egg. 

Meiosis results in cells that are genetically _______ from the parent cell and each other.

Branch of biology that studies heredity

The passing of traits from parent to offspring

Segment of DNA that codes for a trait

Dominant

Recessive

Is always expressed

Represented by a capital letter

• Allele that is masked or hidden
• Represented by a lower case letter

Two of the same alleles for a trait

TT or tt

Two dominant alleles

TT

Two recessive alleles

tt

2 different alleles for a trait

Tt

• Father of Genetics
• Monk in Austria Monastery
• First person to predict how traits are transferred 
• Work with pea plants 

Parents and their offspring only have one allele of a trait

F1 generation

The offspring from a cross of the p generation

The offspring from a self pollinated cross of the F1 generation

Two genes of a pair on homologous chromosomes are separated from each other at meiosis and end up in different gametes. (refers to how the alleles are separted into 4 gametes)

Genes for different traits can segregate independently during the formation of gametes during metaphase I. (does not hold true if the different traits are on the same chromosome)

The phenotype of the heterozygote is intermediate between the dominant and recessive (blending)

The phenotypes of both homozygotes are produced

(see both alleles)

Traits controlled by more than two alleles

O blood type

Is the most common

AB blood type

Is the rarest blood type

Type A blood has __ antigens and __ antibodies

A

B

Type B blood has __ antigens and __ antibodies.

B

A

Type AB blood has __ antigens and __ antibodies.

A & B

none

Type O blood has __ antigens and __ antibodies.

none

A & B

In Rh blood typing __ is dominant to __

+ (positive)

-(negative)

A person with A+ blood can give blood to

A person with blood type AB- can give blood to

A person with blood type O+ can receive blood from

A person with blood type B- can receive blood from

If a cell has 22 chromosomes, at the end of meiosis I how many chromosomes are in the cell?  Are the duplicated or unduplicated?

11

duplicated

If a cell has 60 chromosomes, how many chromosomes are in the cell during anaphase II?  Are the duplicated or unduplicated?

60

unduplicated

What is the difference between metaphase I and metaphase II?

If 25 cells undergo meiosis, how many polar bodies will be produced?

The process of meiosis produces ____ cells that are _______.

4

haploid

If 25 cells undergo meiosis, how many sperm cells will be produced?

In a monohybrid cross, if two heterozygotes are crossed what is the genotypic and phenotypic ratio?

Genotypic Ratio - 1:2:1

Phenotypic Ratio - 3:1

In a dihybrid cross, when two heterozygotes are crossed, what is the genotypic and phenotypic ratios?

Genotypic Ratio-1:2:1:2:4:2:1:2:1

Phenotypic Ratio - 9:3:3:1