Introduction to Genetics- Meiosis and Gamete cells

what does heredity mean?

traits passed down from parents to offspring

list examples of character traits passed from parents to offspring

• shape of eye, nose hair etc

do plants have heredity?

yes, they inherit traits from their parent plants through genetic material.

every species has a certain number of chromosomes in each cell nucleus.

true

how many chromosomes does humans have?

46 chromosomes

how many chromosomes will the offspring get from its parents?

• 23 from dad

• 23 from mom

what are homologous chromosomes?

pairs of chromosomes, that carry the same gene

a cell that contain both sets of homologous chromosomes are called..

diploid

What is the number of chromosomes in a diploid cell represented by?

2n

gametes are what type of cells?

sex cells

how many chromosomes do gametes cells have?

half the number of chromosomes

• ex) we each have 46 chromosomes, so half of that would be 23

if a cell only has 1 set, what is it called?

haploid

what is the symbol for haploid?

N

haploid (N) cells are also known as gametes

true

gamete cells are produced from a diploid cell by the process of what?

Meiosis

what happens in Meiosis 1 & 2 ?

4 daughter haploid cells are made

what happens in prophase 1

• each chromosome pairs up with a homologous chromosome to form a tetrad

• they cross-over chromatids

• produce new combinations of alleles

what happens in metaphase1

• tetrads meet at the middle

• homologous chromosomes line up along the middle of the cell by spindle fibers

what happens in Anaphase 1

• spindle fibers pull apart tetrads to opposite ends of the cell

• sister chromatids still remain attatched

what happens in Telophase 1 and cytokinesis?

• nuclear membranes form

• cell separates into two cells

• 2 cells are produced

What happens in Meiosis 2?

cells produced by meiosis 1 do not go through dna replication

what happens in Metaphase 2

• sister tetrads line up in the center of the cell

what happens in anaphase 2

the sister chromatids separate and move toward opposite ends of the cell

what happens in telophase 2 and cytokinesis?

Meiosis 2 results in four haploid (N) daughter cells

in male animals, meiosis results in how many gametes?

4 gametes

male gametes are called …

sperm

In female animals, meiosis only results in how many eggs?

1 egg

the scientific study of heredity began with an Austrian monk named..

Gregor Mendel

Mendel was the first to develop rules that accurately predicted patterns of heredity, he achieved these by carrying out experiments with garden peas.

true

during reproduction, sperm and egg cells join in a process called..

fertilization

what does fertilization produce?

a new cell

peas and most plants are..

self- pollinating ( meaning they get themselves pregnant)

what does it mean if a plant is true-breeding?

parent plants that produce offspring that are identical to themselves.

what is cross- pollination?

the process of transferring pollen from one plant to another

Each original pair of true breeding plants is called the..

P ( parental) generation

The offspring are called the..

F1 or “first filial generation

what are the 4 mendelian concepts?

• 1- alles have alternative versions, each gene resides at a specific locus or on a specific chromosome

• 2- there are 2 alleles, one from each parent

• 4- dominant alles determine the organism’s appearance, the recessive allele has no noticeable effect on the appearance

• 5- law of segregation- two alleles separate during gamete formation and end up in different gametes (anaphase)

organisms that have two identical alleles for a particular trait are said to be

homozygous

TT

homozygous

Organisms that have two differenta alleles for the same trait are ..

heterozygous

heterozygous

Tt

the physical appearance of a character/trait is called its..

phenotype

The set of alleles that an individual has for a trait or the genetic makeup of an organism is called

genotype

crosses between 2 organisms or single traits are called…

monohybrid crosses

crosses that examine the inheritance of two different traits are called

dihybrid crosses

when one allele is not completely dominant over another it is caled..

incomplete domianace

in incomplete dominance an offspring will have an blend

for example - mixed kids, they’re not fully white or black.

if a red and white flower mix- the flower will be pink

• neither one phenotype is dominant so it blends

when both traits are fully expressed it is called..

codominance

in codominant alleles both traits are expressed

example- white and black cow offspring would not be mixed but may be black with white spots

what is an example of multiple allele inheritance?

human blood type

how many possible phenotypes do blood types have?

4 phenotypes

there are 3 alleles for the gene that determines blood type

true

what are the 3 alleles that determine blood type?

Ia, Ib, i

the blood type AB is a

universal recipient

the blood type O is a

universal donor

what is the most common blood type?

O+

what percent of the U.S population are 0+

37%

what is the second most frequently occurring blood type?

A+

what percent of the U.S population are type A+

34%

what blood type is the most rarerest?

AB negative

what percent of the U.S population are AB negative?

0.6%

what are traits that are controlled by two or more genes called?

polygenic traits

the genes for a polygenic trait may be scattered along the same chromosome or located on different chromsomes.

true

skin color in humans is a polygenic trait controlled by more than 4 different genes

true