Meiosis and Inheritance

What do mitosis and meiosis both start with?

duplicated chromosomes after interphase

What do mitosis and meiosis both do?

• divide cells 

• go through similar stages

What is the purpose of mitosis?

to grow and repair by making identical cells

What is the purpose of meiosis?

to produce gametes for sexual reproduction

How many divisions happen in mitosis?

1 division

How many divisions happen in meiosis?

2 divisions

How many daughter cells are made in mitosis?

2

How many daughter cells are made in meiosis?

4

Are cells made by mitosis identical or different?

identical to the parent cell

Are cells made by meiosis identical or different?

different, they have genetic variety 

What is a diploid?

two copies of every chromosome (body cells)

What is a haploid?

one copy of every chromosome (gametes)

Homologous

chromosomes that are the same size and have the same genes in the same order

What happens to the chromosome number in mitosis?

it stays the same (still a diploid)

What happens to the chromosome number in meiosis?

it’s cut in half (diploid to haploid) 

Do homologous chromosomes pair up in mitosis?

no

Do homologous chromosomes pair up in meiosis?

yes, during prophase

What increases genetic diversity in meiosis?

crossing over and random chromosome alignment

What is a phenotype?

a visible trait or behavior

What is a genotype?

the genetic code that determines a trait

Alleles

different versions of the same gene that can cause variations in a trait

Crossing Over

when maternal/paternal genetic material mix on each chromatid during meiosis (homologous recombination)

Reassortment of Homologues 

random distribution of sister chromatids during meiosis (independent assortment)

Independent Assortment

random way of homologous chromosome pairs line up and separate during meiosis

Dominant Allele

gene version that shows its trait over a recessive allele when both are present (capital letter)

Recessive Allele

gene version that shows its traits only when two copies are present (lowercase letter)

Homozygous

two identical alleles for a trait (PP or pp)

Heterozygous

two different alleles for a trait (Pp)

Incomplete Dominance

when two parent traits blend to make an in-between trait

Pleiotropy

when one gene affects many different traits

Polygenic Inheritance

when many genes together influence one trait

Co-Dominance

when both alleles are fully expressed at the same time

Can environment influence traits?

yes, can affect how traits appear

What are sex-linked genes?

genes located on sex chromosomes, often affects males more

Nondisjunction

when chromosomes don’t separate equally during meiosis

What happens if fertilization occurs after nondisjunction?

the zygote has an altered number of chromosomes

Monosomy

having only one copy of a chromosome

Trisomies

having three copies of a chromosome