Meiosis + Genetics (u7)

Describe the difference between meiosis and mitosis ASEXUAL VS SEXUAL REPROD

AS: single parent, all genes from single parent, identical to parent, clone

S: 2 parents, each gives half of. genes, unique combo, variation.

What is the purpose of meiosis

introduce genetic variation + half genetic material

What is the ploidy of the cell

diploid vs haploid.

What are somatic cells

body cells (diploid)

What are gametes

haploid - sex cells

What is a karyotype

looking at chromosomes to match them up (pairs have genes for some similar traits likke eye color). It is the procedure to look at and analyze chrosome number.

What are homologues or homologus pairs

genes for the same traits (23 pairs in humans).

What is XX and XY, who determines sex of baby

XX = female

XY = male

dad determines sex of the baby.

What are autosomes

non-sex chromosomes

What is an allele

Different version of a gene for the same trait.

Why does meiosis introduce genetic variation

Crossing over + Independent assortment (pairs line up independently of other pairs) generates 2^(23) unique gametes for example

Describe Prophase I

homologous chromosomes pair up and crossing over occurs.

What is crossing over

inter-chromosome exchange of homologus DNA which makes recombinant chromosomes during Prophase !. Recombinant chromosomes are the mixing up of DnA with other chromosomes

What are recombinant chromosomes

mixing up of DnA w/ other chromosomes

What is metaphase I? and what’s cool about it

homologus pairs of chromosomes line up in the middle which introduces genetic variation through indepdnedent assortment.that’s when homologus chromosomes can line up in lots of different orientations. 2^n is the number of potential arrangements.

What is independent assortment? what is the equation for potential arrangements

when homologous pairs can line up in different orientations: 2^n is the equation for the number of potential arrangements.

What is anaphase I

chromosomes pulled to opposite ends: cells become haploid bc eveyrthing is separated.

What’s the difference between diploid and haploid

Haploid means there is one characteristic for each trait

What is telophase I

sometimes it doesn’t happen: the nuclear envelope may reform.

What is prophase II

if neeed, chromosomes will condense and the nuclear membrane will redisappear

What is metaphase ii

Chromosomes will line up in the middle.

What is telophase II

the nuclear membrane reforms.

What is nondisjunction

When chromosomes are not evenly split into 2 daughter cells = twoo many or to few chromosomes in the daughter cell

What are trisomy and monosomy

trisomy = 3 in a pair, most dont survive

Monosomy = 1 in a pair = wont survive a few days past fertilization

What’s the difference between genotype and phenotype

Genotype = Aa, aa, AA

Phenotype = dominant, recessive

What’s a gene and an allele

A gene is a DnA sequence which codes for traits An allele is a variation of a gene.

What is Mendal’s law of dominance

Traits are controlled by “factors” (genes) and the dominant allele is observed when present, overriding the recessive allele.

What is Mendel’s law of segregation

traits are controlled by pairs of alleles which segregate during gamete formation (meiosis)

What is true breeding / pure bred

When something is bred with a copy of itself to produce an exact replica.

How to do dihybrid crosses and find the phenotype ratio

Ex: AaBb x aaBB

Just do two separate punnett squares with Aa x aa and Bb x BB

the phenotypes are the probabilities, multiplied together:

ex: ¾ dom * ¾ dom = 9/16 dom.

What is the law of independent assortment

alleles for differentt traits are inherited independently of each other (sorting into gametes in dihybrid crosses)

What is a test cross?

Doing aa with Aa and AA to figure out the mystery genotype in a problem

What is incomplete dominance?

AA, Aa, and aa are expressed differently (eg. white, red, and pink roses)

What is codominance?

When Aa expresses both dom and rec separately (eg. red and white flower)

What are pedigrees? what are the circles and squares

inheritance family trees. square = male, circle = female.

What is autosomal dominant

Male and female inherit equally, you only need one mutant allele to express the trait = 50% chance of inheritance.

What is autosomal recessive

male and female inherit equally: must have 2 mutant alleles to express = when two carriers mate, 25% will be dominant (no expression), 50% will be acarriers, and 25% will be expressing homozygous mutants

What is X-linked recessive

X^rX^r or XrX, affecting males more.

What is X-linked dominant

YOu only need ONE Xr to express the mutant trait, meaning a carrier woman will have 50% mutant offspring.