Meosis & Genetic Diversity Quiz

review notes, lab slideshow, RF worksheet, helpful videos

asexual reproduction

produces genetically identical cells from a single parent

examples of asexual reproduction

binary fission in bacteria, mitosis, budding

sexual reproduction

production of genetically different cells; leads to genetic diversity in offspring

examples of sexual reproduction

meiosis

meiosis

produces genetically different haploid gamete cells; undergoes two rounds of division

when does interphase occur?

before meiosis I

prophase I

chromosomes condense, synapsis occurs, crossing over occurs

synapsis

when homologous chromosomes pair up, forming a tetrad

crossing over

when parts of the p/q arm of non-sister chromatids swap at the chiasmata; creates recombinants/non-recombinants

when does crossing over occur?

during prophase I only

chiasmata

physical connection point between non-sister chromatids

non-recombinant chromosomes

offspring with the same phenotype as one of the parental chromosomes, aka parental types

recombinant chromosomes

offspring with different phenotypes from the parent chromosomes

metaphase I

independent assortment occurs as homologous pairs align at the metaphase plate

independent assortment

homologous pairs randomly line up in the middle, increasing genetic variation

anaphase I

spindle fibers shorten to pull homologous chromosomes apart to opposite poles of the celll

telophase I/cytokinesis

daughter nuclei form around each set of chromosomes and two haploid cells form

prophase II

chromosomes condense again

metaphase II

chromosomes align at the metaphase plate

anaphase II

spindle fibers shorten to pull sister chromatids apart

telophase II/cytokinesis

daughter nuclei form and cells split

result of meiosis

four genetically different haploid cells

law of independent assortment

alleles will separate independently into gamete cells if they are unlinked

how to calculate the number of ways homologous chromosomes can arrange themselves during metaphase

2ⁿ

recombination frequency

determines if two genes are linked and how tightly linked they are

linked genes

genes that are located close to each other on a chromosome; oftentimes inherited together

linkage map

genetic map that shows the order of genes and the distances between each gene; help determine how likely crossing over will occur

unit used to measure distance between genes?

map units/centimorgans (cM)

conversion between cM and recombination frequency

1 cM = 1% RF

what does a 50% RF mean?

genes are very far apart on the chromosome/on different chromosomes; genes will independently assort

what does a RF of <50% mean?

linked genes; lower chance of recombination/independent assortment

what does a lower recombination frequency mean

the genes are more likely to be linked

what does a higher recombination frequency mean

the genes are more likely to be unlinked

if the RF of two genes is 20%, what percentage of gametes would be recombinant types? parental types?

20% recombinant, 80% parental types

how to calculate recombination frequency

(number of recombinants / total offspring) x 100

chromosomal mutations

nondisjunction, duplication, inversion, deletion, insertion, translocation

nondisjunction

chromosomes fail to separate properly during cell division; results in aneuploid cells; creates a zygote with a trisomy or monosomy

aneuploid cells

cells with an abnormal amount of chromosomes

trisomy

3 copies of the chromosome

monosomy

1 copy of the chromosome

duplication

an extra copy of part or the whole chromosome is created, lengthening the chromosome

insertion

part of a chromosome is removed and inserted into another, shortening one chromosome and lengthening the other

translocation

pieces of two chromosomes swap

deletion

part of a chromosome is removed, shortening it

inversion

a piece of the chromosome is flipped

karyotype

diagram to show an individual’s chromosomes; shows their chromosome abnormalities, biological gender, and species

autosome

non sex chromosomes; pairs 1-22 in humans

sex chromosomes

biological gender; pair 23 in humans

binary fission

how prokaryotes divide; don’t need microtubules because they don’t have them and they only have one chromosome; produces two identical daughter cells

name this (this is chromosome X)

Xp11.4