chapter 4 Flashcards
cytoplasmic inheritence
mitochondria and chloroplast organelles can cause inheritance of rare diseases by mtRNA (mitochondrial)
uniparental inheritence
only one parent is responsible for inheritence (usually mom’s cytoplasm and mitrochondria)
linked genes
genes on same chromosome that form linkage group, do not assort independently
how are linked genes inherited
inherited together but can be separated by crossing over
about how many times does crossing over occur per chromosome during one meiosis
once or twice
notation for unlinked genes
A/a ; D/d
notation for linked genes
AB/ab
closely linked genes
segregate together in dihybrid cross, results in all parental products (similar to monohybrid cross, aka punett that mofo)
crossing over
non sister chromatids break and join reciprocally in prophase I, frq depends on distance between alleles
recombination frequency
calculated with frq of product, percent of recombinant chromosomes reflects gene to gene distance
recombo frq calculation
( total # of recombo / total progeny ) * 100
map unit
used to measure distance between genes, centiMorgan with R = 1%
independent assortment (recombo frq, description, gamete frq)
recombo frq: 50 %
description: unlinked genes
gamete frq: 1: 1: 1: 1
crossing over (recombo frq, description, gamete frq)
recombo frq: 0 < R < 50
description: partially linked
gamete frq: < 1 : > 0 : > 0 : < 1
linkage (recombo frq, description, gamete frq)
recombo frq: 0
description: strictly linked
gamete frq: 1: 0: 0: 1
physical maps
using physical distance and number of base pairs
genetic maps
shows distances between genes
num of linkage groups =
num of chromosomes
recombination maps _______ distance between close genes
underestimate
three point mapping criteria (3)
1) Genotype of P should be Heterozygous at all loci
2) cross should be test cross (hetero x homo recess)
3) representative sample and sufficient offsprint
typically, how many diff gametes are there in a three point map?
8 categories
if categories are missing, what can you leave out?
double cross over
Parental (NCO) Size
greater than 50%
SCO
less than NCO, middle ground
DCO
smallest, product of both SCO
coefficient of coincidence
observed DCO / expected
inference
1 - c.o.c
inference meaning
-crossovers aren’t at random
if inference increases, it shows _____ DCO
less
if inference decreases, it shows ______ DCO
more
