Yellow dots mark the locus of a specific gene on a homologous pair of human chromosomes
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Transcript of Yellow dots mark the locus of a specific gene on a homologous pair of human chromosomes
Yellow dots mark the locus of a specific gene on a homologous pair of human chromosomes
The chromosomalbasis for Mendel’sLaws
Sex-linked inheritance
Evidence for linked genes in Drosophila
Page 9 #3
etb
ETB EeTtBb
P: EETTBB X eettbb
F1p%: 100% Long ears, brown tails, and brown eyes
ETB ETb etB etb
ETB EETTBB EETTBb EeTtBB EeTtBb
ETb EETTBb EETTbb EeTtBb EeTtbb
etB EeTtBB EeTtBb eettBB eettBb
etb EeTtBb EeTtbb eettBb eettbb
F1 cross EeTtBb X EeTtBb
F2p%:56.25% Long, brown, brown18.75% Long, brown, blue18.75% short, cotton, brown 6.25% short, cotton, blue
Page 9 #4
eTB
Etb EeTtBb
P: EEttbb X eeTT BB
F1p%: 100% Long ears, brown tails, and brown eyes
EtB Etb eTB eTb
EtB EEttBB EEttBb EeTtBB EeTtBb
Etb EEttBb EEttbb EeTtBb EeTtbb
eTB EeTtBB EeTtBb eeTTBB eeTTBb
eTb EeTtBb EeTtbb eeTTBb eeTTbb
F1 cross EeTtBb X EeTtBb
F2p%:18.75% Long, cotton, brown37.5% Long, brown, brown6.25% Long, cotton, blue12.5% Long, brown, blue18.75% short, brown, brown6.25% short brown, blue
Production of recombinant gametes by a dihybrid female
Phenotypes %’s If linked Actual %’s %’s If Not linked
Gray, normal
Gray, vestigial
Black, normal
Black, vestigial
636 Gray body, normal wings 50 Gray body, vestigial wings253 Black body, vestigial wings 61 black body, normal wings
page 10 #1
Yes, 11.1 map units
75%
25%
63.6%
5.0%
6.1%
25.3%
56.25%
18.75%
18.75%
6.25%
Phenotypes %’s If linked Actual %’s %’s If Not linked
Long, brown
Long, white
Short, brown
Short, white
364 Long ears, brown fur 6 Long ears, white fur122 short ears, white fur 8 short ears, brown fur
page 10 #2
Yes, 2.8 map units
75%
25%
72.8%
1.2%
1.6%
24.4%
56.25%
18.75%
18.75%
6.25%
Page 11 #4P BBNN X bbnn
bn
BN BbNn
F1p%: 100% brown eyes, normal wings
F1 cross BbNn X BbNn
BN bn
BN BBNN BbNn
bn BbNn bbnn
F2p%:
.75 .25x.08 x.080.06 0.02
75%-6%=69% Brown eyes, normal wings4% Brown eyes, vestigial wings 4% Red eyes, normal wings
25%-2%=23% Red eyes, vestigial wings
Page 11 #5P llgg X LLGG
LG
lg LlGg
F1p%: 100% Long proboscis, clear wings
F1 cross LlGg X LlGg
LG lg
LG LLGG LlGg
lg LlGg llgg
F2p%:
.75 .25x.18 x.180.135 0.045
75%-13.5%= 61.5% Long proboscis, clear wings9% Long proboscis, gray wings 9 % Short proboscis, clear wings
25%-4.5%= 20.5% Short proboscis, gray wings
Recombination frequencies can be used to construct a genetic map.
A partial genetic map of a Drosophila chromosome
Chromosomal systems of sex determination.
In human males the SRY gene codes a protein that regulates genes that triggers the development of testes and many other maleness genes.
The transmission of sex-linked recessive traitsSex-linked traits in humans include red-green color blindnesshemophilia, and Duchenne muscular dystrophy
X inactivation and the tortoiseshell cat. The tortoiseshell gene is on the X chromosome and the phenotype requires the present of both alleles (one on each X chromosome) The XIST gene on one X chromosome is active and codes RNA which coats that X chromosome which initiates the methylation of that X and causes it to condense and form a Barr body
Meiotic nondisjunction
Nondisjunction results in aneuploidy
XO-Turner Syndrome only human monosomy that survives no Barr bodies/cellXXY-Klinefelter Syndrome one Barr body/cellXYY – Super male greater chance of violenceXXX & XXXX – Super female greater chance of violence
2 or 3 Barr bodies/cell Trisomy 21-Down syndrome-can also be caused by translocation of part of chromosome 21cri du chat-deletion of part of chromosome 5CML-translocation of part of 22 to the tip of 9
A tetraploid mammal??
Prader-Willi syndrome when inherited from male
Angelman syndrome when inherited from female
Genomic Imprinting is accomplished by methylation of genes to turn them off “silence them” or areas near them to turn them on. Male imprinting is designed to produce a larger, stronger, fetus and female imprinting is designed to produce a smaller fetus.
Genomic imprinting is an attempt by the male to produce larger, stronger offspring; the female imprints are an attempt to produce smaller less energy draining offspring
fragile X syndrome-one section of the X hangs by a thin thread of noncoiled DNA which is composed of long sets of triplet repeats – CGG
genomic imprinting by the mother is more likely to cause the syndrome
Variegated leaves caused byextranuclear genes that are inherited from the ovum.
Where did all your mitochondria come from?