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?