Yellow dots mark the locus of a specific gene on a homologous pair of human chromosomes

The chromosomal basis for Mendel’s Laws

Sex-linked inheritance

Evidence for linked genes in Drosophila

Page 9 #3 etb ETBEeTtBb P: EETTBB X eettbb F 1 p%: 100% Long ears, brown tails, and brown eyes ETBETbetBetb ETBEETTBBEETTBbEeTtBBEeTtBb ETbEETTBbEETTbbEeTtBbEeTtbb etBEeTtBBEeTtBbeettBBeettBb etbEeTtBbEeTtbbeettBbeettbb F 1 cross EeTtBb X EeTtBb F 2 p%: 56.25% Long, brown, brown 18.75% Long, brown, blue 18.75% short, cotton, brown 6.25% short, cotton, blue

Page 9 #4 eTB EtbEeTtBb P: EEttbb X eeTT BB F 1 p%: 100% Long ears, brown tails, and brown eyes EtBEtbeTBeTb EtBEEttBBEEttBbEeTtBBEeTtBb EtbEEttBbEEttbbEeTtBbEeTtbb eTBEeTtBBEeTtBbeeTTBBeeTTBb eTbEeTtBbEeTtbbeeTTBbeeTTbb F 1 cross EeTtBb X EeTtBb F 2 p%: 18.75% Long, cotton, brown 37.5% Long, brown, brown 6.25% Long, cotton, blue 12.5% Long, brown, blue 18.75% short, brown, brown 6.25% short brown, blue

Production of recombinant gametes by a dihybrid female

Phenotypes%’s If linkedActual %’s%’s If Not linked Gray, normal Gray, vestigial Black, normal Black, vestigial 636 Gray body, normal wings 50 Gray body, vestigial wings 253 Black body, vestigial wings61 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% 6.25%

Phenotypes%’s If linkedActual %’s%’s If Not linked Long, brown Long, white Short, brown Short, white 364 Long ears, brown fur 6 Long ears, white fur 122 short ears, white fur8 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% 6.25%

Page 11 #4 P BBNN X bbnn bn BNBbNn F 1 p%: 100% brown eyes, normal wings F 1 cross BbNn X BbNn BNbn BNBBNNBbNn bnBbNnbbnn F 2 p%: x %-6%=69% Brown eyes, normal wings 4% Brown eyes, vestigial wings 4% Red eyes, normal wings 25%-2%= 23% Red eyes, vestigial wings

Page 11 #5 P llgg X LLGG LG lgLlGg F 1 p%: 100% Long proboscis, clear wings F 1 cross LlGg X LlGg LGlg LGLLGGLlGg lgLlGgllgg F 2 p%: x %-13.5%= 61.5% Long proboscis, clear wings 9% 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 traits Sex-linked traits in humans include red-green color blindness hemophilia, 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/cell XXY-Klinefelter Syndrome one Barr body/cell XYY – Super male greater chance of violence XXX & 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 21 cri du chat-deletion of part of chromosome 5 CML-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 by extranuclear genes that are inherited from the ovum. Where did all your mitochondria come from?