Genetics what you should know

Transcription

1 Genetics what you should know Sexual vs. asexual epoduction Meiosis and fetilization Cossing ove, independent assotment, andom fetilization as ways to incease genetic vaiability Genetic poblems and tems Allele vs. gene Chomosome theoy of inheitance Sex-linked Mutations Genetic impinting and mitochondial DNA inheitance

2 Figue 5.2 P Geneation R R ellow-ound seeds (RR) y y Geen-winkled seeds (yy) Meiosis Gametes R Fetilization y All F plants poduce yellow-ound seeds (yr). F Geneation R y R y LAW OF SEGREGATION The two alleles fo each gene sepaate duing gamete fomation. R y Meiosis Metaphase I R y LAW OF INDEPENDENT ASSORTMENT Alleles of genes on nonhomologous chomosomes assot independently duing gamete fomation. R R y Anaphase I y R R 2 2 y Metaphase II y Gametes y y y y R R R R / 4 / 4 / R y 4 / 4 yr F 2 Geneation An F F coss-fetilization 3 Fetilization ecombines the R and alleles at 3 andom. 9 : 3 : 3 : Fetilization esults in the 9:3:3: phenotypic atio in the F 2 geneation.

3 Figue 5.2c LAW OF SEGREGATION LAW OF INDEPENDENT ASSORTMENT F 2 Geneation An F F coss-fetilization 3 Fetilization ecombines the R and alleles at andom. 9 : 3 : 3 : 3 Fetilization esults in the 9:3:3: phenotypic atio in the F 2 geneation.

4 Pleiotopy Most genes have multiple phenotypic effects, a popety called pleiotopy Fo example, pleiotopic alleles ae esponsible fo the multiple symptoms of cetain heeditay diseases, such as cystic fibosis and sickle-cell disease 20 Peason Education, Inc.

5 EPISTASIS: LECTURE PRESENTATIONS Fo CAMPBELL BIOLOG, NINTH EDITION Jane B. Reece, Lisa A. Uy, Michael L. Cain, Steven A. Wasseman, Pete V. Minosky, Robet B. Jackson BbEe BbEe Eggs Spem / 4 BE / 4 be / 4 Be / 4 be / 4 BE BBEE BbEE BBEe BbEe / 4 be BbEE bbee BbEe bbee / 4 Be BBEe BbEe BBee Bbee / 4 be BbEe bbee Bbee bbee 9 : 3 : 4 Lectues by Ein Baley Kathleen Fitzpatick

6 POLGENETIC: LECTURE PRESENTATIONS Fo CAMPBELL BIOLOG, NINTH EDITION Jane B. Reece, Lisa A. Uy, Michael L. Cain, Steven A. Wasseman, Pete V. Minosky, Robet B. Jackson AaBbCc AaBbCc Spem / 8 / 8 / 8 / 8 / 8 / 8 / 8 / 8 / 8 / 8 / 8 Eggs / 8 / 8 / 8 / 8 / 8 Lectues by Phenotypes: / 6 64 / 5 64 / / 5 64 / 6 64 / 64 / 64 Ein Baley Numbe of Kathleen Fitzpatick dak-skin alleles:

7 Pedigees

8 Natue and Nutue: The Envionmental Impact on Phenotype Anothe depatue fom Mendelian genetics aises when the phenotype fo a chaacte depends on envionment as well as genotype The nom of eaction is the phenotypic ange of a genotype influenced by the envionment 20 Peason Education, Inc.

9 Coelating Behavio of a Gene s Alleles with Behavio of a Chomosome Pai 20 Peason Education, Inc.

10 The Chomosomal Basis of Sex In humans and othe mammals: X vs. is tiny!! The SR gene on the chomosome Some disodes caused by ecessive alleles on the X: Colo blindness (mostly X-linked) Duchenne muscula dystophy Hemophilia 20 Peason Education, Inc.

11 X Inactivation in Female Mammals Ba body Females ae mosaic 20 Peason Education, Inc.

12 Figue 5.8 Ealy embyo: X chomosomes Allele fo oange fu Allele fo black fu Two cell populations in adult cat: Active X Cell division and X chomosome inactivation Inactive X Active X Black fu Oange fu

13 Figue 5. Linked genes tend to be inheited togethe because they ae located nea each othe on the same chomosome Recombination fequencies Chomosome 9% 9.5% 7% b cn vg

14 Figue 5.2 Shot aistae Mutant phenotypes Black body Cinnaba eyes Vestigial wings Bown eyes Long aistae (appendages on head) Gay body Red eyes Nomal wings Wild-type phenotypes Red eyes

15 (a) Deletion Mutations Nondisjunction à Aneuploidy Beakage of a chomosome: Deletion Duplication Invesion Tanslocation A B C D E F G H A B C E F G H (b) Duplication (c) Invesion A deletion emoves a chomosomal segment. A B C D E F G H A duplication epeats a segment. A B C B C D E F G H A B C D E F G H An invesion eveses a segment within a chomosome. A D C B E F G H (d) Tanslocation A B C D E F G H M N O P Q R A tanslocation moves a segment fom one chomosome to a nonhomologous chomosome. M N O C D E F G H A B P Q R 20 Peason Education, Inc.

16 Figue 5.5 Down Syndome (Tisomy 2)

17 Aneuploidy of Sex Chomosomes Nondisjunction of sex chomosomes: XXX Klinefelte syndome (XX) Monosomy X, called Tune syndome, (X0) females, who ae steile 20 Peason Education, Inc.

18 Genomic Impinting Mutant Igf2 allele inheited fom mothe Mutant Igf2 allele inheited fom fathe Nomal-sized mouse (wild type) Nomal Igf2 allele is expessed. Dwaf mouse (mutant) Mutant Igf2 allele is expessed. Mutant Igf2 allele is not expessed. Nomal Igf2 allele is not expessed. (b) Heteozygotes

19 Inheitance of Oganelle Genes Mitochondia, chlooplasts, and inheited matenally 20 Peason Education, Inc.