1 / 25

Chapter 14

Chapter 14. Mendel and the Gene Idea. Removed stamens from purple flower. Transferred sperm- bearing pollen from stamens of white flower to egg- bearing carpel of purple flower. LE 14-2. Parental generation (P). Stamens. Carpel. Pollinated carpel matured into pod. Planted seeds

penda
Télécharger la présentation

Chapter 14

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 14 Mendel and the Gene Idea

  2. Removed stamens from purple flower Transferred sperm- bearing pollen from stamens of white flower to egg- bearing carpel of purple flower LE 14-2 Parental generation (P) Stamens Carpel Pollinated carpel matured into pod Planted seeds from pod Examined offspring: all purple flowers First generation offspring (F1)

  3. P Generation LE 14-3 (true-breeding parents) Purple flowers White flowers F1 Generation (hybrids) All plants had purple flowers F2 Generation

  4. Table 14-1

  5. Mendel’s Laws • Law of dominance • Dominant alleles • Recessive alleles • Law of segregation • Distribution of homologous chromosomes • Law of independent assortment

  6. LE 14-4 Allele for purple flowers Homologous pair of chromosomes Locus for flower-color gene Allele for white flowers

  7. Genotype Phenotype PP (homozygous Purple 1 LE 14-6 Pp (heterozygous 3 Purple 2 Pp (heterozygous Purple pp (homozygous White 1 1 Ratio 1:2:1 Ratio 3:1

  8. P Generation Purple flowers PP White flowers pp Appearance: LE 14-5_2 Genetic makeup: p P Gametes F1 Generation Appearance: Genetic makeup: Purple flowers Pp Gametes: 1 1 p P 2 2 F1 sperm P p F2 Generation P PP Pp F1 eggs p Pp pp 3 : 1

  9. LE 14-7 Dominant phenotype, unknown genotype: PP or Pp? Recessive phenotype, known genotype: pp If Pp, then 1 2 offspring purple and 1 2 offspring white: If PP, then all offspring purple: p p p p P P Pp Pp Pp Pp P P pp pp Pp Pp

  10. P Generation YYRR yyrr Gametes yr YR LE 14-8 YyRr F1 Generation Hypothesis of dependent assortment Hypothesis of independent assortment Sperm YR Yr yR yr 1 1 1 1 4 4 4 4 Sperm Eggs YR yr 1 1 2 2 YR 1 4 Eggs YYRR YYRr YyRR YyRr YR 1 2 F2 Generation (predicted offspring) YYRR YyRr Yr 1 4 YYRr YYrr YyRr Yyrr yr 1 2 YyRr yyrr yR 1 4 YyRR YyRr yyRR yyRr 3 1 4 4 yr 1 4 Phenotypic ratio 3:1 YyRr Yyrr yyRr yyrr 9 3 3 3 16 16 16 16 Phenotypic ratio 9:3:3:1

  11. Rr Rr Segregation of alleles into eggs Segregation of alleles into sperm LE 14-9 Sperm R r 1 1 2 2 R R R r R 1 2 1 1 4 4 Eggs r r R r r 1 2 1 1 4 4

  12. Complex Inheritance Patterns • Codominance • Incomplete dominance • Multiple alleles • Pleiotropy • Epistasis • Polygenic inheritance • Norm of reaction/Multifactorial

  13. P Generation Red CRCR White CWCW LE 14-10 Gametes CR CW Pink CRCW F1 Generation 1 1 Gametes CR CW 2 2 Sperm 1 1 CR CW 2 2 Eggs F2 Generation 1 CR 2 CRCR CRCW 1 CW 2 CRCW CWCW

  14. Table 14-2

  15. BbCc BbCc LE 14-11 Sperm bC Bc 1 1 1 1 BC bc 4 4 4 4 1 BC BBCC BbCC BBCc BbCc 4 1 bC BbCC bbCC BbCc bbCc 4 BBcc Bbcc BBCc BbCc 1 Bc 4 bbcc Bbcc 1 bbCc bc BbCc 4 9 3 4 16 16 16

  16. AaBbCc AaBbCc LE 14-12 aabbcc Aabbcc AaBbcc AaBbCc AABbCc AABBCc AABBCC 20/64 15/64 Fraction of progeny 6/64 1/64

  17. Figure 14-13

  18. First generation (grandparents) Ww ww ww Ww LE 14-14a Second generation (parents plus aunts and uncles) Ww ww ww Ww Ww ww Third generation (two sisters) WW ww or Ww Widow’s peak No widow’s peak Dominant trait (widow’s peak)

  19. First generation (grandparents) Ff Ff ff Ff LE 14-14b Second generation (parents plus aunts and uncles) FF or Ff ff ff Ff Ff ff Third generation (two sisters) ff FF or Ff Free earlobe Attached earlobe Recessive trait (attached earlobe)

  20. Human Traits and Mendelian Inheritance • Pedigree charts • Recessive Disorders • Albinism • Tay-Sachs • Cystic fibrosis • Sickle-Cell Disease

  21. More on human traits… • Dominant disorders • Less common than recessive alleles that cause disease • Huntington’s disease • Multifactorial disorders • Heart disease • Diabetes • Cancer • Schizophrenia

  22. Testing and Counseling • Identifying carriers • Fetal testing • Amniocentesis • Chorionic villus sampling

  23. Amniocentesis A sample of amniotic fluid can be taken starting at the 14th to 16th week of pregnancy. Amniotic fluid withdrawn LE 14-17a Fetus Centrifugation Placenta Uterus Cervix Fluid Fetal cells Biochemical tests can be performed immediately on the amniotic fluid or later on the cultured cells. Biochemical tests Several weeks Fetal cells must be cultured for several weeks to obtain sufficient numbers for karyotyping. Karyotyping

  24. Chorionic villus sampling (CVS) A sample of chorionic villus tissue can be taken as early as the 8th to 10th week of pregnancy. LE 14-17b Fetus Suction tube inserted through cervix Placenta Chorionic villi Fetal cells Biochemical tests Karyotyping and biochemical tests can be performed on the fetal cells immediately, providing results within a day or so. Several hours Karyotyping

  25. LE 14-UN273 George Arlene Sandra Tom Sam Wilma Ann Michael Carla Daniel Alan Tina Christopher

More Related