LE 14-4 Allele for purple flowers Homologous pair of chromosomes Allele for white flowers Locus for flower-color gene
LE 14-5_2 Appearance: P Generation Genetic makeup: Gametes F 1 Generation Appearance: Genetic makeup: Gametes: F 2 Generation Purple flowers Pp P p P p F 1 sperm F 1 eggs PPPp pp P p 3: 1 Purple flowers PP White flowers pp P p
LE 14-7 Dominant phenotype, unknown genotype: PP or Pp? If PP, then all offspring purple: pp P P Pp If Pp, then 1 2 offspring purple and 1 2 offspring white: pp P P pp Pp Recessive phenotype, known genotype: pp
LE 14-8 P Generation F 1 Generation YYRR Gametes YR yr yyrr YyRr Hypothesis of dependent assortment Hypothesis of independent assortment Sperm Eggs YR Yr yrYR yr Eggs YYRRYyRr yyrr yR yr Phenotypic ratio 3:1 F 2 Generation (predicted offspring) YYRR YYRrYyRRYyRr YYRrYYrrYyRrYyrr YyRRYyRryyRRyyRr YyRrYyrryyRryyrr Phenotypic ratio 9:3:3:1 YRYryRyr Sperm
LE 14-14a Wwww Ww wwWwww Ww WWww or Ww No widows peak Third generation (two sisters) Widows peak Second generation (parents plus aunts and uncles) First generation (grandparents) Dominant trait (widows peak)
LE 14-14b First generation (grandparents) Ff FF or Ffff Ff ff Ff Second generation (parents plus aunts and uncles) Third generation (two sisters) Attached earlobe Free earlobe ffFF or Ff Recessive trait (attached earlobe)
LE 14-17a Amniocentesis Amniotic fluid withdrawn Fetus A sample of amniotic fluid can be taken starting at the 14th to 16th week of pregnancy. Centrifugation PlacentaUterusCervix Fluid Fetal cells Biochemical tests can be performed immediately on the amniotic fluid or later on the cultured cells. Biochemical tests Several weeks Karyotyping Fetal cells must be cultured for several weeks to obtain sufficient numbers for karyotyping.
LE 14-17b Chorionic villus sampling (CVS) PlacentaChorionic villi Fetus Suction tube inserted through cervix 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 A sample of chorionic villus tissue can be taken as early as the 8th to 10th week of pregnancy. Karyotyping