Today: Inheritance for 1 gene
Fig 13.5 {Producing gametes} Sexual reproduction creates genetic diversity by combining DNA from 2 individuals, but also by creating genetically unique gametes. {Producing more cells}
haploid X 23 in humans X 23 in humans diploid X 23 in humans Inheritance = The interaction between genes inherited from Mom and Dad.
Do parents’ genes/traits blend together in offspring?
In many instances there is a unique pattern of inheritance. Fig 14.3 In many instances there is a unique pattern of inheritance. Traits disappear and reappear in new ratios.
Genotype Phenotype Fig 14.6
Human blood types Fig 14.11
Fig 14.11 One gene with three alleles controls carbohydrates that are found on Red Blood Cell membranes A A B RBC A B RBC RBC B A B A B A A B B A A B B Allele O = no carbs Allele A = A carbs Allele B = B carbs
Human blood types Fig 14.11
We each have two versions of each gene… RBC A A A So A A A A Genotype could be A and A OR A and O
Recessive alleles do not show their phenotype when a dominant allele is present. RBC A A A A A A A Genotype could be A and A OR A and O
What about… RBC Genotype = ??
What about… RBC Genotype = OO
What about… A B RBC B A A B B A A B
What about… A B RBC B A A B B A A B Genotype = AB
Human blood types Phenotype Result of transfusion Phenotype Genotype Fig 14.11 Phenotype Phenotype Genotype Result of transfusion AA or AO BB or BO AB OO
If Frank has B blood type, his Dad has A blood type, And his Mom has B blood type… Should Frank be worried?
Mom=B blood BB or BO Dad=A blood AA or AO possible genotypes
Mom=B blood BB or BO Dad=A blood AA or AO all B / 50% B and 50% O possible genotypes all B / 50% B and 50% O all A / 50% A and 50% O Gametes
Mom=B blood BB or BO Dad=A blood AA or AO Gametes all B / 50% B and possible genotypes Gametes all B / 50% B and 50% O all A / 50% A and 50% O Frank can be BO = B blood …no worries
Mom=B blood BB or BO Dad=A blood AA Gametes all B / 50% B and 50% O Grandparents AB and AB Mom=B blood BB or BO Dad=A blood AA possible genotypes Gametes all B / 50% B and 50% O all A Frank can be BO or BB = B blood …Uh-Oh
Some simple dominant/recessive relationships in humans Fig 14.15
We can also predict the future Fig 14.3
Inheritance of blood types Mom = AB Dad = AB
Inheritance of blood types Mom = AB Dad = AB Gametes: A or B A or B
Mom = AB Dad = AB A or B A or B Gametes: Dad A or B 25% AA 50% AB Inheritance of blood types Mom = AB Dad = AB A or B A or B Gametes: Dad A or B Chance of each phenotype for each offspring 25% AA 50% AB 25% BB AA A or B AB Mom AB BB
Testcross: determining dominant/ recessive and zygosity Fig 14.7
Sickle-cell anemia is caused by a point mutation Fig 17.22
Sickled and normal red blood cells
Sickle-Cell Anemia: Mom = HS Dad = HS Dad H or S possible offspring A dominant or recessive allele? S=sickle-cell H=normal Mom = HS Dad = HS Dad H or S possible offspring 75% Normal 25% Sickle-cell HH HS H or S Mom HS SS
Coincidence of malaria and sickle-cell anemia Fig 23.17 Coincidence of malaria and sickle-cell anemia
Sickle-Cell Anemia: Mom = HS Dad = HS possible offspring A dominant or recessive allele? S=sickle-cell H=normal Mom = HS Dad = HS possible offspring Oxygen transport: 75% Normal 25% Sickle-cell Malaria resistance: 75% resistant 25% susceptible Dad H or S HH HS H or S Mom HS SS
2 genes, each coding for a trait: Variation in pea shape and color
Fig 14.8 Phenotype Genotype
The inheritance of genes on different chromo- somes is independent. Fig 14.8 The inheritance of genes on different chromo- somes is independent.
Approximate position of seed color and shape genes in peas Gene for seed color Y y r R Gene for seed shape Chrom. 1/7 Chrom. 7/7
Fig 15.2 The inheritance of genes on different chromosomes is independent: independent assortment
Fig 15.2 meiosis I
Fig 15.2 meiosis I meiosis II
Fig 15.2 The inheritance of genes on different chromosomes is independent: independent assortment
Fig 14.8
Next: more complex inheritance