CH 11 PATTERNS OF INHERITANCE
What is inheritance?
Process by which traits of an organism is passed on to offspring.
Inheritance has to do with:
Genes: sequences of nucleotides at specific locations on chromosomes
o Gene: “unit of inheritance (nucleotide = base, sugar, phosphate)”
↓
o DNA: polymer composed of nucleotides
↓
o Chromosomes: DNA + proteins. 2 DNA polymers wrapped around each other in
double helix.
Mutations: changes in the nucleotide sequence of the DNA
Alleles: different versions of a gene at a locus (2 alleles may be identical/different)
Alleles:
Homozygous: the same allele at a given locus in 2 homologous
Heterozygous: different alleles at a given locus in 2 homologous
Hybrids: organisms that are heterozygous at a specific locus
3 steps to prove pattern of inheritance:
1. Choose the right organism to work with
2. Design & perform experiment correctly
3. Proper data analysis
True breeding: one specific trait seen in all offspring produced by self-fertilization.
Dominant allele: always present & always masks the expression of other allele.
Recessive allele: weaker allele in a heterozygous situation
, Genotype: Pp combination of alleles Phenotype may be same but genotype differ
Phenotype: external characteristics
PP = homozygous dominant
Pp = heterozygous dominant offspring will differ
Pp = homozygous recessive
Heterozygous recessive don’t exist. Correct term: heterozygous dominant
How are sex 7 sex-linked traits inherited?
In mammals, the offspring is determined by the sex chromosomes in the sperm.
Y smaller than X
Y carries fewer genes than X
Y chromosome ≠ matching size (size differs) unlinked
X of XY carries recessive, Y carries nothing
Genes on the chromosome is linked
Dominant (homo/heterozygous)
Recessive homozygous
Male usually expresses genotype
Female genotype may not match
Trans = phenotype XY & genotype XX or vice versa genotype cannot change
Majority of traits found on X chromosome (eye color)
Genes on Y chromosomes have no matching counterpart unlinked
(Dominant + recessive = linked genes)
How are genetic disorders inherited?
What is inheritance?
Process by which traits of an organism is passed on to offspring.
Inheritance has to do with:
Genes: sequences of nucleotides at specific locations on chromosomes
o Gene: “unit of inheritance (nucleotide = base, sugar, phosphate)”
↓
o DNA: polymer composed of nucleotides
↓
o Chromosomes: DNA + proteins. 2 DNA polymers wrapped around each other in
double helix.
Mutations: changes in the nucleotide sequence of the DNA
Alleles: different versions of a gene at a locus (2 alleles may be identical/different)
Alleles:
Homozygous: the same allele at a given locus in 2 homologous
Heterozygous: different alleles at a given locus in 2 homologous
Hybrids: organisms that are heterozygous at a specific locus
3 steps to prove pattern of inheritance:
1. Choose the right organism to work with
2. Design & perform experiment correctly
3. Proper data analysis
True breeding: one specific trait seen in all offspring produced by self-fertilization.
Dominant allele: always present & always masks the expression of other allele.
Recessive allele: weaker allele in a heterozygous situation
, Genotype: Pp combination of alleles Phenotype may be same but genotype differ
Phenotype: external characteristics
PP = homozygous dominant
Pp = heterozygous dominant offspring will differ
Pp = homozygous recessive
Heterozygous recessive don’t exist. Correct term: heterozygous dominant
How are sex 7 sex-linked traits inherited?
In mammals, the offspring is determined by the sex chromosomes in the sperm.
Y smaller than X
Y carries fewer genes than X
Y chromosome ≠ matching size (size differs) unlinked
X of XY carries recessive, Y carries nothing
Genes on the chromosome is linked
Dominant (homo/heterozygous)
Recessive homozygous
Male usually expresses genotype
Female genotype may not match
Trans = phenotype XY & genotype XX or vice versa genotype cannot change
Majority of traits found on X chromosome (eye color)
Genes on Y chromosomes have no matching counterpart unlinked
(Dominant + recessive = linked genes)
How are genetic disorders inherited?
