Chapter 10 Patterns of Inheritance Flashcards
Genes encode __.
proteins
What creates new alleles?
mutations
What is a chromosome?
continuous molecule of DNA with associated proteins
What are the chromosome pairs a diploid contains?
22 homologous autosomes and one set of sex chromosomes (23 pairs in total = 46)
What does fertilization do?
unites gametes and restores the diploid number (46)
What did Mendel’s experiments do?
uncovered basic laws of inheritance
Why did Mendel study inheritance through pea plants?
developed quickly, produce abundant offspring, and easy to breed
What happens in true-breeding?
Self-fertilization yields only offspring identical to the parent
What happens in a hybrid?
Characteristics from 2 different parents
The dominant allele is…
always expressed if present
The recessive allele is…
masked by dominant allele
In a gene, a cell’s two alleles may be?
alike or different
Heterozygous:
different, phenotype = dominant gene (Bb)
Homozygous:
same, dominant (BB), recessive (bb)
What is a phenotype?
a physically observed characteristic
What is a wildtype?
allele that is most common in a population
A change in a gene is a…
mutation
Mutations can create…
mutant phenotypes
What does P stand for?
Purebred Parental generation
What does F1 stand for?
1st generation of offspring
What does F2 stand for?
2nd generation of offspring
Two alleles of a gene end up in…
different gametes
How many genes does a Simple Punnett Square track?
one
What is monohybrid crossing?
mating between 2 individuals that are heterozygous for the same gene (Bb, Bb)
What does a testcross reveal?
an unknown genotype by breeding the individual to a homozygous recessive individual
What is Mendel’s Law of Segregation?
Two alleles of the same gene separate into different gametes
How are genes on different chromosomes inherited?
independently
Tracking 2-gene inheritance requires what?
a larger Punnett Square
What is dihybrid crossing?
mating between individuals that are heterozygous for two genes
What does Mendel’s Law of Independent Assortment and Meiosis state?
Inheritance of 1 gene does not affect the inheritance of another gene on a different chromosome. Independent Assortment occurs because homologous pairs of chromosomes align randomly during Metaphase I of Meiosis.
What aids the completion of complex Punnett Squares?
The Product Rule (Rule is an alternative to Punnett squares for following the inheritance of 2 or more traits at a time)
Genes on the same chromosome may be what?
inherited together
What are linked genes?
genes located on the same chromosome
What are linkage genes?
Collections of genes that are often inherited together
What is crossing over?
Farther apart two linked genes are on a chromosome
What have studies of linked genes yielded?
chromosomes maps
What have breeding studies revealed?
the crossover frequencies used to create linkage maps
What is incomplete dominance?
Alleles are heterozygous in incomplete dominance, originally from two homozygous
What is codominance?
Alleles are heterozygous but contain two dominant alleles, both phenotypes are displayed
Gene expression can alter what?
phenotypic rations
What happens when a gene is Pleiotropic?
gene affects multiple phenotypes (When multiple proteins participate in a biochemical pathway, mutations in genes encoding any of the proteins can produce the same phenotype)
What happens in Epitasis?
one gene masks the affect of another
Sex genes for a female:
XX
Sex genes for a male:
XY
What disorders affect males more than females?
X-linked recessive disorders
X-linked recessive disorders?
- Hemophilia A
- Red-green color blindness
- Duchenne Muscular Dystrophy
X-linked dominant disorders?
- extra hairiness
- retinis pigmentosa
What does X-inactivation prevent?
“double dosing” of proteins
What does X-inactivation shut down?
all but one X-chromosome in a female mammal
What is the purpose of a pedigree model?
traces phenotypes in families and reveals modes of inheritance
What is an Autosomal Dominant disorder?
disorder from one affected parental
Autosomal Dominant disorders?
- Huntington Disease
- Marfan Syndrome
- Polydactyl
What is an Autosomal Recessive disorder?
disorder from two affected parents (affects mostly males)
Autosomal Dominant disorders?
- Cystic Fibrosis
- Albinism
- Tay-Sachs disease
