unit 8 Flashcards
What does heredity mean?
Transmission of traits from one generation to the next
Genetics
Scientific study of heredity
What is a gene?
A character being passed from one generation to the next
What is an allele?
The alternate versions of the genes
What is the law of segregation?
Two alleles from one generation are passed onto offspring separately. Offspring only get one allele
How many alleles do individuals have?
2 alleles (homo or hetero)
What can alleles be?
Dominant or recessive
When and why do alleles separate?
During meiosis so they are inherited independently
What is a dihybrid cross?
Two trait cross
What is the law of independent assortment?
Genes of different characters separate from one another during gamete formation and can be inherited individually
What happens to genes on different chromosomes?
They are separated into different gametes
What happens to genes on the same chromosome?
They can have crossing over between them
How do you fill out a dihybrid cross?
Determine the gametes of both parents using foil
What is incomplete dominance?
Neither allele is dominant over the other
What happens to an offspring’s appearance during incomplete dominance?
The appearance is a blend between the phenotypes of the two parents
What is codominace?
When neither allele is dominant over the other
What happens to the offsprings appearance in codominace?
Both alleles are expressed at the same time and a mixture is observed, the appearance contains both traits
What is human blood type an example of?
Codominace and multiple allelism
What is multiple allelism?
More than 2 alleles possible for a given gene
What blood type is the universal receiver?
AB
What blood type is the universal donor?
O
What does the sec of an individual depend on?
The X and Y chromosome
What are sex-linked genes?
Genes that are located on the X chromosome
What are sex-linked traits?
Traits determined by the sex-linked genes
Are sex-linked traits dominant or recessive?
Recessive: Both X chromosomes must have the genes in order for the trait to be expressed
What is a carrier?
A person that has the trait on only one chromosome and does not express the trait (always women)
What are pedigrees?
Studies how a trait is passed from one generation to the next
What can pedigrees be used for?
To determine if a disorder is genetic and what type of
Memorize parts of pedigree
…
How do you know if a trait is recessive in a pedigree?
It may “skip” a generation. Can shave unaffected parents
How do you know if a trait is dominant in a pedigree?
50% chance of each offspring getting the trait from an affected parent
How do you know if a pedigree is autosomal?
Affects males and females equally
How do you know if a pedigree is sex linked (X chromosome)?
Affects males more than females
How do females get the trait?
From an affected father or carrier/affected mother
How do males get a trait?
Get it from their mother and give it to their daughters to “carry”
Clues for recessive autosomal inheritance
-individual expressing trait has 2 normal parents
-two affected parents can not have an unaffected child
Clues for dominant autosomal inheritance
-every affected person has at least one affected parent
-each generation will have affected individuals
Clues for recessive sex-linked inheritance
-no father to son transmission
-predominantly males affected
-trait may skip generations
