Genetics Flashcards
(34 cards)
what is incomplete dominance
Heterozygous individuals express a blended phenotype.
There is still a dominant trait, but it is expressed at a lower level, causing a blended phenotype.
what is codominance
A heterozygous individual expresses both phenotypes.
There are 2 dominant alleles and BOTH can be expressed in a heterozygous individual.
what is the dominant blood type
A & B
what is the recessive blood type
O (no protein)
where are alleles carried (sexually)
the X chromosome
- phenotypes vary based on sex chromosomes combinations.
what are pedigrees used for
to observe patterns of inheritance of a particular trait within a family of biologically related individuals.
what will pedigrees depict
the phenotype of an individual which may be used to determine the genotypes.
what does the info from pedigrees allow us to determine
whether the trait is autosomal, dominant, recessive, or sex-linked
what is genetics
The study of heredity and inherited traits
what is a gene
a unit of heredity - a gene is a segment of DNA that codes for a particular peptide or protein
where are genes found
on our chromosomes
how many versions of a gene can there be
one or more
what are different versions of a gene called
alleles
what do alleles determine
traits
Dominant allele traits
- The presence of a dominant allele masks the expression of all other alleles. Only one copy needs to be present to be expressed
- represented with capital letters
Recessive allele traits
- The recessive allele is masked by the dominant allele. Two copies of the recessive allele need to be present in order to be expressed
- represented with lowercase letters
genotype
the combination of alleles present on chromosomes
Homozygous dominant
Both copies of the alleles are dominant - PP
Heterozygous
Both versions of the alleles are present - Pp
Homozygous recessive
Both copies of the alleles are recessive - pp
What is the result of allele combinations?
A protein is expressed - a trait is shown. This is a phenotype.
genotype vs. phenotype
genotype: PP or Pp
phenotype: purple
genotype: pp
phenotype: white
How can we predict inheritance?
Punnett squares! Punnett squares determine the probability of inheriting a particular trait(s) by crossing two organisms
What do the punnett squares represent?
The Punnett squares represent the combination of gametes (sperm and egg) to form zygotes: Fertilization!
