Exam 1 Flashcards
Cystic fibrosis can be inherited even if neither parent has the disease. This is because the disease
is caused by a recessive allele
If a homozygous dominant is crossed with a homozygous recessive for a given character, the offspring will be
all of the dominant phenotypes
In Mendel’s monohybrid cross of purple-flowered and white-flowered peas, all members of the F1 generation were of the
___ phenotype because their genotype
was ___
for the flower-color gene.
purple flowered, heterozygous
An AABb individual is mated with another AABb individual. The possible number of genetically distinct offspring is
3
A carrier of a genetic disorder who does not show symptoms is most likely to be ________
to transmit it to offspring.
heterozygous (carrier) for the disorder and able to pass it on
All the offspring of a cross between a red-flowered plant and a white-flowered plant have pink flowers. This means that the allele for red flowers is ___
to the allele for white flowers.
incompletely dominant
Traits that show a continuous distribution and a bell shaped curve are usually the result of
A polygenic trait
What is the prediction if colorblind man produces offspring with a heterozygous woman?
half of their sons and half of their daughters will be colorblind.
Genes located close together on the same chromosomes are referred to as ____ genes and generally ____
linked, do not sort independently during meiosis
We have a pea plant with purple flowers, determined by the dominant allele P. How might you determine whether the plant is homozygous (PP) or heterozygous (Pp).
Perform a testcross: Cross the plant with a white one, which must be homozygous recessive, or pp.
Flower color in snapdragons is an example of incomplete dominance. If a red-flowered plant is crossed with a white-flowered plant, the F1 generation has pink flowers.
If a pink-flowered plant is crossed with a pink-flowered plant, the progeny plants will be
25% red, 50% pink, and 25% white
Which of the following matings can NOT produce a child with blood type O? The letters refer to blood types (phenotypes).
O x AB
A woman with type O blood is expecting a child. Her husband is type A. Both the woman’s father and her husband’s father had type B blood. What is the probability that the child will have type O blood?
50%
The inheritance of height can best be described as?
Polygenic
Polygenic
Controlled by many genes, traits show gradual variation ie. varying heights, multiple genes and environmental factors effect a polygenic trait.
Complete Dominance is _____
One allele completely dominates the other
Incomplete Dominance-
The heterozygous phenotype is a blend of both alleles
Co-Dominance
The alleles share traits within offspring without blending.
What is the expected phenotype ratio of the offspring between double heterozygous individuals?
9:3:3:1
Dihybrid cross phenotypic ratio
If a fly is hererozygous for 2 genes, how many unique gametes will they make?
2^n Law of Independent Assortment
N= number of heterozygous pairs
If a AaBbCc individual mates with a AaBbCc individulal what is the probability of an AABBCC offspring?
1/64
What is the phenotype of a fly that is homozygous dominant for body color and heterozygous for wing size?
Wild type body and wings
Wild type
Most common allele in a population
If a gene has a homozygous dominate lethal genotype, the genotype ratio of the offspring would be:
2:1 excluding the AA which does not survive
Genetic Linkage Mapping
How frequently genes are inherited together
Distance between genes is found by
- Find recombinant offspring by calculating possible offspring.
- Number of Recombinant offspring/total offspring x 100.
- Convert percent to centimorgans.
Linked genes
Genes on one chromosome that are usually inherited together.
Linkage Map
Show the order and distance of genes on the chromosome
Unlinked genes
Genes found on different chromosomes or far away on the chromosome. Assorts independently which creates more recombination.
Why is there a change of a non-predicted phenotype showing up in offspring?
Recombination
Linked Genes: What is the genotype of the parental gametes of a heterozygote for flower color and pollen shape gene?
Pl, pl
Gained from Punnet Square crossing PL and pl
Heterozygote
Carries two different versions of each gene
(PpLl)
Linked Genes: What is the expected phenotype ratio when you breed PpLI *
PpLI?
Only parental types present since linked
3:1
Unlinked genes: What is the genotype of F1 offspring? RRYY * rryy
RrYy
Cross: a homozygous colorblind (X^cX^c) woman and a typical vision man (X^TY)
Proportion female offspring colorblind:
None because normal vision allele dominates colorblind
Most genetic conditions are recessive but “polydactyl” is dominant. Which genotype expresses the wild type trait?
dd since polydactyl is dominant
What would indicate Polygenic inheritance?
Continuous variation between one phenotype to the next.
Color blindness is a trait that is ____ linked
X chromosome
Homozygous lethal genotype ratio:
2:1 as AA would die
A, B, O blood type is best described as:
Dominant/Recessive: A or B over O
Co-Dominance: A and B make AB
Self-Fertilization
Multiply genotype with itself
