Genetics [Module 2.1] Flashcards
In a species of birds, blue feather (B) are incompletely dominant to the gene for white feathers (b). Individuals that are heterozygous (Bb) have blue-tipped feathers.
A blue with blue-tipped feathers is crossed with a white bird.
What is the chance that the offspring will have blue feathers?
0%
This cross will only produce Bb and bb offspring.
What type of non-Mendelian inheritance is depicted based on the phenotypic ratio below?
3:0
Lethal allele
When white-coated cattle (W) are mated with red-coated cattle (R), the offspring are roan (WR), meaning their coats contain both white and red hairs.
A farmer breeds two roan cattle with one another.
What is the chance that their offspring will be roan?
50%
1/4 of the offspring will be white (WW), 1/4 of the offspring will be red (RR), and 2/4 of the offspring will be roan (WR).
2/4 WR = 1/2 = 50%
P1 - White-coated cattle (W)
P2 - Red-coated cattle (R)
Offspring / F1 - Roan (WR)
What is the allelic interaction presented?
Codominance
A black sheep is bred with a white sheep. All of their offspring have a phenotype of gray coats.
What is the most likely pattern of inheritance for coat color in sheep?
Incomplete dominance
Since the offspring have an intermediate phenotype (in between the colors black and white i.e. gray), this is an example of incomplete dominance.
In humans, three alleles affect blood type. The A and B alleles are codominant, and the O allele is recessive.
An AB blood type father has children with an A blood type mother (genotype AO).
What are the chances that their children will have AB type blood?
25%
1/4 offspring will have AB blood type.
1/4 = 25%
In humans, the gene for curly hair (H) is incompletely dominant to the gene for straight hair (h). Individuals that are heterozygous (Hh) have wavy hair.
Two wavy-haired heterozygous parents have a child.
What is the likeliness that the child will have wavy hair?
1/2
In humans, three alleles affect blood type. Which of the following are true?
A. The A and B alleles are codominant because both alleles are simultaneously expressed in the heterozygote.
B. The O blood type is least common in the human population
C. Human blood type is an example of incomplete dominance.
D. Human blood type is an example of multiple allele inheritance.
D. Human blood type is an example of multiple allele inheritance.
In camellia flowers, petal color is controlled by codominance. When a red flower is crossed with a white flower, all of the offspring are covered in both red and white petals.
A scientist crosses a red flower (RR) with a red-and-white (RW) flower.
What are the predicted phenotypes of their offspring?
50% - red
50% - red-and-white
Pleiotropy is when one gene affects multiple characteristics (Cystic fibrosis).
True or False?
True
A gene for corn has two alleles, one for yellow kernels and one for white kernels.
A farmer mates yellow and white corn. All of the offspring have a nearly even mix of yellow and white kernels.
What type of inheritance most likely explains the relationship between the two alleles?
Codominance
Because both alleles (yellow and white) are expressed, this is an example of codominance.
Agouti - C - dominant
Black - Cb - dominant to albino
Albino - c - recessive
A scientist crosses a black mouse (CBc) with an agouti mouse (CCb).
What are the predicted phenotypes of their offspring?
50% of the offspring will have agouti coats, and 50% will have black coats.
2/4 offspring will have agouti coats (CCB or Cc) and 2/4 offspring will have black coats (CBCB or CBc).
Hemophilia is an X-linked recessive trait that affects blood clotting. If a carrier woman (XX) and a hemophiliac man (XY) have a daughter, what is the percent chance that she will have hemophilia?
50%
A group of students are studying flower color inheritance in the garden pea plant (Pisum sativum). They obtain a purple-flowered pea plant of unknown ancestry, allow it to self-pollinate, and collect 60 of its seeds. After planting the seeds, they observe the growth of 42 purple-flowered plants and 18 white-flowered plants.
Why are there white-flowered plants present?
White flower color is a trait recessive to purple flower color.
Pattern of heredity in which one allele is not completely dominant over another
Incomplete dominance
