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 bird 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
Pattern of heredity in which both alleles are simultaneously expressed in the heterozygote
Codominance
A gene that is controlled by more than two alleles
Multiple alleles
When one gene affects multiple characteristics
Pleiotropy
Allele that results in the death of an individual
Lethal allele
A section of DNA which encodes for protein
Gene
The entire set of genes in an organism
Genome
Specific type of variant of genes that occupy the same position on homologous chromosomes and that cover the same trait.
Alleles
mother deroy, have mercy on us
amen
This law states that in a heterozygote, one allele will conceal / hide the presence of another allele for the same gene governing a particular character or phenotype.
Law of Dominance
The allele that conceals/hides the presence of the other allele.
Dominant allele
The allele whose presence is concealed / hidden / masked is known as ___________.
Recessive allele
During the formation of gametes, two alleles of a gene responsible for a character separate from each other as each sister chromatid separates during _________________.
Anaphase II
The Punnett square is named after ______________.
Reginald Punnett
It is a table that shows the genotypes the two individuals can produce when crossed.
Punnett Square
A plant with round and yellow seeds is crossed with plant with wrinkled and green seeds. Round is dominant over wrinkled and is controlled by an allele R, while yellow flower color is dominant over white, controlled by an allele Y. All the resulting F1 progenies are heterozygous for the trait (RrYy)
If the F1 progenies are self-fertilized, what is the genotypic and phenotypic ratio of the F2 progenies?
9:3:3:1
Pea plants can be tall (T) or short (t) and produce purple (R) and white (r) blossoms.
A pure-breeding tall plant with purple flowers (TTRR) is crossed with a pure-breeding short plant with white flowers (ttrr). What will the offspring look like?
All offspring will be tall with purple flowers (TtRr)
Pea plants can be tall (T) or short (t) and produce purple (R) and white (r) blossoms.
A pure-breeding tall plant with purple flowers (TTRR) is crossed with a pure-breeding short plant with white flowers (ttrr).
If two of the hybrid (F1) plants are crossed, what offspring can they produce?
They can produce 9/16 tall purple plants, 3/16 short purple plants, 3/16 tall white plants, and 1/16 short white plants.
It can help predict patterns of inheritance of traits in organisms and even diseases in family lines.
Probabilities
The phenotypic measurements of F1 progeny exceed s or higher than compared to both parents is known as __________________.
Heterozygote advantage / Hybrid vigor
An AB blood type mother has children with a B blood type father (genotype BO).
What are the chances that their children will have AB type blood?
25%
An AB x BO cross will produce:
- 1/4 AB
- 1/4 BB
- 1/4 BO
- 1/4 AO
Bonus:
Hemophilia is an X-linked recessive disorder that causes problems with the blood clotting process. Hemophilia is caused by mutations in the F8 gene.
An affected female (XhXh) is paired with an unaffected male (XHY). They have 2 unaffected daughters and 2 affected sons.
What is the genotype of the unaffected daughters?
It is a circumstance where the expression of one gene is masked, inhibited or suppressed by the expression of one or more other genes.
Epistasis
There is complete dominance in both gene pair but one gene when homozygous recessive hides or mask the effect of the other gene.
Recessive Epistasis (9:3:4)
There is complete dominance in both gene pair; but one gene, when dominant, hides or mask the effect of the other gene.
Dominant Epistasis (12:3:1)
There is complete dominance in both gene pair, but either recessive homozygote is epistatic to the effects of the other gene.
Duplicate Recessive Epistasis (9:7)
Dominant and Recessive epistasis
13:3
Duplicate genes
15:1
