# LIFESCI 4 Lecture Notes - Lecture 18: Allele Frequency, Zygosity, Blue Arrow

575 views6 pages
School
Department
Course
Professor
LIFESCI 4 - Lecture 18 - Homozygosity by Descent
Clicker 1:
In a particular population the allele frequency of the ABO blood type alleles are as follows:
is 31%, I is 60%, and i is 9%IA B
If mating is random and the population is in Hardy-Weinberg equilibrium, approximately what
percent of the population will have blood type B?
A) 36%
B) 41%
C) 47%
D) 69%
E) None of the Above
Explanation:
- To get blood type B, an individual can either have genotype I or I iIB B B
- Allele frequency for .6 and i 0.09IB= 0 =
- Let’s define allele as (p), as (q), and as (r)IAIB i
- P[B phenotype] = p[ ] + p[ ] = = (0.6)(0.6) + 2 (0.6)(0.09) = 0.47IIB B iIB 2qrq2+
Clicker 2:
Which statement describes the swallow with the greatest evolutionary fitness?
A) A swallow that lives to be 3 years old and has four offsprings, two of which survive to
reproduce themselves
B) A swallow that live to be 5 years old and has five offsprings, one of which survive to
reproduce
C) A swallow that live to be 2 years old and has four offsprings, all of which survive to
reproduce
D) A swallow that live to be 7 years old and has three offsprings, all of which survive to
reproduce
E) All are equally fit
Explanation:
- Although the swallow lives only to 2 years, it has the highest number of offspring which
will continue to pass down the swallow’s genes
Clicker 3:
Within a certain population (that is in Hardy-Weinberg equilibrium) the frequency of the L allele
of the LM blood group is 0.2 and the frequency of the M allele is 0.8. This population has just
been infected with a virus that kills everyone with blood type M, but individuals with blood type
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 6 pages and 3 million more documents.

LM or L are unaffected by the virus. What is the allele frequency of L and M in the population
after the viral infection.
The allele frequency of L is:
A)
B) 4/9
C) 5/9
D)
E) None of the above
Explanation
- The genotype frequency can be predicted before the infection
since it was in
Hardy-Weinberg equilibrium
- We are given that L = p = 0.2
and M = q = 0.8
- Frequency of LL = = 0.04p2
- Frequency of LM = = 0.32pq2
- Frequency of MM = = 0.64q2
- Where 0.04 + 0.32 + 0.64 = 1
- After the viral infection, there is no more equilibrium since selection is involved
- M does not survive
- Frequency of LL remains unchanged = 0.04
- Frequency of LM remains unchanged = 0.32
- Frequency of MM = 0 since they all die
- Calculate frequency of L after the infection (p’) = = 5/9
0.04 + 0.32
0.04 + 0.32/2
- The new frequency (p’) was found by adding the proportion of (p) alleles
post-infection and dividing it by the total
- Dividing by total is necessary since after the infection, the frequency of LL
and LM are no longer percentages (does not add up to 1) the
percentage needs to be recalculated
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 6 pages and 3 million more documents.

## Document Summary

Lifesci 4 - lecture 18 - homozygosity by descent. In a particular population the allele frequency of the abo blood type alleles are as follows: If mating is random and the population is in hardy-weinberg equilibrium, approximately what percent of the population will have blood type b? is 60%, and i is 9% B is 31%, i: 36, 41, 47, 69, none of the above. To get blood type b, an individual can either have genotype. Although the swallow lives only to 2 years, it has the highest number of offspring which will continue to pass down the swallow"s genes. Within a certain population (that is in hardy-weinberg equilibrium) the frequency of the l allele of the lm blood group is 0. 2 and the frequency of the m allele is 0. 8. This population has just been infected with a virus that kills everyone with blood type m, but individuals with blood type. Lm or l are unaffected by the virus.

## Get access

\$8 USD/m\$10 USD/m
Billed \$96 USD annually
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class