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BIOLOGY 2C03 Chapter 1: Genetics Chapter 1

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biomajor2021
14 Dec 2021
School
McMaster University
Department
Biology
Course
BIOLOGY 2C03
Professor

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Document Summary

What is genetics a sub-field of biology that investigates genotypic and phenotypic variations among organisms and how such variations are inherited. Play a critical role in understanding diseases. Guides biotechnology industry for drug design, development, & production. Gene a region of dna that helps determine a character. Allele one of two or more alternative forms of a gene. Locus specific place on a chromosome occupied by an allele. Genotype combination of alleles at one or more loci possessed by an individual organism. Heterozygote an individual organism possessing two different alleles at a locus (for diploid or higher ploidy organism) Homozygote an individual organism, possessing the same alleles at a locus. Phenotype or trait the appearance or manifestation of a character. Humans have been aware of genetics, via selective breeding for over 10000 years. Early breeding work included those of rice, maize, wheat, and domesticated animals for production and enhancement of desirable traits.

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Related Questions

These all relate to exceptions to the inheritance patterns encountered by Mendel.​

Why do multiple and lethal alleles often result in modifications of the classic Mendelian monohybrid and dihybrid ratios?

Select the four correct statements.

-When an essential gene is mutated, it can result in a lethal phenotype. There are no classic Mendelian monohybrid and dihybrid ratios.
-In the case of codominance, heterozygotes produce gene products from both alleles of a gene. Classic Mendelian monohybrid and dihybrid ratios are modified by codominance.
-In the case of incomplete dominance, the phenotype of the heterozygote is distinct from and often intermediate to the phenotypes of homozygous individuals. Classic Mendelian monohybrid and dihybrid ratios are modified by incomplete dominance.
-Genes exist in a large number of allelic versions and a diploid organism has two homologous gene loci that may be occupied by different alleles of the same gene. This can result in many different phenotypes for traits, which may not follow typical Mendelian ratios.
-When an essential gene is mutated, it can result in a lethal phenotype. This results in a modification of classic Mendelian ratios.
-The phenotype of the heterozygous genotype is distinct from and often intermediate to the phenotypes of the homozygous genotypes. The joint expression of both alleles in a heterozygote is called codominance. There are no classic Mendelian monohybrid and dihybrid ratios.
-Genes exist in a large number of allelic versions, but in a diploid organism, only one allele of the gene can occupy one homologous gene loci. Classic Mendelian inheritance cannot explain this phenomenon.
-Each gene produces a unique gene product. The effect of one allele in a heterozygote completely masks the effect of the other. Classic Mendelian genetics cannot explain this phenomenon.

15. Population genetics provides answers for all of thefollowing questions except:

a. What is the frequency ofgenetic disease in a population?

b. What fraction of thephenotypic variation in a trait is the result of geneticvariation?

c. What alleles are most likelyto mutate?

d. Given certain quantifiablevariables, how long is a disease likely to persist?

e. How rapidly can a disease gaina foothold in a population?

16. Which of the following is not one of the assumptions of theHardy-Weinberg law?

a. The population is verylarge.

b. There is non-random matingwithin the population.

c. Mutations in the alleles donot occur.

d. No migration occurs into orout of the population.

e. The ability of all genotypesfor survival and reproduction is the same.

17. The heterozygote genotype frequency term for a gene with twoalternate alleles A (frequency p) and a (frequency q) in theHardy-Weinberg equation is:

a.p2 b.q2 c.2pq d.(p+q)2 e. p+q

18. In humans, brachydactyly is a dominant condition. Sixthousand four hundred people in a population of 10,000 show thedisease (1,600 are BB, 4,800 are Bb) and 3,600 are normalphenotypes (bb). The frequency of the b allele is:

a.0.6 b.0.8 c.0.36 d..48 e. 0.16

19. Fitness is described as:

a. an individual’s ability tosurvive to adulthood

b. an individual’s ability toreproduce

c. an individual’s ability toadapt to change

d. all of the above are true

QUESTION 1

Jim is blood type A, his brother John is type O and his sister Jane is type AB. What are the genotypes of their parents?
A.
IAi and IBi
B.
IAIA and IBIB
C.
IAi and IBIB
D.
IAIB and ii
E.
IAIA and IBi

QUESTION 2

Which of the following is true for alleles that show incomplete dominance?
A.
Heterozygotes have a genotype like the dominant allele.
B.
Homozygotes have a genotype like the recessive allele.
C.
Heterozygotes have a phenotype intermediate between the dominant and recessive alleles.
D.
Homozygotes have the same phenotype as the heterozygotes.
QUESTION 3

Which principle of inheritance concluded that when games are formed in meiosis, the two alleles of each gene separate from one another, and each gamete receives only one allele?
A.
independent assortment
B.
heterozygosity
C.
segregation
D.
dominance
QUESTION 4

Which term best describes a condition in which alleles at one locus can alter the expression of alleles at another locus?
A.
polygenic inheritance
B.
codominance
C.
multiple alleles
D.
pleiotropy
E.
epistasis
QUESTION 5

A single unit of genetic information located on a chromosome defines:
A.
a trait
B.
an allele
C.
a chromosome
D.
a locus
E.
a gene
QUESTION 6

The physical expression (appearance or function) of an organism's genes defines:
A.
genotype
B.
a single characteristic
C.
physiology
D.
mutation
E.
phenotype
QUESTION 7

Palomino horses (golden color with a blond mane) are an incompletely dominant trait produced by the combination of the chestnut color allele and the cream color allele. If you wanted to produce as many palominos as possible, which mating strategy below would be the best choice?
A.
Chestnut x Cream
B.
Palomino x Cream
C.
Palomino x Chestnut
D.
Palomino x Palomino
QUESTION 8

Which term best describes the effect of a single gene on multiple aspects of the phenotype?
A.
epistasis
B.
pleiotropy
C.
multiple alleles
D.
codominance
E.
polygenic inheritance
QUESTION 9

Which term best describes the separate expression of both alleles for a single trait in the same cell?
A.
multiple alleles
B.
codominance
C.
pleiotropy
D.
epistasis
E.
polygenic inheritance
QUESTION 10

One form of a gene found on a single chromosome defines:
A.
an allele
B.
a locus
C.
a chromosome
D.
a trait
E.
a gene
QUESTION 11

A chocolate lab (whose mother was a yellow lab) is mated with a black lab whose genotype is BbEe. What fraction of the offspring would be expected to be yellow labs?
A.
1/4
B.
none
C.
1/2
D.
3/16
E.
1/8
QUESTION 12

What type of allele is always expressed regardless of whether the individual is homozygous or heterozygous for it?
A.
Both the dominant and recessive alleles
B.
Recessive allele
C.
Allosteric allele
D.
Lethal allele
E.
Dominant allele
QUESTION 13

Given the parents AABBGgHhrr × AabbGgHhRr, assume simple dominance and independent assortment. What proportion of the progeny will be expected to have the genotype AaBbggHHrr?
A.
1/256
B.
1/64
C.
1/16
D.
1/32
E.
1/128
QUESTION 14

___________________ is defined as having two of the same type of allele for a particular trait.
A.
Homozygous
B.
Dominance
C.
Incomplete dominance
D.
Heterozygous
E.
Genotype

QUESTION 15

The physical position of an allele on a single chromosome defines:
A.
an allele
B.
a chromosome
C.
a gene
D.
a locus
E.
a trait
QUESTION 16

Which term best describes two or more genes affecting the phenotype in an additive fashion?
A.
codominance
B.
polygenic inheritance
C.
multiple alleles
D.
pleiotropy
E.
epistasis