Genetics Exam test questions and
answers graded A+
Nucleosome - ANS✅✅Wound DNA around a protein complex.
little balls for DNA to wrap around made of 8 histone proteins: 2(histone 2B) +2(histone 3)
+1(Histone 2A) + 2(histone 4) + 1(histone 1, which secures DNA to this structure)
Neutralizing their positive charges would have which effect on the histone proteins? -
ANS✅✅They would bind less tightly to the DNA
(because DNA is negatively charged)
pure breeding stock - ANS✅✅homozygous (dominant or recessive) individuals who are used to
produce the heterozygous F1 generation. The P generation (parents)
Mendel's law of segregation - ANS✅✅each gamete has 1 copy of each gene, each offspring gets 2
copies of each gene
Mendel's 4 conclusions from Monohybrid crosses - ANS✅✅1) F1 display only one parent's
characteristics, but are heterozygous
2) alleles separate when gametes are formed
3) Concept of dominance
4) Two alleses of an individual plant separate with equal probability into the gametes.
Incomplete dominance - ANS✅✅-red x white = pink
-1:2:1 ratio; red, pink, white
codominance - ANS✅✅-phenotypes of both homozygotes are expressed
-AB bloodtype have both dominant A proteins and B proteins->equal amount; not one more than
other
dominance - ANS✅✅affects how genes are EXPRESSED not how they are inherited
-result of interactions between genes on the same locus (allelic interaction)
, incomplete penetrance - ANS✅✅not all people with a homozygous genotype fully express that in
their phenotype
ex: some people genetically have Huntington's but never express the disease
Conditional probability - ANS✅✅Probability a tall plant is Tt?
Not 1/2 because it is tall, so it's either TT or Tt. There are 2 Tt and one TT in a Monohybrid cross of a
homo and hetero, so there's a 2:1 ratio, and 2 out of 3 are Tt. So 2/3 probability.
reciprocal crosses - ANS✅✅recessive female x dominant male then dominant female x recessive
male helps test for sex linkage
lethal allele - ANS✅✅causes death
-usually expressed as 2:1 (dominant) ratio
-a single copy of the allele produces color
//Gg produces yellow, but gg kills
//GG produces normal, living green
Test Cross - ANS✅✅unknown X recessive
sex linkage - ANS✅✅genes that only exist on X or Y chromosomes
ex: hemophilia(x-linked recessive) & colorblindness(x-linked recessive)
Epistasis - ANS✅✅when 1 gene effects/covers another gene 9:3:3:1
A_B_ 9
A_bb 3
aaB_ 3
aabb 1
-Labrador dogs
independent events - ANS✅✅presence of 1 event doesn't influence the presence of another
key word AND=multiply
answers graded A+
Nucleosome - ANS✅✅Wound DNA around a protein complex.
little balls for DNA to wrap around made of 8 histone proteins: 2(histone 2B) +2(histone 3)
+1(Histone 2A) + 2(histone 4) + 1(histone 1, which secures DNA to this structure)
Neutralizing their positive charges would have which effect on the histone proteins? -
ANS✅✅They would bind less tightly to the DNA
(because DNA is negatively charged)
pure breeding stock - ANS✅✅homozygous (dominant or recessive) individuals who are used to
produce the heterozygous F1 generation. The P generation (parents)
Mendel's law of segregation - ANS✅✅each gamete has 1 copy of each gene, each offspring gets 2
copies of each gene
Mendel's 4 conclusions from Monohybrid crosses - ANS✅✅1) F1 display only one parent's
characteristics, but are heterozygous
2) alleles separate when gametes are formed
3) Concept of dominance
4) Two alleses of an individual plant separate with equal probability into the gametes.
Incomplete dominance - ANS✅✅-red x white = pink
-1:2:1 ratio; red, pink, white
codominance - ANS✅✅-phenotypes of both homozygotes are expressed
-AB bloodtype have both dominant A proteins and B proteins->equal amount; not one more than
other
dominance - ANS✅✅affects how genes are EXPRESSED not how they are inherited
-result of interactions between genes on the same locus (allelic interaction)
, incomplete penetrance - ANS✅✅not all people with a homozygous genotype fully express that in
their phenotype
ex: some people genetically have Huntington's but never express the disease
Conditional probability - ANS✅✅Probability a tall plant is Tt?
Not 1/2 because it is tall, so it's either TT or Tt. There are 2 Tt and one TT in a Monohybrid cross of a
homo and hetero, so there's a 2:1 ratio, and 2 out of 3 are Tt. So 2/3 probability.
reciprocal crosses - ANS✅✅recessive female x dominant male then dominant female x recessive
male helps test for sex linkage
lethal allele - ANS✅✅causes death
-usually expressed as 2:1 (dominant) ratio
-a single copy of the allele produces color
//Gg produces yellow, but gg kills
//GG produces normal, living green
Test Cross - ANS✅✅unknown X recessive
sex linkage - ANS✅✅genes that only exist on X or Y chromosomes
ex: hemophilia(x-linked recessive) & colorblindness(x-linked recessive)
Epistasis - ANS✅✅when 1 gene effects/covers another gene 9:3:3:1
A_B_ 9
A_bb 3
aaB_ 3
aabb 1
-Labrador dogs
independent events - ANS✅✅presence of 1 event doesn't influence the presence of another
key word AND=multiply
