Exam 2 Practice Flashcards
(54 cards)
If you crossed a true-breeding big male with a true-breeding small female, what
distribution of phenotypes would be expected in the F1? what distribution of phenotypes
would be expected in the F2?
Parents are XE y and Xe Xe, so F1 will be Xe y (small males) and XE Xe big females.
F2 will be 1 XE y big male : 1 Xe y small male : 1 XE Xe big female : 1 Xe Xe small female
If you crossed a true-breeding small male with a true-breeding big female, what
distribution of phenotypes would be expected in the F1? what distribution of phenotypes
would be expected in the F2?
Parents are Xe y and XE XE, so F1 will be XE y (big males) and XE Xe big females.
F2 will be 1 XE y big male : 1 Xe y small male : 1 XE Xe big female : 1 XE XE big female
You are studying a new phenotype in mice. You cross a true-breeding black-eared
mouse with a true-breeding white-eared mouse and you get an all grey-eared F1. If ear
color is controlled by a single gene that exhibits incomplete dominance, what
distribution of phenotypes would you expect in a cross of two grey-eared mice?
E1 E1 (black) x E2 E2 white gives E1 E2 grey
Cross of E1 E2 x E1 E2 1 E1 E1 black : 2 E1 E2 grey : 1 E2 E2 white
Name four of the enzymes that are directly involved in DNA replication, and briefly
describe their roles in DNA replication
DNA helicase – unwinds double-stranded DNA to provide template for DNA polymerase
DNA primase – creates RNA primer that provides 3’OH for DNA polymerase III
DNA polymerase III – creates daughter strand in complementary antiparallel fashion by
adding nucleotides to 3’ end
DNA polymerase I – removes RNA primer and replaces it with DNA nucleotides
DNA ligase – makes phosphodiester bond between Okazaki fragments
DNA topoisomerase – relieves supercoiling
DNA helicase
unwinds double-stranded DNA to provide template for DNA polymerase
DNA Primase
creates RNA primer that provides 3’OH for DNA polymerase III
DNA polymerase III
creates daughter strand in complementary antiparallel fashion by
adding nucleotides to 3’ end
DNA ligase
makes phosphodiester bond between Okazaki fragments
DNA polymerase I
removes RNA primer and replaces it with DNA nucleotides
DNA topoisomerase
relieves supercoiling
What is a kinase?
a protein that adds phosphates to other proteins
What electrical charge does DNA have, and what gives it this charge?
negative from the phosphates
There are only 2 alleles for a given gene in a particular population– allele A and
allele a. Allele A is dominant over allele a. This means that
In a heterozygote (Aa), the dominant phenotype is expressed
Which of the following statements best describes the results of this experiment? If a
G1 cell is fused with a cell in the S or M stage, the G1 cell will enter the S or M stage
because …
..proteins in the S and M cells control the progression to those stages
INcomplete dominance is
the heterozygote has a phenotype in between the phenotype of either homozygote
codominance is
both alleles are dominant; neither is recessive to each other
Flower color in snapdragons is an example of incomplete dominance
If you cross a red snapdragon with a white snapdragon, you get an F1 that is
If you then cross two F1s you get a phenotypic distribution of
incomplete dominance, pink
A botanist has determined that flower color in a new species of orchid is determined by a gene with two alleles, one of which is dominant. The dominant flower color is red.
How many dominant alleles must an orchid possess in order to demonstrate red flowers?
How many recessive alleles must an orchid possess in order to demonstrate white flowers?
What flower color is expected in a heterozygous orchid?
1 ; 2; red
The MLH1 gene is located on chromosome 3 in humans and four different alleles have been identified. You examine a cell in G1 of the cell cycle (ie, that has not yet replicated its DNA).
How many copies of the gene are present?
The maximum number of different alleles a single normal individual can have is:
2 ; 2
The MLH1 gene is located on chromosome 3 in humans and four different alleles have been identified. You examine a cell in G1 of the cell cycle (ie, that has not yet replicated its DNA).
The minimum number of different alleles a single normal individual can have is:
The maximum number of different alleles a single normal gamete (ie a reproductive cell, a sperm or egg) can have is:
1 ; 1
Heterozygous means
an individual has two different alleles of a gene
A phenotype is
the way something or someone looks
An allele of a gene of interest is best described as
a variation in the nucleotide sequence of the gene that may or may not result in a detectable phenotype.
A gene is
A region of the DNA that encodes an enzyme and a Mendelian particle that produces a phenotype
