DNA Replication
Mitosis
Meiosis
Genetics
Random
100
What is semiconservative replication?
Each DNA molecule is composed of one parental and one daughter strand
100
What are the stages of the cell cycle?
Interphase (G1, S-phase, G2), M-phase
100
How many daughter cells are produced by meiosis? What is their ploidy?
4; haploid
100
Which of the following are homozygous dominant?
aa, Aa, RR, BB, Cc, cc
RR & BB
100
What is cancer?
Uncontrolled cell division which results in abnormal masses of cells
200
This enzyme opens and unwinds the DNA double helix, forming the replication bubble.
Helicase
200
What is the difference between sister chromatids and homologous chromosomes?
Sister chromatids: Identical chromosomes following DNA replication
Homologous chromosomes:A chromosome pair with each inherited from one parent, same length and carry the same genes
200
What is separated during meiosis I? Meiosis II?
Meiosis I: Homologous chromosomes
Meiosis II: Sister chromatids
200
What does it mean for an allele to be dominant?
When two different alleles are present, the dominant allele will mask the presence of the recessive allele
200
What is the function of topoisomerase?
Breaks and rejoins DNA to relieve twisting force created by helicase
300
The lagging strand is synthesized in what direction?
5' to 3'
300
Identify the phase of mitosis for each diagram.
A- Metaphase
B- Telophase & Cytokinesis
C- Anaphase
D- Prophase
300
What phase of meiosis is shown?
Anaphase II
300
What gametes will an individual with the genotype aaBB produce?
aB
300
Brown eyes in humans are dominant to blue eyes. A brown-eyed man, whose mother was blue-eyed, marries a brown-eyed woman whose father had blue eyes. What is the probability that this couple will have a blue-eyed child?
Bb x Bb
¼ or 25% of having a blue-eyed child
400
What occurs after DNA polymerase I replaces RNA primer with DNA nucleotides?
Ligase joins Okazaki fragments to create a continuous strand
400
Identify the function of mitosis, the relationship between parent and daughter cells, and what cells in the body undergo mitosis.
Function: Growth, repair, maintenance
Parent and daughter cells are genetically identical, both diploid
Somatic/body cells undergo mitosis
400
What are the 3 mechanisms that generate genetic diversity? Describe each.
Crossing over- Reciprocal exchange between non-sister chromatids in a homologous pair
Occurs in prophase I of meiosis I
Independent assortment- During metaphase I, chromosomes align at random, independently of whether they are maternal or paternal
Random fertilization- Gametes fuse randomly, independent of the genetic information they carry
400
Hemophilia is an X-linked recessive condition in which blood does not clot properly. Queen Victoria of England had one allele for hemophilia. Most of her male descendants had the disorder, but few females had it. Why did hemophilia occur more frequently in Queen Victoria’s male descendants?
a. Males mature more slowly than females, allowing recessive traits more time to appear.
b. Males have hormones that enhance the expression of X-linked traits.
c. Replication of the X chromosome occurs often in males but rarely in females.
d. Only one copy of the X chromosome is found in cells of males, but two copies are found in cells of females.
d. Only one copy of the X chromosome is found in cells of males, but two copies are found in cells of females.
Hemophilia is encoded by a gene on the X-chromosome. Females (XX) carry two copies (one on each X), and males (XY) only carry one. Because males only have one X-chromosome, whatever allele is present on that single X-chromosome will be expressed.
400
Put the steps of DNA replication in order:
DNA poly III adds DNA nucleotides using the parental DNA strand
DNA polymerase I replaces RNA primer with DNA nucleotides
Primase adds a short segment of RNA primer, creating an open 3’ end
Ligase closes gaps in sugar-phosphate backbone
Replication bubble is formed
Replication bubble is formed
Primase adds a short segment of RNA primer, creating an open 3’ end
DNA poly III adds DNA nucleotides using the parental DNA strand
DNA polymerase I replaces RNA primer with DNA nucleotides
Ligase closes gaps in sugar-phosphate backbone
500
Draw a replication bubble, labeling:
-The origin of replication
-Leading and lagging strands (and their directionality)
-Okazaki fragments
500
Identify all the cell checkpoints and what is "checked" for at each.
G1 checkpoint- Cell size is adequate, plenty of nutrients for the cell, undamaged DNA
G2 checkpoint- Are chromosomes replicated, DNA is undamaged
M-phase checkpoint- chromosomes attached to spindle apparatus successfully
500
Draw a 2n=4 cell, then draw all the possible ways the chromosomes could align themselves during metaphase I.
500
Male-pattern baldness is an X-linked recessive trait, labelled Xb, with the dominant normal hair gene being XB. A father with the genotype XBY and a mother with the genotype XbXb have a son. What is the percent chance that the son will inherit male-pattern baldness?
a. 0%
b. 25%
c. 75%
d. 100%
d. 100%
Mother can only contribute Xb to her sons, so all sons will be XbY and therefore have male-pattern baldness.
500
Identify the function of all the enzymes involved in DNA replication: Helicase, topoisomerase, SSBPs, DNA poly I, DNA poly III, primase, ligase
Helicase- Opens and unwinds DNA double helix (breaks hydrogen bonds)
SSBPs- Stabilize the single stranded DNA so it doesn’t rewind into a double helix
Topoisomerase- Breaks and rejoins DNA to relieve twisting force created by helicase
DNA poly I- Removes RNA primer and replaces it with DNA nucleotides
DNA poly III- Adds DNA nucleotides to 3’ end to create leading and lagging strands
Primase- Synthesizes RNA primer at the beginning of both the leading and lagging strands, this creates an open 3’ end for DNA polymerase to begin working
Ligase- Joins Okazaki fragments to make a continuous strand