Cells
What are the three major components of the cytoskeleton?
Microtubules, microfilaments, and intermediate filaments.
Name the start codon and one of the three stop codons
AUG
UAA
UAG
UGA
Antigens on human red blood cells will show both A and B in the same concentration if our parents are blood types A and B. What is this an example of?
Co-dominance
Name the cellular components of a virus?
Viruses are acellular. They cannot survive, grow, or reproduce on their own. Sorry not sorry for the trick question.
Suppose a cancer-causing agent is known to primarily promote cell division. At what stage is it most likely to act: G0, G1, G2, or M?
M = mitosis
The cells of our skin allow very little water to escape. These cellular junctions are called:
Tight junctions
In what directions do DNA replication, transcription, and translation proceed?
DNA REP- moves in the 5' -> 3' direction so the leading strand is 3' -> 5' and the lagging is 5' -> 3'.
Transcription- RNA poly moves 5' -> 3' so the template strand is 3' -> 5' and the mRNA is 5' -> 3'.
Translation- 5' -> 3'
If one gene was responsible for making Mentor Eliza tall, brunette, wildly successful, and totally humble, this would be an example of...
Pleiotropy
Do fungi spend the majority of their life as haploid or diploid cells?
Haploid
What do the outer leaflet and inner leaflet of the cell membrane interact with?
Outer = extracellular fluid
Inner = cytoplasm
Suppose a novel protein is discovered that is easily incorporated into micelles. This protein is most likely a/an:
A) integral membrane protein
B) peripheral membrane protein
C) beta-barrel protein
D) structural protein
A
How many chromosomes do humans have?: a) before replication, b) after replication, c) during interphase, d) before S-phase, e) after S-phase, f) in a diploid cell, g) in a haploid cell. Describe how the mass of DNA differs for each of the above scenarios.
a) 46; b) 46; c) 46; d) 46; e) 46; f) 46; g) 23
In a human diploid cell, prior to S phase, there are 46 unreplicated chromosomes, 23 of which originated from the father and 23 of which originated from the mother. These unreplicated chromosomes do not contain sister chromosomes. Let’s define these unreplicated chromosomes as having a mass of m. After replication, there are 46 dyads, or duplicated chromosomes. A dyad features two identical sister chromatids attached to the same centromere. The mass of a dyad would be 2m. Therefore, during DNA synthesis the mass changes from m to 2m, but the number of chromosomes does NOT change. In a human diploid cell, the chromosome number will always be 2n, but the mass could be m or 2m depending on whether or not S-phase has occurred. A tetrad is the set of two dyads aligned at the metaphase plate during Meiosis I, which are physically adjoined to one another by at least one DNA crossover. A human gamete, which is haploid, would have a mass of 0.5m.
Mosaicism
List 3 differences between gram positive and gram negative bacteria (multiple answers accepted).
+
stain purple, very thick cell wall, form endospores, single cell membrane
-
stain pink, relatively thin cell wall, do not form endospores, contain two cell membranes (inside outside cell wall)
If I have a disease that prevents the growth of desmosomes, what symptoms might I have.
Desmosomes occur in tissues subject to shear stress such as the epidermis. They are particularly common in stratified epithelium. An autoimmune disease that produces antibodies against the desmosome protein (desmoglein) leads to separation of skin layers and large, painful blisters.
If my cell lacks free ribosomes, what proteins will I not be able to produce?
Proteins bound for the cytosol
What is the best experimental method to analyze the effect of tdh2 gene deletion on the rate of histone acetylation? Comparing histone acetylation in WT and mutant cells by:
A) Western Blot
B) Southern Blot
C) Northern Blot
D) RT-PCR
A- Western Blot
Given a genome content of 50% AT, and assuming random nucleotide variability, the probability of the AUUUA sequence is one in every:
A) 25 bases
B) 45 bases
C) 2.0 x 105 bases
D) 4.0 x 105 bases
B
(1/4)(1/4)(1/4)(1/4)(1/4) = 1/1025
basically, probability is 1 in every 1025 bases = 45
A vDNA sequence encoding a protein is inserted into a host genome. The protein is translated from the hypothetical mRNA sequence shown:
5'-GGCAACUGACUA-3'
Based on the passage (that tells us this virus is a retrovirus), the segment of the original viral genome that encoded this protein had what nucleotide sequence?
Since we know this is a retrovirus, we know that the original mRNA transcript is going to be the same as what is later transcribed by mRNA.
Prions are infectious agents composed entirely of protein. In human hosts, prions cannot:
A) be inherited or coded for by a gene
B) convert normal proteins into pathogenic proteins
C) cause pathology outside the CNS
D) be acquired through food consumption
C
"Prions are misfolded proteins that are able to alter the folding of WT proteins. They’re exclusively neurological because the immune system would nuke them anywhere outside of the brain, and are invariably fatal." - JB
Capases activate apoptosis through signal transduction pathways. Upregulation of capase activity would most likely lead to:
A) induction of DNA repair enzymes
B) fragmentation of nuclear DNA
C) plasma membrane fragmentation and leakage into the extracellular space
D) rapid oxidative phosphorylation to increase ATP
B
Not C because C is more like necrosis
Describe how telomerase could be used to extend life? Why is this too good to be true?
Telomeres are long sections of repetitive DNA nucleotides found at both ends of each chromosome. They provide a buffer region of non-coding DNA so that these repetitive losses in length do not affect a gene sequence. Approximately 50 replication cycles will consume the entire telomere region and any subsequent replications will result in the loss of gene sequences.
Because telomeres are shortened by each round of cell division, they provide somewhat of a “time clock” for cells. After the telomeres are gone, subsequent division will quickly damage important coding sections of the DNA. Presumably the cell could not survive very many additional divisions without being directed into apoptosis. This would act to prevent the uncontrolled cell division found in tumors. However, if the enzyme telomerase were present, the cell could replace the telomere as it was being used up—essentially removing the “clock function” of the telomeres and theoretically allowing for unlimited cell division.
In an isolated population of 10,000 rabbits, 900 are homozygous for the recessive mutant Sp1 allele. Given this, what percentage of rabbits in the population who carry the mutant Sp1 allele but do not express the mutant phenotype? (Assume the population is in HW equilibrium)
42%
Describe the lysogenic and lytic cycles.
Lytic cycle- Infecting phage will ultimately kill the host to produce their own progeny. Following injection, the phage synthesizes proteins that break down host DNA, allowing the phage to control cellular machinery. The phage uses the host cell to build phage particles. Host cells become weakened and eventually burst, released 100-200 new phage progeny.
Lysogenic cycle- Does not kill the host cell, uses it as refuge where it exists in a dormantt state. Following injection, phage integrates itself into the host genome. The genome is replicated passively along with the host cell. Eventually the cell will transition into the lytic cycle (UV light, low nutrient, chemicals, transduction).
The cheetahs that survived the environmental catastrophe that occurred 12,000 years ago are at greater risk of extinction because of:
A) naturally selected changes in allele frequencies
B) random changes in allele frequencies
C) changes in allele frequencies due to migration
D) changes in allele frequencies due to random mating
B- Genetic drift describes the natural variations in allele frequencies of a population due to random genetic changes that are not related to natural selection. Although all populations are affected by genetic drift, its effects are more significant in smaller populations due to the reduced gene pool. Smaller gene pool cannot buffer random variations in allele frequencies that occur due to change events. Since the cheetahs experienced a bottleneck event, their population was reduced.