ap bio unit 6 frq

9a. Identify the hsp mRNA that has the slowest rate of concentration increase in response to heat-shock treatment.

mRNA III has the slowest rate of concentration increase in response to heat-shock treatment

10b. Information flow can be altered by mutation. Describe THREE different types of mutations and their effect on protein synthesis.

A silent mutation is a mutation in which a nucleotide is changed in the gene sequence, however there is no effect of protein synthesis. A missense mutation or substitution is when nucleotide change creates a stop codon and this results in a different amino acid or protein sequence. Finally, nondisjunction is a mutation that fails to separate chromosomes and this effects protein synthesis as it can alter gene expression.

7a. Describe why translation of an mRNA can start before transcription of the mRNA is complete in prokaryotes but not in eukaryotes.

Eukaryotes have a nuclear envelope that separates the genome from the ribosomes in the cytoplasm of the cell, while prokaryotes do not therefore allowing them to start translation of an mRNA before transcription is complete.

8c. Predict the most likely effect on cell division for a cell containing DNA with double-strand breaks. Justify your prediction.

I predict cell division will not occur if the cell containing DNA with double-strand breaks. This is because the DNA replication will not be able to be completed and the daughter cells will not form.

4a. Explain how ligand A and ligand B can cause identical cellular responses in a cell.

Ligand A and B can cause identical cellular responses in a cell since both proteins have the same intracellular domain meaning they both activate the same signal transduction pathways. Thus, they have identical responses.

10d. Epigenetics is the study of heritable changes in the phenotype caused by mechanisms other than changes in the DNA sequence. Describe ONE example of epigenetic inheritance.

One example of epigenetic inheritance is pollution, as environmental factos can change the phenotype of an organism in order to increase chances of survival.

8d. Point mutations alter the DNA sequence at a single nucleotide. Describe how point mutations affect the genetic makeup of the population AND impact the evolution of the population.

Point mutation affect the genetic makeup of a population by increasing genetic diversity through each mutation (possible addition of phenotypes) and they impact evolution of population as the point mutations are subject to evolutionary forces.

5a. Assuming that species I is the ancestral species of the group, explain the most likely genetic change that produced the polypeptide in species II and the most likely genetic change that produced the polypeptide in species III.

DNA replication is a semiconservative process because one strand of DNA serves as the base template strand of DNA for the new strand of complementary DNA. This means if an error occurs during DNA replication (such as external harm such as radiation), following strands of DNA will also contain errors in their nucleotide sequence which leads to random mutations such as those in pathogens with a mutator phenotype.

6a. Describe why DNA replication is said to be a semiconservative process. Explain how random mutations such as those in pathogens with a mutator phenotype may arise in the DNA of an organism.

DNA replication is a semiconservative process because one strand of DNA serves as the base template strand of DNA for the new strand of complementary DNA. This means if an error occurs during DNA replication (such as external harm such as radiation), following strands of DNA will also contain errors in their nucleotide sequence which leads to random mutations such as those in pathogens with a mutator phenotype.

2. A student claims that mitochondrial DNA sequence comparisons provide a more accurate phylogeny of bear species than do LYST protein sequence comparisons. Provide ONE piece of reasoning to support the student's claim.

Mitochondrial DNA sequencing are more accurate because they show evolutionary relationships over time, while LYST protein sequencing does not.

11b. Researchers inserted a small fragment of human DNA into the pTET-KAN plasmid. Cultures of E. coli were transformed with the modified plasmid. The transformed bacterial cells were able to survive in the presence of tetracycline but were unable to survive in the presence of kanamycin. Draw an "X" on the plasmid template provided below to indicate where the human DNA fragment was most likely inserted. Justify your placement of the inserted human DNA.

The X is on the kan gene as the human DNA likely disrupted the kan gene/promoter which is why the bacterial cells were unable to survive in the presence of kanamycin.

9b. Describe the trend in the average concentration of mRNA throughout the experiment.

The average concentration of mRNA increased throughout the experiment (notably at a great rate from. to 10 hours for 4 hours after the heat shock), however the concentration decreased after hour 10.

5b. Predict the effects of the mutation on the structure and function of the resulting protein in species IV. Justify your prediction.

The dependent variable is the number of colonies produced per 10^7 cells for each of the C.neoformans strains. By testing a number of colonies produced by strains C3-PBB and C6-PBB, the scientists were able to test the respective control studies when only the plasmid backbones are being introduced. This analysis allows the scientists to know that when the strains were plated on a growth medium lacking the toxic chemical, a positive control was produced to demonstrate that all of the strains can grow and produce colonies.

9c. The scientists hypothesized that the heat-shock protein ( HSP) translated from mRNA I plays a greater role in refolding proteins than does the HSP translated from mRNA II. Use the data to support the hypothesis.

The hypothesis is supported by the data that presents the mRNA I still being expressed at a high level after the heat shock period, while mRNA II decreased. This shows that mRNA II was unable to refold proteins while mRNA I was.

7c. Fill in the boxes in the template to identify the nucleotide sequence, from 3' to 5', of the tRNA anticodon that will recognize codon 5 and the tRNA anticodon that will recognize codon 510 of the mRNA template and to identify the amino acids that will be added at these two positions. A codon table is provided for reference.

The nucleotide sequence from 3' to 5' of the tRNA anticodon that will recognize codon 5 GCG and the amino acid added is Arg. Then the nucleotide sequence that will recognize codon 510 of the mRNA will not have a tRNA complementary anticodon, because the mRNA codes for UAG which is a stop sequence and no amino acid is added.

7d. Referring to the figures provided, explain why the polypeptide produced when the transformed bacteria translate the introduced eukaryotic mRNA provides evidence for the common ancestry of all living organisms.

The polypeptide produced when the transformed bacteria translate the introduced eukaryotic mRNA provides evidence for common ancestry of all living organisms because the polypeptide produced by translation by a eukaryotic or a prokaryotic cell should have the same amino acid sequence because the genetic code is practically universal.

7b. Referring to Figure 1, explain the process illustrated between Step 1 and Step 2.

The process between step 1 and 2 shows a growing polypeptide chain attached to the tRNA aligned with codon 3 of the mRNA is transferred to the amino (NH2 ) terminus of amino acid 4 (AA4) attached to the aligned with codon 4 of the mRNA.

3a. Justify the use of eDNA sampling as an appropriate technique for detecting the presence of silver carp in an environment where many different species of fish are found. Propose ONE advantage of identifying long eDNA fragments as opposed to short fragments for detecting silver carp.

The use of eDNA sampling is appropriate because it can be used to detect fish without having to catch the fish. When doing this, an advantage that occurs is that long eDNA fragments will identify more recent presence of fish.

9d. mRNAs I and II are transcribed from the same gene. Explain how a cell can produce two different mRNAs from the same gene.

A cell can produce two different mRNAs from the same gene if the cell expresses different exons and performs alternative splicing.

10a. Describe the role of THREE of the following in the regulation of protein synthesis: RNA splicing repressor proteins methylation siRNA

In regulation of protein synthesis, RNA splicing removes introns, repressor proteins inhibit transcription and translation, methylation protects against restriction enzymes, and siRNA facilitates degradation of mRNA.

6b. Identify a dependent variable in the experiments. Identify the reasoning of the scientists when they tested the number of colonies produced by strains C3-PBB and C6-PBB. The scientists also analyzed the number of colonies produced from each of the environmental and clinical isolate strains when the strains were plated on a growth medium lacking the toxic chemical. Justify this analysis.

The dependent variable is the number of colonies produced per 10^7 cells for each of the C.neoformans strains. By testing a number of colonies produced by strains C3-PBB and C6-PBB, the scientists were able to test the respective control studies when only the plasmid backbones are being introduced. This analysis allows the scientists to know that when the strains were plated on a growth medium lacking the toxic chemical, a positive control was produced to demonstrate that all of the strains can grow and produce colonies.

1. Using the data, provide justification for the claim that antibiotic resistance may arise in bacterial species.

Antibiotic resistance occurs when bacteria develop immunity to the drugs implemented and designed to kill them. The data provides that most patients admitted to the ICU with a bacterial infection have developed antibiotic resistance to old medication. Hence, their condition becoming so severe. Most notable patients treated with ampicillin have developed the highest amount of resistance and patients treated with imipenem develops the least resistance to this antibiotic. The principle of antibiotic resistance comes from natural selection.

6c. Based on the data in Figure 1, for each strain describe the relationship between the number of colonies observed and the likely mutation rate of the strain.

As the strains that contained DNA mutations and produced a large amount of colonies increased are less susceptible to damage by the toxic chemicals. Essentially the more number of colonies observed, the higher the likely mutation rate of the strain, and the less damage they recieve.

12b. Predict the length of the mature gene X mRNA if the full-length gene is introduced and expressed in prokaryotic cells. Justify your prediction.

I predict the length of the mature gene xmRNA is going to be longer than the mature mRNA in the eukaryote if the full length gene is introduced and expressed in prokaryotic cells. This is because mRNA processing does not typically occur in prokaryotes and therefore will not shorten the XmRNA.

4b. Predict the most likely effect of a two-nucleotide deletion in the middle of the intron located between exons 4 and 5 on the structure of protein A. Justify your prediction.

I predict the most likely effect of a two-nucleotide deletion in the middle of the intron located between exons 4 and 5 on the structure of protein is that there will be no change. This is because the intron will be removed during the experiment and therefore not translated in order to cause a change.

11a. Predict the most likely outcome of culturing transformed E. coli in the presence of tetracycline. Justify your prediction.

I predict the most likely outcome of this culturing is an increase in cell growth because the cells will develop resistance after long exposure, specifically the tet-resistance gene which will lead to less cells being killed by tetracycline and more unhindered growth.

12a. The primary transcript in the figure is 15 kilobases (kb) long, but the mature mRNA is 7 kb in length. Describe the modification that most likely resulted in the 8 kb difference in length of the mature mRNA molecule. Identify in your response the location in the cell where the change occurs.

The modification that most likely resulted in the 8 kb difference in the length of the mature mRNA molecule was RNA processing and the change occurs in the nucleus.

6d. State the null hypothesis for the experiment whose data are graphed in Figure 2. Provide evidence to support or refute the scientists' claim that more colonies grew in strains C3 and C6 than in the other strains because the genes for proteins that are normally targeted by the toxic chemical contain nucleotides with incorrect bases in the C3 and C6 cells. The scientists additionally determined that the C3 and C6 strains had no decrease in virulence (disease-causing ability) in comparison with the virulence of the other clinical isolate strains and concluded that these two strains have mutator phenotypes. Explain why mutator phenotypes were found only among clinical isolate strains and not among environmental strains.

The null hypothesis is that the mutations to the gene MSH2 are not responsible for the high mutation rate or large number of colonies produced by the C3 and C6 strains in the presence of the toxic chemical. As MSH2 gene increased in the C3 and C6 cells, the number of colonies decreased which shows evidence that the gene is able to produce a DNA repair enzyme, suggesting that the mutations were repaired. This evidence thus refutes the scientists claim as the number of colonies decreased when in C3 and C6. Finally mutator phenotypes were found only among clinal isolate strains because there is a selective advantage to C.neoformans that are isolated and less likely to be killed by anti-fungal drugs or environmental factors.

8b. Using the results from all treatments, describe the effect of BaP alone and UVA alone compared with the effect of the combined treatment of BaP and UVA on DNA.

There is no effect of BaP and/or UVA alone, however the effect of the combined treatment of BaP and UVA on DNA is harmful and causes damage.

3b. The researchers tested a large number of water samples from Lake Michigan and found eDNA specific to silver carp in a single sample in the lake, as indicated in Figure 2. The researchers concluded that the single positive sample was a false positive and that no silver carp had entered Lake Michigan. Provide reasoning other than human error to support the researchers' claim.

The researchers claim is supported if eDNA entered the lake by a means other than fish. This could occur through river flow, boats, waste from predators, etc.

10c. Identify TWO environmental factors that increase the mutation rate in an organism, and discuss their effect on the genome of the organism.

Two environmental factors that increase the mutation rate in an organism are carcinogens (ex: asbestos) and radiation (ex: gamma rays). They can negatively effect the genome of an organism by altering and damaging the DNA (ex: double strand breaks).