Ap Bio 16-18

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

A mutation will not effect the protein because the intron is removed

Identify a dependent variable in the researchers' experiment shown in Figure 3. Justify the analysis of normal stomach cells ( NS ) in the experiments shown in Figure 3. Based on the data in Figures 1 and 3, describe the relationship between SIRT3 expression and glucose uptake. Calculate the percent change in lactic acid production by SC-1 cells compared with SC+RNA cells.

dependent variable is lactic acid production normal stomach cells are used as a control for comparison to determine whether metabolic indicators of the other groups changed. There is a positive correlation between SIRT3 and glucose uptake. Percent change is 117%

Identify a dependent variable in the experiment represented in Figure 3A . Identify the control group for the experiment represented in Figure 4. Based on the data in Figure 4, describe the effect of elevated FGF5 on the rate of hair growth in culture. Based on Figure 2, if individuals 19 and 20 have another child, calculate the probability that the child will be affected with FT , assuming that individual 20 has no family history of FT .

dependent variable- sampled length of hair control group- no treatment effect- decreased rate of hair growth Child has 0% chance to be affected

Researchers analyzing regulation of SIRT3 gene expression engineer a SIRT3 gene that is identical to the normal gene except that the normal SIRT3 gene promoter is replaced by the promoter for a gene encoding a protein typically found only in human nerve cells. The researchers introduce this gene into normal human stomach cells to determine how much SIRT3 mRNA AND protein will be expressed from the engineered SIRT3 gene in the stomach cells. Predict the results of this experiment. The researchers claim that metabolic activity increases in cancerous cells. Provide reasoning based on the data provided to justify the claim. Based on the information provided, predict the cause of a decrease in CO2 production by the three groups of cancer cells ( SC-1 , SC+plasmid , and SC+RNA ) treated with the compound that blocks the electron transport chain compared with the same groups of cells not treated with the compound.

no mRNA or protein will be produced from the introduced gene because the cancer cells in figure 3 had an increase in fermentation. If the ETC is inactive, NADH accumulation will increase, krebs cycle will decrease, and less CO2 will be produced

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

prokaryotes don't have a nuclear envelope that separates genome from rybosomes, but eukaryotes do

identify the dependent variable measured in the experiments.

size of population

Predict the effect of a treatment that reduces the expression of HBA1 on the symptoms of individuals with beta-thalassemia. Justify your prediction.

symptoms will be less severe because the cells will not go through apoptosis due to less hemichromes

Researchers claim that the ability of fetal hemoglobin to bind oxygen more tightly than the hemoglobin of the mother increases the fitness of the fetus. Provide reasoning to support the claim.

The ability of fetal hemoglobin to bind oxygen more tightly ensures that the fetus gets enough oxygen from the mother

(b) Using the codon chart provided, predict the change in the codon sequence that resulted in the substitution of alanine for threonine at amino acid position 229.

The change that caused the substitution was G to A at the first position of the codon

(a) 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 resulted in the difference in length was removal of introns and RNA processing. This change occurs in the nucleus

Describe one outcome that would demonstrate that a given population has evolved.

a change in allele frequency

FGF5-LFGF5-L mRNAmRNA consists of exons 11, 22, and 33, while FGF5-SFGF5-S mRNAmRNA consists only of exon 11 and part of exon 33. Describe the modification of FGF5FGF5 pre-mRNApre-mRNA that leads to the production of both the FGF5-LFGF5-L and FGF5-SFGF5-S proteins.

alternate splicing removes different introns resulting in different mRNA sequences

Calculate the minimum number of nucleotides required in the coding region of the LDS2B mRNA molecule to produce and terminate the 565-amino acid polypeptide. Provide TWO reasons that the number of nucleotides in the mature mRNA may differ from the number of base pairs in the gene.

565 (amino acids) x 3 (nucleotides)= 1695 + 6 (triplet code for start and stop) = 1701 nucleotides required. Number of nucleotides may differ because of removing of introns or due to alternative splicing mixes different exons

One genetic change associated with the disorder results in a methionine-to-valine substitution at amino acid position 425 of the encoded polypeptide, as shown in Figure 1. Using the codon table in Figure 2, predict a DNA point mutation that will result in a methionine-to-valine substitution.

AUG becomes GUG

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.

Codon 5: amino acid- arginine anticodon-GCC Codon 510: UAG is a stop sequence so there is no amino acid

Based on the data provided, explain how testing for SIRT3SIRT3 gene expression in samples of stomach cells might be used by physicians to predict which individuals have an increased risk of developing stomach cancer. Human stomach cells have plasma membrane receptors for the binding of certain extracellular signaling molecules such as growth factors. Explain why the irreversible binding of chemicals that mimic the growth factors will most likely change the normal cells into cancer cells.

Determining level of expression could tell if someone is likely to develop cancer. Irreversible attachment can continually stimulate the cell cycle

(c) Describe how individuals with one (heterozygous) or two (homozygous) copies of the wild-type GA3H allele can have the same phenotype.

Enough enzyme will be produced from one dominant allele

A stomach cell line growing in nutrient broth has a mutation in the gene encoding a particular type of tRNA . Assuming the mutation is not lethal to the cells, explain why the amount of SIRT3 mRNA in this cell line is identical to the amount produced by a normal stomach ( NS ) cell line but the amount of SIRT3 protein is less than in the NS cells.

If it is mutated it won't be able to carry the correct amino acid, so the mutated cell will produce less of the protein

Based on the pedigree shown in Figure 2, describe the HBB alleles inherited by individual 6 , including the parent from which each allele came.

Individual 6 inherited a mutant allele from the father and a normal one from the mother

Explain how individuals with one normal FGF5FGF5 allele and one mutant FGF5FGF5 allele can have normal hair growth. Explain why individuals affected with FTFT do not appear to have unusual growth of scalp hair, but their eyelashes grow longer than those of an individual without FT

Individuals with one allele will produce enough of the protein for normal hair growth. Mutation does not change growth of hair on scalp

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

It will be 15 kb in length because mRNA processing does not happen in prokaryotes

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

Polypeptides produced by this process should have the same amino acid sequence because the genetic code is almost universal

(a) The wild-type allele encodes a GA3H enzyme with alanine (Ala), a nonpolar amino acid, at position 229. The mutant allele encodes a GA3H enzyme with threonine (Thr), a polar amino acid, at position 229. Describe the effect of the mutation on the enzyme and provide reasoning to support how this mutation results in a short plant phenotype in homozygous recessive plants.

The mutation will change the shape and function of the protein because mutation removes gibberellin production

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

The protein will have different function and structure due to change in amino acid sequence

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.

There is a base pair substitution in species II There is a nonsense mutation that codes for a stop signal in species III

Predict the effect of a deletion mutation of the first codon of exon 11 of the gene on the translation of the FGF5-LFGF5-L transcript produced from the mutated gene. Justify your prediction. Researchers isolated a mutation that disrupts the receptor-binding site of FGF5FGF5. Predict the effect of this mutation on the ratio of hairs in growth phase to hairs in rest phase.

Translation cannot begin because there is no start codon. More hairs will grow than rest

Explain why the symptoms associated with beta-thalassemia are often undetectable at time of birth. A study of the gene encoding the gamma-globin subunit showed that, shortly after birth, the gene becomes methylated ( CH3 groups are added to the DNA ). Explain how DNA methylation could cause the change in the amount of gamma-globin protein that is represented in Figure 1.

symptoms are a result of nonfunctional beta-globin subunits, which are not part of the hemoglobin until months after birth. Methylation of DNA can lead to repression of gene expression which can decrease gamma-globin

The researchers claim that the Cit+ mutation increases the fitness of the bacteria. Provide reasoning to support the claim.

the bacteria can use citrate faster meaning they are more fit