Biology · Unit 6 · Paper 1

Gene Expression & Regulation unit test

A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.

Paper 1 Paper 2 Paper 3

Each paper is built from this unit’s 40 terms and is the same for everyone, so a teacher can assign “Unit 6, Paper 1” and every student sits the identical test. Multiple choice is marked objectively; the written sections you mark yourself against the model answer and rubric.

Suggested time 36 min 33 points0/17 attempted

Operon

Lab: Restriction Enzyme Analysis

Translation

Plasmid

Homeotic genes

DNA polymerase

Topoisomerase

Origin of replication

Alternative splicing

lac operon

Promoter and TATA box

Point mutation types

Short answer 1. Define or explain: Lab: Bacterial Transformation

3 pts

Short answer 2. Define or explain: Ribosome A, P and E sites

3 pts

Short answer 3. Define or explain: Transcription factors

3 pts

Short answer 4. Define or explain: Mismatch repair and proofreading

3 pts

Free response

9 pts

Eukaryotic cells use small interfering RNA (siRNA) molecules that regulate expression of certain genes by binding to complementary sequences in target mRNAs. This binding causes the protein AGO2 to cleave the target mRNAs, and the cleaved mRNAs are not translated. To investigate the role of AGO2 in the cleavage of mRNA from two genes, Gene G and Gene H, scientists determined the amount of each mRNA produced in cells with three AGO2 genotypes: homozygous wild type (AGO2 +/+), heterozygous for a nonfunctional allele (AGO2 +/−), and homozygous for the nonfunctional allele (AGO2 −/−). Amounts are relative to AGO2 +/+ cells. TABLE 1. RELATIVE AVERAGE AMOUNTS OF GENE G AND GENE H mRNA (± SE of the mean) Gene AGO2 +/+ cells AGO2 +/− cells AGO2 −/− cells Gene G 1.0 ± 0.1 0.9 ± 0.4 1.5 ± 0.5 Gene H 1.0 ± 0.1 2.0 ± 0.1 3.0 ± 0.4

(a) Describe one location where ribosomes are found in eukaryotic cells.

(b)(i) The released exam supplies a grid. State what type of graph represents the data in Table 1 appropriately, and why that type fits data of this kind.

(b)(ii) State what belongs on each axis, including units, and what the error bars represent.

(b)(iii) State how the two genes should be arranged across the three genotypes so that the comparison the question asks for is visible, and confirm an error bar is plotted on every mean.

(b)(iv) Based on the table, determine all the cells in which the amount of Gene G mRNA produced is statistically the same as the amount in the cells with the AGO2 +/+ genotype.

(c)(i) Based on the table, describe the relationship between the number of wild-type copies of the AGO2 gene and the amount of Gene H mRNA in the cells.

(c)(ii) Based on the data in the table for Gene H, calculate the percent by which the average amount of mRNA in AGO2 −/− cells increases compared with that in AGO2 +/− cells.

(d)(i) The scientists claim that siRNA binding and AGO2 cleavage of mRNAs play a greater role in the regulation of Gene H expression than in the regulation of Gene G expression. Based on the table, support the scientists’ claim.

(d)(ii) Anaphase I of meiosis is blocked in mice with the AGO2 −/− genotype. Scientists hypothesize that the block occurs because the continued presence of a spindle-fiber stabilizing protein prevents the chromosomes from separating. Based on the table, explain how the AGO2 −/− genotype could cause this effect on the dividing cells.