Unit 6 check
Unit 6 check: Gene Expression and Regulation
10 questions from 8 lessons in Unit 6. Answer each one, and if you miss, follow the link back to where it is taught, then try again. Your score counts first tries.
Question 1 · from 6.1 · Sort it
Each card describes the chromosomes of a cell. Tap a card, then the kind of cell it typically describes.
Prokaryotic cell
Eukaryotic cell
Question 2 · from 6.2 · Match
Match each enzyme to its job during DNA replication.
Question 3 · from 6.3 · Sort it
Each card describes what a change to a eukaryotic transcript does. Tap a card, then the change it describes.
Adding a poly-A tail
Adding a GTP cap
Removing introns
Question 4 · from 6.4 · Multiple choice
A drug blocks reverse transcriptase. A retrovirus enters a host cell treated with the drug. What is the most likely result?
Setup for question 5
A new operon. Its genes code for the enzymes a bacterium uses to make the amino acid tryptophan. Researchers grow the bacteria with no tryptophan in the medium, then with plenty, and measure the enzymes: 100 units without tryptophan and 4 units with it. These numbers are a teaching example.
Question 5 · from 6.5 · Calculate
Bacteria make 100 units of the enzymes for building tryptophan when the medium has none, and 4 units when it has plenty. By what percentage does the enzyme level fall?
Setup for question 6
A new gene. Researchers suspect that protein R holds back gene H by binding a site in the DNA near H's promoter. They measure H's mRNA in three kinds of cell: normal cells, 6 units; cells lacking protein R, 120 units; cells with protein R but with its binding site in the DNA changed so R cannot bind, 118 units. These numbers are a teaching example.
Question 6 · from 6.6 · Decide and justify
Gene H gives 6 units of mRNA in normal cells, 120 units in cells lacking protein R, and 118 units in cells that have R but whose binding site for R in the DNA is changed. Do the data support the claim that R inhibits H by binding to DNA?
Which evidence supports your decision?
Setup for question 7
Researchers expose dishes of yeast cells to different doses of ultraviolet (UV) light, a form of radiation, then count the cells with a mutation in one test gene, per million cells. These numbers are a teaching example.
| UV dose (relative) | Mutant cells per million |
|---|---|
| 0 | 3 |
| 10 | 24 |
| 20 | 45 |
| 40 | 93 |
Question 7 · from 6.7 · Calculate
Using the table: the number of mutant cells per million at a UV dose of 40 is how many times the number at a dose of 0?
Setup for question 8
Investigators use PCR to copy three stretches of DNA from a sample found at a crime scene and from three suspects, then run the copies on a gel. The table gives the size of the fragment each person has at each of the three stretches. These numbers are a teaching example.
| Sample | Stretch 1 | Stretch 2 | Stretch 3 |
|---|---|---|---|
| Crime scene | 1,200 | 850 | 400 |
| Suspect 1 | 1,200 | 900 | 400 |
| Suspect 2 | 1,200 | 850 | 400 |
| Suspect 3 | 1,000 | 850 | 300 |
Question 8 · from 6.8 · Multiple choice
Using the table: whose DNA fingerprint matches the crime scene sample at all three stretches?
Question 9 · from 6.1 · Decide and justify
A yeast cell has a nucleus with linear chromosomes. A researcher also finds a small circular DNA molecule in it, separate from those chromosomes. Can this molecule be a plasmid?
Which statement supports your decision?
Question 10 · from 6.2 · Fill the statement
Complete the description of how the two new strands are made at a replication fork.
New DNA is synthesized in the direction. On the leading strand it is made ; on the lagging strand it is made , in fragments that joins.
0 of 10 answered.