This exam consists of 50 multiple-choice questions. Each one has only one right answer. Read each question and all possible answers carefully before answering.

Please mark your answers on the Scantron form provided, using only #2 lead pencil. If you erase an answer, make sure you erase it fully, or the machine may mark it incorrect. Check carefully to ensure that your answers are on the correct rows on the Scantron form.

Turn in both the Scantron form and the test paper when you are finished. Make sure your name is on both. You may write on the test paper if you wish, but anything you write on the test paper will not be graded.

Good luck.

1. A single strand of DNA reads

GAAAGGCAAGAGGGC

What would be the order of bases in a complimentary strand of messenger RNA?

CUUUCCGUUCUCCCG

2. The messenger RNA would be made by a process known as

transcription

3. Each consecutive group of three DNA bases makes up a triplet codon, which

usually "stands for" only one amino acid in a protein

4. If you did a procedure known as PCR on this strand of DNA, you would be

making millions of copies of it

5. What did Francis Crick and James Watson get the credit for doing?

They showed that DNA has a "double helix" shape.

6. You could insert the above piece of DNA into a human cell using

a virus

Questions 7-12 deal with the Ames test, a simple, cheap procedure to test whether a chemical (in food, industry, cosmetics, etc.) is dangerous to humans: Grow bacteria in a dish, add a small amount of the chemical, and watch what happens.

7. The bacteria that are used in the Ames test have to have a source of an amino acid called histidine in order to survive. How many other amino acids does the bacterium use?

19

8. The bacteria used in the Ames test need histidine because they are not able to produce a molecular "tool" that allows them to make histidine themselves. This "tool" is a / an

enzyme

9. The chemical is potentially dangerous if the bacteria exposed to the chemical show random changes in their DNA (that allow them to grow without histidine). Such changes are

mutations

10. Why would testing a chemical on bacteria tell us anything about hazards to human health?

DNA is universally found in all living things.

11. A chemical that damages DNA could cause _______ if it happened to affect an oncogene.

cancer

12. Oncogenes regulate the process of

mitosis

13. Disorders such as Down's syndrome and Klinefelter's syndrome start when an egg cell or sperm cell has an extra copy of one of its chromosomes. This can happen when paired-up chromosomes fail to separate from each other in _______ of meiosis.

anaphase I

14. Normally an egg or sperm cell has only one copy of each chromosome; in other words, it is

haploid

15. The drug colchicine blocks the action of a cell's spindle fibers. A cell affected by colchicine would not be able to

Move its chromosomes during cell division

This is the chemical formula of a molecule called canavanine, which is found in alfalfa seeds:

16. Canavanine is

an amino acid

17. The part of the canavanine molecule that's indicated by the question mark is called

the R group

18. Canavanine isn't usually found in most living things. When, say, an insect eats alfalfa seeds or sprouts, canavanine becomes part of the _______ made by the insect.

proteins

19. When a canavanine molecule becomes part of a larger molecule, since it's not normally supposed to be there, it can cause the larger molecule to

fold into the wrong shape

20. In general, any relatively simple molecule that can be "strung together" in long chains or strands is called a

monomer

21. What does a zygote directly come from?

an egg cell and sperm cell

22. Griffiths discovered the "transforming principle" when he

mixed live and dead bacteria of different types

23. Outside of a host cell, a virus cannot do

anything at all

24. There is a remote village on Lake Maracaibo, in the country of Venezuela, where the villagers have a very high rate of developing the genetic disease Huntington's chorea. All the villages are descended from one Spanish sailor who settled there and married a local woman in the 1800s. This is an example of

the founder effect

25. The frequencies of alleles in a population will change from generation to generation if:

natural selection is going on

26. If the allele frequencies don't change, the population is said to be in

Hardy-Weinberg equilibrium

27. The main difference between a fish embryo and a mammal embryo is that the mammal embryo always has what the fish embryo never has:

amniotic membranes

28. A mammal embryo uses some of the structures mentioned in question 30 to form another structure that fish don't have:

a placenta

29. Which of the following was NOT discovered by Gregor Mendel in his experiments with pea plants?

Genes are sections of DNA molecules.

30. In the process of translation, which of these steps happens first?

A length of messenger RNA attaches to a ribosome.

31. The second step in translation involves a number of ____ that are attached to specific amino acids.

transfer RNAs

32. Once this second step is done, what happens next?

The ribosome moves three bases down the mRNA.

33. Translation continues until

the ribosome reaches a stop codon.

34. The protein alcohol dehydrogenase, which is found in your liver and breaks down alcohol, can be described as a string of the following amino acids: valine-isoleucine-lysine-cysteine-lysine-alanine-alanine-valine-leucine-tryptophan. . . This describes its

primary structure

35. Heat is able to change the shape of alcohol dehydrogenase so that it no longer works. This is called ______ it.

denaturing

36. In a bacterium called Rickettsia, 32% of the DNA is guanine + cytosine. How much cytosine is present?

16%

37. In the same bacterium, Rickettsia, what percentage of the DNA is adenine?

34%
Since 100% of the DNA is A + T + G + C, then the percentage of A+T is 100% - 32%, or 68%. The percentage of adenine must be one-half of that, or 34%.

38. Suppose one of the computers in the library had a video game on it that you thought was cool. What would be the equivalent of transcription?

Copying the game to a floppy disk.

39. The gene for the disorder Duchenne muscular dystrophy (MD) is carried on the X chromosome. The result is that

MD is more common in males than in females.

40. A couple, neither of whom has MD, has a son afflicted with MD. If they have another son, what are the odds that he will have MD?

50%

41. If the couple has a daughter, what are the odds that she will have MD?

0%

42. What happens in prophase?

Chromosomes supercoil and become visible in a light microscope.

43. What's the difference betwee prophase in mitosis and prophase I in meiosis?

Chromosomes don't pair up in mitotic prophase.

44. The "Central Dogma of Molecular Biology" states that genetic information is always transmitted in the following order:

DNA - transcription - RNA - translation - protein

45. Which of these provides an exception to the "Central Dogma"?

retroviruses such as HIV

46. In what ways is RNA different from DNA?

A and C only [RNA is usually single-stranded, and RNA uses the base U (uracil) instead of the base T (thymine)]

47. If something went wrong with the process of gastrulation, an embryo would have a defect in its

digestive tract

48. Cytokinesis usually happens at about the same time as

telophase

49. Random, undirected change in the frequencies of alleles in a population is known as

genetic drift

50. UCA stands for:

University of Central Arkansas