Bio 304 Genetics Exam (Page 2 of 4) in pdf

11.

_topoisomerase

is a protein found ahead of the DNA replication fork that relaxes supercoiling

which develops ahead of the advancing DNA polymerase.

12. The Meselson & Stahl experiments with E. coli showed that DNA is synthesized by a

_semi-

conservative

process.

13. Processing of pre-mRNA in eukaryotes includes polyadenylation (polyA addition) at the

______3’______________

end of the molecule.

14. Chiasmata are visible during the

__prophase I / metaphase I

stage of meiosis.

15.

_nucleosome

are a basic organizational structure of eukaryotic chromosomes, consisting of

DNA wrapped around a histone protein core.

Fill-in the blanks of questions #16-21 with the best term or number (2 pts. for each blank):

16. The diploid chromosome number in voles is 2n=14. In the space provided, give the

number of indicated structures that should be present in a single cell at the indicated time

during oogenesis:

a. chromosomes in a Metaphase I cell ___________14_______________

b. centromeres in a Prophase II cell

___________7________________

c. chromatids in a Prophase II cell

___________14_______________

d. chromosomes in a Metaphase II cell ___________7________________

17. By freely substituting bases within a nine-nucleotide segment of RNA (three codons), how

many different peptide sequences could be

encoded?__20

= 8000 (or

nonsense→fewer)_

18. In mRNA, UUA codes for leucine. What anticodon sequence must occur in leucyl-tRNA to

recognize this codon? ____UAA________

19. How many centromeres are there in a human lymphocyte in metaphase of mitosis? __46____

20. Name three types of noncovalent chemical interactions that contribute to the stability of the

double-stranded helix formed by DNA.

____hydrogen bonds between bases

______

____hydrophobic interactions between bases

___

hydrophilic interactions of PO

and water

Bio 304 Genetics Exam Page 2