Molecular biochem

Question 1

AA necessary for purine synthesis

Answer 1

glycine
aspartate
glutamine

Question 2

term: most AA are coded by multiple codons

Answer 2

Degenerate/redundant

Question 3

what AA are only coded by one codon

Answer 3

methionine (AUG)

tryptophan (UGG)

Question 4

term: each condone specifies only 1 AA

Answer 4

unambiguous

Question 5

term: read from a fixed starting point as a continuous sequence of bases

Answer 5

comma less
nonoverlapping
exceptions: some viruses

Question 6

In both prokaryotes and eukaryotes, DNA replication is

Answer 6

semiconservative
both continuous and discontinuous (Okazaki fragments)
5’ to 3’ direction

Question 7

Bloom syndrome (BLM gene mutation)

Answer 7

helicase deficiency

cannot unwind DNA template at replication fork

Question 8

Makes RNA primer so DNA polymerase III can initiate replication

Answer 8

Primase

Question 9

Prevents strands from reannealing

Answer 9

single-stranded binding proteins

Question 10

DNA polymerases that prokaryotes only have

Answer 10

Polymerase I and III

Question 11

Create single or double stranded break in helix to add or remove supercoils

Answer 11

DNA topoisomerase

Question 12

Irinotecan/topotecan MOA

Answer 12

(eukaryote) inhibit topoisomerase I

Question 13

etoposide/teniposide MOA

Answer 13

(eukaryote) inhibit topoisomerase II

Question 14

fluoroquinolone MOA

Answer 14

(prokaryotes) inhibit TOP II (DNA gyrase) and TOP IV

Question 15

• Elongates leading strand by adding deoxynucleotides to 3’ end
• Elongates lagging strand until reaches primer of preceding fragment

Answer 15

DNA polymerase III

prokaryotes only

Question 16

DNA polymerase III synthesizes in what direction

Answer 16

5’ to 3’

Question 17

DNA polymerase III proofreads in what direction

Answer 17

3’ to 5’ exonuclease

Question 18

Drugs blocking DNA replication often have

Answer 18

modified 3’ OH that prevents addition of next nucleotide = chain termination

affects DNA polymerase III

Question 19

Degrades RNA primer and replaces w/DNA

Answer 19

DNA polymerase I
prokaryotes only
same functions as DNA polymerase III
excises RNA primer w/ 5’ to 3’ exonuclease

Question 20

T or F: All prokaryotic DNA polymerases can proofread using 3’ to 5’ exonuclease activity

Answer 20

True

Question 21

Reverse transcriptase (RNA dependent DNA polymerase) that adds DNA (TTAGGG) to 3’ end of chromosomes to avoid loss of genetic material w/every duplication

Answer 21

telomerase

eukaryotes only

Question 22

what is often dysregulated in cancer cells, allowing unlimited replication

Answer 22

telomerase

Question 23

RNA processing that happens in the nucleus

Answer 23

capping of 5’ end w/7-methylguanosine cap
polyadenylation of 3’ end
splicing out introns

Question 24

mRNA quality control occurs at

Answer 24

cytoplasmic processing bodies (P-bodies)

Question 25

P-bodies contain

Answer 25

exonucleases decapping enzymes microRNAs mRNA may be degraded or stored in P-bodies for future translation

Question 26

fMet in prokaryotes stimulates

Answer 26

neutrophils chemotaxis

Question 27

transcription and translation occurs in (gene expression)

Answer 27

G1, S, G2 | never in M

Question 28

Chemodrugs that affect S phase

Answer 28

5-FU (inhibits thymidylate synthase) | MTX (inhibits DHF reductase)

Question 29

Chemodrugs that affect G2 phase

Answer 29

Bleomycin Hodgkin lymphoma causes pulmonary fibrosis

Question 30

Chemodrugs that affect S phase

Answer 30

Paclitaxel Vincristine Vinblastine

Question 31

Chemodrugs that are non-cell cycle dependent

Answer 31

cyclophosphamide cisplatin (blocks cycle nonspecifically)

Question 32

DNA replication occurs during

Answer 32

S phase

Question 33

Lynch syndrome (hereditary nonpolyposis colorectal cancer) has defect in what kind of DNA repair

Answer 33

``` Mismatch repair (single strand) S phase ```

Question 34

Dry skin, extreme light sensitivity, skin cancer has defect in what kind of DNA repair

Answer 34

nucleotide excision repair (single strand) | G1 phase

Question 35

DNA repair important for spontaneous/toxic deamination

Answer 35

Base excision repair (single strand) | throughout cell cycle

Question 36

Ataxia-telangiectasia has defect in what kind of DNA repair

Answer 36

Nonhomolgous end joining (double strand)

Question 37

Brings 2 ends of DNA fragments to repair double strand breaks - no homology requirement - some DNA may be lost

Answer 37

Nonhomologous end joining (double strand)

Question 38

Requires two homologous DNA duplexes - strand from damaged dsDNA repaired using complementary strand from intact homologous dsDNA as template - restores duplexes accurately without loss of nucleotides

Answer 38

Homologous recombination (double strand)

Question 39

Breast/ovarian cancer w/BRCA1 mutation and Fanconi anemia have defect in what kind of DNA repair

Answer 39

Homologous recombination (double strand)

Question 40

alpha-amanitin found in Amanita phalloides death cap mushrooms inhibits

Answer 40

RNA polymerase II = no mRNA | severe hepatotoxicity

Question 41

Actinomycin D or dactinomycin inhibits

Answer 41

RNA polymerase in both prokaryotes and eukaryotes

Question 42

variants in splicing occurs in oncogenesis and many genetic disorders

Answer 42

beta thalessemia Gaucher disease Tay-sachs disease Marfan syndrome

Question 43

microRNAs are

Answer 43

- small non-coding RNA - post transcriptionally regulate gene expression - targets 3' untranslated region of specific mRNA for degradation or translational repression

Question 44

Part of tRNA necessary for tRNA ribosome binding

Answer 44

T-arm

Question 45

Part of tRNA that has dihydrouridine residues necessary for tRNA recognition by correct aminoacyl tRNA synthetase

Answer 45

D-arm