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Molecules 2 People > Central Dogma > Flashcards

Central Dogma Flashcards

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1
Q

Helicase

A

Unwinds DNA

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2
Q

Topoisomerase (Euk)

A

Cut and Paste

Relieves overwound supercoils, called DNA gyrase in Prok,

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3
Q

Single Strand DNA Binding Protein (SSPB)

A

Binds with single strand DNA to prevent annealing

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4
Q

DNA polymerase alpha (in complex w primase)

A

Synth of RNA-DNA primer

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5
Q

DNA polymerase delta and epsilon

A

Synth new DNA in 5’-3’ direction (DNA Pol III in Prok)

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6
Q

Flap Endonuclease 1 (FEN1)

A

Removes RNA primers (DNA Pol I in Prok)

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7
Q

DNA polymerase delta

A

Fills in gaps (DNA pol I in Prok)

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8
Q

DNA ligase

A

Seals nicks

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9
Q

Carcinogens such as benzopyrene forms

A

Bulky adducts with guanine residue

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10
Q

UV rays excite pyrimidine bases, forming

A

Covalent dimers such as Thymine Dimer

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11
Q

Doxorubicin inhibits which enzyme

A

Topoisomerase II

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12
Q

Cross -linking agents such as nitrogen mustard, cisplatin, mitomycin C, and carmustine are used for what?

A

Forming cross-links between Guanine and comp base strands or same strand, used for antitumor drug, by blocking DNA replication

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13
Q

Alkylating agents

A

Dimethyl sulfate (DMS) and methylmethanesulfonate (MMS) cause cytotoxic methylation.

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14
Q

Exceptions to the dogma:

A

RNA viruses w RNA as genetic material, single or dbl strand, HIV
Prion (Proteinaceous infection) Microscopic particle that multiply by mis-folding of normal protein to prion, causes Creutzafeldt-Jakob disease (CJD)

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15
Q

DNA coils around histones because

A

DNA is neg charge, histones are positive (H2A, H2B, H3, H4)

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16
Q

Each turn of the DNA helix has how many base pairs

A

10

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17
Q

A nucleosome consists of

A

DNA covered octamer of histone proteins (beads on string, 10nm fiber)

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18
Q

What ties one nucleosome to another?

A

H1 histone and linker DNA tie the nucleosomes, which are then further condensed to 30nm

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19
Q

DNA synth occurs by

A

replication, at replication fork

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20
Q

What unwinds the parental strands in Prokaryotes

A

Helicases and topoisomerases

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21
Q

Prok enzyme that copies parental template

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A

DNA polymerase

22
Q

Enzyme in prok that initate the synthesis in 5’ to 3’ direction

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A

RNA primer (primase)

23
Q

Okazaki fragments form on which strand, joined by what enzyme

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A

DNA ligase, on lagging strand

24
Q

Enzyme that synthesizes replication of ends of chromosomes

25
Which sequence of nucleotides are found in promoter and origins of replication?
AT-rich (such has TATA box region)
26
What is the structure of DNA polymerase similar to?
A hand, with fingers, thumb, and palm making up the 5'-3' polymerization domain, the wrist makes the 3'-5' exonuclease domain
27
Why is a primer required before DNA polymerase can start working?
DNA polymerase requires a free -OH group
28
Prok Enzyme that removes sections of RNA primer and replaces w DNA nucleotides at end of DNA synth
DNA polymerase I
29
Bacterial enzyme that repairs DNA
Polymerase II
30
Bacterial Enzyme that does replication and synth of DNA
Polymerase III
31
What are the three stages of DNA strand separation in eukaryotes?
1. Helicase 2. Topoisomerase 3.SSBPs
32
3 stages of Eukaryotic DNA synth/Chain elongation
1. DNA poly alpha and primase 2. DNA poly delta and epsilon 3. DNA poly delta and DNA ligases
33
In contrast to bacterial chromosomes, eukaryotic chromosomes have what?
Multiple origins at which replication begins, so "bubbles "appear at these points
34
Which amino acids gives histones a positive charge?
Lysine and arginine
35
What gives DNA a negative charge?
phosphate groups
36
What are the stages of mitosis?
G0-stimulus G1-growth and metabolism S-DNA replication (DNA and histone synth)
37
What enzyme does Ciproflaxin and Doxorubicin inhibit?
Topoisomerase II (DNA gyrase in prok)
38
What does PCNA stand for and what does it do?
Proliferating cell nuclear antigen | Enhances processivity of DNA polymerases,; binds to many proteins at rep fork
39
Eukaryotic chromosomes are _____ and the ends are called _____
Linear | Telomeres
40
Parts of euk chromosome that consist of possibly thousands of repeating bases: TTAGGG in humans
Telomeres
41
Enzyme that maintains length of telomere by replacing them in parent strand
telomerase
42
How does DNA repair mechanisms, in general, work in Euk and Prok?
Euk- recognized distortion, endo- and exonucleases remove portion, gap filled by DNA poly in 5'-3', ligase seals nick Prok- remove thymine dimers via photoactivated enzymes that cleave bonds between bases w light energy (no nucleotides are released)
43
Cyclobutane pyrimidine dimers generated by ____ can be repaired with ____
``` UV light DNA photolyase (absorbs at 370nm, activated to catalyze breakage of bonds in photo-reactivation) ```
44
MGMT (methyl guanine methyl transferase) does what
Manages to transfer methyl group from a guanine to cysteina, reversing mutagenic action by O6-methylguanine (binds to T not C)
45
What are the Steps of Base Excision Repair (BER) in toxic/spontaneous deamination of E. Coli? (Happens throughout cell cycle)
Mismatch recognized by DNA glycosylase which removes the base, making an AP site (apyrimidinic/apurinic) AP endonuclease cuts at AP site, then filled by DNA poly I and ligase.
46
Humans with problems in Nucleotide-Excision Repair (NER) during G1 phase develop what?
Xeroderma Pigmentosum, leading to skin cancers after UV exposure.
47
Bulky adducts such as Oxidized Benzo[a]pyrene or mismatched bases are repaired via what process in Eukaryotes?
Nucleotide-Excision Repair (NER)
48
Lynch Sydrome (Hereditary nonpolyposis colorectal cancer (HNPCC)) is caused by
Defective Mismatch excision repair (MER) mechanism, which replaces a wrong nucleotide inserted in a newly synth'd daughter strand The MERman had a daughter w colorectal cancer
49
What types of damage are respectively repaired in Direct Repair (enzymatic repair), BER, NER, and MER?
Pyrimidine dimers+ O6 methylguanine (ER) Single-Base mismatches, non-distorting alterations (BER) Bear doesn't distort Chemical Adducts that distort DNA (NER) Mismatched base in daughter strand (MER)
50
BER Pneumonic
GEL PLease - Glycosylase - ap Endonuclease (cleaves 5' end) - Lyase (cleaves 3' end) - Polymerase (replaces) - Ligase (seals)

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