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Biochem exam 3 > DNA, RNA, and DNA replication > Flashcards

DNA, RNA, and DNA replication Flashcards

1
Q

James Watson is…

A

a sexist asshole that stole info from people

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2
Q

What did Rosalind Franklin do?

A

used X-ray diffraction data

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3
Q

what are the purines?

A

adenine and guanine

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4
Q

what are the pyrimidines?

A

cytosine, uracil, and thymine

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5
Q

What are the complementary base pairs in DNA?

A

adenine-thymine (2 hydrogen bonds)
guanine-cytosine (3 hydrogen bonds)

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6
Q

what is Chargaff’s rule?

A

A pairs to T and G pairs to C

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7
Q

What is the basic chemical composition of DNA?

A

sugar phosphate backbone and a base combine to form a nucleotide
-nucleotides form to make a DNA strand
-make a double stranded DNA
-form a double helix

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8
Q

What is a gene?

A

a unit of heratity

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9
Q

How is DNA organized in prokaryotes?

A

linear or contiguous fashion

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10
Q

Can transcription and translation occur on the same strand at the same time in prokaryotic organisms?

A

yes, because there is no nucleus , there is no separation between transcription and translation

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11
Q

What are exons?

A

regions of DNA that will give rise to the protein sequence

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12
Q

What are introns?

A

regions of DNA that do not code for protein

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13
Q

What are UTR?

A

untranslated regions that are on the 5’ and 3’ ends of the DNA

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14
Q

What is the process of removing introns from a transcript?

A

splicing

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15
Q

Is there only one way to splice a transcript?

A

no, there are other regulatory elements that can alter the splicing (alternative splicing)
-this can create multiple proteins that can be made from one transcript

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16
Q

How is DNA condensed in prokaryotes?

A

by a set of polyamines and proteins in back and forth loops
(look like a bobby pin)

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17
Q

How is DNA condensed in eukaryotes?

A

first condensed with nucleosomes (involve about 200 bp each) and a set of core proteins
-nucleosomes looks like beads on a string and are packages together to give chromatin fiber structure

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18
Q

What is euchromatin?

A

more relaxed structure and transcriptionally active

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19
Q

What is heterochromatin?

A

more highly condensed and generally not transcriptionally active

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20
Q

What are the even more condensed that heterochromatin form of DNA?

A

solenoids and then supersolenoids and then into chromosomes

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21
Q

How were chromosomes arranged and numbered?

A

by size
-biggest is chromosome 1
-smallest chromosome 22 (or the Y chromosome)

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22
Q

What is the DNA entity in bacteria called?

A

plasmids

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23
Q

How many protein coding genes are in the human genome?

A

around 20,000-25,000

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24
Q

How much of the DNA is made up of coding genes?

A

1%

25
Q

how many isoforms does the average gene give?

A

8

26
Q

How long is the average gene?

A

27,000 bp

27
Q

What is the proteome?

A

the complete set of proteins in an organism
(more complex than the average estimate)

28
Q

How many bp is the human genome?

A

around 3.2 billion

29
Q

What is the smallest mutation that can cause disease?

A

1 bp

30
Q

What is the difference between siblings?

A

around 1-2 million bp

31
Q

What is the difference between unrelated humans?

A

around 6 million bp

32
Q

Base pair difference between humans and chimps?

A

around 50 million bp

33
Q

Base pair difference between humans and mice?

A

around 100 million bp

34
Q

Is only one strand of DNA able to be used for replication?

A

no, both strands are able to be used for replication

35
Q

What is the central dogma of genetic information flow?

A

DNA -> RNA -> protein

36
Q

What does DNA polymerase do?

A

makes new strand of DNA in the 5’ - 3’ direction
-requires a template strand and a strand to build off of with a free 3’ OH group
-has 5’-3’ polymerase activity and 3’-5’ exonuclease activity

37
Q

Which direction is DNA made?

A

5’-3’

38
Q

What are the origins of replication rich in?

A

AT regions

39
Q

What is the active region of replication?

A

replication fork

40
Q

How many replication forks on a circular chromosome?

A

two replication forks moving in opposite directions

41
Q

What is the leading strand of DNA?

A

daughter strand that is synthesized continously

42
Q

What is the lagging strand of DNA?

A

daughter strand that is synthesized discontinously

43
Q

What are the fragments created on the lagging strand of DNA replication?

A

Okazaki fragments

44
Q

Why are Okazaki fragments created?

A

since DNA replication happens 5’-3’, there are small fragments made that are then ligated together

45
Q

what attaches Okazaki fragments?

A

DNA ligase
*requires ATP

46
Q

What are the general steps of DNA replication?

A

-DNA rich in A-T pairs (replication origin)
-local opening of DNA helix
-RNA primer synthesis
-leading strand DNA synthesis begins
-RNA primers start lagging strand synthesis

47
Q

How fast is DNA polymerase in bacteria?

A

500 nt/sec

48
Q

How fast is DNA polymerase in eukaryotes?

A

50 nt/sec

49
Q

What enzyme makes the RNA primers for DNA replication?

A

DNA primase
-creates a new polynucleotide chain

50
Q

How long is the RNA primer?

A

10 nt

51
Q

Why is the RNA primer needed for DNA synthesis?

A

DNA polymerase is not able to start their own nucleotide chains

52
Q

Steps of lagging strand synthesis:

A

-RNA primer made by DNA primase
-DNA polymerase adds to new RNA primer to start new Okazaki fragment
-DNA polymerase finished DNA fragment
-old RNA primer erased and replaced by DNA
-nick sealing by DNA ligase joins new Okazaki fragment to the growing chain

53
Q

What enzyme seals that broken phosphodiester bond?

A

DNA ligase

54
Q

Is DNA replication accurate?

A

yes, there are a lot of mechanisms in place that remove the chance for a lot of mutations to cause huge harm
-only 3 nucleotide changes at each time of cell division

55
Q

What is DNA helicase?

A

enzyme that moves along DNA strand and break any portions that are double stranded

56
Q

What do single strand DNA binding proteins do?

A

bind to exposed DNA strands
-unable to open DNA strands themselves, but aid helicases by stabilizing unwound helix
-binding coats and straightens out regions of single-stranded DNA on the lagging strand template
-prevent formation of short hairpin helix

57
Q

What does the sliding clamp do for DNA replication?

A

holds DNA polymerase on the DNA

58
Q

What is Werner syndrome?

A

premature aging disease
-cells divide more slowly
-allow DNA damage to accumulate
-impair normal cell activities and cause health problems

59
Q

How do retroviruses replicate?

A

use reverse transcriptase to turn their RNA into DNA that can be inserted into the human genome

Biochem exam 3 (10 decks)

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