DNA Replication, Transcription, and Translation Flashcards Preview

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Flashcards in DNA Replication, Transcription, and Translation Deck (179)
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1

What is the central dogma of molecular biology?

DNA makes RNA, RNA makes protein

2

What are the two kinds of nucleic acid?

DNA and RNA

3

How do DNA and RNA differ?

in chemical composition and structure
- RNA is single-stranded; DNA double
- RNA is made of ribose; DNA of deoxyribose (missing an OH group that RNA has)
- RNA contains uracil; DNA contains thymine

4

Who first suggested a double-helical model for the structure of DNA?

James Watson and Francis Crick

5

How did they figure out that DNA must have a double-helix structure?

best way molecule could fit together from the evidence they had (including x-ray crytallography)

6

What was the chemical evidence about the structure of DNA?

puring and pyrimiding nigrogenous bases; deoxyribose sugar, phosphate

7

What is the biological evidence about the structure of DNA?

ratios between bases (proportion of A = T; C = G)

8

What is the physical evidence about the structure of DNA?

x-ray crystallography; 2 nm diameter, double helical structure

9

What does the fact that nitrogenous bases are located on the inside of a DNA molecule indicate about their nature?

they're relatively hydrophobic

10

What deductions did evidence from Rosalind Frankland's work enable Watsom to make?

- DNA was helical
- width of the helix
- spacing of the nitrogenous bases
- nitrogenous bases on inside

11

What is Chargaff's rule?

the proportion of A = T; C = G

12

Does A + C have to equal G + C?

no

13

What are the two types of nitrogenous basees?

pyrimidines and purines

14

What is the difference between a pyrimidine and a puring?

purines are made of two carbon-nitrogen ring bases (4 N in total); pyrimidines are made of one nitrogen ring base (2 N in total)

15

What type of nitrogenous base is adenine?

purine

16

What type of nitrogenous base is thymine?

pyrimidine

17

What type of nitrogenous base is guanine?

purine

18

What type of nitrogenous base is cytosine?

pyrimidine

19

What two components of a DNA molecule interact to form the phosphate-sugar backbone of DNA?

the free 3'-OH group of deoxyribose in the 1st nucleotide and the 1st 5' phosphate in the 2nd nucleotide (5'P - 3'OH)

20

How many nucleotides may be present in a single DNA molecule?

many millions

21

How many strands is a DNA molecule made of?

2

22

How are the two strands of a DNA molecule oriented with respect to each other?

antiparallel (one strand goes from 3' to 5'; other from 5' to 3')

23

What are the base pairings in a DNA molecule?

A:T and C:G

24

How many hydrogen bonds are present between adenine and thymine?

2

25

How many hydrogen bonds are present between cytosine and guanine?

3

26

In what direction does a DNA molecule grow?

from 5' to 3' (must add 5'P to free 3' OH)

27

What do restriction enzymes do?

break DNA phosphodiester bond at a recognized "binding site"

28

How did evidence indicate that a purine and a pyrimidine had to pair (instead of purine-purine or pyrimiding-pyrimidine)?

process of elimination - knew that the pairing had to be 2 nm wide; only pair that fit that was purine-pyrimidine?

29

How did evidence indicate that A paired with T and C paired with G?

only pairings that allowed bases to hydrogen bind

30

What would the diameter of a DNA molecule be if a pyrimidine bonded to another pyrimidine, and how does that relate to the X-ray data?

less than 2.0 nm (too thin compared to X-ray data)