A1.2 Nucleic Acids Flashcards

structure, RNA vs DNA, base pairs, anti-parallelism, hershey-chase, chargaff

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1
Q

what is a chromosome and how many are in most human cells?

A

polymer of nucleosomes; 46

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2
Q

what do DNA and RNA stand for?

A

deoxyribonucleic acid and ribonucleic acid

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3
Q

how is DNA evidence of common ancestry?

A

universal genetic material, with mutations influencing evolution

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4
Q

define gene

A

a sequence of nucleotides

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5
Q

what defines cell identity and function?

A

the proteins it can synthesize

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6
Q

describe the structure of a nucleotide

A

1 phosphate group, 1 pentose sugar, and 1 nitrogenous base connected by covalent bonds

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7
Q

what nitrogenous bases are in DNA and RNA?

A

adenine, thymine (uracil in RNA), cytosine, guanine

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8
Q

how many different nucleotides are in DNA and RNA?

A

8; 4 in DNA have deoxyribose sugar, 4 in RNA have ribose and uracil instead of thymine

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9
Q

draw a section of DNA with the four different nucleotides

A

pentagonal sugar, circle phosphate connected to 5’ carbon, rectangular base connected to 1’, 3’ connected to phosphate of next nucleotide, strands antiparallel, left side 5’-3’, right 3’-5’, carbons labelled, thymine bonded to adenine with 2 hydrogen bonds, cytosine to guanine with 3, solid lines for covalent bonds, dotted for hydrogen bonds

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10
Q

what are the differences between DNA and RNA?

A

DNA:
* deoxyribose
* double helix shape
* two chains
* thymine
* permanent genetic code

RNA:
* ribose
* various shapes
* one chain
* uracil
* no permanent genetic code

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11
Q

draw deoxyribose

A

2 C’s bonded to OH and H, 2’ C bonded to 2 H’s, top O, 4’ C bonded to HOC5’H2

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12
Q

draw ribose

A

3 C’s bonded to OH and H, top O, pentagon, 4’ C bonded to HOC5’H2

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13
Q

what is mRNA?

A

messenger RNA; RNA copy of DNA sequence, relays genetic information

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14
Q

what is tRNA?

A

transfer RNA; ensures correct order of amino acids

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15
Q

what is rRNA?

A

ribosomal RNA; synthesizes ribosomes

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16
Q

what is ATP?

A

adenosine triphosphate; single nucleotide with 3 phosphate groups, energy source

17
Q

how many bases are in the shortest DNA molecule?

A

50 million

18
Q

define triplet codon

A

set of 3 nitrogenous bases that code for 1 amino acid

19
Q

how many bases are in the longest DNA molecule?

A

260 million

20
Q

define replication

A

the process in which DNA polymerase and other enzymes “unzip” DNA molecule and “zip” back up with new strand

21
Q

define transcription

A

the process in which RNA polymerase generates RNA copy of DNA sequence (mRNA)

22
Q

define translation

A

the process in which a ribosome attaches to mRNA, which relays genetic code, and tRNA, which determines correct order of amino acids, and synthesizes a protein

23
Q

in replication and transcription, what end of the DNA/RNA strand are nucleotides always added to?

A

3’ end

24
Q

in translation, what end of the RNA strand do ribosomes travel towards?

A

3’ end

25
Q

define purine

A

nitrogenous base with 2 rings of atoms (adenine and guanine)

26
Q

define pyrimidine

A

nitrogenous base with 1 ring of atoms (thymine and cytosine)

27
Q

what is the importance of purine-pyrimidine bonding?

A

always 2 rings + 1 ring, maintains same structure all along helix, adds stability

28
Q

how long can a DNA molecule be?

A

2 m

29
Q

define nucleosome

A

package of 8 histone proteins wrapped in DNA, with 1 histone holding it together and linker DNA extending out the sides

30
Q

when, where, and by who was the hershey-chase experiment performed?

A

alfred hershey and martha chase from 1951-52 in new york

31
Q

what was the purpose of the hershey-chase experiment?

A

to prove whether DNA or proteins were the genetic material

32
Q

describe the process of the hershey-chase experiment

A
  1. bacteriophage was grown in 2 types of cultures: 1 with radioisotope P-32 and 1 with S-35
  2. because DNA has phosphorous and protein has sulphur, bacteriophage in P-32 culture had inner DNA cores labelled and those in S-35 culture had outer protein coats labelled
  3. bacteriophage were allowed to infect E. coli
  4. infected E. coli was blended, separating bacteriophage nad bacteria into supernatant and pellet
  5. mixture with P-32 had radioactivity in pellet, while mixture with S-35 had radioactivity in supernatant, meaning that DNA was the genetic material, not protein
33
Q

who was erwin chargaff?

A

disproved tetranucleotide theory, proved that adenine bonded to thymine and cytosine bonded to guanine in late 1940s

34
Q

what is chargaff’s rule?

A

in any given DNA sequence, the number of adenine and thymine bases will be the same and the number of cytosine and guanine bases will be the same

35
Q

what is the tetranucleotide theory?

A

DNA is composed of repeating set units of 4 nucleotides, so there would be same amount of all 4 in any given DNA sequence

36
Q

describe the process used by chargaff to develop his rule

A
  1. lined up various DNA sources on chromatography paper and dipped bottom of paper in water
  2. water was soaked up, forcing substances up
  3. molecules moved different distances based on molecular size and charge