paper 1: Nucleic Acids and DNA Replication Flashcards

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1
Q

what does DNA stand for

A

deoxyribonucleic acid

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2
Q

what does RNA stand for

A

ribonucleic acid

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3
Q

what does DNA do in the body

A

holds genetic information which codes for proteins

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4
Q

what does RNA do in the body

A

transfers genetic information from DNA to ribosomes

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5
Q

draw the structure of a DNA/ RNA nucleotide

A
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6
Q

what is the difference between the structure of DNA and the structure of RNA

A
  • the pentose sugar for DNA is deoxyribose, for RNA it’s ribose
  • the bases for DNA can be A, C, G, T but for RNA its A, C, G, U.
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7
Q

what are the names of the organic bases in DNA

A

adenine, thymine, cytosine, guanine

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8
Q

what are the names of the organic bases in RNA

A

adenine, uracil, cytosine, guanine

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9
Q

describe the formation of polynucleotides

A
  • nucleotides join together by condensation reactions
  • to form a phosphodiester bond between the phosphate group of one nucleotide and the pentose sugar of another
  • to make the sugar-phosphate backbone
  • which is strong and stable
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10
Q

what is the word used to describe the phosphate backbones running in opposite directions

A

anti-parallel

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11
Q

what does the 3’ and the 5’ relate to

A

the carbon number of the deoxyribose

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12
Q

describe an RNA strand

A

relatively short, single stranded polynucleotide strand

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13
Q

why must DNA be replicated accurately

A

so each daughter cell recieves an exact copy of DNA

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14
Q

when does DNA replication take place

A
  • during cell division
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15
Q

describe the 3 stages of DNA replication

A

stage 1: DNA helicase breaks hydrogen bonds between complimentary bases in the polynucleotide strand. this causes the DNA helix to unwind and separate

stage 2: new DNA nucleotides are attracted to exposed bases on the template strands and hydrogen bonds form between complimentary bases.

stage 3: DNA polymerase joins the adjacent nucleotides together via a condensation reaction to form phosphodiester bonds.

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16
Q

why is DNA replication described as semi-conservative

A

a strand from the original DNA molecule acts as a template which joins a new strand

17
Q

why does DNA polymerase run in opposite directions

A
  • the active site of DNA polymerase is only complimentary to the 3’ end of nucleotides so runs in opposite directions along the 2 template strands
18
Q

how does the structure of DNA allow it to carry out its function

A
  • sugar-phosphate backbone and double helix structure: provides strength and stability, protects bases and hydrogen bonding between bases
  • long molecule: can store lots of information
  • helix structure: compact
  • base sequence: codes for amino acids and therefore proteins
  • double stranded: allows for semi conservative replication
  • complimentary base pairing: allows accurate replication
  • weak hydrogen bonds between bases: allows unwinding of strands for replication
  • many hydrogen bonds in the whole molecule: strong and stable molecule
19
Q

describe the function of DNA helicase

A

breaks hydrogen bonds between complementary bases which causes the double helix to unwind

20
Q

describe the function of DNA polymerase

A

joins adjacent nucleotides via a condensation reaction to form phosphodiester bonds