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aqa a level biology > 2.1 — nucleic acids: DNA and RNA > Flashcards

2.1 — nucleic acids: DNA and RNA Flashcards

covers: the structure of nucleotides; the reactions that synthesise and breakdown nucleic acids; the role and structures of DNA and RNA; the similarities and differences between DNA and RNA

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1
Q

what are nucleotides?

A

the building blocks of nucleic acids such as DNA and RNA

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2
Q

what dimers and polymers do nucleotides form?

A

dinucleotides and polynucleotides

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3
Q

what is a nucleic acid the functional molecule made up of?

A

one or more polynucleotide chains

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4
Q

what components make up a nucleotide?

A
  1. a pentose sugar — contains 5 carbon atoms
  2. a nitrogenous base — contains carbon and nitrogen
  3. a phosphate group — contains a phosphate group
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5
Q

how are polynucleotides made?

A

nucleotides are joined together via condensation reactions.

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6
Q

what type of bonds join the nucleotides in polynucleotides?

A

(covalent) phosphodiester bonds

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7
Q

how is a phosphodiester bonds formed?

A

when the phosphate group of one nucleotide forms a covalent bond with the sugar of another

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8
Q

what is a sugar phosphate backbone?

A

a chain of phosphates and sugars (joined by phosphodiester bonds)

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9
Q

how can a phosphodiester bond be broken?

A

hydrolysis reactions

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10
Q

what is released when phosphodiester bonds undergo hydrolysis reactions?

A

the nucleotide and monomers

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11
Q

what does DNA stand for?

A

deoxyribonucleic acids

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12
Q

what does DNA contain the information for?

A

the instructions needed to make proteins

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13
Q

what components make up a DNA nucleotide?

A
  1. deoxyribose sugar — a pentose/ 5 carbon sugar
  2. A, T, G, or C —nitrogen containing organic base
  3. a phosphate group
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14
Q

who was credited in working the structure of DNA?

A

James Watson and Francis Crick

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15
Q

what is the structure of DNA made up of?

A

two polynucleotide strands wound around each other to form a double helix

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16
Q

what are the features that allow DNA to pass genetic information from one generation to another?

A
  1. sugar phosphate backbone — protects coding bases on the inside of the helix
  2. double stranded — allows strands to act as templates in DNA replication
  3. large molecule — stores lots of information
  4. double helix — makes it compact
  5. complimentary base pairing — allows accurate DNA replication
  6. weak hydrogen bonds — allows strands to serve rate in DNA replication
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17
Q

how does having a sugar phosphate backbone allow DNA to pass genetic information?

A

protects coding bases on the inside of the helix

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18
Q

how does being double stranded allow DNA to pass genetic information?

A

this allows strands to act as templates in DNA replication

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19
Q

how does being a large molecule allow DNA to pass genetic information?

A

it stores a lot of information

20
Q

how does being a double helix allow DNA to pass genetic information?

A

makes the molecule compact

21
Q

how does having complimentary base pairing allow DNA to pass genetic information?

A

allows accurate DNA replication

22
Q

how does having a weak hydrogen bonds allow DNA to pass genetic information?

A

they allow strands to separate in DNA replication

23
Q

what are the four nitrogenous bases found in DNA?

A

adenine (A), guanine (G), thymine (T) and cytosine (C)

24
Q

what groups can the nitrogenous bases in DNA be grouped into?

A

purines and pyrimidines

25
Q

what nitrogenous bases in DNA are purines?

A

adenine and guanine

26
Q

what nitrogenous bases in DNA are pyrimidines?

A

thymine and cytosine

27
Q

what is a purine?

A

larger nitrogenous bases that contain two carbon ring structures (A and G)

28
Q

what is a pyrimidine?

A

smaller nitrogenous bases that contain one carbon ring structures (T and C)

29
Q

how are the complimentary base pairings in DNA held together?

A

by hydrogen bonds (between A+T and C+G)

30
Q

what type and how many bonds form between adenine and its complimentary base?

A

two hydrogen bonds between adenine and thymine

31
Q

what type and how many bonds form between cytosine and its complimentary base?

A

three hydrogen bonds between cytosine and guanine

32
Q

what allows a constant distance between the two sugar phosphate backbones of the DNA double helix?

A

the (smaller) pyrimidine bases always bond to the (larger) purine bases.

33
Q

what does RNA stand for

A

ribonucleic acid

34
Q

what is RNA?

A

a nucleic acid that uses information from DNA to synthesise proteins

35
Q

what is RNA made from?

A
  1. ribose — a pentose sugar
  2. A, U, G, or C — nitrogen containing organic base
  3. a phosphate group
36
Q

unlike DNA, RNA nucleotides contain the sugar ______ rather than __________. they also contain the base ______ in place of _______.

fill in the missing terms:

A
  1. ribose
  2. deoxyribose
  3. uracil
  4. thymine
37
Q

what is RNA?

A

RNA is a single stranded molecule made up of just one polynucleotide strand, which are much shorter than DNA strands.

38
Q

what pentose sugar does DNA contain?

A

deoxyribose

39
Q

what pentose sugar does RNA contain?

A

ribose

40
Q

what bases does DNA contain?

A

A, T, G, C

41
Q

what bases does RNA contain?

A

A, U, G, C

42
Q

what is the relative size of DNA?

A

long

43
Q

what is the relative size of RNA?

A

relatively short

44
Q

what is the number of strands in DNA?

A

2

45
Q

what is the number of strands in RNA?

A

1

aqa a level biology (29 decks)

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