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AS-Biology(*) > Nucleic acids > Flashcards

Nucleic acids Flashcards

1
Q

DNA and RNA are both polymers of _________

A

nucleotides

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2
Q

what are the 3 components in a nucleotide

A
  • phosphate group
  • pentose
  • nitrogen containing base
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3
Q

describe the structure of a DNA nucleotide

A
  • phosphate group
  • 5 carbon pentose sugar called deoxyribose
  • one of 4 nitrogen bases
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4
Q

what are the 4 bases in a DNA nucleotide

A
  • adenine
  • cytosine
  • guanine
  • thymine
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5
Q

describe the structure of an RNA nucleotide

A
  • phosphate group
  • 5 carbon pentose sugar called ribose
  • one of 4 nitrogen bases
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6
Q

what are the 4 bases in an RNA nucleotide

A
  • adenine
  • cytosine
  • guanine
  • uracil
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7
Q

what is the diffeence between bases in DNA and RNA

A

in RNA uracil replaces thymine

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8
Q

how are dinucleotides formed

A
  • condensation reaction
  • between the phosphate group (5’ end) of one nucleotide and the ribose (RNA) or the deoxyribose (DNA) (3’ end) of another
  • the bond formed is called a phosphodiester
  • one molecule of water is produced
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9
Q

how are polynucleotides formed

A
  • more nucleotides are added by condensation reactions
  • many phosphodiester bonds form and these bonds form the sugar-phosphate “backbone” which is stable and strong
  • nucleotides can only be added in a 5’ - 3’ direction
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10
Q

name the molcule that catalyses the joining of nucleotides in the following:
1. DNA
2. RNA

A
  1. DNA polymerase
  2. RNA polymerase
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11
Q

describe the structure of a DNA molecule

A
  • double helix with two polynucleotide chains held together by hydrogen bonds between specific complementary base pairs
  • both polynucelotide strands run in opposite directions, this means they are antiparralel
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12
Q

structure of the DNA double helix:

A

DNA

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13
Q

what bonds and how many are formed between these base pairs:
1. adenine and thymine
2. cytosine and guanine

A
  1. 2 hydrogen bonds
  2. 3 hydrogen bonds
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14
Q

what is the function of DNA

A

hold genetic information

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15
Q

explain how this structure feature helps the function of DNA:

  • sugar phosphate backbone and double helix structure
A
  • provides strength and stability
  • protects information coded in the bases
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16
Q

explain how this structure feature helps the function of DNA:

  • long molecule
A

can store alot of information

17
Q

explain how this structure feature helps the function of DNA:

  • helix structure
18
Q

explain how this structure feature helps the function of DNA:

  • base sequence
A

codes for amino acids

19
Q

explain how this structure feature helps the function of DNA:

  • double stranded
A

allows semi-conservative replication beacause each strand can act as a template

20
Q

explain how this structure feature helps the function of DNA:

  • complemantary base pairing
A

allows accurate replication

21
Q

explain how this structure feature helps the function of DNA:

  • weak hydrogen bonds between bases
A

easily broken and seperation of strands for semi-conservative replication

22
Q

explain how this structure feature helps the function of DNA:

  • many hydrogen bonds in the whole molceule
A

strong and stable molecule

23
Q

what is chargaffs base pairing rule

A
  • adenine bonds with thymine and makes 2 H bonds
  • cytosine bonds with guanine and makes 3 H bonds
24
Q

what is mRNA

A
  • messenger RNA
  • single stranded, linear polynucleotide
  • single stranded copy of a gene and takes this information to the ribosome to make proteins
25
Q

what is tRNA

A
  • transfer RNA
  • single stranded polynucleotide folded into a cloverleaf shape
  • it brings amino acids to the ribosome during protein synthesis
26
Q

what is rRNA

A
  • ribosomal RNA
  • found in ribosomes along with protein
27
Q

explain the steps of the process of semi conservative replication

A
  1. The two strands of DNA seperate by breaking the hydrogen bonds between complementary base pairs. This is catalysed by DNA helicase
  2. Each strand acts as a template and free DNA nucleotides are attracted to exposed complementary bases on the template strands
  3. DNA polymerase joins together the nucleotides through condensation reactions that form phosphodiester bonds
  4. Two DNA molecules are formed that each contain an original strand and a new strand
28
Q

explain why polynucleotides are formed only in a 5’ to 3’ direction

A
  • DNA polyermase has a specific active site that is complementary to the 5’ end of the incoming free DNA nucleotide and the 3’ end of the new strand

AS-Biology(*) (22 decks)

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