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AS Biology > Nucleotides and nucleic acids > Flashcards

Nucleotides and nucleic acids Flashcards

1
Q

2.1.3 a)

What is a monomer?

A
  • Molecule that when repeated makes up a polymer
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2
Q

2.1.3 a)

What is a nucleotide?

A
  • Biological molecule (contain elements H, C, O, N, P) consisting of:
    • five-carbon sugar
      • ribose (RNA) or deoxyribose (DNA)
    • phosphate group (PO42-)
    • inorganic molecule that is acidic and negatively charged
      • attached to either C3 or C5 of sugar
    • nitrogenous base e.g. A,C,G,T,U
    • complex, organic, containing nitrogen, and containing one or two carbon rings
      • attached to C1 of sugar
  • participate in nearly all biochemical processes
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3
Q

2.1.3 a)

What does the nitrogenous base A stand for?

A
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4
Q

2.1.3 a)

What does the nitrogenous base C stand for?

A
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5
Q

2.1.3 a)

What does the nitrogenous base T stand for?

A
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6
Q

2.1.3 a)

What does the nitrogenous base G stand for?

A
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7
Q

2.1.3 a)

What does the nitrogenous base U stand for?

A
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8
Q

2.1.3 a)

What is the difference between RNA and DNA nucleotides?

A
  • DNA has the pentose monosaccharide deoxyribose (one less oxygen)
  • RNA has the pentose monosaccharide ribose
  • DNA has nitrogenous bases A,C,G,T
  • RNA has nitrogenous bases A,C,G,U
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9
Q

2.1.3 a)

What is a pyrimidine?

A
  • the smaller bases e.g. T and C
  • containing one carbon ring structure
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10
Q

2.1.3 a)

What is a purine?

A
  • larger bases e.g. A, G
  • containing two carbon ring structures
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11
Q

2.1.3 d) i)

What base is complementary to A?

A
  • A is purine, T is pyrimidine
  • T (in DNA), U (in RNA)
  • 2 hydrogen bonds are formed
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12
Q

2.1.3 d) i)

What base is complementary to T?

A
  • A is purine, T is pyrimidine
  • A
  • 2 hydrogen bonds are formed
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13
Q

2.1.3 d) i)

What base is complementary to C?

A
  • G is purine, C is pyrimidine
  • G
  • 3 hydrogen bonds are formed
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14
Q

2.1.3 d) i)

What base is complementary to G?

A
  • G is purine, C is pyrimidine
  • C
  • 3 hydrogen bonds are formed
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15
Q

2.1.3 b)

What is a polynucleotide?

A
  • A large molecule formed by condensation reaction of many nucleotides
  • Phosphate group of C5 covalently bonds by condensation with the hydroxyl (OH) group at C3 of the nucleotide above
  • This bond is called a phosphodiester bond
  • forms a long strong, strong, sugar phosphate backbone with a base attached to each sugar
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16
Q

2.1.3 a)

How is a nucleotide formed?

A
  • phosphate and pentose sugar form a covalent bond by condensation reaction
  • nitrogenous base and pentose sugar form a covalent bond by condensation reaction
17
Q

2.1.3 b)

How is a polynucleotide broken down?

A
  • Hydrolysis reactions (gaining water)
    • opposite of condensation reaction
  • releasing individual nucleotides
18
Q

2.1.3 c)

What does ADP stand for?

A
  • adenosine diphosphate
19
Q

2.1.3 c)

What does AMP stand for?

A
  • adenosine monophosphate
20
Q

2.1.3 c)

What does ATP stand for?

A
  • adenosine triphosphate
21
Q

2.1.3 c)

When does a nucleotide form a phosphorylated nucleotide?

A
  • when the nucleotide has more than one phosphate group
    • e.g. ATP and ADP
22
Q

2.1.3 c)

What is ATP?

A
  • adenosine triphoshphate
  • energy-rich end-product of most energy releasing biochemical pathways (reactions)
  • used to drive most energy requiring metabolic processes in cells
  • ATP, AMP and ADP all help to regulate metabolic pathways
23
Q

2.1.3 d) i)

Where is DNA found?

A
  • Nuclei of all eukaryotic cells
    • Each large molecule of DNA is wound around special histone proteins into a chromosome
    • Each chromosome = one DNA molecule
    • in eukaryotic cells, there is a loop of DNA without histone proteins, inside mitochondria and chloroplasts
  • Cytoplasm of prokaryotic cells
    • not enclosed in a nucleus and not wound around histone proteins (naked)
  • In some viruses
    • viruses that have DNA, dont have histone proteins or a nucleus, similar to prokaryotic cells, the DNA in the viruses that have DNA is naked
24
Q

2.1.3 d) i)

What is DNA?

A
  • DNA is a hereditary material
  • carries coded instructions used in development and function of all living organisms
  • DNA is an important macromolecule
    • makes up structure of living organism
    • other important macromolecules that make up structure include, proteins, lipids, carbohydrates
25
Q

2.1.3 d) i)

Describe the structure of DNA?

A
  • DNA is a polymer
  • One DNA molecule has two polynucleotide strands
    • run in opposite directions (antiparallel)
  • DNA = long
    • therefore can carry lots of coded information
  • hydrogen bonds formed between complementary base pairs
    • purine always bonds with pyrimidine
      • forming equal length ladder like rungs
      • twisted (coiled) into a double helix structure, for molecules stability and integrity of the coded information within the double helix is protected
26
Q

2.1.3 d) i)

What does antiparallel mean?

A
  • DNA - two polynucleotide strands are antiparallel
  • arranged so that they run in opposite directions
    • opposite directions - refers to the direction that the third and fifth carbon of the pentose sugar are facing
27
Q

2.1.3 d) i)

When was the DNA structure determined?

A
  • 1953
  • by Watson and Crick
28
Q

2.1.3 d) i)

If a double strand of DNA has 14% Guanine, what percentage of the other nucleotides does the double strand contain?

A
  • 14% Cytosine
  • 100 - 2(14)
  • 100 - 28 = 72
  • 72/2 = 36
  • 36% Thymine
  • 36% Adenine
    • Because of complementary base pairing, DNA always has equal amounts of adenine and thymine, as well as equal amounts of guanine and cytosine
    • this was known before Watson and Crick determined the structure of DNA
29
Q

2.1.3 e)

What were the three theories in the 1950s of how DNA was a self-replicating molecule?

A
  • conservative replication
    • the original molecule acts as a template and a new molecule is made
  • dispersive replication
    • the orginal molecule breaks up into nucleotides, each one joins to a complementary nucleotide, and the base pairs join up again
  • semi-conservative replication
    • the new molecule consists of one original strand and one newly formed strand
30
Q

2.1.3 e)

Why do living organisms need DNA replication to happen?

A
  • DNA within a cell (genome) carries the coded instructions for an organism
  • DNA replication happens for cell division
    • more cells need to be produced for growth and repair
31
Q

2.1.3 e)

When does DNA replication take place?

A
  • DNA replication takes place during interphase before the cell divides
  • (each chromosome makes a copy of itself)
    • first chromosomes are joined by centromere
    • two sister chromatids are formed
  • DNA in mitochondria and chloroplasts also needs to be replicated before the cell divides
32
Q

2.1.3 e)

What is semi-conservative replication?

A
  • Double helix unwinds
    • by gyrase enzyme
  • Polynucleotide strands are unzipped, hydrogen bonds between the nucleotide bases are broken
    • catalysed by DNA helicase
    • results in two single strands of DNA with exposed nucleotide bases
  • free nucleotides in the nucleoplasm in the nucleus are bonded to the exposed bases, by complementary base pairing (A and T), (C and G)
    • addition of new nucleotides is catalysed by the enzyme DNA polymerase, in the 5’ to 3’ direction, to the single strands of DNA
      • each unzipped DNA strand is used as a template
  • leading strand

AS Biology (8 decks)

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