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(bio year 1) 2.3 nucleic acids > 2.3.1 DNA - deoxyribonucleic acid > Flashcards

2.3.1 DNA - deoxyribonucleic acid Flashcards

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1
Q

double helix

A

shape of DNA molecule - due to coiling of 2 sugar-phosphate backbone strands into right-handed spiral configuration

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2
Q

monomer

A

molecule that repeats to become a monomer eg. amino acids are monomers of proteins & nucleotides are monomers of nucleic acids

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3
Q

nucleotide

A

molecule consisting of 5-carbon sugar, phosphate group & nitrogeneous base

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4
Q

polynucleotide

A

large molecule containing many nucleotides

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5
Q

describe nucleotides

A
  • biological molecule that are in (nearly) all biochemical processes
  • phosphate esters of pentose sugars
  • nitrogeneous base linked to C1 of sugar residue & phosphate group linked to C5 or C3
    —> via covalent bonds formed from condensation reactions
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6
Q

properties of nucleotides

A
  • monomers of nucleic acids, DNA & RNA —> in RNA, nucleotide pentose sugar = ribose & in DNA = deoxyribose
  • become phosphorylated nucleotides when contain 1+ phosphate group eg. ADP & ATP
  • helps regulate metabolic pathways
  • may be components of many coenzymes eg. adenine nucleotides are components of NADP, coenzyme A, FAD & NAD
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7
Q

what is ATP

A

energy-rich end-product of most energy-releasing biochemical pathways

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8
Q

ATP

A

adenosine triphosphate

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9
Q

ADP

A

adenosine diphosphate

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10
Q

AMP

A

adenosine monophosphate

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11
Q

where is DNA found

A
  • nuclei of all eukaryotic cells
  • in cytoplasm of prokaryotic cells
  • inside some types of viruses
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12
Q

descibe DNA

A
  • hereditary material
  • carries coded instructions used in development & functioning of all known living organisms
  • one of important macromolecules making up structure of living organisms
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13
Q

structure of DNA

A
  • polymer (repeating monomeric units called nucleotides)
  • molecule of DNA = 2 polynucleotide strands
  • 2 strands run in opposite directions (antiparallel)
  • each DNA nucleotide = phosphate group, 5-carbon sugar (deoxyribose) & 1 of 4 nitrogenous bases (A, G, T or C)
  • covalent bond between sugar residue & phosphate group = phosphodiester bond
  • DNA molecules are long & can carry a lot of encoded genetic info
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14
Q

when are phosphodiester bonds broken/made

A

broken = when polynucleotides break down
formed = when polynucleotides are synthesised

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15
Q

how many types of nucleotides does DNA consist of

A

4

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16
Q

purine

A

adenine or guanine = 2 rings

17
Q

pyrimidine

A

thymine or cytosine (1 ring)

18
Q

what are the 2 antiparallel DNA strands joined by

A

hydrogen bonds between nitrogeneous bases

19
Q

adenine pairs with…
how many H bonds

A

thymine
2 hydrogen bonds

20
Q

guanine pairs with…
how many H bonds

A

cytosine
3 hydrogen bonds

21
Q

what does a purine always pair with

A

pyrimidine

22
Q

why does a purine always pair with a pyrimidine

A
  • gives equal sized ‘rungs’ on DNA ladder
    —> can twist into double helix (coil)
    = stability to molecule
23
Q

what to hydrogen bonds allow

A

allow molecule to unzip for transcription & replication

24
Q

what is the upright part of the large DNA molecule (resembling a ladder) formed by

A

formed by sugar-phosphate backbones of antiparallel polynucleotide strands

25
Q

what does the ‘opposite directions’ of the 2 strands refer to

A

the direction that the 3rd & 5th carbon molecules on the 5-carbon sugar (deoxyribose) are facing

26
Q

describe the 5’ end of the antiparallel sugar-phosphate backbone

A

phosphate group is attached to 5th carbon atom of deoxyribose sugar

27
Q

describe the 3’ end of the antiparallel sugar-phosphate backbone

A

phosphate group attached to 3rd carbon atom of deoxyribose sugar

28
Q

what do the rungs of the ladder consist of

A

complementary base pairs joined by h bonds

29
Q

is the antiparallel sugar-phosphate backbone stable

A

yes

30
Q

what’s protected within the antiparallel sugar-phosphate backbone

A

integrity of the coded info within the base sequence

31
Q

how is DNA organised in eukaryotic cells

A
  • majority of DNA content/genome is in nucleus
  • each large molecule of DNA is tightly wound around special histone proteins into chromosomes –> each chromosome = 1 molecule of DNA
  • loop of DNA (without histone proteins) inside mitochondria & chloroplasts
32
Q

how is DNA organised in prokaryotic cells

A
  • DNA is in loop & within cytoplasm (not enclosed in nucleus)
  • not wound around histone proteins (naked)
33
Q

draw structure of ATP (& ADP/AMP)

A
  • 3 phosphate
  • ribose sugar
  • adenine
    –> check pg. 86 of OCR textbook

(bio year 1) 2.3 nucleic acids (5 decks)

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