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Biology > 1.2 Nucleic acids > Flashcards

1.2 Nucleic acids 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 monomers make up DNA and RNA?

A

nucleotides

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4
Q

what three components make up a nucleotide?

A

phosphate group, pentose sugar and nitrogenous organic base

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5
Q

what nitrogenous organic bases are components of DNA nucleotides?

A

adenine, thymine, guanine, cytosine

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6
Q

what nitrogenous organic bases are components of RNA nucleotides?

A

adenine, uracil, guanine, cytosine

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7
Q

name the pentose sugar found in DNA nucleotides

A

deoxyribose sugar

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8
Q

name the pentose sugar found in RNA nucleotides

A

ribose sugar

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9
Q

what bond is formed when two nucleotides join together?

A

phosphodiester bond

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10
Q

describe how two nucleotides join together in a DNA molecule [3]

A
  • phosphodiester bond
  • between deoxyribose sugar and phosphate group
  • condensation reaction
  • catalysed by DNA polymerase
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11
Q

describe the structure of DNA [5]

A
  • polymer of nucleotide monomers
  • nucleotides made of a phosphate group, deoxyribose sugar and nitrogenous organic base
  • phosphodiester bonds between nucleotides form sugar-phosphate backbone
  • antiparallel strands coil into double helix shape held by hydrogen bonds
  • hydrogen bonds between complimentary base pairs: adenine and thymine, guanine and cytosine
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12
Q

describe the structure of RNA [5]

A
  • polymer of nucleotide monomers
  • nucleotides made of a phosphate group, ribose sugar and nitrogenous organic base
  • phosphodiester bonds between nucleotides form sugar-phosphate backbone
  • short, single-stranded chain
  • exposed nitrogenous organic base pairs: adenine and uracil, guanine and cytosine
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13
Q

state four differences between the structures of DNA and RNA

A
  • in DNA, adenine pairs with thymine, but in RNA it pairs with uracil
  • DNA has two strands coiled into a double helix, whereas RNA is single-stranded
  • RNA is much shorter than DNA
  • pentose sugar is deoxyribose in DNA, but ribose in RNA
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14
Q

how many hydrogen bonds form between adenine and thymine?

A

two

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15
Q

how many hydrogen bonds form between guanine and cytosine?

A

three

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16
Q

how many hydrogen bonds form between adenine and uracil?

A

two

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17
Q

when was DNA first observed?

A

1800s

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18
Q

when was the double helix structure of DNA discovered?

A

1953

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19
Q

who discovered the double helix structure of DNA?

A

Watson and Crick

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20
Q

do strands of DNA run in the same direction?

A

no, they are antiparallel

21
Q

in what direction do the two strand run in a DNA molecule?

A

they are antiparallel
one runs in 5’ to 3’ direction
other runs in 3’ to 5’ direction

22
Q

describe and explain how DNA is a stable molecule [3-4]

A
  • sugar-phosphate backbone protects chemically reactive organic base inside double helix
  • hydrogen bonds between complimentary base pairs form bridges between DNA strands
23
Q

how does the proportion of G-C pairings affect the stability of a DNA molecule?

A

G-C pairings have three hydrogen bonds between them, whilst A-T pairs have two, meaning the higher the proportion of G-C pairings, the more stable the DNA molecule will be.

24
Q

what is the function of DNA?

A

to store genetic information and pass it between cells and down generations

25
Q

what is the main function of RNA?

A

to transfer genetic information from DNA to ribosomes

26
Q

what are ribosomes made of?

A

RNA and proteins

27
Q

how is the structure of DNA suited to its functions? [4-6]

A
  • two strands joined by hydrogen bonds allows them to separate during DNA replication and protein synthesis
  • sugar-phosphate backbone and helical shape protect base pairs and genetic information from outside chemical and physical forces
  • complimentary base pairing allow DNA to replicate and transfer information as mRNA
28
Q

why does DNA replicate before cell division?

A

so that each new cell has the full amount of DNA

29
Q

by what process does DNA replicate?

A

semi-conservative replication

30
Q

name for requirements for DNA replication to take place

A
  • presence of free nucleotides with either adenine, thymine, guanine or cytosine as their organic base
  • both DNA strands act as templates for free nucleotides to attach to
  • presence of DNA polymerase enzyme
  • a source of chemical energy
31
Q

describe the process of semi-conservative replication [5-6]

A
  • enzyme DNA helicase breaks hydrogen bonds between complimentary base pairs
  • double helix separates and unwinds to form two single strands
  • each exposed strand acts as a template for a new strand
  • free nucleotides bind to complimentary base pairs on template strands with hydrogen bonds
  • DNA polymerase joins new nucleotides together to form the new sugar-phosphae backbone
  • two new strands are identical and contain half of the original DNA material
32
Q

what does ATP stand for?

A

adenosine triphosphate

33
Q

why is energy important?

A

plant and animal cells need energy for biological processes to occur

34
Q

what components make up ATP?

A

adenine, ribose, three phosphate groups

35
Q

where is energy stored in ATP?

A

phosphate bonds between the phosphate groups

36
Q

how is energy released from ATP?

A

ATP is broken down into ADP
bonds between phosphate groups break
hydrolysis reaction
catalysed by ATP hydrolase
hydrolysis of phosphate bonds releases energy

37
Q

what molecule is released when ATP breaks down to ADP?

A

inorganic phosphate

38
Q

how can ADP be converted back to ATP

A

add an inorganic phosphate molecule
condensation reaction
catalysed by ATP synthase

39
Q

what type of reaction converts ATP to ADP

A

reversible reaction

40
Q

how can the inorganic phosphate lost from the conversion of ATP to ADP be used?

A

phosphorylation
it can be added to another compound to make it more reactive

41
Q

give two reasons why ATP is a better immediate energy source than glucose

A
  • ATP releases smaller amounts of energy than glucose, meaning its much more manageable
  • hydrolysis of ATP to ADP is a single reaction, so releases energy immediately, whilst breakdown of glucose is multiple reactions so takes longer
42
Q

name the two products of ATP hydrolysis

A

ADP and an inorganic phosphate

43
Q

give two ways in which the hydrolysis of ATP is used in cells

A
  • to provide energy for other reactions
  • to add phosphate to other substances and make them more reactive
44
Q

name the process of adding phosphate to a substance to increase its reactivity

A

phosphorylation

45
Q

describe the atomic structure of water

A

two hydrogen atoms covalently bonded to one oxygen atom

46
Q

describe/explain the polarity of water

A
  • dipolar molecule
  • no overall charge
  • oxygen atom slightly negatively charged
  • hydrogen atoms slightly positively charged
47
Q

how are multiple water molecules bonded together?

A
  • water is dipolar
  • opposite poles attract
  • positive oxygen on one molecule attracts negative hydrogens of another and vice versa
  • attractive forces are hydrogen bonds
48
Q

explain five properties that make water important for organisms [5]

A
  • metabolite in condensation and hydrolysis reactions
  • good solvent to transport substances
  • high specific heat capacity to buffer temperature change
  • high latent heat of vaporisation to provide cooling effect through evaporation
  • cohesion between water molecules to support continuous column of water in plants
49
Q

what is a metabolite?

A

substance involved in a metabolic reaction

Biology (14 decks)

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