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Nucleic Acids Flashcards

(61 cards)

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1
Q

What is the structure of DNA nucleotides?

A

A deoxyribose sugar, an inorganic phosphate and nitrogenous base

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2
Q

What is the basic function of DNA?

A

Holds genetic information

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3
Q

What is the structure of RNA nucleotides?

A

Ribose sugar, inorganic phosphate and nitrogenous base

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4
Q

What is the basic function of RNA?

A

Transfer generic information from DNA to ribosomes

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5
Q

What are the nitrogenous base pairs in DNA?

A

Cytosine and guanine (3 hydrogen bonds between them)
Thymine and adenine (2 hydrogen bonds between them)

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6
Q

What are the nitrogenous base pairs in RNA?

A

Cytosine and guanine
Uracil and adenine

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7
Q

What bond joins nucleotides?

A

Phosphodiester bonds

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8
Q

What reaction forms a phosphodiester bond?

A

Condensation reaction (removal of water)

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9
Q

What reaction breaks phosphodiester bonds?

A

Hydrolysis reactions (addition of water)

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10
Q

Between what compounds in a nucleotide does a phosphodiester bond form?

A

Between the pentose sugar of one nucleotide and the phosphate group of another

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11
Q

What is the structure of DNA?

A
  • double helix
  • long
  • strands joined by H bonds
  • base pairings complimentary
  • they are anti parallel
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12
Q

What is the function of the phosphodiester backbone?

A

Gives stability and protects the less stable organic bases

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13
Q

Compare and contrast the structure of DNA and RNA.

A
  • both are polynucleotides
  • both have pentose and phosphate e backbones
  • both have nitrogenous bases (cytosine, guanine and adenine)
  • both form a helix
  • DNA has thymine whereas RNA has uracil
  • DNA has 2 strands of polynucleotides whereas RNA only has 1
  • DNA has a deoxyribose sugar whereas RNA has ribose
  • RNA is shorter than DNA
  • DNA has hydrogen bonds whereas RNA doesn’t
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14
Q

What is mRNA?

A

Messenger RNA

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15
Q

What is tRNA?

A

Transfer RNA

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16
Q

Why does DNA copy itself for mitosis?

A

So daughter cells can have a full set of chromosomes

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17
Q

What is the mechanism for DNA replication that is widely accepted?

A

Semi-conservative replication

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18
Q

What is DNA helicase?

A

Separates the 2 DNA strands before replication by breaking the hydrogen bonds

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19
Q

What is DNA ligase?

A

Joins together the short sections of the lagging strand

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20
Q

What is the single stranded binding protein?

A

Keeps the separated DNA strands apart during replication

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21
Q

What is DNA polymerase?

A

Catalyses the formation of a new polynucleotide strand

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22
Q

How does DNA polymerase work?

A

Is complimentary to 3’ end of original strand, moves in 5’ to 3’ due to antiparallel strands it works in opposite direction

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23
Q

What is the process of semiconservative DNA replication?

A
  • DNA helicase breaks hydrogen bonds between bases of two polynucleotide strands
  • each strand acts as a template
  • complimentary base pairings from free nucleotides align
  • DNA polymerase joins the new strand with phosphodiester bonds through condensation reactions
  • each DNA molecule contains one original and one new strand
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24
Q

Who provided evidence for semi conservative replication?

A

Meselson and Stahl

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25
What was Meselson and Stahl’s procedure?
- grew bacteria in a heavier isotope of nitrogen - transferred that bacteria to a light medium - left it in the lighter medium for a further 20 minutes and observed a light band and a heavy and light band
26
What is ATP?
Adenosine triphophate
27
What makes up ATP?
- ribose sugar - adenosine - 3 inorganic phosphates
28
How is ATP formed?
- condensation reaction - ADP + PI -> ATP + water - ATP synthase
29
How is ATP broken?
- hydrolysis reaction - ATP + water -> ADP + Pi - ATP hydrolase
30
What are the uses of ATP?
- metabolic processes - movement - active transport - secretion - activation of chemicals
31
How does metabolic processes use ATP?
Protein and hormone synthesis to make macromolecules e.g. polysaccharides
32
How does movement use ATP?
- within the organism (ciliary action/spindle action) - organism itself (muscle contraction)
33
How does active transport use ATP?
To allow carrier proteins in plasma membrane to change shape so molecules/ions can be moved against concentration gradient
34
How does secretion use ATP?
Productions of cell products and formation of lysosomes
35
How does activation of chemicals use ATP?
The Pi during hydrolysis of ATP can be used to phosphorylate other molecules to make them more reactive e.g. glucose
36
Why is AP a better energy source than glucose?
- 1 glucose molecule gives 38 ATP - hydrolysis of ATP is quick and simple for rapid energy release - ATP is rapidly resynthesised - ATP energy is in small manageable amounts - ATP cannot leave cells
37
What is a negative of ATP?
- not a long term energy store as bonds between Pi are unstable and easily broken down
38
What is an ion?
An atom/group with an electrical charge
39
What is a cation?
Positively charged ion
40
What is an anion?
Negatively charged ion
41
What makes an inorganic ion inorganic?
Doesn’t contain carbon
42
Where are inorganic ions found?
Cytoplasm and body fluids
43
What are the examples of inorganic ions?
- hydrogen ions - iron ions - sodium ions - phosphate ion - calcium ions
44
What is a hydrogen ion?
Proton of hydrogen
45
What Is the effect of hydrogen ions?
- determines pH - more hydrogen ions lower pH
46
What is the role of hydrogen ions?
Maintain body pH so enzymes don’t denature
47
What are the 2 versions of iron ions?
Fe2+ and Fe3+
48
What is the role of iron ions?
Found in haemoglobin which binds to oxygen
49
What are sodium ions involved in?
Involved in movement across cell surface membranes
50
What is the roles of sodium ions?
- co-transport in small intestines as it is needed to move glucose and amino acids across small intestine lumen - nerve impulses as sodium ions diffuse into nerve cells generating an action potential
51
What is the general role of phosphate ions?
Attaches to other molecules to form phosphate groups
52
What is the roles of phosphate ions?
- in ATP bonds between phosphate store energy that is released when the bond is broken - in DNA and RNA allowing nucleotides to join together
53
What is the general role of calcium ions?
- can pass across membranes - essential in movement of organisms
54
What are the roles of calcium ions?
- stimulate the chemical transmitter movements across a synapse - muscle contractions by calcium ions being released from sarcoplasmic reticulum
55
What is the structure of water?
- hydrogen and oxygen covalently bonded - oxygen has slightly negative charge and hydrogen has slightly positive - bipolar molecule with no overall charge
56
What are the functions of water?
- cohesion and surface tension - solvent for metabolic reactions - is a metabolite - large latent heat of vaporisation - high specific heat capacity
57
How does water create cohesion and surface tension?
- cohesion tension = tendency of water molecules to stick together - surface tension = when water acts like a solid a surface - due to water molecules forming hydrogen bonds between eachother so they stick together - e.g. xylem or pond skaters
58
How is water a solvent for metabolic reactions?
- water readily dissolved other substances due to its polarity - e.g. inorganic ions and small hydrophilic molecules
59
How is water a metabolite?
- hydrolysis and condensation reactions - chemical reactions take place in aqueous solutions - water is essential in lots of reactions e.g. photosynthesis
60
How does water have a large latent heat of vaporisation?
- hydrogen bonds between molecules need lots of heat to break - allows animals to cool down with little water loss as when sweat evaporates it carries heat energy away - maximum heat loss with minimal water loss
61
How does water have a high specific heat capacity?
- lots of energy needed to break hydrogen bonds - acts as a buffer against temperature changes - keeps aquatic environments stable - keeps body temperature stable

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