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Biology Y12 > Section 1:Nucleic Acids > Flashcards

Section 1:Nucleic Acids Flashcards

1
Q

What does DNA stand for?

A

Deoxyribonucleic acid

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2
Q

What are the monomer units in DNA?

A

Nucleotides

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3
Q

What is the structure of DNA?

A
  • Two polynucleotide chains in an α-helix
  • Nucleotides:deoxyribose sugar,phosphate group and a nitrogen containing organic base
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4
Q

What organic bases can be found in DNA and what are the complementray pairs?

A
  • Adenine,thymine,guanine and cytosine
  • Adenine+Thymine
  • Guanine+Cytosine
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5
Q

How are nucleotide joined together?

A

Nucleotides are joined together in a condensation reaction and are held together by phosphodiester bonds

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6
Q

Where is a phosphodiester bond in a polynucleotide chain?

A

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

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7
Q

What bonds are formed between the two strands in DNA?

A

Hydrogen bonds between the organic bases

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8
Q

What does RNA stand for?

A

Ribonucleic acid

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9
Q

What’s the structure of RNA?

A
  • Single,relatively short polynucleotide chain
  • Nucleotides:ribose sugar,phosphate group and nitrogen containing organic base
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10
Q

What are the organic bases found in RNA and the complementary pairs?

A
  • Adenine,uracil,guanine and cytosine
  • Adenine+Uracil
  • Guanine+Cytosine
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11
Q

What are the three types of RNA and their roles?

A
  • mRNA~transfers genetic info from DNA to ribosomes
  • tRNA~directly involved in protein synthesis
  • rRNA~the ribosomes are made up of protein and RNA
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12
Q

What is the role of RNA?

A

To transfer genetic information from DNA to the ribosomes in order for the correct proteins to be produced

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13
Q

Why is RNA used to transfer genetic information instead of RNA?

A

DNA is a very large molecule meaning it can’t fit through the nuclear pores, but RNA is smaller so it can

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14
Q

Describe the differences between RNA and DNA

A
  • DNA has thymine, RNA has uracil
  • DNA is double strand, but RNA is single strand
  • DNA contains ribose sugar,deoxyribose sugar
  • DNA is a α-helix shape, RNA is a straight chain
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15
Q

What is meant by antiparallel in terms of DNA strands?

A

One strand has a base sequence that is complementary to the other strand, so the strands run in opposite directions

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16
Q

Two points

Why is DNA a stable molecule?

A
  • Strong phosphodiester bonds in sugar phosphate backbone~backbone the more chemically reactive bonds
  • Many hydrogen bonds linking the organic bases~collectively provides strength
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17
Q

Six points

How does DNA’s structure relate to its function?

A
  • Very stable(rarely mutates) via HB and double helix structure
  • Two strands joined by HB~easily seperated during replication and protein synthesis
  • Large molecules~carries lots of info
  • Coiling gives compact shape=lots of info stored in a small space
  • Sugar phosphate backbone=protect base pairs from chemical and physical forces
  • Base pairing=DNA can be replicated and transfered to mRNA
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18
Q

What are the main stages in cell divison?

A
  1. Nuclear divison~mitosis or meiosis
  2. Cytokinesis~whole cell divides
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19
Q

Why must DNA be replicated?

A

To ensure the daughter cells have the same genetic information as the parent cells to produce enzymes and other proteins

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20
Q

Why is required for DNA to be replicated?

A
  • DNA helicase
  • DNA polymerase
  • Energy
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21
Q

What is the role of DNA helicase?

A

Breaks hydrogen bonds linking the base pairs in two polynucleotide strands in DNA

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22
Q

What is the role of DNA polymerase?

A

Synthesis the new DNA strand by joining the two polynucleotide chains

23
Q

Five points

Describe the process semi-conservative DNA replication

A
  1. DNA helicase breaks HB linking base pairs in DNA
  2. Double helix unwinds and seperates into 2 strands
  3. Each exposed polynucleotide chain acts as a template
  4. Free nucleotides bind by specific base pairing to a ‘template’ strand
  5. This is done in a condensation reaction via DNA polymerase
24
Q

What does ATP stand for?

A

Adenosine triphosphate

25
Describe the structure of ATP
Adenosine organic base,ribose sugar and three phosphate groups
26
Why is ATP hydrolysed easily?
The bonds between the three phosphate groups are unstable~low activation energy
27
How does ATP provide energy?
When the bonds between phosphate groups are broken, energy is released
28
What enzyme catalyses the breakdown of ATP?
ATP hydrolase
29
What is produced when ATP is broken down?
ADP + inorganic phospate + energy
30
What enzyme catalyses the reaction between ADP and Pi?
ATP synthase
31
What is phosphoylstion?
Adding an inorganic phosphate to ADP tp create ATP
32
What are the three types of phosphoylation + description?
* Photophosphotylation~in chlorophyll containing plants during photosynthesis * Oxidative phosphorylation~in plant and animal cells during respiration * Substrate-level phosphotylation~in plant and animal cells when phosphate groups are transfered from donor molecules to ATP
33
Why is ATP a better 'intermediate energy source' than glucose?
* Breakdown of ATP is a single reaction~makes energy instantly available * Releases a small,managable amount of energy~glucose releases more energy which is lost as heat
34
# Four points What are the roles of ATP?
* Metabolic processes~provides the energy needed to build up macromolecules from their basic units * Movement~provides the energy for muscle coordination * Active transport~provides the energy to change the shape of carrier proteins in plasma membranes * Activation of molecules~inorganic phosphate used to phosphorylate other molecules=lowering activation energy
35
Why does water have no overall charge?
* Oxygen has a slightly negative charge * Hydrogen has a slightly positive charge
36
Is water a polar molecule?
Yes it is described as dipolar
37
# Three points Describe the hydrogen bonding in water
* Water forms a lattice as the molecules stick together * HB allow molecules to flow as a continuos streamm(mass flow) * Positive pole of one molecule is attracted to the negative pole of another~forms a HB
38
Describe the specific heat capacity of water
High SPC~because water molecules stick together=buffers against sudden temp changes for aquatic organisms
39
Describe the latent heat of vaporisation of water
*Large latent heat Provides cooling effect through evaporation~due to hydrogen bonding between water molecules
40
Describe the cohesion and surface tension of water
*Large cohesion forces*~due to HB allows water to be pulled up though a tube e.g. xylem *Surface tension*~water molecules pulled back into water when water meets air
41
# Three points Why is water important in metabolism of living organisms?
* Used to breakdown molecules by hydrolysis * Produced in condensation reactions * Water is a raw material in photosynthesis and is produced in respiration
42
# Two points Why water important as a solvent?
* So metabolic reactions can occur * Easily dissolves other substances=allowing transport of substances e.g. gases,inorganic ions
43
Why is it important that water can evaporate?
Cools organims and allows them to control their temperature
44
# Two points Why is it important that water is transparent?
* Allows aquatic plants to photosynthesis * Light rays can penetrate the jelly-like fluid in the eye so it can reach the retina
45
Why is important that water provides support(not easily compressed)?
* Hydrostatic skeleton of animals * Turgor pressure in plants
46
Give three examples of inorganic ions
1. Hydrogen(H+) 2. Iron(Fe2+) 3. Sodium(Na+)
47
Give the role of three inorganic ions
1. Hydrogen~determines pH and affects enzyme 2. Iron~transport oxygen in haemoglobin 3. Sodiun~transport of glucose and amino acids
48
What is a solvent?
A liquid substance which can dissolve a wide range of molecules
49
Define specific heat capacity
The amount of energy it requires to increase the temperature of 1kg of a substance by 1°C
50
Define latent heat of vaporization
The amount of heat needed to turn a substance into a gas
51
Define adhesion
The tendency of molecules to be attracted to other molecules of a different type
52
Define cohesion
The tendency of molecules of a substance to attract one another
53
Define viscosity
A fluid's resistance to flow

Biology Y12 (11 decks)

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