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BIOLOGY YR12 > 12.3 Nucleic acids > Flashcards

12.3 Nucleic acids Flashcards

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1
Q

what is the structure of the DNA nucleotide?

A

Phosphate group, deoxyribose sugar and nitrogen containing base (Adenine - Thymine and Guanine - Cytosine)

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2
Q

what’s the structure of RNA nucleotide?

A

Phosphate group, deoxyribose sugar and ribose sugar and nitrogen containing base (Adenine - Uracil, Guanine - Cytosine)

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3
Q

What bond does the condensation reaction from between 2 nucleotides monomer?

A

Phosphodiester bond

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4
Q

Describe the DNA model of Watson and Crick

A

-DNA molecule has a double helix structure
- Double stranded
- Complementary base pairs ( Adenine-Thymine and Guanine-Cytosine)
- hydrogen bonds between the base pairs

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5
Q

Describe mRNA molecule

A

-it’s shorter than DNA molecule
- uses uracil instead of thymine
- single stranded

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6
Q

What is it called when 2 strands of DNA run in opposite directions

A

Antiparallel

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7
Q

On a complimentary strand the top has… end and bottom has … end

A

3’ end
5’ end

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8
Q

Structure and function of DNA

A
  1. Sugar phosphate backbone and double helix structure - provides strength and stability, protects bases and protects hydrogen bonds
  2. long/large molecule - stores a lot of information
  3. coiled structure - compact
  4. Base sequence - allows information to be stored and codes for amino acids (proteins)
  5. Double stranded - so semi conservative replication can happen and each strand can act as a template
  6. Complementary base pair - allows accurate replication
  7. Weak hydrogen bonds - easy strand seperation for semi-conservative replication
  8. Many weak hydrogen bonds - so DNA is strong / stable molecules
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9
Q

How semi-conservative replication occurs

A
  • DNA helicase attach and moves along DNA molecule unwinding the DNA breaking hydrogen bonds between complementary bases
    2. strands seperate
    3. each strand acts as a template
    4.Free DNA nucleotides are attracted to exposed complementary bases on template strands by base pairing (Adenine to Thymine and Cytosine to Guanine)
    5. DNA polymerase joins adjacent nucleotides together through concentration reaction making phosphodiester bonds
    6. new DNA is made
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10
Q

How is ATP formed?

A

ADP (adesonine diphosphate) + Pi (an in organic phosphate (phosphorylation)

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11
Q

what are the uses of ATP?

A
  1. energy for active transport, muscle contraction and protein synthesis
  2. Phosphorylation pf molecules lower activation energy to make substrates more reactive and altering enzyme’s tertiary structure
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12
Q

what enzymes are used for the condensation and hydrolysis of ATP?

A

ATP synthase and ATP hydrolase

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13
Q

ATP is useful because…

A

Releases relatively small amount of energy (so little energy is lost as heat)
Releases energy instantaneously
phosphorylates other compounds making them more reactive
can be rapidly re-synthesised
Is not lost from/ doesn’t leave calls (is also soluble)

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14
Q

ATP is an energy source used in many cell processes. Give two ways in which ATP is a suitable energy source for cells to use.

A
  1. Releases relatively small amount of energy/ little energy is lost as heat;
  2. Releases energy instantaneously;
  3. Phosphorylates other compounds, making them more reactive;
  4. Can be rapidly re-synthesised;
  5. Is not lost from/ does not leave cells;
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15
Q

Give 2 ways in which the hydrolysis of ATP is used in

cells (2)

A
  1. Phosphorlylates other compounds and makes them more reactive;
  2. Provides energy for (named process) – protein synthesis/active transport/glycolysis/semi-conservitive replication
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16
Q

Describe how ATP is resynthesized in cells (2)

A
  1. ADP + Pi
  2. By ATP synthase
  3. In respiration
17
Q

Adenosine triphosphate (ATP) is a nucleotide

derivative.

Contrast the structures of ATP and a nucleotide

found in DNA to give TWO differences. (2)

A
  1. ATP has ribose and DNA nucleotide has deoxyribose
  2. ATP has 3 phosphate (groups) and DNA nucleotide has 1 phosphate (group);
  3. ATP- base always adenine and in DNA nucleotide base can be different/ varies;
18
Q

7 properties of water

A
  • is an important solvent in which metabolic reactions occur

· is a metabolite in many metabolic reactions, including condensation and hydrolysis reactions

  • has a relatively high (specific) heat capacity, buffering changes in temperature
  • has a relatively large latent heat of vaporisation, providing a cooling effect with little loss of water through evaporation
  • has strong cohesion between water molecules; this supports columns of water in the tube-like transport cells of plants and produces surface tension where water meets air
19
Q

Give two properties of water that are important in biology. Explain the importance of each property you identify. (4

A
  1. Polar (molecules);
  2. Dissolves charged particles/acts as a (universal) solvent; OR
  3. A metabolite;
  4. Involved in metabolic/cell reaction/condensation/hydrolysis; OR
  5. Water molecules stick together/cohesion between water molecules;
  6. Provides surface tension/prevents columns of water breaking; OR
  7. High specific heat capacity;
  8. Reduces fluctuations in temperature (of water bodies); OR
  9. High latent heat of evaporation;
  10. Evaporation of small amount of water cools organisms;
20
Q

Suggest why water becomes lighter
as it expands. (2)

A
  1. Density = mass ÷ volume;
  2. Ice has same mass of water but greater volume;
21
Q

Suggest one biological advantage of

this property of water. (2)

A
  1. Ice is colder than water; 2. (Being lighter than water) ice floats on water; 3. Reduces freezing of water (below ice);
22
Q

Scientists looking for extra-terrestrial
life are looking for planets with
evidence of free water. Explain why water is considered so important for life to occur. (6

A
  1. Life (thought to have) evolved in water;
  2. Water provides support (for bodies of organisms);
  3. Water a major component of cytoplasm;
  4. Water is a universal solvent/metabolic reactions occur in aqueous solution;
  5. Water is a metabolite/a reactant in many cell reactions;
  6. Water stabilises (external) temperature; 7. Water important in cooling/stabilising internal temperature (of organisms);
23
Q

When an atom loses or gains an electron it becomes…

A

an ion.

24
Q

Hydrogen: H+ (acid)

Hydroxide: OH- (alkali) function

A

Affect the acidity of solutions (pH) H+ used in respiration to provide energy to make ATP H+ Used in photosynthesis to provide energy to make ATP

25
Q

Iron: Fe2+/Fe3+ (function?)

A

Structural component of haemoglobin (binds O2) to allow the transport of oxygen to respiring tissues

26
Q

Sodium: Na+ function?

A

Used in the co-transport of glucose and amino acids from the lumen of the small intestine, into intestinal epithelial cells. Changes the water potential of the immediate area. Also used in nervous conduction.

27
Q

Phosphate: PO43- function?

A

Components of phospholpipds (make the cell and organelle membranes), DNA, RNA and ATP

28
Q

Nitrites and Nitrates: NO2- and

NO3- function?

A

Taken up from the soil by plant roots. Used in making amino acids.

29
Q

Chloride: Cl- function?

A

Used in regulating the water potential of the small intestine

BIOLOGY YR12 (13 decks)

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