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Biochemistry Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

How do you make enzyme reactions faster?

A

-increasing the temperature which makes the molecules move faster
-biological systems are very sensitive to temperature changes
-enzymes can increase the rate of reaction without increasing the temperature
-they do this by lowering the activation energy
-they create a new reaction pathway

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2
Q

What is the lock and key hypothesis?

A

-the fit between the substrate and the active site of the enzymes is exact
-like a key fits into a lock very precisely
-the key is analogous to the enzyme and the substrate analogous to the lock
-temporary structure called the enzyme-substrate complex formed
-products have a different shape from the substrate
-once formed, they are released from the active site

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3
Q

What is the induced fit hypothesis?

A

-some proteins can change their shape (conformation)
-when a substrate combines with an enzyme it induces a change in the enzymes conformation shape
-the active site is the moulded into a precise conformation
-making the chemical environment suitable for the reaction
-the bonds (ionic, hydrogen and disulfide bridges) of the substrate are stretched to make the reaction easier (lowers activation energy)

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4
Q

What are cofactors?

A

Cofactors are an additional non-protein molecule that is needed by some enzymes to help the reaction.
E.g. in photosynthesis there is NADP
E.g. in respiration there is NAD, FAD and co-enzyme A

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5
Q

What are factors affecting enzymes?

A

-temperature
-pH
-inhibitors
-concentration of substrate

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6
Q

What are the two types of inhibitors?

A

-competitive inhibitors
-non-competitive inhibitors

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7
Q

What are inhibitors?

A

-inhibitors are chemicals that reduce the rate of enzymic reactions
-they are usually specific and they work at low concentrations (non-competitive inhibitor)
-they block the enzyme but they do not usually destroy it (competitive inhibitors)
-many drugs and poisons are inhibitors of enzymes in the nervous system

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8
Q

What are chromosomes?

A

Linear structure that stores DNA with proteins (histones).

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9
Q

What are genes?

A

Short sequences of DNA that codes for a specific protein.

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10
Q

What is an allele?

A

Different version of the same gene.
Recessive or dominant.

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11
Q

What is the structure of DNA?

A

Double helix

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12
Q

What are the difference in DNA between eukaryotes and prokaryotes?

A

Eukaryotes have a nucleus which contains chromosomes, prokaryotes have a loop of DNA and plasmids.

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13
Q

What are differences between DNA and RNA?

A

DNA is a double helix and has complementary bases A and T, and G and C.
RNA is a single strand and has complementary bases A and H, and
G and C.
RNA can move out of the nucleus.

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14
Q

What are codons?

A

Three bases in a gene.

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15
Q

What does a DNA nucleotide consist of?

A

-phosphate
-bases
-deoxyribose sugar

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16
Q

What does a RNA nucleotide consist of?

A

-phosphate
-bases
-ribose sugar

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17
Q

Polynucleotide

A

-sugar phosphate backbond
-phosphodiester bond forms by a condensation reaction
-it is broken down by a hydrolysis reaction

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18
Q

What does it mean by DNA strands are antiparallel?

A

One strand goes from 5’ to 3’ direction (phosphate is at the top). The other is 3’ to 5’ (phosphate is at the bottom).

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19
Q

What type of bond joins bases together?

A

Hydrogen bonds
Weak

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20
Q

How many hydrogen bonds are between adenine and thymine?

A

Two

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21
Q

How many hydrogen bonds are between cytosine and guanine?

A

Three

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22
Q

DNA polymerase

A

-enzyme
-helps form strands of DNA using nucleotides

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23
Q

DNA helicase

A

-enzyme
- unwinds the double helix and separates the strands

24
Q

How does DNA replicate?

A

By semi conservative replication.

25
Q

What does semi conservative replication mean?

A

Half the strands in the new DNA molecule are from the original DNA molecule.

26
Q

How does temperature affect enzyme action?

A

-low temperatures has few enzyme-substrate complexes
-medium temperatures has an increase in enzyme-substrate complexes
-optimum temperatures has maximum rate of enzyme-substrate complexes
-above optimum denatures the enzyme which decreases enzyme-substrate complexes

27
Q

How does pH affect enzyme action?

A

-Further than optimum causes reversible denaturing but prevents formation of enzyme-substrate complexes
-Closer to optimum increases the formation of enzyme-substrate complexes

28
Q

How does concentration affect enzyme action?

A

-low concentration has excess substrate molecules so enzymes work at an optimum
-medium concentration results in optimum working as all substrates occupy all active sites
-high concentrations has excess enzyme so not all enzymes work at an optimum

29
Q

Competitive inhibitors

A

Substrates has a similar tertiary structure so is complimentary to the same active site on an enzyme.
This can result in inhibition if one type of substrate forms an enzyme-substrate complex.

30
Q

Non-competitive inhibitor

A

Substrates have a different tertiary structure to one another.
Each are complimentary to different active sites on the enzyme.
Once one enzyme-substrate complex forms, the shape of the other active site changes due to changes in the quaternary structure.

31
Q

What does specific heat capacity mean?

A

Requires a lot of energy to heat up/increase temperature.

32
Q

What gives the hydrogen atom in water a slight positive charge?

A

The shared negative hydrogen electrons are pulled towards the oxygen atom giving the hydrogen atom a slight positive charge.

33
Q

What gives oxygen a slight negative charge?

A

The unshared negative electrons on the oxygen give it a slight negative charge.

34
Q

Why is water a polar molecule?

A

Because one side has a partial negative charge and the other a partial positive charge.

35
Q

What is a polar molecule?

A

Different charges within a molecule.

36
Q

Opposite charges are … attracted to each other. Between water molecules this form H-bonds. Finish the word…

A

Electrostatically

37
Q

Properties of water:

A

-Water is an important metabolite.
-Water has a high latent heat of vaporisation.
-Water can buffer changes in temperature.
-Water is a good solvent.
-Water molecules have strong cohesions.

38
Q

What does latent heat of vaporisation mean?

A

Requires a lot of energy for water to evaporate.

39
Q

What does high surface tension mean?

A

Waters surface contracts, supporting small organisms.

40
Q

What does cohesion mean?

A

Water molecules stick together, forming droplets.

41
Q

What does cohesion mean?

A

Water molecules stick together, forming droplets.

42
Q

What is an inorganic ion?

A

Atom or molecule with a net electric charge.

43
Q

Hydrogen ion (H+)

A

Determines pH; affects enzyme activity.

44
Q

Sodium (Na+)

A

Facilitates transport of glucose and amino acids.

45
Q

Iron (Fe2+)

A

Component of haemoglobin, binds oxygen.

46
Q

Phosphate ion (Ph4^3-)

A

Part of DNA,RNA and ATP.

47
Q

Cohesion-tension theory.

A

Explains water movement in plants.

48
Q

How much % of a cell is water?

A

80%

49
Q

Describe waters high latent heat of vaporisation.

A

Water evaporates when the hydrogen bonds holding it together are broken.
This allows water molecules on the surface to escape into the air as a gas.
It takes a lot of energy to break the hydrogen bonds between water molecule so a lot of energy is used up when water evaporates.
This means water has a high latent heat of vaporisation- lots of heat is used to change from a liquid to a gas.
This is useful because it means organisms can use water loss via evaporation to cool down without losing too much water.
When water is evaporated it series away heat energy from the surface which cools the surface, lowering the temperature.

50
Q

Describe water’s cohesiveness.

A

Cohesion is the attraction between molecules of the same type.
Water molecules are very cohesive (tend to stick) because they are polar.
Strong cohesion allows water to flow, making it good for transporting substances. For example, it’s how water travels in columns up the xylem.
Strong cohesion also means water has a high surface tension when it comes into contact with the air, this is why sweat forms droplets, which evaporate from the skin to cool down an organism.

51
Q

Describe waters high specific heat capacity.

A

Hydrogen bonds give water a high specific heat capacity, the energy needed to take the temperature of 1kg of a substance by 1degrees.
When water is heated, a lot of energy is used to break the hydrogen bonds between water molecules.
This means there is less heat energy available to actually increase the temperature of water.
So it takes a lot of energy to heat up.
This is useful for living organisms because it means water doesn’t experience rapid temperature changes, making water a good habitat because the temperature underwater is more stable than on land.
The water inside organisms also remains fairly stable, helping them to maintain a constant internal body temperature.

52
Q

Why is water a good solvent?

A

Water is polar,the slight positive charged end is attracted to a negative ion end is the slight negative end is then attracted to the positive ion.
This means ions are surrounded by water molecules, they dissolve.
So waters polarity makes it useful as a solvent.
This means living organisms can take up useful substances (mineral ions) dissolved in water and can be transported around an organisms body.

53
Q

Name 4 reactions where water is a metabolite.

A

Photosynthesis
Respiration
Hydrolysis
Condensation

54
Q

Describe two reasons why water being a solvent is important.

A

Allows metabolic reactions to occur.
Allows transport of substances.

55
Q

What three parts make up ATP.

A

Adenine
Ribose
Phosphates

56
Q

What is ATP?

A

The energy-carrying molecule that provides the energy to drive many processes inside living cells.

57
Q

Role of ATP

A

Small,soluble molecules that provides short-term store of chemical energy that cells can use to do work.

Biology (2 decks)

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