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AEHBY > ch3 metabolism > Flashcards

ch3 metabolism Flashcards

1
Q

Metabolism

also state the types

A

All the chemical reactions that take place in cells. Catabolism, anabolism.

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2
Q

Catabolism

A
  • Reactions in which large molecules are broken down into smaller ones.
  • Release energy
  • E.g., cellular respiration
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3
Q

Anabolism

A
  • Process in which small molecules are built up into larger ones.
  • Require energy
  • E.g., protein synthesis
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4
Q

Define:

Nutrient

A

Any substance in food that is used for growth, repair, or maintaining the body. i.e., any substance required for metabolism.

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5
Q

List:

Groups of nutrients

A
  • water
  • carbohydrates
  • lipids
  • proteins
  • minerals
  • vitamins
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6
Q

Define:

Organic compound

A

Molecules containing a carbon chain, a number of hydrogens, and may contain oxygen, nitrogen, and sulphur.

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7
Q

Describe:

Carbohydrate

A

Always contain carbon, hydrogen, and oxygen.

  • Always twice as many hydrogen as oxygen.
  • The main source of energy for cells.
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8
Q

List:

Three types of carbohydrates

A
  • Monosaccharides
  • Disaccharides
  • Polysaccharides
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9
Q

Define:

Monosaccharide

Give examples

A

Simple/single-unit sugars

  • E.g., glucose, fructose, galactose
  • Used in cellular respiration to release energy
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10
Q

Define:

Disaccharides

Give examples

A

Two simple sugars joined together
- E.g., sucrose, maltose, lactose
- Sucrose: glucose + fructose

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11
Q

Define:

Polysaccharides

A

Many simple sugars joined together
- E.g., glycogen, cellulose

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12
Q

Describe:

Lipids

Types, breakdown, most common.

A

Fats and oils.
Fat → solid at room temperature.
Oil → liquid at room temperature.
- Broken down into fatty acids and glycerol.
- Glycerol can enter the glycolysis pathway of cellular respiration and is broken down to release energy in a similar way to glucose.
Most common fat in the body: triglyceride - glycerol, and three fatty acids.

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13
Q

Lipid structure

A
  • One molecule of glycerol.
  • One, two, or three fatty acid molecules.
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14
Q

Define:

** Protein

A

Compounds made of amino acids.
Proteins always contain carbon, hydrogen, oxygen, and nitrogen. And, often sulphur and phosphorus.

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15
Q

Define:

Amino acid

What happens when they join

A

Amolecule that contains both:
- Amino group
- Carboxylic acid group
- When two amino acids join together, they form a peptide bond, releasing a water molecule.

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16
Q

Dipeptide vs polypeptide vs protein

A

Dipeptide: two amino acids.

Polypeptide: more than 10 amino acids.

Protein: 100 or more amino acids.

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17
Q

Define:

Nucleic acids

And the two main classes

A

Very large molecules containing carbon, hydrogen, oxygen, nitrogen, and phosphorus.
- Made up of nucleotides - each of which contains a nitrogen base, sugar, and phosphate.
Main ones: RNA, DNA

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18
Q

Define:

RNA

Structure and function

A

Single chain of nucleotides that contain the sugar ribose.

  • Carry the information from DNA in the nucleus to parts of the cell where proteins are made.
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19
Q

Define:

DNA

Structure and function

A

Two chains of nucleotides that contain the sugar deoxyribose.
- Genetic material that stores inherited information.

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20
Q

Define:

Inorganic compounds

A

Compounds that are not based on a carbon chain.

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21
Q

What is the role of water in metabolism?

A

Important in metabolism because it is the fluid in which other substances are dissolved.

  • Some chemical reactions occur in water.
  • In others, water molecules take part in the reaction.
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22
Q

What is the role of minerals in metabolism?

A

Important in metabolism because:
- May be a part of enzymes.
- May function as cofactors for enzymes.
- May be a part of substances such as adenosine triphosphate (ATP) that are involved in metabolism.

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23
Q

What is the role of vitamins in metabolism?

A

Important in metabolism because they act as coenzymes for many of the chemical reactions.

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24
Q

Define:

Activation energy

A

The energy required to start a reaction.
Reacting particles need to collide with enough energy to break bonds in order for a chemical reaction to occur.

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25
Q

What do catalysts do?

A

Lower the activation energy while not being consumed in the reaction.
Lower activation energy → more particles have enough energy to react → increased rate of reaction.

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26
Q

Define:

Enzyme

A

Biological catalysts that speed up chemical reactions by lowering the activation energy. They are not consumed or altered in the reaction.

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27
Q

Enzyme structure

A

3D globular proteins.

28
Q

Define:

Substrate

A

The molecule on which an enzyme acts.

29
Q

Define:

Active site

A

The part of the enzyme molecule that combines with the substrate.

30
Q

Define:

Enzyme-substrate complex

A

A temporary molecule formed when the substrate binds to the enzyme.

31
Q

Describe:

Lock and key model

A

The shape of the enzyme (key) is always complementary to the shape of the substrate (lock). Therefore, they will fit exactly together to form the enzyme-substrate complex.

32
Q

Describe:

Induced-fit model

A

When the enzyme and substrate join, they form weak bonds that cause the shape of the enzyme to change, creating complementary shapes.

33
Q

List:

7 factors affecting enzyme activity

A
  1. Temperature
  2. pH
  3. Enzyme concentration
  4. Substrate concentration
  5. Product concentration
  6. Cofactors
  7. Presence of enzyme inhibitors
34
Q

How does temperature affect enzyme activity?

A
  • As the temperature increases, the enzymes and substrates move faster (higher kinetic energy) so the active sites and substrates collide more often, speeding up the rate of activity.
  • (Problem) However, continually raising the temperature causes hydrogen bonds in the enzyme’s active site to break, causing it to change shape (denature), so the substrate(s) can no longer bind to them. this results in a decline in the rate of activity.
35
Q

Define:

pH

A

Stands for potential of hydrogen. It is a measure of the concentration of hydrogen ions in a substance.
Lower pH = acidic
Higher pH = basic/alkaline

36
Q

How does pH affect enzyme activity?

A
  • Enzymes work at specific pH.
    • e.g., pepsin works in acidic conditions.
  • Changing pH alters the enzyme’s shape, affecting rate of activity.
37
Q

How does enzyme concentration affect enzyme activity?

A
  • As enzyme concentration increases, there are more active sites available for substrates to bind to.
  • Unless the substrate increases, the product(s) produced remains the same (conservation of mass).
38
Q

How does substrate concentration affect enzyme activity?

A
  • As the substrate concentration increases, so does the rate of activity until all the active sites are occupied.
  • We are limited by the available active sites, so rate no longer increases. this is called the turnover number.
39
Q

How does product concentration affect enzyme activity?

A

The products must be continually removed otherwise the rate of reaction will slow because it becomes more difficult for the substrate molecules to make contact with the enzyme molecules (because products are in the way).

40
Q

Define:

Cofactor

A

Ions or non-protein molecules that catalyse a reaction by changing the shape of the active site so that the enzyme can combine with the substrate.

41
Q

Define:

Coenzyme

A

Cofactors that are non-protein organic molecules. Many vitamins function as coenzymes.

42
Q

How do cofactors affect enzyme activity?

A

Without a cofactor, the enzyme is intact but cannot function.

43
Q

Define:

Enzyme inhibitors

A

Substances that slow or even stop the enzyme’s activity. May be used by cells to control reactions so that the products are produced in specific amounts.
Many drugs are enzyme inhibitors.
- E.g., penicillin inhibits an enzyme in bacteria that is involved in construction of the cell wall.

44
Q

Define:

Competitive inhibitor

A

An inhibitor that binds to the enzyme’s active site. When the inhibitor occupies the active site, it forms an enzyme-inhibitor complex and the enzyme cannot react until the inhibitor dissociates.

45
Q

Define:

Non-competitive/allosteric inhibitor

A

An inhibitor that binds to an enzyme at a site other than the active site. The shape of the active site is altered so that the enzyme can no longer bind to its substrate.

46
Q

Difference between the effects of competitive and non-competitive inhibitors on enzyme activity.

A

The effect of competitive inhibitors on enzyme activity can be reduced by increasing the concentration of enzyme - leading to an increase in the number of active sites available. Or by increasing the concentration of substrate causing there to be a higher chance of that substrate molecules will occupy the active sites of the enzyme, therefore competing more effectively with the inhibitor for binding to those active sites.

47
Q

Define:

Cellular respiration

A

The process by which organic molecules are broken down to release energy.

48
Q

Define:

ATP

A

Adenosine triphosphate - a compound composed of:
- Adenosine: made up of nucleic acid base adenine and the sugar ribose.
- Three phosphate groups.

49
Q

How does ATP store/release energy?

A
  • ATP is formed when an inorganic phosphate group is joined to a molecule of adenosine diphosphate (ADP).
  • The phosphate groups are joined by high-energy chemical bonds.
    • Some of the energy from cellular respiration is stored in the bond between the ADP molecule and the third phosphate group. This bond is more easily broken than the bond between the first and second phosphate groups, allowing more energy to be released when needed.
    • The ADP formed when the energy is released can be reused to store more of the energy from cellular respiration.
50
Q

What is the first step of cellular respiration?

+ Define

A

Glycolysis: a glucose molecule is broken down (in 10 steps) into two molecules of pyruvate.

51
Q

Glycolysis location

A

Cytosol

52
Q

Define:

Anaerobic respiration

A

Pyruvate is converted into lactic acid/lactate by fermentation. Occurs when no oxygen is available.

53
Q

How much energy (ATP) does anaerobic respiration produce?

A
  • Fermentation does not produce any additional ATP. However, the glycolysis of one molecule of glucose releases enough energy to convert two molecules of ADP to ATP.
    • Therefore, anaerobic respiration allows cells to produce some energy in the absence of oxygen.
54
Q

Fermentation location

A

Cytosol

Enzymes required for anaerobic respiration are available in the cytosol.

55
Q

When is anaerobic respiration important?

A

During vigorous physical activity, when the respiratory and circulatory systems are unable to supply muscles with enough oxygen to meet all the energy requirements of the contracting muscles. — In such cases, anaerobic respiration supplies the extra energy.

56
Q

What causes muscle pain during exercise?

A

Anaerobic respiration results in the accumulation of lactic acid in the muscles, which may cause muscle pain.

57
Q

Why does anaerobic respiration cause the body to breathe heavily?

A

Lactic acid from anaerobic respiration is taken by the blood to the liver, where it is recombined with oxygen to form glucose and eventually glycogen.

This process requires oxygen, so when cells are respiring anaerobically, the body is developing an oxygen debt which causes one to breathe heavily for some time after vigorous exercise in order to ‘repay’ the oxygen debt.

58
Q

How many molecules of ATP does the anaerobic respiration of one glucose molecule produce?

+ in which step(s)

A

2 ATP molecules.
* Only from glycolysis

59
Q

Define:

Aerobic respiration

A

Pyruvate is completely broken down into carbon dioxide and water. Occurs when oxygen is available.

60
Q

Aerobic respiration location

A

The enzymes for the reactions of aerobic respiration are attached to the internal membrane (cristae) of the mitochondria. Folding produces a large surface area on which the reactions can take place.

61
Q

Steps of aerobic respiration

A
  1. Pyruvate are converted into acetyl coenzyme A (acetyl CoA).
  2. The acetyl CoA enters the citric acid cycle, also known as the Krebs cycle.
  3. Electron transport system.
62
Q

What happens in the Krebs/citric acid cycle?

+ how much energy it produces

A
  • Carbon atoms in the acetyl CoA are released in carbon dioxide.
  • For every 1 acetyl CoA that enters the Krebs cycle, 1 molecule of ATP is also produced. This means that 2 ATP molecules are produced per 1 glucose molecule.

(1 glucose → 2 pyruvate → 2 acetyl CoA → 2 ATP)

63
Q

What is the only stage in cellular respiration that uses oxygen?

A

Electron transport system (also known as oxidative phosphorylation).

64
Q

Describe the electron transport system/chain.

+ how much energy it produces

A

Electrons are passed between molecules, finally resulting in oxygen molecules forming water. This process produces between 26 and 34 ATP molecules.

65
Q

How many molecules of ATP does the aerobic respiration of one glucose molecule produce?

+ how many per step

A

Aerobic respiration of one molecule of glucose can produce up to 38 ATP molecules.
* Glycolysis: 2 ATP
* Krebs cycle: 2 ATP
* Electron transport system: up to 34

66
Q

What % of energy released in cellular respiration is lost as heat?

A

Only about 40% of the energy released is incorporated into ATP; the other 60% is lost as heat.

AEHBY (9 decks)

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