3.2 enzymes & metabolism and cellular respiration

Question 1

define metabolism

Answer 1

all the chemical reactions that take place in the cells

Question 2

what are the two types of metabolic reations?

Answer 2

catabolic and anabolic reactions

Question 3

define catabolism/ catabolic reactions (catabolic metabolism) and give example

Answer 3

the reactions in which large molecules are broken down into smaller molecules. this process releases energy. eg. digestion

Question 4

define anabolism/ anabolic reactions (anabolic metabolism) and give example

Answer 4

the reactions in which small molecules are built up into larger ones. this process requires energy. eg protein synthesis

Question 5

define a nutrient

Answer 5

a nutrient is any substance in food that is used for growth, repair, or maintaining the body; that is any substance that is required for metabolism.

Question 6

what are the six groups of nutrients?

Answer 6

water, carbohydrates, lipids, proteins, minerals, vitamins

Question 7

what are organic compounds?

Answer 7

organic compounds are any molecule that have a carbon chain, this includes carbohydrates, lipids, and proteins.

Question 8

what are inorganic compounds?

Answer 8

molecules that don’t have a carbon chain, including water, minerals, and vitamins.

Question 9

carbohydrates are the main source of ______ for cells

Answer 9

energy

Question 10

what are carbohydrates broken down into? and state whether they are water soluble or not.

Answer 10

• simple sugars (monosaccharides) eg. glucose used in cellular respirations.
  (water soluble)
• simple sugars can join together to form disaccharides

Question 11

what are polysaccharides, and state whether they are water soluble or not

Answer 11

polysaccharides are larger carbohydrate molecules formed when many simple sugars join together.

(not water soluble)

Question 12

describe the structure and function of lipids

Answer 12

• lipids are another important source of energy.
• they are broken down into fatty acids and glycerol
• ## each lipid molecule consists of one glycerol molecule and two or three fatty acid molecules

Question 13

can fatty acids be essential

Answer 13

yes, some fatty acids are essential to the body but they cannot produced by the body, so they must be consumed as a part of healthy diet.

Question 14

describe proteins

Answer 14

• organic compounds made up of many amino acids
• consist of 100 or more amino acids, their type and order is determined by the DNA that codes for the protein’s production.
• each protein has a characteristic shape due to the folding of the chain

-Shorter lengths of amino acids include dipeptides and polypeptides

Question 15

what happens when two amino acids bond together?

Answer 15

they form a peptide bond and release a water molecule

Question 16

what is the importance of water in metabolism?

Answer 16

• Water is important in metabolism because it is the fluid in which other substances are dissolved.
• some of cell’s chemical reactions occur in water and in others water is a part of the reaction

Question 17

what is the importance of minerals in metabolism?

Answer 17

are important because they may be a part of enzymes, function as cofactors for enzymes, or be part of substances such as ATP

Question 18

what is the function of vitamins in metabolism?

Answer 18

Vitamins act as coenzymes for many of the chemical reactions
of metabolism.

Question 19

describe nucleic acids

Answer 19

nucleic acids are organic compounds
- eg. ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)

DNA consists of two chains of nucleotides that contain the sugar deoxyribose. It is the genetic material in the nucleus that stores inherited information.

RNA is made up of a single strand of nucleotides that contain the sugar ribose. These molecules carry information from the DNA in the nucleus to the ribosomes for protein production.

Question 20

define enzymes

Answer 20

enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy, and are not consumed or altered in the reaction.

Question 21

what is a substrate?

Answer 21

The molecule on which an enzyme acts is known as the substrate

Question 22

The enzyme that breaks down lactose is called lactase. lactase is the only enzyme that will combine with lactose, why is that?

Answer 22

Each enzyme will combine with only one particular substrate so is
involved in only one specific reaction

Question 23

what is the active site?

Answer 23

the part of the enzyme molecule that combines with the substrate is called the active site.

Question 24

when does the enzyme-subrate complex occur

Answer 24

When the enzyme and substrate are combined.

Question 25

what is activation energy?

Answer 25

Activation energy is the energy needed to start a chemical reaction. Particles need to collide with enough energy to break the bonds.

Question 26

describe the effect of enzymes on activation energy

Answer 26

Enzymes speed up reactions by lowering the activation energy, thereby enabling the reaction to take place earlier.

Question 27

describe the lock and key model

Answer 27

the lock and key model states that shape of the enzyme (the lock) is always complementary to the shape of the substrate (the key). Therefore, the two will fit exactly to form the enzyme–substrate complex.

Question 28

describe the induced fit model

Answer 28

the induced fit model states that when the enzyme and substrate join, they form weak bonds that cause the shape of the enzyme to change, creating complementary shapes.

Question 29

what are the six factors that affect enzyme activity

Answer 29

substrate concentration, enzyme concentration, temperature, ph, cofactors, inhibitors,

Question 30

explain substrate concentration as a factor of enzyme activity

Answer 30

Increasing substrate concentration increases the rate of the reaction, because there will be more substrate molecules coming into contact with the enzyme molecules. Increasing the substrate beyond a certain concentration will cease to have an effect because the active sites on all the enzyme molecules will be fully occupied.

Question 31

explain enzyme concentration as a factor of enzyme activity

Answer 31

The higher the concentration of enzyme, the faster the rate of a chemical reaction because there are more enzyme molecules to influence reactants. By regulating the type and number of enzymes present, the body is able to control which reactions occur and the rate at which they proceed.

Question 32

explain temperature as a factor of enzyme activity

Answer 32

the rate of most chemical reactions increases as temp increases. enzyme reactions will increase as temperature increases. This is true of most enzyme reactions but only within a limited temperature range. Because enzymes are proteins, beyond about 45–50°C their structure changes; they are denatured. As the shape of the enzyme is crucial for its functioning, denatured enzymes are inactive. The optimum temperature for most enzymes in the human body is 30°C to 40°C.

Question 33

explain ph as a factor of enzyme activity

Answer 33

Enzymes are very sensitive to the pH of the medium in which a reaction is taking place. Each enzyme has an optimum pH at which it will work most effectively.

Question 34

what are denatured enzymes

Answer 34

A denatured enzyme is one that has lost its proper shape due to factors like high heat or the wrong pH. This means it can no longer bind to the molecule it’s supposed to help break down or build. As a result, the metabolic reaction it normally speeds up will slow down or stop.

Question 35

explain cofactors as a factor of enzyme activity

Answer 35

Many enzymes require the presence of certain ions or non-protein molecules before they will catalyse a reaction, called cofactors. - Cofactors change the shape of the active site so that the enzyme can combine with the substrate. - Without a cofactor the enzyme molecule is intact but cannot function.

Question 36

explain inhibitors as a factor of enzyme activity

Answer 36

enzyme inhibitors are substances that slow or even stop the enzyme’s activity. Inhibitors may be used by cells to control reactions so that products are produced in specific amounts. Many drugs are enzyme inhibitors, e.g. penicillin.

Question 37

define cellular respiration?

Answer 37

Cellular respiration is the process by which organic molecules, taken in as food, are broken down in the cells to release energy for the cell’s activities.

Question 38

what can cellular respiration release energy from?

Answer 38

Cellular respiration can release energy from glucose, amino acids, fatty acids and glycerol, but the main food material utilised is glucose.

Question 39

what is the aerobic respiration equation

Answer 39

C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (ATP)

Question 40

what is the remaining energy of cellular respiration used for?

Answer 40

The remaining energy is used to form a compound called adenosine triphosphate (ATP)

Question 41

describe structure and function of ATP

Answer 41

ATP is composed of adenosine and three phosphate groups and can be used to transfer energy between cellular respiration and processes in the cell requiring energy.

Question 42

what are the two types of cellular respiration?

Answer 42

Anaerobic and Aerobic Respiration.

Question 43

what is the first phase of both types of cellular respiration and describe the process.

Answer 43

the first phase is called glycolysis and does not require oxygen. A glucose molecule is broken down, in a series of 10 steps, to two molecules of pyruvate.

Question 44

explain anaerobic respiration

Answer 44

If no oxygen is available, the pyruvate produced in glycolysis is then converted to lactic acid by fermentation. The fermentation stage of anaerobic respiration 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.

Question 45

where does anaerobic respiration take place and why is it crucial

Answer 45

Anaerobic respiration takes place in the cytosol and is crucial during intense physical activity when oxygen supply is insufficient.

Question 46

What does anaerobic respiration provide and how is lactic acid removed from the body?

Answer 46

Anaerobic respiration provides temporary energy but causes lactic acid buildup, which can lead to muscle pain. The lactic acid is taken to the liver and converted back into glucose using oxygen. This creates an oxygen debt, which is repaid by breathing heavily after exercise.

Question 47

how many ATP molecules are produced in anaerobic respiration?

Answer 47

Estimates of the exact number of ATP molecules that are produced range between 26 and 34 molecules.

Question 48

define aerobic respiration

Answer 48

The complete breakdown of glucose to carbon dioxide and water, requiring oxygen. The pyruvate produced from glycolysis is completely broken down to carbon dioxide and water.

Question 49

Where does aerobic respiration take place, and what happens to the pyruvate molecules from glycolysis?

Answer 49

Aerobic respiration happens in the mitochondria. The two pyruvate molecules from glycolysis enter the mitochondria, where enzymes help break them down further in the next steps of respiration.

Question 50

explain the steps of aerobic respiration once pyruvate have entered the mitochondrion

Answer 50

1. The pyruvate is first converted to acetyl coenzyme A (acetyl CoA). No ATP is produced during this process. 2. The acetyl CoA then enters the citric acid cycle (Krebs cycle). Here the carbon atoms in the acetyl CoA are released in carbon dioxide. For every acetyl CoA that enters the citric acid cycle, one molecule of ATP is also produced. This means that two ATP molecules are produced per glucose molecule. 3. The final stage is the electron transport system; the only stage that uses oxygen. Recharging of the ADP molecule occurs when an electron is moved along the electron transport chain by the molecule nicotinamide adenine dinucleotide or NAD/NADH + H+ finally resulting in oxygen molecules forming water.

Question 51

how many ATP molecules are produced in anaerobic respiration?

Answer 51

aerobic respiration of one molecule of glucose has the potential to generate up to 38 molecules of ATP.