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biological molecules, enzymes and human nutrition Flashcards

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1
Q

what are biological molecules? state the main 4

A

chemical substances that make up every living being. carbohydrates, proteins, lipids (fats), nucleic acids

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2
Q

name 2 physical aspects of biological molecules

A

often very large, made up of many smaller molecules joined together

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3
Q

complete: enzymes are a type of _______

A

protein

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4
Q

complete: water is also an important ________

A

molecule

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5
Q

suggest reasons on why we need carbohydrates (4)

A

energy source, energy store, structural roles (plant cell wall - cellulose), to form larger molecules

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6
Q

state the three different sizes of carbohydrates

A

monosaccharide (sugar molecule), disaccharide, polysaccharide

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7
Q

what are monosaccharides made of?

A

glucose, fructose, galactose

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8
Q

what are disaccharides made of?

A

maltose, sucrose, lactose

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9
Q

what are polysaccharides made of?

A

starch, glycogen, cellulose

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10
Q

describe this biological molecule: starch (4)

A

it is the main storage plants (chloroplasts - made here, starch grains - stored here), no effect on water potential, long chains with no branches, the amount of starch stored in the cell does not affect movement of water by osmosis

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11
Q

describe this biological molecule: glycogen (5)

A

storage polysaccharide in animals, long branched chain (more than starch), side chains, releases glucose quickly, storage in liver and muscle cells

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12
Q

describe this biological molecule: proteins (5)

A

most abundant molecule, contains carbon, hydrogen, oxygen and nitrogen, may contain sulphur, important for growth and repair in all organisms, made of amino acids

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13
Q

name 5 jobs of proteins

A

enzymes (catalyse reactions), hormones (chemical messengers), antibodies (immunity), membrane-transport, structural role (e.g. muscle fibres)

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14
Q

describe this biological molecule: lipids (fats and oils) (4)

A

made out of carbon, hydrogen, oxygen, made up of a molecule of glycerol joined to three molecules of a fatty acid, fats form part of the cell membranes and the membranes that make up organelles, droplets of fat stored in the cytoplasm are also a source of energy

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15
Q

how can you show the presence of starch?

A

by adding a solution of iodine indicator

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16
Q

how do you know if there is starch present?

A

the yellow-brown colour turns to a blue-black colour

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17
Q

how can you reduce sugar?

A

heat it with Benedict’s solution

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18
Q

how do you know if there is sugar present?

A

the blue changes to a cloudy orange-red colour

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19
Q

how can you show the presence of protein?

A

by adding Biuret reagent (2-part reagent ‘solution a’ & ‘solution b’)

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20
Q

how do you know if there is protein present?

A

The colour changes from a pale blue to lilac colour

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21
Q

how can you show the presence of lipids?

A

by using the ethanol emulsion test, mix this with the sample, add water and shake

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22
Q

how do you know if there are lipids present?

A

a cloudy white emulsion will form near the top of the water

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23
Q

how can you show the presence of vitamin c?

A

add 1cm3 of DCPIP solution to a test tube and a small amount of food sample

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24
Q

how do you know if there is vitamin c present?

A

the blue colour of the dye will disappear

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25
what molecules make of carbohydrates?
carbon, hydrogen, oxygen
26
define chromosome
a long DNA molecule wound around protein
27
what are chromosomes 1-22?
autosomes
28
what are chromosomes X and Y?
sex chromosomes
29
define monomer
a molecule that can bond together with other similar molecules to form a polymer
30
define polymer
a large molecule formed by bonding together many monomers
31
what is a DNA monomer also called?
nucleotide
32
what are the four types of nitrogenous bases?
A (adenine), T (thymine), G (guanine), C (cytosine)
33
give 5 physical structures of DNA
- large, stable double stranded molecule - forms a double helix (twisted ladder) shape - found in chromosomes in nuclei of living cells - contains genes that code for proteins - contains deoxyribose sugar
34
explain why an increase in temperature causes an increase in enzyme activity
- increasing the temp increase the energy of enzyme and substrate particles - particles move faster at higher temp - increases number of collisions between particles - more successful collisions - more enzyme substrate complexes forming
35
name two factors that affect enzyme activity
pH and temperature
36
define catalyst
a substance that speeds up the rate of a chemical reaction without being used up or permanently changed in the process.
37
describe enzyme
Enzymes are proteins that act as biological catalysts. They speed up the chemical reactions that occur in cells during metabolism without being changed themselves.
38
explain why enzymes are important in all living organisms in terms of a reaction rate necessary to sustain life
Enzymes are essential because they allow metabolic reactions to occur quickly enough to sustain life. Without enzymes, these reactions would be too slow for cells to survive and function properly.
39
Describe enzyme action with reference to the shape of the active site of an enzyme being complementary to its substrate and the formation of products
Enzymes have an active site with a specific shape that fits the shape of its substrate. The substrate binds to the active site to form an enzyme-substrate complex, and the enzyme then converts the substrate into products.
40
describe the effect of changes in temperature and pH on enzyme activity with reference to optimum temperature and denaturation
Enzymes work best at an optimum temperature and pH. If the temperature or pH is too high or too low, the enzyme can become denatured—its active site changes shape and can no longer bind to the substrate, stopping the reaction.
41
Explain the effect of changes in temperature on enzyme activity in terms of kinetic energy, shape and fit, frequency of effective collisions and denaturation
As temperature increases, enzyme and substrate molecules gain more kinetic energy, leading to more frequent collisions and higher reaction rates. However, if the temperature gets too high, the enzyme’s active site changes shape (denatures), reducing activity or stopping the reaction altogether
42
Explain the effect of changes in pH on enzyme activity in terms of shape and fit and denaturation
Each enzyme works best at a specific pH. If the pH is too high or too low, the enzyme’s active site may change shape (denature), meaning the substrate no longer fits and the enzyme cannot catalyze the reaction.
43
Describe what is meant by a balanced diet
consuming a variety of foods from all major food groups in the right proportions to provide the body with the necessary nutrients for optimal health and function
44
State the principal dietary sources and importance of carbohydrates
Sources: Pasta, rice, potatoes, bread, cereals Importance: Carbohydrates provide the primary source of energy for cellular respiration. They are essential nutrients that are broken down during digestion to release the energy needed for all bodily functions and physical activities
45
State the principal dietary sources and importance of fats and oils
Sources: Fatty meats, cheese, butter, cooking oils Importance: Fats serve multiple functions including energy storage, insulation to maintain body temperature, protection of vital organs, waterproofing, and providing structural components for cells
46
State the principal dietary sources and importance of proteins
Sources: Meat, fish, eggs, dairy products Importance: Proteins are broken down into amino acids during digestion and then used by cells to synthesize new proteins. They function as enzymes catalyzing reactions, structural components in tissues, hormones, and transport proteins like haemoglobin
47
State the principal dietary sources and importance of vitamin c
sources: Citrus fruits, berries, green vegetables Importance: Essential for the synthesis of collagen, which forms skin, ligaments, and blood vessels. It aids in wound healing and tissue repair, and supports immune function
48
State the principal dietary sources and importance of vitamin d
Sources: Dairy products, eggs, fish oil, and produced in skin exposed to sunlight Importance: Facilitates calcium absorption in the intestines and is crucial for maintaining healthy bones and teeth. A deficiency causes rickets in children
49
State the principal dietary sources and importance of calcium
Sources: Dairy, fish, green leafy vegetables Importance: Essential for building and maintaining strong bones and teeth. Also vital for blood clotting, muscle contraction, nerve transmission, and the release of hormones and enzymes
50
State the principal dietary sources and importance of iron
Sources: Red meat, liver, beans, nuts, dried fruits, whole grains, dark green leafy vegetables Importance: Critical component of haemoglobin in red blood cells, enabling oxygen transport throughout the body. Also plays an important role in the cellular respiration process
51
State the principal dietary sources and importance of fibre
Sources: Wholemeal bread, bran, cereals, nuts, seeds, fruits, vegetables Importance: Insoluble fibre cannot be digested but adds bulk to food, aiding its passage through the digestive tract. It maintains bowel health, prevents constipation, and reduces the risk of digestive disorders
52
State the principal dietary sources and importance of water
Sources: Drinking water, beverages, fruits, vegetables Importance: Essential for all cell functions, regulates body temperature, transports nutrients and waste products, serves as a medium for chemical reactions, and helps maintain blood volume.
53
state causes of scurvy
-Caused by a severe deficiency of vitamin C -Results from inadequate consumption of fresh fruits and vegetables containing vitamin C
54
state causes of rickets
-vitamin d deficiency -limited sun exposure -insufficient calcium or phosphorus
55
describe the function of ingestion
the taking of substance (eg. food/drinks) into the body through the mouth
56
describe the function of chemical digestion
the breakdown of large, insoluble molecules into small, soluble molecules
57
describe the function of absorption
the movement of small food molecules and ions through the wall of the intestine into the blood
58
describe the function of assimilation
the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells
59
describe the function of egestion
the passing out of food that has not been digested or absorbed, as faeces, through the anus
60
describe physical digestion
the breakdown of food into smaller pieces without any chemical change to the food molecules
61
what does physical digestion increase?
Physical digestion increases the surface area of food for the action of enzymes in chemical digestion
62
what are the types of human teeth?
incisors, canine, premolar, molar
63
what are the different structures of the human teeth?
enamel, dentine, pulp, nerves, blood vessels and cement
64
functions of the human teeth
incisor: cutting food canine: tearing food premolar/molar: grinding and crushing food
65
describe the function of the stomach in physical digestion
the function of the stomach in physical digestion is to churn and mix food, breaking it into smaller pieces by muscular action
66
what is the role of bile
bile emulsifies fats and oils, breaking them into smaller droplets to increase the surface area for chemical digestion by enzymes and neutralises stomach acid to provide optimum pH for enzymes in small intestine
67
functions of enzymes in actions
Amylase breaks down starch to simple reducing sugars. Proteases break down protein to amino acids. Lipase breaks down fats and oils to fatty acids and glycerol
68
state where, in the digestive system, amylase, protease and lipase are secreted and where they act
Amylase is secreted by the salivary glands (acts in the mouth) and by the pancreas (acts in the small intestine). Protease is secreted as pepsin by the stomach (acts in the stomach) and as trypsin by the pancreas (acts in the small intestine). Lipase is secreted by the pancreas and acts in the small intestine
69
Describe the functions of hydrochloric acid in gastric juice
Kills harmful microorganisms in food. Provides an acidic pH for optimum enzyme activity
70
Describe the digestion of starch in the digestive system
Amylase breaks down starch to maltose. Maltase breaks down maltose to glucose on the membranes of the epithelium lining the small intestine
71
Describe the digestion of protein by proteases in the digestive system
Pepsin breaks down protein in the acidic conditions of the stomach. Trypsin breaks down protein in the alkaline conditions of the small intestine
72
what is bile
Bile is an alkaline mixture that neutralises the acidic mixture of food and gastric juices entering the duodenum from the stomach, providing a suitable pH for enzyme action
73
what is the small intestine?
the small intestine is the region where nutrients are absorbed
74
where is water absorbed?
most water is absorbed from the small intestine but that some is also absorbed from the colon
75
Explain the significance of villi and microvilli in increasing the internal surface area of the small intestine
Villi are small, finger-like projections that line the wall of the small intestine. Each villus is covered with even smaller projections called microvilli. Together, villi and microvilli greatly increase the internal surface area of the small intestine, allowing for more efficient absorption of nutrients. This increased surface area enables more digested food molecules to be absorbed quickly and efficiently
76
Describe the structure of a villus
A villus is a small, finger-like projection about 0.5–1 mm long. Each villus has: -A thin wall made of a single layer of columnar epithelial cells (with microvilli on their surface) -A network of blood capillaries -A central lymphatic vessel called a lacteal -Connective tissue and a small amount of smooth muscle
77
Describe the roles of capillaries and lacteals in villi
Capillaries in the villi absorb amino acids and simple sugars (such as glucose) into the bloodstream. Lacteals are lymphatic vessels in the villi that absorb fatty acids and glycerol (as chylomicrons) into the lymphatic system, which eventually drains into the bloodstream

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