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Biology 2025 > Chemicals of life and human nutrition > Flashcards

Chemicals of life and human nutrition Flashcards

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1
Q

List the chemical elements which make up carbohydrates, fats and proteins

A

Carbohydrates → Carbon (C), Hydrogen (H), Oxygen (O)

Fats (Lipids) → Carbon (C), Hydrogen (H), Oxygen (O)

Proteins → Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N) (sometimes Sulfur (S))

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2
Q

Describe how carbohydrates break down into smaller molecules

A

Carbohydrates
→ monosaccharides (simple sugars) e.g. glucose, fructose
→disaccharides e.g. lactose, maltose, sucrose
→polysaccharides e.g. starch, glycogen, cellulose

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3
Q

Describe how lipids break down into smaller molecules

A

glycerol molecule, three fatty acid molecules
polymers- steroids, waxes

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4
Q

Describe how protein break down into smaller molecules

A

polymer- protein
monomer- amino acids
amino acids joined by peptide bonds- polypeptide chain

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5
Q

Many glucose molecules join together to create starch, cellulose, and glycogen. Where are these found?

A

starch (found in plant cells)
cellulose (make up plant walls)
glycogen (found in animal cells)

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6
Q

Carbohydrates function

A

Carbohydrates are broken down into glucose, which provides quick energy for cells. (releases 17kJ energy)

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7
Q

Lipids function

A

Used in a cell to release energy; many cells only use fat for energy once all carbohydrate has been used up
(1g lipid releases 39 kJ of energy)
Stored under the skin (adipose tissue), providing insulation – e.g. blubber
Making cell membranes

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8
Q

protein function

A

Make new cells for growth and repair
Antibodies
Make enzymes to drive biochemical reactions
Provide structure (e.g. keratin in hair)
Hormones (e.g. insulin)
Transport molecules (e.g. haemoglobin)

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9
Q

protein primary structure

A

sequence of amino acids held together with peptide bonds

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10
Q

protein secondary structure

A

polypeptide chain folds into structures (α-helices or 𝛽-sheets).
Hydrogen bonds hold the structures together.

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11
Q

protein tertiary structure

A

three-dimensional folding of a protein - give a proteins its specific shape
Structure held in place by hydrogen bonds, disulfide bridges, ionic bonds.

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12
Q

protein quaternary structure

A

contain more than 2 tertiary units.
e.g. Haemoglobin is made up of four different tertiary units bonded together.

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13
Q

Why do our bodies need water?

A

Solvent for the metabolic reactions that occur in our cells
Dissolves substances like glucose in blood so that they can be transported around the body
Dissolves enzymes / nutrients in digestive system so digestion can occur
Allows us to get rid of waste products in kidneys

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14
Q

What is a balanced diet and the 7 types of nutrients?

A

Diet that includes each of the seven types of nutrients in the correct amounts and proportions
Carbohydrates
Proteins
Fats
Vitamins
Minerals
Fibre
Water

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15
Q

Why do we need a balanced diet?

A

Meet our energy needs (carbs, fat)
Meet our nutritional needs (vitamins, minerals, protein, carbs, fat)
Keep our alimentary canal working properly (fibre, water)

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16
Q

Carbohydrates

A

Provides quick energy

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17
Q

Lipids

A

store energy, insulate body, protect organs

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18
Q

Protein

A

growth, repair, enzymes

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19
Q

Vitamin C

A

supports immune system

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20
Q

Vitamin D

A

helps absorb calcium (strong bones)

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21
Q

Minerals

A

strong bones, red blood cells

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22
Q

Fibre

A

aids digestion, prevents constipation

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23
Q

Water

A

vital for all bodily functions

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24
Q

Starvation

A

Cause: Taking in less energy/food than is required
Effect: body begins to break down energy stores (fat/muscle)

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25
Coronary heart disease
Cause: diet high in lipids and salts and cholesterols Effect: fat depoist builds up in arteries, making them narrow, reducing blood supply to body/ muscles
26
Obesity
Cause: taking in more energy than is required Effect: extra energy. stored as fat, heart diseases, stroke, type 2 diabetes
27
Constipation
Cause: not enough fibre Effect: food lacks bulk for muscles to push it through alimentary canal
28
Scurvy
Cause: not enough vitamin c Effect: body unable to make collagen which keeps skin and tissue in good repair
29
Kwashiorkor
Cause: not enough protein Effect: underweight but swollen belly
30
Marasmus
Cause: insufficient protein and carbohydrates Effect: lower weight than normal
31
Vitamin D
Cause: lack of sunlight Effect: calcium not absorbed (rickets)
32
Iron deficiency
Cause: lack of iron rich foods (red meat, dark green veges) Effect: iron needed to make haemoglobin (red pigment that carried oxygen through blood) therefore body doesn't make sufficient red blood cells.
33
What happens in the mouth during digestion?
Mechanical digestion (chewing). Salivary amylase breaks down starch → maltose.
34
What is the function of the esophagus?
Transports food to the stomach using peristalsis (wave-like muscle contractions). No digestion occurs here.
35
What happens in the stomach during digestion?
Pepsin breaks down proteins → peptides. Hydrochloric acid (HCl) kills bacteria & provides an acidic environment. Food is churned into chyme (semi-liquid).
36
What enzymes are released into the small intestine (duodenum)?
Amylase → Breaks starch → maltose. Trypsin (protease) → Breaks proteins → peptides. Lipase → Breaks fats → fatty acids & glycerol. Bile (from liver) → Emulsifies fats & neutralizes stomach acid.
37
What happens in the small intestine (ileum)?
Villi & microvilli absorb nutrients into the bloodstream. Maltase breaks maltose → glucose. Peptidase breaks peptides → amino acids.
38
What happens in the large intestine?
Water absorption occurs. Helpful bacteria digest fiber & produce vitamins. Undigested food turns into feces.
39
What is the role of the rectum & anus?
Rectum stores feces. Anus removes waste (egestion).
40
What does amylase do & where is it produced?
Produced in: Salivary glands & pancreas. Breaks down: Starch → Maltose.
41
What does maltase do & where is it found?
Found in: Small intestine. Breaks down: Maltose → Glucose.
42
What does pepsin do & where is it produced?
Produced in: Stomach. Breaks down: Proteins → Peptides.
43
What does trypsin (protease) do & where is it produced?
Produced in: Pancreas. Breaks down: Proteins → Peptides.
44
What does peptidase do & where is it found?
Found in: Small intestine. Breaks down: Peptides → Amino acids.
45
What does lipase do & where is it produced?
Produced in: Pancreas. Breaks down: Fats → Fatty acids & Glycerol.
46
Pancreatic juice contains?
- amylase - lipase - trypsin - maltase - sodium hydrogen carbonate
47
Gastric juice contains
- HCL - Mucus - Pepsin - Water
48
What are villi
Wall of the small intestine is covered with millions of tiny projections called ‘villi’ Important for 2 reasons Cells covering the villi make enzymes that complete the digestion of food This is where the biomolecules from food (simple sugars, amino acids, fatty acids, glycerol, minerals, vitamins) are absorbed into the bloodstream
49
Assimilation:
Movement of digested food molecules into the cells of the body, where they are used, becoming part of the cells Monosaccharides and amino acids are absorbed into the blood (hepatic portal vein) via the villi They are then transported to the liver by the hepatic portal vein The liver processes some of the nutrients before they go any further The nutrients are dissolved in blood plasma and travel from the liver to other parts of the body, where they may become assimilated as part of a cell
50
Egestion:
Passing of food that has not been digested or absorbed, as faeces, through the anus By the time the food reaches the rectum, most absorbable substances will have reached the blood Faeces is a combination of: Indigestible food (e.g. fibre) Bacteria Some dead cells from inside the alimentary canal
51
what is a catalyst
Many chemical reactions can be sped up by using a catalyst. A catalyst alters the rate of a chemical reaction, without being changed itself. In living things, chemical reactions are essential for life processes. Need a catalyst to increase rate of reaction, otherwise they would proceed too slowly to sustain life These biological catalysts are called enzymes.
52
what is an enzyme
biological catalyst Are proteins Can help break molecules down or build larger molecules Very specific – one enzyme catalyses on only one type of reaction
53
maltose is broken down by______into_____
maltase, glucose
54
Sucrose is broken down by______into_____
sucrase, glucose
55
Lipids are broken down by______into_____
lipase, fatty acid and glycerol
56
Proteins are broken down by______into_____
protease, amino acids
57
Starch is broken down by ______into_____
Amylase, maltose
58
What is the lock and key theory
Enzyme works by allowing the molecule that it is working on (substrate) to fit into it’s active site. This is referred to as a lock-and-key mechanism
59
Enzyme denaturing
The active site of an enzyme can change when they are subjected to increases in temperature or changes in pH - they are said to be denatured and no longer can no longer act as a catalyst.
60
Chemical digestion
Chemical digestion is the breaking down of large insoluble (food) molecules into small soluble molecules. Once these molecules are small and soluble they can be absorbed and used by the body for growth, repair and in biological reactions essential for life. The chemical reactions would proceed without the enzymes but too slowly to sustain life. (Chemical digestion is carried out largely by enzymes but also by other chemicals in the body such as HCl).
61
How does temperature effect enzyme activity
The rate of enzymatic reactions typically increases as the temperature increases – more kinetic energy Enzymes work best at a particular temperature - called the optimum temperature ~37oC in humans Enzymes become inactive at high temperature Protein is denatured at high temperatures (about ~40oC+ in mammals) – lock and key no longer fit!
62
How does pH effect enzyme activity
Amino acid chain of an enzyme (protein) is folded into specific shape and held together by bonds and electrostatic charges pH of the environment can affect the charges, causing the amino acid chain to coil or uncoil – become denatured Lock and key no longer fit! Enzymes work best at a particular pH
63
What is the test called for simple sugars and what colour will the mixture turn if sugars are present?
Benedicts test, Red if present, blue is absent
64
What is the test called for starch and what colour will the mixture turn if starch is present?
Iodine solution test, black/blue if present, orange/brown if absent
65
What is the test called for lipids and what colour will the mixture turn if lipids are present?
Emulsion test (ethanol) milky if present, clear if absent
66
What is the test called for proteins and what colour will the mixture turn if proteins are present?
Biuret test purple if present, blue if absent
67
What is the test called for vitamin C and what colour will the mixture turn if vitamin C is present?
DCPIP test, The more drops needed to turn blue means less vitamin C present

Biology 2025 (3 decks)

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