Cellular & Molecular Bioscience - Nutrition. macro-nutrients

Question 1

Nutrition

Nutrient

Answer 1

Science of foods and their actions within the body. This includes: Relationship between health and disease (malnutrition)

any substance that is absorbed into the bloodstream from the diet and used to promote the various functions of the body.

Question 2

Diet

Answer 2

selection of foods and beverages that an individual eats and drinks
balanced diet - appropriate intake of nutrients for health

Question 3

What are the 6 nutrient classes?

Answer 3

Macronutrients
carbohydrates
proteins
lipids
water

Micronutrients
vitamins
mineral salts

Question 4

Macronutrients - energy-yielding nutrients:

Answer 4

Organic nutrients that are broken down to provide energy

Question 5

energy released from nutrients can be measured in;

Answer 5

calories
or
kcal

1000 cals in 1 kcal

Question 6

daily calorie intake

Answer 6

2,000 Kcal - women
2,500 Kcal - men

Question 7

Excessive prolonged lower calories intake – weight loss

Answer 7

Nutrient/energy deficiencies

Question 8

Consistent higher calories intake

Answer 8

weight gain - Obesity/risk of chronic diseases

Question 9

what are carbohydrates made up of?

Answer 9

Monosaccharides – simple sugars –
Smallest sugar Unit
General formula (CH2O)n, where n is 3 to 6.

Question 10

Disaccharides

Answer 10

two linked monosaccharide units

Question 11

Polysaccharides

Answer 11

composed of between a few and thousands of monosaccharides linked together.
E.g. cellulose, glycogen, starches, chitin (fungal cell wall component)

Question 12

examples of monosaccharides

Answer 12

1) Glucose – enters the cells via an active transport
source of immediate energy (via cellular respiration, generating ATP – Lecture 6). 1g produces 4 Kcal
Excess are stored as glycogen (by condensation reactions) by hepatic (liver) and muscle cells
Blood glucose regulation by insulin and glucagon

2) Fructose

3) Galactose

Question 13

examples of Disaccharides (units of 2 monosaccharides)

Answer 13

1) Sucrose - composed of a glucose + fructose

2) Lactose - composed of a galactose + glucose

3) Maltose – composed of 2 glucose units
Key structural motif of starch. It is released during starch breaking down (digestion)

Question 14

examples of Polysaccharides – chains of monosaccharides

Answer 14

1) Glycogen - multibranched polysaccharide of glucose

in meats (in a limited extent)

Storage form of glucose, mainly in hepatic and skeletal muscle cells
If glycogen is abundant, glucose excess can be used to make fats

2) Starch - long, branched or unbranched glucose chains

in grains, rice, wheat (storage form of glucose in plants)

Broken down during digestion, by salivary and pancreatic amylases into disaccharides (maltose), then hydrolysed into monosaccharides (glucose)  energy source

Question 15

Polysaccharides in nutrition (Dietary fibres)

Answer 15

Vegetables, fruits, whole grains, and legumes
Digestion - undigested until the large intestine, where some are broken down by bacteria

Trap/get rid of bile ( cholesterol levels) and molecules in the gut  regulate bowel activity
Prevention of heart diseases, obesity, as they help lower cholesterol

Question 16

What are the risks of low fibre intake diets?

Answer 16

Constipation and haemorrhoids

Increased risk of heart diseases and some types of tumours
E.g. colon cancer

Question 17

Glycaemic Index (GI)

Answer 17

Degree to which a food increases blood sugars and elicit insulin response
(diff carbo. digested and absorbed at different rates)

High GI (processed carbs, white bread, potatoes, watermelon) > raise blood sugar high and rapidly

Low GI (fruit, legumes, whole wheat)  raise blood sugar slowly and to a lesser extent

Question 18

Why has unhealthy foods such as crisps and chocolates have low GI

Answer 18

contains a lot of fat so the lipophilic effect means less carbohydrates absorption

Question 19

what type of food should type 2 diabetes consume?

Answer 19

low GI foods
Help stabilise long-term blood glucose levels
(contains a lot of fat)

Question 20

What are the Recommended intake of free sugar in the UK:

Answer 20

Limit the intake of free sugars (either added to food/drink or naturally present in fruit/vegetables, e.g. honey/smoothies) to 5% of the overall energy daily intake (30g of free sugars a day)

Question 21

Sugar Deficiency

Answer 21

hypoglycaemia
Energy deficit > CNS suffering, dizziness, mental and physical weakness

Protein breaking down to produce energy  kidney stress, digestive problems

Question 22

High free sugar intake effects on health

Answer 22

Obesity > weight gain and obesity

Increased chronic diseases risk (type 2 diabetes, cancers, hypertension, heart diseases)

Dental Caries bacterial fermentation of added sugars producing acids, contributing to tooth decay

Question 23

how many different types of amino acids?

Answer 23

20 with unique R group

Question 24

Non essential amino acids

Answer 24

can be synthesised by the body

Question 25

Essential amino acids

Answer 25

CANNOT be synthesised by the body MUST be provided in the diet

Question 26

*Conditionally Essential Amino Acid.

Answer 26

In some cases, some nonessential amino acids become essential (e.g. in newborns)

Question 27

Complete proteins

Answer 27

containing all the essential amino acids in the required proportions meat, fish, soya beans, milk, and eggs.

Question 28

Incomplete proteins

Answer 28

do NOT contain all the essential amino acids in the correct proportions. mainly of vegetable origin (cereals, peas, beans, and lentils). a diet based on a wide variety of incomplete proteins can avoid amino acid deficiencies. Essential consideration for strict vegetarian or vegan diets.

Question 29

Proteins are the only source of _______

Answer 29

nitrogen

Question 30

Protein Deficiency

Answer 30

Diet consistently suppling too little protein or lacks essential amino acids E.g. Marasmus and kwashiorkor (swollen abdomen), clinical syndromes in children/infants It can cause severe weight loss, slowed growth, impaired brain functions, etc Eating disorders, cancer, difficults to absorb nutrients

Question 31

Excess of Proteins

Answer 31

Diet consistently suppling too much protein (especially from animal sources). A risk factor for: Cardiovascular diseases Cancer (processed & red meat as carcinogens), Osteoporosis - calcium excretion increases, depleting the bone Kidney stones

Question 32

Digestion of stomach - describe process

Answer 32

starts in stomach; pepsin and acid > shorter polypeptides In pancreas, enzyme peptidases break down the polypeptides in the cells of small intestine to a.a

Question 33

Amino acid absorption (crucial for the essential ones)

Answer 33

Intestinal cells uptake amino acids and: released into the bloodstream used to make proteins converted to glucose, if needed broken down to provide energy via deamination producing ammonia (NH3) that is then converted to urea

Question 34

how much lipid should be in a daily intake?

Answer 34

20 - 35 %

Question 35

why are lipid important for diet?

Answer 35

Major fuel source during light/moderate exercise more energy per gram than carbohydrates (9 vs 4 kCal/g) Major store of energy from food (Triglycerides) Adipose cells uptake lipids and expand in size.

Question 36

advantages of lipid

Answer 36

Primary component of cell membranes and nerve sheaths (myelin) Cushioning and thermal insulation for the organs Required for the synthesis of steroid hormones Serve as a vehicle for the absorption of lipid soluble vitamins

Question 37

Types of fatty acids (3)

Answer 37

1) triglycerides - Primary lipid in food and in body GLYCEROL BACKBONE + 3 fatty acids 2) Phospholipids - Amphipathic molecule Cell membrane component HEAD GROUP PHOSPHATE GLYCEROL BACKBONE 2 FATTY ACID CHAINS 3) Sterols (cholestrol) Components of vitamins, hormones, cell membrane STEROID NUCLEUS HYDROXYL GROUP

Question 38

Fatty acids

Answer 38

Aliphatic building blocks of triglycerides, phospholipid and glycolipids. They differ by: Chain Length - 4 to 24 carbons long (even numbers) – Short (<6 C), medium (6-12 C), long (>12 C)

Question 39

Degree of saturation

Answer 39

presence & No. of double bonds in the chain Saturated – No double bonds Monounsaturated – having one double bond Polyunsaturated – having two or more double bonds

Question 40

Locations of Double Bonds

Answer 40

position of the double bond closest to the methyl (omega No.) Omega-3 Omega-6 Omega-9

Question 41

What are the properties of fatty acids? firmness stability food sources health effects

Answer 41

SATURATED - more solid at room temp - more stable / resistant to oxidation - animal-based food (milk, cheese, butter, eggs, fatty meat) - factor risk for heart diseases UNSATURATED - the more unsaturated points has, the more liquid it is (at room temp.) - more unsaturated points, the less stable/resistant to oxidation - plant-based food (avocados, olives, vegetable oils, etc), seafood - protective against chronic diseases (heart disease, stroke, cancer, etc)

Question 42

Essential fatty acids - The body can make fatty acids, except for:

Answer 42

Linolenic acid (an omega-3) and linoleic acid (an omega-6) These essential fatty acids MUST be provided by the diet (vegetable oils, seeds, nuts, fish, seafoods) Fatty Acid Deficiencies (infants) Impaired growth, reproductive failure, skin lesions, kidney and liver disorders

Question 43

Trans-fatty acids

Answer 43

Hydrogenation of unsaturated fatty acids - some unsaturation points are saturated by adding hydrogen molecules, (reducing the double bonds in the structure) Partially hydrogenation in food industry, to prevent oxidation, and ensure a longer shelf life some double bonds that remain after processing change their configuration from cis to trans Trans unsaturated fatty acids - in which the H are located on opposite sides of a double bond

Question 44

What os the health effect when LDL cholesterol in blood is increased??

Answer 44

^ risk of heart diseases

Question 45

Describe the process of Lipids digestion:

Answer 45

1) Mouth - lingual lipases released by salivary glands Important in infants - minor role in adults 2) Stomach - little lipid digestion by gastric lipases 3) Small Intestine – lipids activates the cholecystokinin (CCK) that release bile from the gallbladder Bile emulsifies fat for digestion - promotes the dispersal of fats in watery fluids, so that pancreatic & intestinal lipases can degrade triglycerides

Question 46

What are emulsifiers/

Answer 46

required to make lipids accessible to lipases water & oil > emulsification (micelles) > emulsified oil

Question 47

Describe the process of Absorption of lipids

Answer 47

1) Long chain fatty acids and monoglycerides combine with the bile, forming micelles, diffuse into intestinal cells and are reassembled into triglycerides 2) Triglycerides and phospholipids are packaged with proteins as chylomicrons 3) Chylomicrons are transport vehicles released into lymph vessels and reach the bloodstream (thoracic duct)

Question 48

Where are lipids (triglycerides) stored

Answer 48

adipose tissue energy deficit, triglycerides are hydrolysed to release energy