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PMP-101 > Cellular & Molecular Bioscience - Nutrition. macro-nutrients > Flashcards

Cellular & Molecular Bioscience - Nutrition. macro-nutrients Flashcards

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1
Q

Nutrition

Nutrient

A

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.

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2
Q

Diet

A

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

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3
Q

What are the 6 nutrient classes?

A

Macronutrients
carbohydrates
proteins
lipids
water

Micronutrients
vitamins
mineral salts

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4
Q

Macronutrients - energy-yielding nutrients:

A

Organic nutrients that are broken down to provide energy

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5
Q

energy released from nutrients can be measured in;

A

calories
or
kcal

1000 cals in 1 kcal

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6
Q

daily calorie intake

A

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

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7
Q

Excessive prolonged lower calories intake – weight loss

A

Nutrient/energy deficiencies

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8
Q

Consistent higher calories intake

A

weight gain - Obesity/risk of chronic diseases

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9
Q

what are carbohydrates made up of?

A

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

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10
Q

Disaccharides

A

two linked monosaccharide units

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11
Q

Polysaccharides

A

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

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12
Q

examples of monosaccharides

A

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

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13
Q

examples of Disaccharides (units of 2 monosaccharides)

A

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)

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14
Q

examples of Polysaccharides – chains of monosaccharides

A

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

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15
Q

Polysaccharides in nutrition (Dietary fibres)

A

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

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16
Q

What are the risks of low fibre intake diets?

A

Constipation and haemorrhoids

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

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17
Q

Glycaemic Index (GI)

A

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

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18
Q

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

A

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

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19
Q

what type of food should type 2 diabetes consume?

A

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

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20
Q

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

A

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)

21
Q

Sugar Deficiency

A

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

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

22
Q

High free sugar intake effects on health

A

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

23
Q

how many different types of amino acids?

A

20 with unique R group

24
Q

Non essential amino acids

A

can be synthesised by the body

25
Q

Essential amino acids

A

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

26
Q

*Conditionally Essential Amino Acid.

A

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

27
Q

Complete proteins

A

containing all the essential amino acids in the required proportions

meat, fish, soya beans, milk, and eggs.

28
Q

Incomplete proteins

A

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.

29
Q

Proteins are the only source of _______

A

nitrogen

30
Q

Protein Deficiency

A

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

31
Q

Excess of Proteins

A

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

32
Q

Digestion of stomach - describe process

A

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

33
Q

Amino acid absorption (crucial for the essential ones)

A

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

34
Q

how much lipid should be in a daily intake?

A

20 - 35 %

35
Q

why are lipid important for diet?

A

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.

36
Q

advantages of lipid

A

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

37
Q

Types of fatty acids (3)

A

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

38
Q

Fatty acids

A

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)

39
Q

Degree of saturation

A

presence & No. of double bonds in the chain

Saturated – No double bonds
Monounsaturated – having one double bond
Polyunsaturated – having two or more double bonds

40
Q

Locations of Double Bonds

A

position of the double bond closest to the methyl (omega No.)

Omega-3
Omega-6
Omega-9

41
Q

What are the properties of fatty acids?

firmness
stability
food sources
health effects

A

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)

42
Q

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

A

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

43
Q

Trans-fatty acids

A

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

44
Q

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

A

^ risk of heart diseases

45
Q

Describe the process of Lipids digestion:

A

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

46
Q

What are emulsifiers/

A

required to make lipids accessible to lipases

water & oil > emulsification (micelles) > emulsified oil

47
Q

Describe the process of Absorption of lipids

A

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)

48
Q

Where are lipids (triglycerides) stored

A

adipose tissue

energy deficit, triglycerides are hydrolysed to release energy

PMP-101 (53 decks)

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