Compendium 3 - Are you what you eat?

Question 1

Carbohydrates

Answer 1

• made of mono/di/polysaccharides
• contain carbon, hydrogen and oxygen (two H and one O for every C)
• most come from plants
• recommended daily intake is 45-65%

Question 2

Examples of monosaccharides

Answer 2

• glucose
• fructose
• galactose

Question 3

Examples of disaccharides

Answer 3

• sucrose (table sugar) = fructose + glucose
• lactose (milk) = glucose + galactose
• maltose = glucose + glucose

Question 4

Polysaccharides

Answer 4

• long chains of 3000+ monosaccharides

* glycogen, starch and cellulose

Question 5

Function of carbohydrates in the body

Answer 5

• glucose: produces ATP
• excess glucose: stored as glycogen in muscle and liver cells
• excess glucose beyond storage: converted to fat
• sugars are part of DNA and RNA
• assist in making essential parts of cell membrane

Question 6

Proteins

Answer 6

• contain carbon, hydrogen, oxygen, nitrogen and sometimes sulfur

Question 7

Amino acids

Answer 7

• amino acids are basic building blocks
• amino acids join up to form peptides and proteins
• each amino acid has an anime group (NH2), a carboxyl group (COOH), a hydrogen (H) and a side group
• essential amino acids (histidine, isoleucine) can only be obtained from diet
• non essential amino acids are synthesised from essential amino acids

Question 8

Lipids

Answer 8

• composed of carbon, hydrogen, oxygen, sometimes nitrogen and phosphorus
• relatively insoluble in water
• less oxygen comparing to carbon when comparing lipids to carbs
• triglycerides make up 95% of fats in the body

Question 9

Triglycerides

Answer 9

• glycerol + 3 fatty acids
• have different lengths ( either 14 or 18 C atoms)
• H atoms determine whether a fat is saturated, unsaturated or trans fat

Question 10

Function of proteins in the body

Answer 10

• regulate body functions such as:

• haemoglobin is a protein that transports oxygen in blood
• enzymes, hormones, antibodies
• muscle proteins
• cell membrane transport

Question 11

Function of lipids in the body

Answer 11

• triglycerides: used to produce ATP (excess stored in adipose or liver)
• cholesterol: found in liver and egg yolks, a component of plasma membrane, modified to form bile salts
• phosolipids: major component of plasma membrane and myelin sheath, part of bile
• eicosanoids: derived from fatty acids, involved in inflammation, blood clotting, tissue repair, smooth muscle concentration

Question 12

Carbohydrate absorption in the body

Answer 12

• Polysaccharides:

• digested by saliva in the oral cavity
• digested by pancreatic amylase in the duodenum

• Disaccharides:
- digested by sucrase in the intestines

• Monosaccharides:
- glucose is absorbed into bloodstream via
microvilli in the intestines
- glucose is transported to liver via hepatic portal vein

Question 13

Protein absorption in the body

Answer 13

• Protein:
- digested by pepsin in stomach

• Polypeptides:
- digested by trypsin in duodenum

• Peptides/amino acids:
- absorbed into blood via microvilli in intestines

Question 14

Lipid absorption in the body

Answer 14

• Triglyerides

• bile from gall bladder emulsifies lipids in the duodenum
• lipase from pancreas causes further breakdown

• Monoglycerides:

• absorbed into lymphatic system via lacteals
• lipids are stored in adipose tissue and liver until needed

Question 15

Vitamins

Answer 15

• Organic molecules in very small quantities in food
• Essential for normal metabolism, cannot be produced by the body
• One food cannot provide all necessary vitamins

Question 16

Vitamin deficiencies

Answer 16

• vitamin C: stomach inflammation, diarrhoea
• vitamin A: toxic to foetus during
• vitamin D: alters calcium metabolism

Question 17

Vitamin abundances

Answer 17

• vitamin C: scurvy
• vitamin D: rickets
• vitamin B1 (thiamine): beriberi

Question 18

Minerals and their functions

Answer 18

• inorganic nutrients (no carbon, cannot be produced by the body)
• functions:
- membrane potential and action potential
- add mechanical strength to bones and teeth

Question 19

Mineral deficiencies

Answer 19

• iron: anaemia
• potassium: muscle weakness, abnormal heart function
• iodine: goitre

Question 20

The digestive process (digestion)

Answer 20

• takes place in mouth, stomach and small intestine
• breakdown of food molecules for absorption into the body
• mechanical: breaks large food molecules to small
• chemical: breaking of covalent bonds by digestive enzymes

Question 21

The digestive process (absorption)

Answer 21

• absorbing nutrients from small intestine, water from large intestine
• molecules are moved out of digestive tract and into circulation for distribution throughout body

Question 22

Enzymes

Answer 22

• a protein catalyst that increases the rate of reaction without permanently changing the enzyme
• highly specific: active site on the enzyme can only bind to a specific reactant
• often have ‘ase’ as a suffix

Question 23

Parts of digestive tract (top to bottom)

Answer 23

• mouth and salivary glands
• pharynx
• oesophagus
• liver and stomach
• gall bladder and pancreas
• small intestine (duodenum, ileum, jejunum)
• large intestine (cecum, colon, rectum, anal canal)
• anus

Question 24

Accessory organs of digestive system

Answer 24

• pancreas
• gall bladder
• liver
• glands secreting fluids into tract

Question 25

Functions of digestive system

Answer 25

• ingestion: introduction of food via mouth to stomach
• mastification: chewing, chemical digestion facilitating chemical digestion
• secretion: lubricate, liquefy, digest
• digestion: mechanical and chemical digestion of food into nutrients
• absorption: movement of nutrients out of digestive tract and into cells
• elimination: removal of waste products from body; defecation