Carbohydrates, Lipids, Proteins

Question 1

Isomers

Answer 1

Compounds that have the same chemical formula but different structures

Question 2

Epimers

Answer 2

Carbohydrate isomers that differ in configuration around only one specific carbon atom

Question 3

Enantiomers

Answer 3

Pairs of structures that are mirror images of eachother

Question 4

Glyceraldehyde

Answer 4

D and L designations are based on the configuration of the single asymmetric carbon atom in this

Question 5

Most naturally occurring sugars are

Answer 5

D isomers (right OH)

Question 6

Glucose

Answer 6

Primary enregy source, preferred for brain, required of cells with few/no mitochondria
essential in exercising muscle
source: diet, degradation of glygogen, gluconeogenesis

Question 7

Fructose

Answer 7

sweeter than glucose

source: fruits, vegetables, honey

Question 8

Galactose

Answer 8

less sweet than glucose

Source: dairy products

Question 9

Sucrose

Answer 9

Glucose + fructose

sugar cane and beets

Question 10

Maltose

Answer 10

Glucose + glucose

Major degradation product of starch, malt sugar

Question 11

Lactose

Answer 11

Galactose + glucose

mammalian milk, milk sugar

Question 12

Cellulose

Answer 12

structural polysaccharide
(maj constituent of plant cell walls)

Question 13

starch

Answer 13

storage polysaccharide
(prevalent in all plant seeds and tubers)

Question 14

glycogen

Answer 14

storage polysachharide

branched polymer

Question 15

Types of starch

Answer 15

Amylopectin/amylose

Question 16

digestion of carbs

Answer 16

mouth - salivary a-amylase
small intestine - pancreatic a-amylase
upper jejunum - dextrinase and glucoamylase cleave oligosaccharides, isomaltase, maltase, sucrase, lactase

Question 17

glucose and galactose absorbed by

Answer 17

sodium-dependent glucose cotransporter 1 (SGLT-1)

Question 18

fructose absorbed by

Answer 18

sodium-independent monosaccharide transporter (GLUT-5)

Question 19

5 Classes of Lipids

Answer 19

1. Fatty Acids
2. Triacylglycerols (fats and oils)
3. Glycerolphospholipids (membrane lipids)
4. Sphingolipids (membrane lipids)
5. Cholesterol

Question 20

Functions of lipids

Answer 20

• Membrane structure in cells and organelles
• Major source of energy
• Cell signalling (steroid hormones and prostaglandins)
• Fat pads around organs and joints
• Provide electrical insulation for myelinated nerves

Question 21

Triacylglycerol

Answer 21

• Simplest form
• Formed from fatty acids and glycerol
• Each triglyceride has 3 ester linkages formed by dehydration reactions between the COOH group of fatty acid and each OH group of the glycerol
• Body’s MAIN source of energy, stored in adipose

Question 22

Non-esterified fats

Answer 22

are free fatty acids which are the major fuel for metabolism

Question 23

Essential fatty acids

Answer 23

Can’t be synthesized by the body, must be acquired from food

Question 24

Membrane lipids are made of

Answer 24

• Phospholipids
• Glycolipids
• Cholesterol - precursor for other substances e.g bile salts, steroid hormone, vitamin D

Question 25

When lipids enter the duodenum..

Answer 25

• The gall bladder secretes bile salts to emulsify the fats before digestion –> small globules.
• Triglycerides are then digested by lipase from the pancreas –> free fatty acids

Question 26

How are free fatty acids absorbed?

Answer 26

Transported to intestinal microvilli on enterocytes for absorption. Small-chain fatty acids can diffuse directly into the bloodstream

Question 27

After larger triglycerides are absorbed

Answer 27

They are reassembled in the SER and packaged with cholesterol into chylomicrons

Question 28

What are chylomicrons?

Answer 28

The largest and least dense lipoproteins which enter the lymphatic system and are deposited into the venous circulation via the thoracic duct.