Lecture 3b

Question 1

Types of carbohydrate

Answer 1

• Carbohydrate Monomer:
  Monosaccharide
• Carbohydrate dimer:
  Disaccharide
• Carbohydrate polymer:
  Polysaccharide

Question 2

3 classes and 2 types of carbs

Answer 2

1. Simple carbs:
   - Monosaccharide
   - Disaccharide
2. Complex carbs
   - Polysaccharide

Question 3

Functions of Carbohydrates

Answer 3

1. ENERGY
2. 1 Immediate energy. Cells use mainly glucose to make ATP (cellular respiration or fermentation): in prokaryotes & eukaryotes (neurons ♥ Carbs)

1.2 Energy STORAGE
Excess glucose stored as a polysaccharide: starch (cells of photoautotrophs) or glycogen (liver, muscle of animals, granules in unicellular organism)
When needed, starch & glycogen are broken down into glucose monomers (see slide 10) to make ATP (slide 12)

2.STRUCTURAL SUPPORT: Polysaccharides

2.1 Cellulose (glucose + other molecules)
Plant cell wall made mainly of cellulose

2.1 Chitin (glucose + other molecules)
Exoskeletons (lobsters, crabs, insects…) & cell wall of fungus

Question 4

Photoautotrophs vs heterotrophs

Answer 4

Photoautotrophs make monosaccharides through photosynthesis
Include plants, photosynthetic protists, & Cyanobacteria
They make disaccharides & polysaccharides (starch & cellulose) by joining monosaccharides together… they don’t consume polysaccharides

Heterotrophs consume monosaccharides, disaccharides, polysaccharides
Include most bacteria, all animals, all fungi, many protists
Can join monosaccharides to form disaccharides & polysaccharides (glycogen or starch, depending on the organism).

Question 5

What cells do with saccharides? mono/di/poly

Answer 5

monosaccharides:
Can be used to make ATP
Can be bonded together to make di/polysaccharides

disaccharides:
Can be digested to monosaccharides or bonded together to make polysaccharides

polysaccharides:
Can be used as a source of
stored energy or for structural support.
Can be digested to disaccharides, then monosaccharides as needed

Question 6

3 different polymers of glucose

Answer 6

1. Starch (granules in plants)
2. Glycogen
   which are energy storage: Excess glucose stored as starch or glycogen
   When needed, hydrolyzed to glucose → used to make ATP.
3. Cellulose (Plant cell wall made mainly of cellulose)
   Structural

Question 7

Dietary Fiber we can’t digest

Answer 7

Cellulose

we don’t have enzymes to break these fibers

Question 8

Dietary Fiber we can digest

Answer 8

Starch (We have enzymes to digest (most) starches)

Question 9

Dietary fiber partially broken down by which microbes

Answer 9

Bacteria in digestive systems of herbivores (cows, sheep: eat grass) & humans
Protists in termites (eat wood)
Fungi in the env’t

Break down cellulose into glucose

Question 10

How is the blood sugar level regulated? Vertebrates and Invertebrates

Answer 10

Produce hormones: insulin & glucagon
Vertebrates (mammals, birds, reptiles & amphibians) make these in a pancreas

Invertebrates: those that have blood (mulluscs, worms…), have cells that produce the hormones (no pancreas though)

Question 11

Hormones released by the pancreas to regulate blood sugar levels

Answer 11

Insulin (hormone) released when blood sugar (glucose) is high: causes a drop in blood glucose

Glucagon (hormone) released when blood sugar low or in response to (sympathetic) nervous system causes an increase in blood glucose

Question 12

3 types of lipids

Answer 12

1. Fats
2. Phospholipids
3. Steroids: Sterols & steroid hormones

Question 13

Fats’ function

Answer 13

1. Fat: 2x more energy/gra, than carbs
   Fat+Oxygen –> ATP + CO2 + Heat
2. Insulates and protects internal organs

Question 14

Fat (triglyceride) Structure

Answer 14

1 glycerol + 3 fatty acids

Question 15

why are FA essential in our diets?

Answer 15

Because we can’t make them

Question 16

Fatty acids can differ in

Answer 16

1. Length of their carbon chain
2. Level of saturation
   Saturated, monunsaturated, polyunsaturated
   Affects the SHAPE of the fatty acid: straight vs bent

Question 17

Fatty acid level of saturation

Answer 17

Saturated fatty acids: have hydrogen atoms surrounding every carbon in the chain; they have no double bonds

Monounsaturated fatty acids: 1 double bond b/w carbons (lack hydrogen atoms in 1 region)

Polyunsaturated fatty acids: 2 or more double bonds b/w carbons (lack hydrogen atoms in 2 or more regions)

Question 18

Cis & trans UNSATURATED FA

Answer 18

Cis FA: H on the same side of double bond

Trans FA: H on the different side of double bond

Question 19

Hydrogenation

Answer 19

add hydrogen
Breaks double bonds and put H
Process developed to increase the shelf life (fat doesn’t get oxidized)

Question 20

Fat is…

Answer 20

the body’s major storage form of energy

Question 21

Phospholipids are

Answer 21

Major constituent of cell membranes

Question 22

Phospholipids are made of

Answer 22

2 molecules of fatty acids: hydrophobic
1 glycerol molecule: hydrophilic
1 phosphate molecule: hydrophilic
(FYI: 1 choline: hydrophilic)

Amphipathic: hydrophobic & hydrophilic

Question 23

Phospholipids form

Answer 23

Phospholipids form cell membranes

Phospholipids self orient into a double layer as the hydrophobic tails (repel from water) attract one another.

Question 24

Steroids

Answer 24

Lipids containing multiple rings of carbon atoms

Question 25

Relationship between Bile acids and sterols

Answer 25

Bile acids are sterols made in the liver

Question 26

Example of steroid hormones in body

Answer 26

Vitamin D is a steroid hormone that needs 3 different organs to be made. Notice that cholesterol is a precursor for vitamin D (as it is for bile acids)