Lecture 5

Question 1

What are carbohydrates?

Answer 1

They’re a source of energy and provide structure and support.

Question 2

What are monosaccharides?

Answer 2

They’re simple sugars, which all have C,H,O ratios of 1:2:1.

Question 3

What are hexose sugars?

Answer 3

They’re 6-carbon atoms and share the same molecular formula C6H12O6 (isomers).

Question 4

Give 4 examples of simple hexose sugars.

Answer 4

1. Glucose
2. Galactose
3. Fructose
4. Mannose

Question 5

What are the 2 configurations sugars can have?

Answer 5

1. Chain or linear configuration (<3% in sol’n)

2. Ring configuration of hexose sugars (>97% in sol’n)

Question 6

What’s glucose?

Answer 6

Its a dietary monosaccharide, it’s the main product of photosynthesis and is the main fuel for cellular respiration.

Question 7

What’s galactose?

Answer 7

It’s a dietary monosaccharide, when it combines with glucose it forms lactose and it can be rapidly converted to glucose.

Question 8

What is fructose?

Answer 8

Its a dietary monosaccharide, when combined to glucose it forms sucrose and is the primary source of energy for sperm.

Question 9

What are glycosidic bonds?

Answer 9

Through these bonds, monosaccharides link to create disaccharides & polysaccharides. The formation is between carbon 1 of one monosaccharide AND one hydroxyl group carried by an atom of a different monosaccharide.

Question 10

What’s a disaccharides?

Answer 10

It’s when a glycosidic bond links two monosaccharides.

Question 11

Give 3 examples of disaccharides.

Answer 11

1. sucrose= glucose + fructose
2. lactose= glucose + galactose
3. maltose= glucose + glucose

Question 12

What are polysaccharides?

Answer 12

They’re long chains of linked monosaccharides. They have two main functions; energy storage and structural support.

Question 13

Polysaccharides; Explain energy storage in plants.

Answer 13

In plants from photosynthesis, when they produce more alpha glucose than they can use, they store the excess in the form of starches, through an alpha 1-4 glycosidic bonds that use the glucose monomers to form starch polymers. Starches are storage polysaccharides. These starches are called amylose and amylopectin.

Question 14

Polysaccharides; Explain energy storage in animals & fungi.

Answer 14

In animals & fungi, when they absorb/ingest more alpha glucose than they can use, they store the excess in the form of glycogen, through an alpha 1-4 glycosidic bonds that use the glucose monomers to form glycogen polymers. Glycogen is a highly branched polysaccharide. These glycogen are called amylase.

Question 15

Polysaccharides; Explain energy storage in plants. Explain amylose and amylopectin.

Answer 15

Amylose: It’s a linear, unbranched, helical polymer and makes up 20-30% of starch.

Amylopectin: Highly branched polymer. Makes up 70-80% of starch.

Question 16

Polysaccharides; Explain energy storage in animals & fungi. Explain amylase

Answer 16

Amylase: its an enzyme that permits digestion of starch (it hydrolyzes the starch) in animals. Amylase can only hydrolyze (addition of H2O) alpha 1-4 glycosidic bonds.

Question 17

Polysaccharides; Explain energy storage in animals & fungi. Explain where glycogen is stored in mammals.

Answer 17

1. In liver cells, called hepatocytes. When blood sugar is low, the pancreas releases glucagon, which causes the liver to break down glycogen and release glucose into the blood stream.
2. In muscle cells, the glycogen stored is only used for the muscle cell itself.

Question 18

Polysaccharides; explain structural support in plants.

Answer 18

In photosynthesis, plants produce beta glucose monomers and link them together through beta 1-4 glycosidic bonds to make the cellulose (polymer) which is the linear structural polysaccharide. Cellulose makes up most of the cell wall.

Question 19

Polysaccharides; explain why animals cannot digest cellulose.

Answer 19

Animals cannot digest cellulose because of the beta 1-4 glycosidic bonds.

Question 20

Polysaccharides; Why can bacteria/fungi and some protists digest cellulose?

Answer 20

Bacteria/fungi and some protists can because they have cellulase which is an enzyme that can digest cellulose.

Question 21

Polysaccharides; What are ruminants?

Answer 21

Ruminants are unable to digest cellulose (like cows). Cows have a four-chambered stomach. Plant materials goes to rumen where bacteria breaks down the cell wall. Cows hav symbiotic relationship w/ these microbes. The pH drops in the last chamber.

Question 22

Polysaccharides; explain structural support in fungi.

Answer 22

Chitin (polymer) is the structural polysaccharide, which is formed the linkage of beta glucose monomers (N-acetylglucosamine) which are the beta 1-4 glycosidic bonds. Chitin makes up the fungi’s cell wall, but can also be found in the exoskeleton of insects and crustaceans.

Question 23

Polysaccharides; explain why most animals cannot digest chitin.

Answer 23

Because of the beta 1-4 glycosidic bonds that link the monomers.

Question 24

Polysaccharides; explain why bacteria/fungi can digest chitin.

Answer 24

Because they have chitinases which allows them to digest chitin.

Question 25

What are lipids?

Answer 25

They are NOT made from repeating monomers. They are defined by a shared property, however, they are hydrophobic. They aren't defined by a structure.

Question 26

What are the 3 types of major lipids?

Answer 26

1. Neutral fats 2. Phospholipids 3. Steroids

Question 27

What are neutral fats?

Answer 27

They're for energy storage, insulation for cold and protection for internal organs. They're made of 2 kinds of molecules; fatty acids and glycerol.

Question 28

What are 2 other ways to say fatty acids?

Answer 28

Palmitic acid and its made of a hydrocarbon chain.

Question 29

How do fatty acids link to a glycerol molecule?

Answer 29

This can happen through a condensation or dehydration synthesis reaction. Fatty acids molecules and glycerol molecules will form an ester bond.

Question 30

The amount of fatty acids per glycerol can range from 1 to 3, what would the 3 options be called?

Answer 30

1 fatty acid per glycerol would be called a monoglyceride. 2 fatty acids per glycerol would be called a diglyceride. 3 fatty acids per glycerol would be called a triglyceride.

Question 31

What is a triacylglycerol?

Answer 31

It is a lipid and is used to store energy.

Question 32

What are saturated fatty acids?

Answer 32

In a hydrocarbon chain the carbon atoms are connected to each other by single covalent bonds which allows them to bind to their full compliment of hydrogen atoms= saturated with hydrogen Since they form linear molecules, they stack easily which form van der waals interactions which then stabilize the molecules. This is what makes them solid at room temperature (like butter)

Question 33

What are unsaturated fatty acids?

Answer 33

In a hydrocarbon chain, most of the carbon atoms are connected to each other by single covalent bonds while some are linked by double bonds. This means they do not have their full compliment of hydrogen atoms= not saturated with hydrogen The double bonds give the molecule a "kink", which makes it hard for them to stack. This is what makes them liquid at room temperature (like oil)

Question 34

What are phospholipids?

Answer 34

These are the major constituents of cell membranes and form lipoproteins. They're made up of 2 fatty acid molecules, 1 glycerol molecule and 1 phosphate molecule.

Question 35

What does it mean when phospholipids are amphipathic?

Answer 35

It means they can contain both hydrophilic and hydrophobic groups in the same molecule. They have a hydrophilic head (polar) and hydrophobic tails (non polar). When they go into water they assemble into bi-layers. They shield the hydrophobic portion.

Question 36

What are steroids?

Answer 36

They are constituents of the cell membrane (aka cholesterol). They are components of vitamins and hormones and are made up of sterol which are four fused rings composed of 20 bonded carbon atoms.

Question 37

What's a lipoprotein?

Answer 37

Since fats are not hydrophilic, they usually travel through the blood THROUGH lipoproteins. Which are typically classified by density.

Question 38

What are high density lipoproteins?

Answer 38

aka HDL=goof cholesterol, HDL particles remove fats and cholesterol from cells & from the circulatory system, and transport it back to the liver for excretion/re-utilization. Those with higher levels of HDL-C tend to have less issues with cardiovascular diseases.

Question 39

What are low density lipoproteins?

Answer 39

aka LDL. They carry cholesterol from the liver to the cells of the body. LDL particles can also transport fat molecules into the artery wall. They're retained there by arterial proteoglycans and attract macrophages that engulf the LDL particles and start the formation of plaques. Increased levels are associated with atherosclerosis.