Lecture 4: Carbohydrates and Lipids

Question 1

carbohydrates

• aka?
• function (4)
• state the names for carbs that are: monomers, dimers, oligomers, and polymers
• formula?

Answer 1

• sugars
• provide energy, can store energy, structural components, and can be used to identify outside of cell
• monosaccharides, disaccharides, oligosaccharides, polysaccharides
• Cn(H2O)n
• C6H12O6

Question 2

In water, pentose and hexose form:

Answer 2

ring structures

Question 3

can you draw the 2 different configurations of glucose in water?

Answer 3

• see notes

Question 4

disaccharides

• made how
• list 1 example and the monomer components

Answer 4

• made through dehydration between 2 hydroxy groups

- sucrose (from glucose and fructose)

Question 5

oligosaccharides

• define
• what type of bonds between components
• shape
• can form bonds with:

Answer 5

• carb with a small amount of monosaccharides
• has glycosidic bonds between monosaccharides
• straight chained or branched
• incredible diversity; can form bonds with proteins or lipids

Question 6

glycoproteins and glycolipids

Answer 6

• oligosaccharides on cell surface bound to proteins or lipids
• cell marker (helps with cell recognition with the human body)

Question 7

polysaccharides

- list the major ones (5) and describe each of their functions briefly

Answer 7

• long linear and branched polymers
• starch: plant cell energy storage
• glycogen: animal cell energy storage
• cellulose: cell walls of plants
• chitin: cell wall of funghi; insect shell
• peptidoglycan: bacteria cell walls

Question 8

lipids

• made up mostly of?
• non polar or polar? what does that mean when placed in water?
• what are the major components of lipids in cells (2)

Answer 8

• hydrogen and carbon
• non polar; meaning they are hydrophobic
  major components of lipids in cells:
• steroids (like cholesterol, or steroid hormones)
• fatty acids (free fatty acids, fats, phospholipids) (note: fats and phospholipids are bound to glycerol)

Question 9

fatty acids

• explain structure
• chain length
• two types of fatty acids

Answer 9

• carobxyl group (weak acid) and a hydrocarbon non polar tail
• 14-22 carbons
• unsaturated and saturated

Question 10

• explain the difference between an unsaturated and saturated fatty acid

Answer 10

• saturated: packed more densley, harder, with a higher melting point
• unsaturated: more fluid, oil, low melting point, liquid at room temperature

Question 11

what is a neutral lipid? Give the 3 types and an example of each

Answer 11

• fatty acid that forms an ester bond with an alcohol
• triglyceride (mostly saturated fatty acids vs mostly unsaturated fatty acids): butter vs safflower oil
• wax ester: bees wax

Question 12

triglyceride

- explain structure and type of lipid

Answer 12

neutral lipid with a glycerol bound to three fatty acid molecules through ester bonds

Question 13

DAG and MAG stand for? made of?

Answer 13

• DAG: diacyl-glycerol; 2 fatty acids, 1 OH

- MAG: monoacyl-glycerol; 1 fatty acid, 2 OH

Question 14

explain phospholipids

• structure (components, top and bottom, interactions environment)
• when phospholipids make a bilayer, how thick is it?

Answer 14

• glycerol ester with 2 fatty acids and 1 phosphoric acid
• polar head with phosphate and glycerol; hydrophilic
• non polar tail; hydrophobic
• phospholipids: heads interact with water and tails interact with each other
• 4nm thick bilayer

Question 15

steroids

• structure
• examples (2)

Answer 15

• non polar 4 ring structure; hydrophilic alcohol group and a non polar tail (includes the rings)
• testosterone, cholesterol

Question 16

amphiphilic molecules

• define
• nature of the molecule:
• example (1)

Answer 16

• molecule with both hydrophilic and hydrophobic segments
• form structures to shield hydrophobic parts from water; expose hydrophilic heads to water
• phospholipids: heads interact with water and tails interact with each other

Question 17

explain the phospholipid bilayer/ membrane

• permeability (3 things that impact it)
• short unsaturated tails vs long saturated tails? explain
• 3 traits
• what impacts the fluidity of the membrane?
• what else is contained in the membrane? (3)

Answer 17

• permeability depends on a molecule’s size, polarity, and the fluidity of the membrane
• short and unsaturated hydrocarbon tails have a higher permeability and fluidity allowing more molecules to pass through
• traits: flexibile, repairable, expandable
• temperature impacts the fluidity of the membrane
• contained in the membrane: cholesterol, carbs, proteins (can move laterally)

Question 18

draw the permeability scale for

- O2, CO2, N2, H2O, glycerol, glucose, sucrose, Cl-, K+, Na+

Answer 18

• see notes

Question 19

explain membrane proteins

• function
• 2 types (how does one type stay anchored?)
• 2 different types of structures?
• describe the side chain interactions

Answer 19

• proteins that interact with the membrane
• membrane proteins allow the passive movement of ions, water or other solutes to passively pass through the membrane down their electrochemical gradient
• peripheral membrane protein: exists on the outside bilayer
• integral membrane protein: exists on the inside bilayer and is anchored in by hydrophobic amino acids; can form pores that allow molecules to pass through (ion channels)
• alpha helix and b barrel structures
• hydrophilic side chains face inside of the pore; hydrophobic side chains face the membrane

Question 20

summarise the 5 different types of membrane transport and what each is used for

Answer 20

• diffusion (small uncharged molecules: H2O, CO2, etc)
• facilitated transport (large/ charged molecules)
• active transport (Na+, K+, etc; moving against gradient and requires ATP)
• endocytosis (vesicles)
• exocytosis (vesicles)
• see notes