Biological Molecules and Enzymes

Question 1

Hydrolysis vs dehydration

Answer 1

Macromolecule broken into smaller molecules with addition of water = hydrolysis, dehydration is opposite and water is a byproduct

Question 2

Roles of lipids

Answer 2

Energy storage (due to long carbon chains)
Cellular organization and structure in the membrane bc they are hydrophobic
Precursor for vitamins and minerals bc they can pass through cellular membranes

Question 3

What is a fatty acid, Saturated vs unsaturated fatty acid

Answer 3

Building block for lipid compounds CHCHCHCOO-

Unsaturated has one or more carbon carbon double bonds

Question 4

What are phospholipids and what are they a component of

Answer 4

Lipids with a phosphate making it polar at one end and non polar at the other (amphiphathic) therefore a good structural component of membranes

Question 5

What do triacylglycerols do and what’s the structure

Answer 5

Store metabolic energy and provide thermal insulation and padding 
Glycerol head (CH3) and 3 fatty acid tails

Question 6

What do steroids (a type of lipid) do, structure

Answer 6

Regulate metabolic activities ex. Vit d, hormones, cholesterol
Four ringed

Question 7

The fatty acid eicosanoid and terpenes can serve as

Answer 7

Hormones/signalling molecules such as prostaglandins

Question 8

How are carbs useful, 2 examples

Answer 8

Energy source

Glucose and fructose

Question 9

Glycogen , starch, and cellulose are____ that differ in their

Answer 9

Glucose polymers with differing linkages (alpha for glycogen)

Question 10

Difference between nucleotide, nucleoside, and nucleic acid

Answer 10

Nucleoside is pentose(5C) sugar + nitrogenous base and nucleotide is formed with addition of phosphate. Nucleotides make up nucleic acids such as DNA

Question 11

Purines

Answer 11

Adenine and guanine

Question 12

Pyrimidines

Answer 12

Cytosine and thymine

Uracil (RNA)

Question 13

Types of bonds in DNA double helix

Answer 13

Phosphodiester bond between the phosphate and carbon of sugar formed via dehydration
Hydrogens bonds between nitrogenous bases (two for AT) ( 3 for CG)

Question 14

What is a primary structure of a protein - what types of bonds

Answer 14

Sequence of amino acids

C-N-C-N

Question 15

Secondary structure of a protein and the type of bonds

Answer 15

Beta pleated sheet of an alpha helix

Hydrogen bonds

Question 16

Which structure of a protein does proline effect

Answer 16

Secondary therefore also tertiary

Question 17

6 factors contributing to tertiary structure

Answer 17

1. Covalent disulfide bonds between 2 cystine amino acids
2. Ionic interactions between acidic and basic side chains
3. Hydrogen bonds
4. Van de waals forces
5. Hydrophobic side chains pushed from water toward center of protein
6. R group of proline

Question 18

What does denatured protein mean

Examples of denaturing agents

Answer 18

When the native conformation of the protein is disrupted
*** rarely effects the primary structure of a protein
Ph, heat

Question 19

When you see nitrogen on the mcat think

Answer 19

Protein

Question 20

What are enzymes

Answer 20

Proteins that act as catalysts (lower the energy of activation)

** forward and reverse of reaction

Question 21

What is Vmax, how can it be increased

Answer 21

Max rate of a reaction

Increase by adding more enzymes (proportional to enzyme concentration)

Question 22

What is the Michaelis constant Km

How can we change it

Answer 22

The substrate concentration at which the reaction rate = 1/2Vmax
Inversely proportional to enzyme affinity
Can’t change with enzymes - but can be altered by certain enzyme inhibition

Question 23

Some enzymes require coenzymes to function, what are some examples

Answer 23

Minerals
Coenzymes
Vitamins

Question 24

How are enzyme reactions effected by temperature, ph and substrate concentration ** think of the graphs

Answer 24

Temp increase reaction rate until at some point the enzyme denatures
Optimal ph depends on the enzyme but generally neutral - optimal pH
Rate of reaction increases with substrate until max rate has been achieved

Question 25

What is a zymogen - think plasminogen

Answer 25

Inactive form of an enzyme that is reversed when peptide bonds are cleaved

Question 26

What is negative feedback ****

Answer 26

One of the products downstream in a reaction comes back and inhibits enzymatic activity of an earlier reaction

Question 27

What is competitive inhibition and the two types

Answer 27

Competes with substrate by binding to active ** can be overcome by substrate Irreversible (if covalent bond) and reversible

Question 28

What is uncompetitive inhibition, effect on km and vmax

Answer 28

Bind to allosteric site of the enzyme substrate complex (so only once enzyme is associated with substrate) Decrease vmax , decreases Km

Question 29

What are mixed inhibitors

Answer 29

Bind to enzyme alone or substrate complex

Question 30

Mixed inhibitors effect on km

Answer 30

Mixed that prefer to bind to complex lower Km | Those that bind to enzyme primarily before substrate would increase Km

Question 31

What are noncompetitive inhibitors and how do they effect Km

Answer 31

Have no preference between enzyme and enzyme substrate complex Bind to allosteric site and change conformation of enzyme Km remains the same because they dont bind to active site

Question 32

What do you think when you see something that has ase in it on the mcat

Answer 32

Think enzyme then know it has nitrogen so is prone to denaturation

Question 33

Explain the structure of a lipoprotein | Why is it like that

Answer 33

Inside contains the triglycerides and cholesterol which is then surrounded by phospholipids. This is to transport insoluble items through the blood

Question 34

Memorize the amino acids ! Everything about them

Answer 34

Ok

Question 35

Basic amino acids at ph 7 why?

Answer 35

Lysine Arginine Histidine They have an NH2(amino group) in their R group that is protonated at a ph of 7

Question 36

Acidic amino acids at ph 7 why?

Answer 36

Aspartic acid Glutamic acid They have a second COOH(carboxylic) group that is deprotonated at ph of 7

Question 37

Amino acid charges in relation to ph (general)

Answer 37

Low ph tend to be positively charged | High ph tend to be negatively charged

Question 38

How do enzymes effect activation energy, do they change overall free energy

Answer 38

They do not lower Ea but provide an alternate pathway with a lower Ea!!! No dont change G

Question 39

Enzyme substrate complex has 2 different models explain them

Answer 39

Lock and key theory - substrate (reactant) fits exactly into active site of the enzymes (enzyme is bigger than the substrate) Induced fit model - active site of enzyme changes shape as substrate binds

Question 40

Structure of glycogen, starch, and cellulose

Answer 40

Glycogen - alpha link with branching Cellulose - beta link no branch Starch - alpha link no branching