Biological Molecules and Enzymes Flashcards
Hydrolysis vs dehydration
Macromolecule broken into smaller molecules with addition of water = hydrolysis, dehydration is opposite and water is a byproduct
Roles of lipids
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
What is a fatty acid, Saturated vs unsaturated fatty acid
Building block for lipid compounds CHCHCHCOO-
Unsaturated has one or more carbon carbon double bonds
What are phospholipids and what are they a component of
Lipids with a phosphate making it polar at one end and non polar at the other (amphiphathic) therefore a good structural component of membranes
What do triacylglycerols do and what’s the structure
Store metabolic energy and provide thermal insulation and padding Glycerol head (CH3) and 3 fatty acid tails
What do steroids (a type of lipid) do, structure
Regulate metabolic activities ex. Vit d, hormones, cholesterol
Four ringed
The fatty acid eicosanoid and terpenes can serve as
Hormones/signalling molecules such as prostaglandins
How are carbs useful, 2 examples
Energy source
Glucose and fructose
Glycogen , starch, and cellulose are____ that differ in their
Glucose polymers with differing linkages (alpha for glycogen)
Difference between nucleotide, nucleoside, and nucleic acid
Nucleoside is pentose(5C) sugar + nitrogenous base and nucleotide is formed with addition of phosphate. Nucleotides make up nucleic acids such as DNA
Purines
Adenine and guanine
Pyrimidines
Cytosine and thymine
Uracil (RNA)
Types of bonds in DNA double helix
Phosphodiester bond between the phosphate and carbon of sugar formed via dehydration
Hydrogens bonds between nitrogenous bases (two for AT) ( 3 for CG)
What is a primary structure of a protein - what types of bonds
Sequence of amino acids
C-N-C-N
Secondary structure of a protein and the type of bonds
Beta pleated sheet of an alpha helix
Hydrogen bonds
Which structure of a protein does proline effect
Secondary therefore also tertiary
6 factors contributing to tertiary structure
- Covalent disulfide bonds between 2 cystine amino acids
- Ionic interactions between acidic and basic side chains
- Hydrogen bonds
- Van de waals forces
- Hydrophobic side chains pushed from water toward center of protein
- R group of proline
What does denatured protein mean
Examples of denaturing agents
When the native conformation of the protein is disrupted
*** rarely effects the primary structure of a protein
Ph, heat
When you see nitrogen on the mcat think
Protein
What are enzymes
Proteins that act as catalysts (lower the energy of activation)
** forward and reverse of reaction
What is Vmax, how can it be increased
Max rate of a reaction
Increase by adding more enzymes (proportional to enzyme concentration)
What is the Michaelis constant Km
How can we change it
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
Some enzymes require coenzymes to function, what are some examples
Minerals
Coenzymes
Vitamins
How are enzyme reactions effected by temperature, ph and substrate concentration ** think of the graphs
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
What is a zymogen - think plasminogen
Inactive form of an enzyme that is reversed when peptide bonds are cleaved
What is negative feedback **
One of the products downstream in a reaction comes back and inhibits enzymatic activity of an earlier reaction
What is competitive inhibition and the two types
Competes with substrate by binding to active ** can be overcome by substrate
Irreversible (if covalent bond) and reversible
What is uncompetitive inhibition, effect on km and vmax
Bind to allosteric site of the enzyme substrate complex (so only once enzyme is associated with substrate)
Decrease vmax , decreases Km
What are mixed inhibitors
Bind to enzyme alone or substrate complex
Mixed inhibitors effect on km
Mixed that prefer to bind to complex lower Km
Those that bind to enzyme primarily before substrate would increase Km
What are noncompetitive inhibitors and how do they effect Km
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
What do you think when you see something that has ase in it on the mcat
Think enzyme then know it has nitrogen so is prone to denaturation
Explain the structure of a lipoprotein
Why is it like that
Inside contains the triglycerides and cholesterol which is then surrounded by phospholipids. This is to transport insoluble items through the blood
Memorize the amino acids ! Everything about them
Ok
Basic amino acids at ph 7 why?
Lysine
Arginine
Histidine
They have an NH2(amino group) in their R group that is protonated at a ph of 7
Acidic amino acids at ph 7 why?
Aspartic acid
Glutamic acid
They have a second COOH(carboxylic) group that is deprotonated at ph of 7
Amino acid charges in relation to ph (general)
Low ph tend to be positively charged
High ph tend to be negatively charged
How do enzymes effect activation energy, do they change overall free energy
They do not lower Ea but provide an alternate pathway with a lower Ea!!!
No dont change G
Enzyme substrate complex has 2 different models explain them
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
Structure of glycogen, starch, and cellulose
Glycogen - alpha link with branching
Cellulose - beta link no branch
Starch - alpha link no branching
