SL Option C Flashcards
(38 cards)
How to make beta pleated sheets
sections of polypeptide run parallel, and hydrogen bonds form between them
How to make alpha helices
polypeptides wind into right-handed helix and hydrogen bonds form between adjacent turns of the helix
Types of intramolecular bonds in proteins
- Ionic bonds form bw positively/negatively charged R groups
- hydrophobic interactions (weak) can form between R groups
- hydrogen bonds can form between some R groups
- disulfide bridges (strong) can form between cysteines
Primary structure of a protein
Number and sequence of amino acids in a polypeptide (50-1000)
Secondary structure of a protein
Regular repeating structures (alpha helix/beta pleated sheet) stabilized by hydrogen bonds in between groups
Tertiary structure of a protein
Three dimensional conformation of a polypeptide (when polypeptide folds up after translation)
-stabilized by intramolecular (disulfide bridges, hydrophobic interactions, hydrogen, ionic) bonds
Quaternary structure of a protein
Linking together of 2+ polypeptides to form a single protein
- some are linked to prosthetic group: non-polypeptide structure
- these proteins are called conjugated proteins
Fibrous protein
Long, narrow shape, insoluble in water
Globular protein
Rounded shape, soluble in water
Four functions of proteins, example, details
Structural - collagen - strengthen bone, tissue, and skin; collagen fibers formed in the spaces between cells
Transport - hemoglobin - bind oxygen to lungs and transport to tissues
Movement - myosin - cause contraction of muscle fibers
Defense - immunoglobulin - act as antibody
Non-polar amino acids
hydrophobic; inside of protein to stabilize structure, cause proteins to stay embedded in membrane
Polar amino acids
hydrophilic; outside of protein to make them water soluble, cause proteins to stick out of membrane, also create channel proteins to let hydrophilic substances to pass through
Activation energy
energy needed to start a reaction
Most biological reactions are…
…exothermic: energy released is > activation energy
What do enzymes do to activation energy?
Lower it in the reactions they are catalyzing, to make the process easier
Induced fit model
Active site isn’t already conformed to substrate…as the substrate gets closer, active site becomes complementary and forms around the substrate. Bonds in substrate weaken, thus causing the reaction, and then disassociate into products and active site returns to original position
Competitive inhibition
Inhibitor binds to active site, thus blocking the substrate
Non competitive inhibition
Inhibitor binds to different part on enzyme, but alters active site so it won’t catalyze reaction
Effect of low concentration of competitive inhibitors
Increases in substrate concentration gradually reduce the effect of the inhibitor bc substrate/inhibitor compete for the same active site, but substrates eventually win due to population size
Effect of low concentration of non competitive inhibitors
Increases in substrate concentration increase enzyme activity, but substrate can’t prevent inhibitor from binding, so maximum enzyme activity rate plateaus at a lower rate than if it weren’t inhibited
Features of a metabolic pathway
- many chemical rxns carried out in particular sequence
- enzymes to catalyze each rxns
- all rxns occur inside cells
- some are a cycle (Krebs) some are a chain (glycolysis)
- some break down organic compounds (catabolic) some build them (anabolic)
End product inhibition
product of the last reaction in a pathway inhibits the enzyme that catalyzed the reaction
Allosteric enzymes
Have two non-overlapping binding sites…one as active site, one as allosteric site
Four steps in glycolysis
- phosphorylation - adding a phosphate group added to glucose provided by ATP
- lysis - splitting molecules
- oxidation - two atoms of hydrogen removed
- ATP is formed - pyruvate
