Lec 7-8 Flashcards
Protein structures
Primary: amino acid sequences
Secondary: spirals and folds
Tertiary: complex 3-D shape that gives proteins their function
Quaternary: for more complicated proteins
The fully mature GLUT1 is made up of 164 amino acids bonded
together, starting with a methionine, and ending with a cysteine. This description is referring to which structure of the GLUT1 protein?
A) Primary
B) Secondary
C) Tertiary
D) Quaternary
A
An amino acid sequence is a primary structure
Enzyme
They speed up the rate of chemical reactions
How do enzymes work?
Brings substate to active site, substrate binds to active site of the enzyme, product is released
Enzyme and substrate fit together because of induced fit, substrate slightly changes shape of enzyme to fit
Enzyme inhibition
Allosteric regulation: regulatory molecule binds somewhere other than active site, changes shape of the enzyme
Competitive inhibition: regulatory binds to active site, blocking substrate from binding
BOTH REVERSIBLE
Riboflavin deficiency is sometimes caused by a RFVT3 that is nonfunctional because the environmental toxin HYU is acting as an inhibitor which changes it’s shape. What type of inhibition is this? What is its
immediate effect?
a) Cleavage of peptide bonds; neither HYU nor RFVT3 can bind.
b) Competitive; riboflavin is physically and directly blocked from binding RFVT3.
c) Competitive; HYU binds somewhere other than the active site. Riboflavin can’t bind.
d) Allosteric; riboflavin is physically and blocked from binding RFVT3.
e) Allosteric; HYU binds somewhere other than the active site. Riboflavin can’t bind
E
The riboflavin can’t bind because the toxin boned somewhere on the enzyme that isn’t the active site. This changes the shape of the enzyme preventing the riboflavin from binding
When there is a higher concentration of product than substrate, the enzyme ________. When there is a higher concentration of substrate compared to product, the enzyme _______.
A) speeds up, slows down
B) slows down, speeds up
C) speeds up, speeds up
D) slows down, slows down
B
What is the endomembrane system?
Endoplasmic reticulum
The primary structure of all proteins are made…
by ribosomes
How are proteins sorted?
signal sequence- first few or last few amino acids in chain
chemical label- chemical group added to a protein after its finished being manufactured, folded and specialized
What does a protein that functions in the cytoplasm get?
Nothing
What does a protein that functions in the nucleus, peroxisome, or mitochondria/chloroplasts get?
Only a nuclear, peroxisome, or mito/chloro signal respectively
what proteins get ER signals?
Proteins that function in the endomembrane system, cell membrane, or outside the cell
Folding of these proteins occur in the endoplasmic reticulum
What proteins don’t get a chemical label?
Proteins that get embedded in the cell membrane or leave the cell
Protein manufacture in endomembrane system
- Amino acid chain begins from ribosome in the cytoplasm
- First amino acids are ER signal
- ER signal sequence binds to signal recognition particle, pauses translation
- SRP binds to receptor in RER
- Amino acid chain enters RER
- SRP detaches, ribosomes complete primary structure, amino acid chain released to be folded
