lecturer 5

Question 1

_______ ______typically occurs by enzymes sensing too much product for their reaction building up via a special regulatory site on the enzyme

Answer 1

Feedback inhibition

Question 2

Phosphorylation of some substrates by ____ _____can serve to inactivate protein functions

Answer 2

protein kinases

Question 3

GTP is bound to the protein and converted to _______ as it acts on another protein

Answer 3

GDP + Pi

Question 4

When a protein binds a ligand or another protein and this induces a conformational change that opens another binding site in the molecule this is known as

Answer 4

allosterism

Question 5

The ____ _____ ____ or concentration of any individual species of protein in the cell will be a unique function of the factors controlling both its _______ &______ .

Answer 5

steady state level, synthesis (production) and degradation (destruction)

Question 6

The half-life of a protein is

Answer 6

is half the average number of minutes (or hours) the protein spends in the cell

Question 7

Ribosomes free in the cytosol and associated with _____ ______

Answer 7

the ER membranes

Question 8

Misfolded proteins in the cell can be degraded by what structures

Answer 8

Proteasomes

Question 9

The posttranslational modification that targets proteins to the proteasome is

Answer 9

Ubquitylation

Question 10

Protein degradation occurs by two mechanisms

Answer 10

Proteasomes, Lysosomes

Question 11

degrade cellular proteins that are damaged or that have been specifically targeted for degradation by modification with _____

Answer 11

ubiquitin

Question 12

Lysosomes (defining factor)

Answer 12

are a membrane bound cellular compartment containing proteases degradation of proteins found in membranes or soluble proteins imported into the cell.

Question 13

Regulated ubiquitin

modification leads to

Answer 13

degradation

Question 14

what is a type of sequestration that can hold can some transcription factors in the cytosol until signals cause modifications that allow their entry into the nucleus where they can function

Answer 14

localization

Question 15

Proteins are typically not active until they have assembled into their

Answer 15

quaternary structures

Question 16

alpha and beta subunits are _________ alone until they assemble into

Answer 16

non-functional

Question 17

Many enzymatic reactions or pathways are
self-regulated by feedback inhibition mediated
by

Answer 17

the end products

Question 18

Transcabamoylase catalyzes an early step in synthesis of pyrimidine nucleotides. CTP a _____ _____ of this pathway the ______ enzyme

Answer 18

downstream product, inhibits

Question 19

sequestering proteins____ and prevent assembly

Answer 19

bind

Question 20

what is a change due to binding of a ligand that promotes the binding of a second ligand

Answer 20

allosteric

Question 21

what are 4 key mechanisms that control protein activities

Answer 21

Modification by attachment of ubiquitin to lysine residues
Modification by protein phosphorylation/dephosphorylation
Nucleotide binding and hydrolysis
Modification by lipid anchor addition to C terminal Cys

Question 22

By modifying proteins, cells create at least __ potential states of activity for _________________

Answer 22

two, any modified protein

Question 23

modifying proteins can _______ functionality without having to ________________

Answer 23

increases, synthesize more proteins.

Question 24

Combinatorial control

Answer 24

groups of regulatory proteins work together to determine teh expression of a single gene

Question 25

eucaryotes can make more complicated tissues and organisms because

Answer 25

Combinations of regulation on synthesis points and post-translational modifications

Question 26

Protein ________ and _____ carry out the reversible modification of many substrate proteins

Answer 26

kinases, phosphatases,

Question 27

binding of the nucleotides ATP/ADP and GTP/GDP….

Answer 27

produces conformation changes controlling protein activities.

Question 28

Conformation changes due to ______ binding and ______ in Elongation Factor Tu during translation

Answer 28

nucleotide, hydrolysis

Question 29

what anchors or localizes proteins to different membranes

Answer 29

Lipid added to proteins

Question 30

what are examples of lipid additiom

Answer 30

GPI) of Prion proteins; prenylation of Ras and Rho proteins affecting growth

Question 31

Modifications that are part of the “histone code”include __________&________
occur as covalent modifications of
_____ _____ ____

Answer 31

methylation and acetylation, basic amino acids

Question 32

DNA + histone =

Answer 32

nucleaosome