lecturer 5 Flashcards

(32 cards)

1
Q

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

A

Feedback inhibition

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2
Q

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

A

protein kinases

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3
Q

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

A

GDP + Pi

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4
Q

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

A

allosterism

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5
Q

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

A

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

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6
Q

The half-life of a protein is

A

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

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7
Q

Ribosomes free in the cytosol and associated with _____ ______

A

the ER membranes

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8
Q

Misfolded proteins in the cell can be degraded by what structures

A

Proteasomes

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9
Q

The posttranslational modification that targets proteins to the proteasome is

A

Ubquitylation

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10
Q

Protein degradation occurs by two mechanisms

A

Proteasomes, Lysosomes

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11
Q

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

A

ubiquitin

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12
Q

Lysosomes (defining factor)

A

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

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13
Q

Regulated ubiquitin

modification leads to

A

degradation

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14
Q

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

A

localization

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15
Q

Proteins are typically not active until they have assembled into their

A

quaternary structures

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16
Q

alpha and beta subunits are _________ alone until they assemble into

A

non-functional

17
Q

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

A

the end products

18
Q

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

A

downstream product, inhibits

19
Q

sequestering proteins____ and prevent assembly

20
Q

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

21
Q

what are 4 key mechanisms that control protein activities

A

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

22
Q

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

A

two, any modified protein

23
Q

modifying proteins can _______ functionality without having to ________________

A

increases, synthesize more proteins.

24
Q

Combinatorial control

A

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

25
eucaryotes can make more complicated tissues and organisms because
*Combinations* of regulation on synthesis points and post-translational modifications
26
Protein ________ and _____ carry out the reversible modification of many substrate proteins
kinases, phosphatases,
27
binding of the nucleotides ATP/ADP and GTP/GDP....
produces conformation changes controlling protein activities.
28
Conformation changes due to ______ binding and ______ in Elongation Factor Tu during translation
nucleotide, hydrolysis
29
what anchors or localizes proteins to different membranes
Lipid added to proteins
30
what are examples of lipid additiom
GPI) of Prion proteins; prenylation of Ras and Rho proteins affecting growth
31
Modifications that are part of the “histone code”include __________&________ occur as covalent modifications of _____ _____ ____
methylation and acetylation, basic amino acids
32
DNA + histone =
nucleaosome