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Biochemistry > Chapter 13: Biochemical Signaling > Flashcards

Chapter 13: Biochemical Signaling Flashcards

1
Q

Intercellular signals coordinate metabolic activities through complex biochemical signaling
systems. Intercellular signals are mediated by chemical messengers known as

A

hormones

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2
Q

that specifically binds a
hormone or other ligand

A

receptor protein

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3
Q

a mechanism for transmitting the ligand-binding event to the cell
interior

A

ligand

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4
Q

chemical changes catalyzed by what

A

kinases and phosphatases

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5
Q

in which a succession of events that each depend on the previous one amplifies the signal

A

enzyme cascades

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6
Q

Control Fuel Metabolism

A

Pancreatic Hormone

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7
Q

examples of Pancreatic Hormone

A

glucagon and insulin

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8
Q

what is the stimuli for the release of insulin

A

high blood glucose concentrations.

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9
Q

what is the stimuli for the release of glucagon

A

low blood glucose concentrations.

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10
Q

It stimulates the liver to release glucose through the breakdown of glycogen (glycogenolysis) and the synthesis of glucose (gluconeogenesis) from noncarbohydrate
precursors.

A

Glucagon

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10
Q

stimulates muscle, liver, and adipose cells to store glucose for later use by
synthesizing glycogen, protein, and fat.

A

Insulin

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11
Q

It also stimulates adipose tissue to release fatty acids through lipolysis.

A

Glucagon

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12
Q

hormone of the adrenal gland

A

epinephrine (adrenalin)

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13
Q

It can stimulate glycogenolysis, gluconeogenesis, lipolysis in adipose tissue, the relaxation of smooth (involuntar muscle in the bronchi and in the blood vessels supplying the
skeletal (voluntary) muscles, and increased heart action

A

epinephrine (adrenalin)

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14
Q

is allosterically controlled by the effectors AMP , A TP , and G6P and is mostly in the T state under
physiological conditions.

A

phosphorylase beta

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14
Q

is unresponsive to these
effectors and is mostly in the R state unless there is a high level of glucose.

A

phosphorylase alpha

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15
Q

Insulin and growth factor bind to receptors whose C-terminal domains have what kind of activity

A

tyrosine kinase activity

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16
Q

Upon binding insulin, the cytoplasmic
protein tyrosine kinase domains get what?

A

phosphorylated on specific T yr residues

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17
Q

This autophosphorylation activates the what so that it can phosphorylate other protein substrates

A

PTK

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18
Q

will then relay signals to their
targets

A

Kinase cascades

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19
Q

SH2-containing proteins that interact
with the insulin receptor substrates

A

some are kinases,
some are
phosphatases,
and some are GTPases that are
therefore known as G proteins.

20
Q

When insulin activates the what, the result is an increase in protein
synthesis that supports cell growth and differentiation

A

Ras signaling pathway

21
Q

a response consistent with
insulin’s function as a signal of fuel abundance.

A

differentiation

22
Q

How a cell prevents inappropriate cross talk between closely related signaling pathways

A

scaffold proteins

23
Q

that bind some or all of the
component protein kinases of a particular signaling cascade so as to ensure that the protein
kinases of a given pathway interact only with one another.

A

scaffold proteins

24
Q

Intracellular signals must be “turned off” when?

A

after the system has delivered its message so that the system can transmit future messages

25
Q

their activities are balanced by the activities of protein phosphatases that hydrolyze the phosphoryl groups
attached to Ser, Thr, or T yr side chains and thereby limit the effects of the signal that activated the kinase.

A

protein kinases

26
Q

is caused by the Yersinia bacteria

A

Bubonic Plague (the flea-transmitted “Black Death”)

27
Q

Bacteria lack what?

A

protein tyrosine kinases

28
Q

are members of the superfamily of regulatory GTPases.

share common structural motifs that bind guanine nucleotides and catalyze the hydrolysis of GTP .
participate in signal
transduction systems

A

Heterotrimeric G proteins

29
Q

transduction systems that consist of three major components

A
  1. G protein–coupled receptors
  2. Heterotrimeric G proteins
  3. Adenylate cyclase. A
30
Q

catalyzes the synthesis of cAMP from ATP .

A

Adenylate cyclase

31
Q

what is Adenylate cyclase main target In eukaryotic cells,

A

protein kinase A (also known as cAMP-dependent protein kinase

32
Q

an enzyme that phosphorylates specific Ser or Thr residues of numerous cellular proteins.

A

protein kinase A (also known as cAMP-dependent protein kinase),

33
Q

is a second messenger, that
is, it intracellularly transmits the
signal originated by the
extracellular ligand.

A

cAMP

34
Q

bind peptide hormones, odorant (having an odor) and tastant (having a taste) molecules, eicosanoids. The importance of these receptors is also evident in the fact that some 60% of
the therapeutic drugs presently in use target them

A

The G protein–coupled receptors include the glucagon receptor, and a host of other proteins

35
Q

In the absence of what , protein kinase A is an inactive heterotetramer of two regulatory and two catalytic subunits, R2C2.

A

cAMP

36
Q

binds to the regulatory subunits to cause the dissociation of active catalytic monomers.

A

cAMP

37
Q

The targets of protein kinase A include

A

enzymes involved in glycogen metabolism.

38
Q

when what binds to the β-adrenoreceptor of a muscle cell, the
sequential activation of this system leads to the activation of glycogen phosphorylase,
thereby making glucose-6-phosphate available for glycolysis.

A

epinephrine

39
Q

Each step of a signal transduction pathway can potentially be

A

regulated

40
Q

In addition, reactions catalyzed by protein kinase A are reversed by protein

A

Ser/Thr
phosphatases.

41
Q

Many drugs and toxins exert their effects by modifying components of the what

A

adenylate cyclase system.

42
Q

The effect of G protein activation is short-lived, because of what

A

G alpha is also a GTPase that
catalyzes the hydrolysis of its bound GTP to GDP + Pi, although at the relatively sluggish rate of 2 to 3 min–1

43
Q

When GTP is bound to G alpha, its phosphate group promotes conformational changes
causing G alpha to do what

A

dissociate from G beta γ.

44
Q

antagonizes adenosine receptors causing an increase in cAMP concentration

A

caffeine

45
Q

Deadlier effects result from certain bacterial toxins that interfere with

A

heterotrimeric G
protein function.

46
Q

The toxin released by the bacterium causing cholera triggers what

A

massive fluid loss of over a liter per hour from diarrhea. Victims die from dehydration unless their lost
water and salts are replaced

47
Q

causes the transfer of the ADP-ribose moiety of NAD to an Arg residue of Gs protein. The modified G protein constantly activates adenylyl cyclase results in an overproduction of cAMP

A

Cholera toxin

48
Q

requires a receptor, a heterotrimeric G protein, a specific kinase, and a phosphorylated glycerophospholipid that is a minor component of the plasma membrane. It

A

Phosphoinositide pathway

49
Q

Phosphoinositide pathway produces what?

A

inositol-1,4,5-
trisphosphate (IP3),

Ca2+

1,2-diacylglycerol (DAG)

50
Q

The sense of taste in vertebrates reflects what?

A

the activity of neurons clustered in taste buds on
the surface of the tongue.

Biochemistry (17 decks)

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