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21 fall: Biochem > Test 3: Lecture 54 > Flashcards

Test 3: Lecture 54 Flashcards

1
Q

___ a molecule secreted by ductless glands into the circulatory system to regulate physiology and behavior of organs throughout the body

A

hormone

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2
Q

hormones are produced by ___ glands

A

endocrine

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3
Q

hormones offer a critical means of ___ between tissues and organ systems in response to internal and external stimuli

A

communication

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4
Q

Hormones do not initiate reactions but rather they affect the ___of pre-existing metabolic functions in a positive or negative fashion

A

rate

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5
Q

Some hormones have specific effects on a single cell type, others a more __ effect

A

general

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6
Q

Hormones are effective at ___ concentrations

A

minute (very small amount)

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7
Q

Hormones have a very ___ half-life in circulation

A

short

(ranging from minutes to hours)

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8
Q

endocrine glands produce and secrete hormones ___ into the circulatory system

A

directly

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9
Q

endocrine glands ___ have ducts

A

do not

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10
Q

key functions of hormones

A

reproduction

growth and dev

homeostasis

energy production, utilization and storage

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11
Q

two main classes of hormones

A

amion acid derived

lipid derived (steroids)

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12
Q

amino acid derived hormones are :

A
  • Whole proteins
  • Peptides (fragments of proteins)
  • Amines (derivatives of the amino acid tryptophan)
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13
Q

Lipid derived hormones are derived from ___

A

cholesterol

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14
Q

how do hormone achieve an effect on target cells?

A

receptors

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15
Q

each type of hormone has a specific ___ to which it can bind

A

receptor

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16
Q

two types of hormone receptors

A

plasma membrane bound

intracellular

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17
Q

plasma membrane bound hormone receptors usually bind to ___

A

peptide hormones

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18
Q

plasma membrane bound hormone receptors work by ___

A

Binding to cell membrane activates intracellular signal transduction programs that lead to gene expression responses in the nucleus.

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19
Q

intracellular hormone receptors usually bind to what type of hormone?

A

steroid (lipid derived)

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20
Q

how do intracellular hormone receptors work?

A

Binding to cell membrane activates intracellular signal transduction programs that lead to gene expression responses in the nucleus.

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21
Q

two types of control of hormone production

A

external and internal stimuli

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22
Q

___ is the main way of regulation of hormone production

A

feedback loops

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23
Q

negative feedback loops

A

end product/ intermediates stop reaction

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24
Q

positive feedback loops

A

intermediate/ end products induce production

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25
Q

pancreas secretion of insulin and glucagon peptides is an examples of ___ hormone

A

amino acid derived

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26
Q

levels of blood sugar regulate secretion of hormones from the ___

A

pancreas

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27
Q

pancreas secretes ___ when glucose levels are high

A

insulin

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28
Q

insulin binds to insulin receptors on fat and muscle and ___ glucose uptake

A

promotes

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29
Q

three types of cells in the pancreas

A

islets of langerhans

alpha

beta

delta

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30
Q

alpha cells:

A

secrete glucagon

facilitate the breakdown of glycogen to glucose. This elevated the blood sugar

(islet of langerhans in pancreas)

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31
Q

___ secrete the hormone insulin, which is essential for the maintenance of normal blood sugar levels. Inadequate levels result in diabetes mellitus

A

Beta cells

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32
Q

beta cells secrete the hormone ___, which is essential for the maintenance of normal blood sugar levels. Inadequate levels result in ___

A

insulin

diabetes mellitus

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33
Q

___ suppress the release of glucagon and insulin in the pancreas

A

delta cells

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34
Q

delta cells suppress the release of ___ and ___.

A

glucagon

insulin

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35
Q

___ secrete glucagon in the pancreas

A

alpha cells

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36
Q

Human insulin consists of 51aa in two chains connected by 2 ___ bridges

A

disulfide

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37
Q

insulin is a single gene product cleaved into 2 chains during ___ modification.

A

post-translational

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38
Q

insulin is degraded by ___

A

glutathione-insulin transhydrogenase (insulinase)

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39
Q

insulinase does what?

A

degrades insulin by cleaving the disulfide links

half life of insulin 5-10 minutes

glutathione-insulin transhydrogenase (insulinase)

40
Q

insulin is synthesized as ___ in the pancreatic beta cells.

A

preproinsulin

41
Q

preproinsulin is cleaved to ___ in the ER

A

proinsulin

42
Q

proinsulin is converted into active insulin by ___ in the ___

A

cellular endopeptidases in the golgi apparatus

43
Q

The endopeptidases cleave ___ at 2 positions, releasing a fragment called the C-peptide, and leaving 2 peptide chains, the B- and A- chains, linked by 2 ___bonds.

A

proinsulin

disulfide

44
Q

what is the quaternary structure of insulin

A
  • Insulin monomers can be in R-state or T-state conformations. (monomer are two strands an alpha and a beta chain)
  • Insulin monomers form dimers (T state and R state combine- 4 in total)
  • Insulin dimers for hexamers around a Zn2+ (zinc) ion ( 3 dimers bind together)
45
Q

Insulin dimers for hexamers around a ___ ion

A

zinc

46
Q

the insulin dimer is stabilized by ___ bonds

A

hydrogen

47
Q

Insulin binding to target cell insulin receptors initiates signal transduction cascades that lead to ___ localizing to plasma membrane

A

glucose transporters (GLUT 4)

glut 4 lives in vesicles of cell, will get triggered to move to cell membrane and will bring glucose into cell

48
Q

___ facilitate influx of glucose into the cell

A

Glucose transporters (GLUT 4)

49
Q

eat high sugar food will trigger :

A

beta cells in pancreas to release insulin: cells will use glucose and liver will store glucose as glycogen= normal levels of blood glucose 90 mg/100 ml

50
Q

if you don’t eat, blood glucose will fall which leads to ___

A

alpha cells in pancreas will release glucagon.

this triggers liver to breakdown glycogen into glucose and blood glucose will increase back to normal levels

51
Q

Type 1 diabetes

A

insulin dependent

insulin not made: can be treated by giving insulin

52
Q

Type 2 diabetes

A

non insulin dependent

insulin not recognized by cells, can’t bring sugar into the body

53
Q

what is the “master” gland that regulated all other endocrine glands and also releases ___

A

pituitary

growth hormone

54
Q

Growth hormone is a ___hormone

A

protein

55
Q

growth hormone is secreted by the ___

A

pituitary gland

56
Q

Pituitary release is controlled by the ___

A

hypothalamus

57
Q

direct effects of growth hormones

A

anti insulin action

increased lipolysis

increased blood and sugar and other anti-insulin effects

58
Q

example of indirect effects of growth hormones

A

will effect liver and other tissues to make insulin- like growth factors (IGFs)

which will then cause an indirect effect of

increased cartilage formation and skeletal growth, increased protein synthesis and cell growth and proliferation

59
Q

___ feedback control of growth hormone release

A

negative

60
Q

negative feedback of GH release

A

growth hormone stops GHRH (growth hormone releasing hormone)

insulin like growth factor 1 (IGF-1) stops growth hormone and activates GHIH (Growth hormone inhibiting hormone)

61
Q

high levels of growth factor will inhibit

A

growth hormone releasing hormone

62
Q

high levels of insulin like growth factor 1 (IGF1) will stimulate __ and decrease __

A

growth hormone inhibiting hormone

secreting of growth hormone

63
Q

neurohormones are ___

A

hypothalamus hormones

64
Q

___ regulate the release of pituitary hormones

A

hypothalamus hormones

65
Q

steroid hormones are produced in the ___

A

adrenal cortex, testis, ovary and some peripheral tissues (adipose tissue)

66
Q

All steroid hormones share a typical (but not identical) ___ ring structure

A

carbon-based

67
Q

All steroid hormones are derived from ___ and differ only in the ring structure and side chains attached to it.

A

cholesterol

68
Q

All steroid hormones are ___soluble but ___ insoluble

A

lipid

water

69
Q

steroid hormones bind to ___ receptors

A

intracellular (they are lipid soluble= can freely move through the lipid bilayer)

70
Q

•While ___hormones are encoded by specific genes, ___ hormones are synthesized from the enzymatic modification of cholesterol.

A

peptide

steroid

71
Q

•There are far fewer different types of ___ hormones than ___ hormones.

A

steroid

peptide

72
Q

•The regulation of ___ involves control of the enzymes which modify cholesterol into the steroid hormone of interest.

A

steroidogenesis

73
Q

•The first enzymatic step in the production of ANY steroid hormone begins with enzymatic modification of ___

A

cholesterol

74
Q

cholesterol can be made within the cells from ___

A

acetyl CoA

(de novo synthesis).

75
Q

A key rate-limiting enzyme for production of cholesterol in the cell from acetyl CoA is ___

A

HMG-CoA reductase.

76
Q

There is negative feedback regulation of ___ activity by cholesterol, so that high intracellular cholesterol inhibits de novo synthesis.

A

HMG-CoA reductase

77
Q

•Cholesterol is also taken up by the cell in the form of ___

A

low density lipoprotein (LDL).

78
Q

•LDL is a complex composed of cholesterol, ___ , ___, and proteins

A

phospholipids, triglycerides

(proteins and phospholipids make LDL soluble in blood).

79
Q

•LDL is taken into cells via LDL receptors, and broken down into ___ and then ___

A

esterified cholesterol,

free cholesterol

80
Q

two ways cell get cholesterol

A

from outside cell (LDL)

make it in cell from acetyl CoA

81
Q

All steroid hormones derive from the ___within the cell.

A

free cholesterol

82
Q

•A series of enzymatic steps in the ___ convert cholesterol into all of the other steroid hormones and intermediates.

A

mitochondria and ER

83
Q

what is the rate limiting step of steroid synthesis

A

The rate-limiting step in this process is the transport of free cholesterol from the cytoplasm into mitochondria.

84
Q

the process of transport of free cholesterol from the cytoplasm into mitochondria is carried out by ___

A

Steroidogenic Acute Regulatory Protein (StAR)

85
Q

1st step of cholesterol breakdown into other hormones is ___

A

CYP11A into pregnenolone

86
Q

•Steroid hormones are not water soluble so have to be carried in the blood complexed to specific binding ___.

A

globulin proteins

87
Q

•Corticosteroid binding globulin (CBG) carries ___

A

cortisol

steroid hormones have to be carried through blood because they are hydrophobic

88
Q

•Sex steroid binding globulin (SHBG) carries ___ and ___

A

testosterone and estradiol

steroid hormones have to be carried through blood because they are hydrophobic

89
Q

Glucocorticoids

A

cortisol is the major representative in most mammals – produced by adrenal cortex

class of steroid hormone

90
Q

Mineralocorticoids

A

; aldosterone being most prominent – produced by adrenal cortex

class of steroid hormone

91
Q

Androgens

A

such as testosterone – produced by testis

class of steroid hormone

92
Q

Estrogens

A

, including estradiol and estrone – produced by ovary

type of steroid hormone

93
Q

Progestogens (also known a progestins)

A

such as progesterone – produced by ovary and adrenal cortex

class of steroid hormone

94
Q

Steroid hormones are classified chemically by number of ___.

A

carbons

95
Q

what are the most common number of carbons for steroid hormones?

A

C18 (ovarian)

C19 (testicular)

C21 (adrenal cortical)

21 fall: Biochem (44 decks)

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