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Flashcards in module 2 Deck (129):
1

glycoproteins

protein with one or more carbohydrate groups linked covalently to amino acid side chains

2

microfilament

polymer of actin, with a diameter of about 7 nm, that is an integral part of the cytoskeleton, contributing to the support, shape and mobility of eukaryotic cells

3

peroxisome

single membrane-bounded organelle that contains catalase and one or more hydrogen peroxide-generating oxidases and is therefore involved in the metabolism of hydrogen peroxide.

4

large ribosomal subunit

component of a ribosome with a sedimentation of 60S in eukaryotes and 50S in prokaryotes; associates with a small ribosomal subunit to form a functional ribosome

5

mitochondria and chloroplasts provide

energy for the cell

6

the ____ assists in the degradation of sugars (oxidation)

mitochondrion

7

the ___ harvests solar energy and converts it to chemical energy in the form of ATP

chloroplast

8

this structure in the mitochondria contains small circular DNA molecules that encode some RNAs and proteins needed in the mitochondria. Also involves ribosomes involved in protein synthesis

matrix

9

this type of electron transport exerts a proton motive force that tends to drive protons back down their concentration gradient

the electrochemical gradient

10

photosynthesis

a process that uses solar energy and CO2 to produce sugars and other organic compounds

11

thylakoids

flattened membranous sacs that surround the chloroplasts

12

reactions that depend on solar energy take place in or on the

thylakoid membrane

13

reaction involved in the reduction of CO2 to sugar occur within the

stroma

14

contain their own ribosomes and a small circular DNA molecule that encodes some RNA's and proteins needed

chloroplasts

15

two major biochemical processes of photosynthesis

-energy transduction reactions
-carbon assimilation reactions

16

energy transduction reactions

light energy is captured and converted into chemical energy

17

carbon assimilation reactions

(carbon fixation reactions)
- carbohydrates formed from CO2 and H2O

18

synthesizes proteins destined for various organelles, cellular membranes or secretion

the endomembrane system

19

endoplasmic reticulum

a continuous network of flattened sacs, tubules and vesicles through the cytoplasm of a eukaryotic cell

20

membrane bound sacs of the ER and the space between them

ER cisternae, ER lumen

21

__ ER forms large flattened sheets

Rough ER

22

___ ER form tubular structure

smooth ER

23

rough ER functions

synthesis, folding and structural maturation of more than a third of all proteins made in the cell

24

Smooth ER functions

involved in lipid synthesis, drug detox, carbohydrate metabolism, and biosynthesis of membrane

25

what synthesizes both membrane-bound and soluble proteins for the endomembrane system and where does it come from?

ribosomes from the cytosolic side of the rough ER

26

glycosylation

the addition of carbohydrate side chains to proteins.

Much of the protein processing carried out in the ER and Golgi involves glycosylation

27

involves a multi-step enzyme-catalyzed reactions resulting in the addition as well as the modification of the carbohydrate side chains (glycoproteins)

glycosylation

28

two general kinds of glycosylation

N-linked glycosylation
O-linked glycosylation

29

N-linked glycosylation

involves the addition of an oligosaccharide to the nitrogen atom of a certain asparagine residue

30

O-linked glycosylation

the addition of the oligosaccharide to the oxygen atom on the hydroxyl group of certain serine or threonine residues

31

initial steps of N-glycosylation

synthesizing oligosaccharides

32

after elongation in in glycosylation

the oligosaccharide is transferred to the asparagine residue of the recipient protein

33

cotranslational glycosylation

usually the oligosaccharide is added to the recipient protein as the polypeptide is being synthesized
(helps promote proper protein folding)

34

what binds to phosphate at the start of glycosylation and what binds to this?

N-acetylglucosamine, mannose units

35

what happens to the oligosaccharide after mannose binds?

translocation from the cytosol to the ER lumen.
more mannose added

36

ER-associated degredation

proteins that are incorrectly folded, modified or assembled are exported for degradation

37

degradation of misfolded proteins occurs where?

in the cytosolic proteasomes

38

ER stress

a buildup of misfolded proteins
- caused by numerous genetic and environmental issues

39

ER stress is emerging as a key contributor to

a growing list of human diseases: diabetes, neurodegeneration, and cancer

40

ER results in either

- ER homeostasis being restored and cell survival
or
-misfolded proteins continue to grow resulting in apoptosis

41

primarily involved in processing or storing nonprotein molecules within cells

smooth ER

42

drug detoxification involves

hydroxylation

43

hydroxylation

adding hydroxyl groups to hydrophobic drugs increases their solubility, making it easier to excrete from the body

44

becoming more resistant to a drug after being exposed to it

tolerance

45

smooth ER involved in the breakdown of stored glycogen. How?

contains glucose-6-phosphatase, an enzyme unique to smooth ER

46

glucose-6-phosphatase

hydrolyzes the phosphate from glucose-6- phosphate to form free glucose

47

liver stores ____ as ____ in granules associated with the smooth ER

glucose; glycogen

48

when glucose is needed by the body, glucose is broken down by

phosphorolysis, producing glucose-6-phosphate

(must be converted to free glucose to leave the cell)

49

concentration is greatest in the? lowest?

extracellular; cytosol

50

the ___ of muscle cells is an example of smooth ER that specializes in calcium storage

sarcoplasmic reticulum

51

the ___ has high concentrations of calcium binding protiens

ER lumen

52

calcium ions pumped into the ER by

ATP-dependent calcium ATPases

53

___ in some cells is the site of cholesterol and steroid hormone synthesis

smooth ER

(large amounts of smooth ER are found in cells that synthesize these steroids)

54

the committed step in cholesterol biosynthesis

hydroxymethylglutaryl-CoA reductase

- found in the smooth ER of liver cells and is targeted by cholesterol-lowering drugs called statins

55

functionally and physically linked to the ER

golgi complex

56

glycoproteins and membrane lipids from the ER undergo further processing and are sorted and packaged for transport here

golgi complex

57

plays a central role in membrane and protein trafficking

golgi complex

58

role in processing/packaging secretory proteins

golgi apparatus

59

synthesis of complex polysaccharides occurs here

golgi apparatus

60

once processed by the Golgi complex, materials to be exported from the cell are packaged into

secretory vesicles

61

a series of flattened membrane-bound cisternae

golgi complex

62

proteins and lipids leave the golgi in ____ that continuously bud from the tips of the trans-golgi network

transport vesicles

63

initial glycosylation occurs in ____ but further processing of N-glycosylated proteins occurs in

golgi complex from cis-golgi network to trans-golgi network

64

two models depict the flow of lipids and proteins through the golgi complex

stationary cisternae model and cisternal maturation model

65

stationary cisternae model

each cisterna in the golgi stack is a stable structure

- shuttling of vesicles enable transport of material

66

cisternal maturation model

the golgi cisternae are transient compartments. Gradual change from CGN through medial cisternae to TGN

67

movement of material toward the plasma membrane

anterograde transport

68

retrograde transport

flow of vesicles from golgi cisternae back to the ER

69

retention

once a protein reaches its destination, it must be prevented from leaving

70

protein tags

may be an amino acid sequence, hydrophobic domain, oligosaccharide side chain or some other feature. Critical for proper trafficking, retention or retrieval of cargo to specific location in the cell

71

sorting of newly synthesized proteins begin in the

ER and CGN

72

retrieval tags

once in the golgi, bind to receptor and then is packaged to a vesicle destined for retrograde transport back to ER

73

sorting of soluble lysosomal proteins to endosomes and lysosomes occurs in the

TGN

The mechanism involve phosphorylation of the carbohydrate tag
(mannose-6-phosphate) which is later bound by a receptor in the
TGN
2. The receptor-ligand complexes are packaged into transport
vesicles and conveyed to an endosome
© 2016 Pearson Education, Inc.
3. Tagged lysosomal proteins
bind to mannose-6-
phosphate receptors
(MPRs)
4. The receptor-ligand
complexes are packaged
into transport vesicles and
conveyed to an endosome
5. In animal cells, lysosomal
enzymes are transported
from the TGN to organelles
known as late endosomes

74

CONSTITUTIVE SECRETION

after budding from the TGN, some vesicles move directly to cell surface and immediately fuse with the plasma membrane
(continuous and independent of external signals)

75

regulated secretion

secretory vesicles first accumulate in the cell and fuse with plasma membrane only in response to specific signals

76

polarized secretion

in many cases, exocytosis of specific proteins is limited to a specific surface of the cell

77

which ion triggers exocytosis with fusion of regulated secretory vesicles

calcium

78

gene knock-out and knock-in is a tool to study

neuronal exocytosis

79

endocytosis imports extracellular molecules by forming

vesicles

80

endocytic vesicles

develop into early endosomes, which fuse from the TGN

81

important for ingestion of essential nutrients, defense against microorganisms

endocytosis

82

receptor mediated endocytosis

cells use receptor on the outer cell surface to internalize many macromolecules (specificity)

83

invagination (endocytosis)

proteins induce curvature and invagination of the pit

84

uncoating (endocytosis)

clathrin coat is released, leaving an uncoated vesicle . coat proteins and dynamin recycled to the plasma membrane

85

an organelle of the endomembrane system bounded by a single membrane

lysosome

86

___contain digestive enzymes called ____

lysosomes; acid phosphatase

87

degrade all major classes of biological macromolecules

lysosomes

88

lumenal side side of the membrane coated with glycoproteins to

protect the membrane from degredation

89

lysosomes develop from

endosomes

90

lysosomal enzymes synthesized in

rough ER and delivered from the TGN to endosomes

91

heterophagic lysosomes

lysosomes containing substances that originated outside the cell

92

autophagic lysosomes

those with materials that originated inside the cell

93

phagocytic vacuoles become ___ by

lysosomes by fusion with endosomes

94

vesicles formed by receptor-mediated endocytosis fuse with

vesicles of the TGN containing hydrolases

95

after digestion ceases, lysosomes become

residual bodies
- some cells release the contents by exocytosis; others accumulate debris contributing to cellular aging

96

lysosomal storage diseases characterized by

accumulation of indigestible material

97

cytoskeleton

network of interconnected filaments and tubules extending through the cytosol

98

plays a role in cell movement and division

cytoskeleton

99

dynamic and can readily remodel (dynamically assembled and disassembled)

cytoskeletal system

100

major structural elements of cytoskeleton

microtubules
microfilaments
intermediate filaments

101

microtubules composed of

tubulin subunits

102

microfilaments composed of

actin subunits

103

microtubules responsible for

-maintaining axon
-formation of mitotic and meiotic spindles
-maintaining or altering cell shape
-placement and movement of vesicles

104

axonemal microtubules

the axoneme, the central shaft of a cilium or flagellum, is a highly ordered bundle of MTs
include the organized and stable microtubules found in structures such as cilia, flagella, basal bodies

105

protein building blocks of microtubules

tubulin heterodimers

106

straight, hollow cylinders of varied length that consist of (usually 13) longitudinal arrays of polymers called protofilaments

microtubules

107

basic subunit of a protofilament

a heterodimer of tubulin, one α-tubulin and one β-tubulin
- These bind noncovalently to form an αβ-heterodimer, which does not normally dissociate

108

all the dimers in the microtubule oriented

the same

109

each alpha and beta subunit contains

an N-terminal GTP-binding domain, a central domain that interacts with MAPs (microtubule-associated proteins)

110

because of dimer orientation, protofilaments have

an inherent polarity

111

two ends of dimer called

plus and minus end and differ both chemically and structurally

112

microtubules form by

addition of tubulin dimers at their ends

113

essential for microtubule polymerization

GTP and Mg

114

tubulin concentration at which MT assembly is exactly balanced by disassembly called

critical concentration

115

addition of tubulin dimers occurs more quickly at which ends

plus ends

116

if the free tubulin concentration is above the critical concentration for the plus end but below that of the minus end, what will occur?

treadmilling

117

drugs can affect the assembly and stability of microtubules

assembly inhibitors and disassembly inhibitors

118

microtubules originate from

microtubule-organizing centers within the cell

ex//centrosome

119

centrosome associated with two _____ surrounded by pericentriolar material

centrioles

120

involved in basal body formation for cilia and flagella . walls formed by 9 pairs of triplet microtubules

centriole

121

microtubule-organizing centers

nucleate and organize the cell
-MTs grow outward from them with a fixed polarity. minus ends anchored in the MTOS
- dynamic growth and shrinkage of mtS OCCURS AT THE PLUS ENDS, NEAR THE CELL PERIPHERY

122

microfilaments

smallest of cytoskeletal filaments
- best known for role in contraction
involved in cell migration, amoeboid movement and cytoplasmic streaming

123

protein building block of microfilaments

actin

124

once synthesized folds into a globular-shaped molecule that can bind ATP of ADP (G-actin; globular actin)

actin

125

actins can be broadly divided into

muscle specific actin (alpha-actins) and nonmuscle specific actin (beta and gama)

126

g-actin polymerize into

f-actin microfibilaments

127

growing MF ends have____ whereas most of the MF is composed of ___

ATP-actin, ADP-actin

128

lamellipodia

allow cells to crawl, have branched network of actin

129

filopodia

form highly oriented parallel bundles allow cell to crawl