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molec and cell exam 3 > exam 3 > Flashcards

exam 3 Flashcards

1
Q

in order for multicellular organisms to communicate you need _______ cell and a _______ cell

A

signaling

target

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2
Q

target cells need _____ proteins to detect the signal

A

receptor

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3
Q

the extracellular signal is converted into a intracellular signal, which is a process known as ____________

A

transduction

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4
Q

_______ has a variety of functions, depending on the cell that receives the signal

A

acetylcholine

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5
Q

intracellular signal molecules generally influence transcription and bind to a member of the nuclear receptor ______________

A

superfamily

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6
Q

these relays involve ___________ signaling pathways, that can operate in the following ways

A

intracellular

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7
Q

_______ of these proteins is typically done by phosphorylation, while ______ is typically done by dephosphorylation

A

activation

deactivation

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8
Q

Many pathways involve several kinases activating the next kinase in the pathway, which activates the next kinase; these are referred to as phosphorylation ______

A

cascades

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9
Q

CPCRs span the plasma membrane back and forth ___ times

A

7

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10
Q

the α subunit has an affinity for ____ when it is ______

A

GDP

inactive

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11
Q

when a signal molecule binds to the GPCR, it causes the αsubunit to exchange the GDP for a _____ (it is now ________)

A

GTP

active

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12
Q

eventually, the α subunit will _______ its GTP to GDP, which will ‘turn off’ the system and restore the G protein to its inactive state

A

hydrolyze

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13
Q

the response of skeletal muscle to __________ is an excellent example of a cAMP pathway

A

adrenaline

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14
Q

________ filaments have a diameter between that of microtubules and actin

A

intermediate

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15
Q

the main purpose of these filaments is to provide _____ strength, which prevents the overstretching of cells

A

tensile

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16
Q

eight of these tetramer ropes come together to form a

single filament, which is made up of a total of __ subunits

A

32

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17
Q

Because of the α and β arrangements of the tubulin subunits, the microtubules have _____ (the α being the - negative end, and the β being the + positive end).

A

polarity

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18
Q

microtubules show _________ instability

A

dynamic

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19
Q

growing microtubules end up with a ‘GTP ____’

A

cap

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20
Q

__________ proteins can help anchor microtubules onto the plasma membrane

A

capping

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21
Q

______ proteins help direct movement in the cell

A

motor

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22
Q

they use the energy of ____ to drive their incremental movement along filaments

A

ATP

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23
Q

there are many other actin-binding proteins that help control the behavior of actin filaments, including capping proteins (prevent depolymerization) and ____________ proteins (provide a starting point for filament growth)

A

nucleating

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24
Q

“cell crawling” is mediated by _______ filaments, where the extending protrusions are driven by actin polymerization at the cell surface (i.e. the growth of actin filaments ‘pushes’ out a cellular protrusion)

A

actin

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25
Q

Common protrusions driven by actin are ______ (“false feet”) of amoebas

A

pseudopods

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26
Q

myosin involved in muscle contraction belongs to the ___________ subfamily

A

myosin-II

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27
Q

myosin-II molecules are _________ of myosin molecules, with each dimer having two heads and a rod-like tail

A

dimers

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28
Q

bundles of actin and myosin filaments can therefore generate a _____________ force seen in muscle cells

A

contractile

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29
Q

muscle fibers are made of several __________, which are composed of contractile units called ____________

A

myofibrils

sarcomeres

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30
Q

when a muscle cell is excited via T _________, Ca2+ is released from the sarcoplasmic reticulum (modified ER)

A

tubules

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31
Q

in the absence of Ca2+, a rod-shaped protein filament called ______________ blocks the actin/myosin binding sites, which prevents muscle contraction

A

tropomyosin

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32
Q

when Ca2+ is available, it binds to _____________, which in turn shifts the position of tropomyosin to expose the actin binding sites

A

troponin

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33
Q

the remaining three phases (G1, S and G2) together are referred to as ____________

A

interphase

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34
Q

the G phases are also times for important ___________

A

checkpoints

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35
Q

if the G1 conditions are not met, the cell enters into a specialized __________ phase known as G0, which can last for the lifetime of the cell in some cases

A

resting

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36
Q

__________ can arise from G1 misregulation - where cells divide without any checks and balances

A

cancer

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37
Q

studying the cell cycle control system has occurred with ________ primarily since the proteins involved are highly conserved in all eukaryotic organisms

A

yeast

38
Q

proteins called ________ activate enzymes known as cyclin-dependent protein kinases (CDKs) by forming complexes

A

cyclins

39
Q

cyclin-CDK is inactive until it is finally turned on by a _______________ (i.e. it is turned on by the loss of a -PO4)

A

phosphatase

40
Q

the concentration of a cyclin depends on ___________

A

proteolysis

41
Q

when cyclins reach a certain level, they are tagged with __________, which sends them to the proteasome

A

ubiquitin

42
Q

at the end of M phase, the cell is split in two in a process known as ___________

A

cytokinesis

43
Q

cleavage begins with a ____________ furrow (near the end of anaphase) perpendicular to the axis of the mitotic spindle

A

cleavage

44
Q

variations in the position of the mitotic spindle can create ____________ division (important for embryogenesis)

A

asymmetric

45
Q

a ______________ ring composed of actin and myosin filaments causes the contraction (the same proteins that allow muscle contraction)

A

contractile

46
Q

a _________________ structure is formed, which attracts Golgi vesicles full of polysaccharides and glycoproteins (young cell wall components)

A

phragmoplast

47
Q

___________ (“rebar” made of glucose strands) and _________ (polyphenolic “glue”) are added to complete the new cell wall

A

cellulose

lignin

48
Q

programmed cell death is known as ________________

A

apoptosis

49
Q

cells that die from injury is called ___________

A

necrosis

50
Q

the cell surface is also changed to attract ________________, which engulf the cell before it bursts open

A

macrophages

51
Q

during apoptosis, enzymes called ____________ initiate an irreversible pathway of cell death (once it starts it can’t be undone)

A

caspases

52
Q

growth and division of cells of multicellular organisms rely on __________ proteins

A

signal

53
Q

____________ factors act by binding to cell-surface receptors, which then regulate the Bcl2 family of proteins

A

survival

54
Q

____________ act by cell-surface receptors, which initiate pathways that lead to release of “molecular brakes” that prevent cells from entering S phase from G1 phase

A

mitogens

55
Q

well-known mitogen is platelet-derived growth factor(PDGF), which is released from ____________ at the site of a wound; PDGF then stimulates cell proliferation of surviving cells at the wound site, which leads to healing

A

platelets

56
Q

when the liver is injured or wounded, _____________ growth factor helps to promote cell division among the surviving liver cells

A

hepatocyte

57
Q

__________ factors operate through cell-surface receptors and stimulate pathways that lead to increased protein production and/or decreased protein degradation

A

growth

58
Q

__________ is an example of signal proteins that prevent cell growth

A

myostatin

59
Q

there are two main stages involved in generating chemical energy via membranes (called _______________ coupling)

A

chemiosmotic

60
Q

with mitochondria, a single glucose molecule produces __ ATP

A

36

61
Q

the _______ membrane contains transport proteins called ________ that allow relatively small molecules (5 kDa or less) to pass through easily

A

outer

porins

62
Q

the ________ membrane is less permeable, and contains ATP synthase and the proteins required for the electron transport chain; it is also convoluted, forming infolds called ____________ that help to increase the surface area within the mitochondria

A

inner

cristae

63
Q

the _________ is the large internal space of the mitochondria that is bordered by the inner membrane

A

matrix

64
Q

the _______________ space is the space between the inner and outer membrane

A

intermembrane

65
Q

the space contained by the inner membrane is called the _________

A

stroma

66
Q

these enzymes are found in the _____________ membrane of disc-like sacs called thylakoids, that exist in stacks called ________

A

thylakoid

grana

67
Q

chloroplasts contain multi-protein complexes called ________________ embedded in the thylakoid membrane

A

photosystems

68
Q

the antenna complex contains hundreds of _______________ and other pigment molecules that are able to funnel energy toward the reaction center

A

chlorophyll

69
Q

when a special chlorophyll molecule (_______) in the reaction center of photosystem II (PSII) is excited by energy from

A

P680

70
Q

the electron is then replaced by the oxidative splitting (____________) of a water molecule, which also generates O2

A

photolysis

71
Q

these protons are then pumped across the thylakoid membrane by ATP synthases, which generate ATP in the stroma in a process known as __________________________

A

photophosphorylation

72
Q

The special chlorophyll (_______) of photosystem I (PSI) also absorbs light energy and loses an electron in the same way as photosystem II

A

P700

73
Q

the ATP and NADPH produced from the light reactions are used for carbon __________

A

fixation

74
Q

the most important enzyme in the Calvin cycle is ___________

A

Rubisco

75
Q

breaking down compounds is referred to as _____________

A

catabolism

76
Q

______________ (“sugar splitting”) occurs in the cytoplasm of cells and does not require oxygen

A

glycolysis

77
Q

for each glucose consumed, two ATP are consumed and four are produced - resulting in a net gain of _ ATP

A

2

78
Q

his production of ATP without the mitochondria is known as ___________-level phosphorylation

A

substrate

79
Q

after glycolysis, pyruvate enters the _______________ where it is converted to acetyl CoA

A

mitochondria

80
Q

a process called _____________ involves the production of more complex molecules from simple ones

A

anabolism

81
Q

notice how glycolysis and the citric acid cycle are central to ___________________

A

metabolism

82
Q

what are the 2 processes that use actin and myosin to generate a contractile force

A

Muscle contraction

Cytokinesis

83
Q

What are the different strategies between a plant and animal cell for cytokinesis?

A

plant walls are rigid whereas animal cells are squishy

84
Q

What is the difference between apoptosis and necrosis?

A

Apoptosis is a planned and organized cell death

Necrosis is a unplanned and messy cell death

85
Q

what are the 2 main types of receptors?

A

cell-surface receptors

intracellular receptors

86
Q

What are the 2 common enzymes targeted by G-protein subunits?

A

Adenylyl cyclase

Phospholipase C

87
Q

What are the 2 main types of motor proteins that move along microtubules?

A

Kinesins (move away from the organizing center) toward positive end
Dynein’s (move toward the organizing center) toward the negative end

88
Q

Give 2 ways actin and microtubules are similar

A

both have polarity

both made of subunits

89
Q

Give 2 ways actin and microtubules are different

A

microtubules are hollow actin is not hollow

actin uses ATP to grow microtubules use GTP to grow

90
Q

What are 2 ways mitochondria and chloroplasts are the same

A

Both have inner membrane

Both have outer membrane

91
Q

What are 2 ways mitochondria and chloroplasts are different

A

Chloroplasts have 3 membranes while mitochondria only have 2

Chloroplast membranes are much larger than mitochondria

92
Q

What are the 3 main types of phosphorylation

A

Oxidative
Photo phosphorylation
substrate level

molec and cell exam 3 (1 decks)

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