Molec And Cell Final

Front 1

________ ______have a diameter (10 nm) between that of microtubules (25 nm) and actin (6 nm)?

Back 1

intermediate filaments

Front 2

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

Back 2

tensile strength

Front 3

eight of these tetramer ropes come together to form a single filament, which is __ µm wide and made up of a total of ___ subunits.

Back 3

10, 32

Front 4

What are the 4 classes of intermediate, filament.

Back 4

1. keratin (in epithelial cells)
2. vimentin (connective tissue, muscles)
3. neurofilaments (nerve cells)
4. nuclear lamins (nuclear membrane support)

Front 5

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)

Back 5

polarity

Front 6

growing microtubules end up with a ____ ___?

Back 6

GTP cap

Front 7

_____ ______ can help anchor microtubules onto the plasma membrane

Back 7

Capping proteins

Front 8

_____ _______ help direct movement in the cell

Back 8

motor proteins

Front 9

motor proteins use the energy of ___ to drive their incremental movement along filaments

Back 9

ATP

Front 10

there are two main types of motor proteins that move along microtubules, which depend on the direction they are moving?

Back 10

1. kinesins (move away from the organizing center)
2. dyneins (move toward the organizing center)

Front 11

both kinesins and dyneins are protein dimers with____ ____ _____ ____ _ _____ where the heads interact with the microtubule (the rail) and the tail carries the cargo

Back 11

two glubular ‘heads’ and a ‘tail’,

Front 12

____ _______ are the smallest cytoskeleton filaments at about __ nm in diameter

Back 12

actin filaments, 7

Front 13

Actin filaments are made of actin subunits that give the filament ______ (a plus and minus end) just like microtubules

Back 13

polarity

Front 14

_____ polymerizes in a similar fashion to tubulin, except actin polymerization and disassociation is controlled by the hydrolysis of ATP to ADP

Back 14

actin

Front 15

free actin subunits carries
___, but this can be converted to ___ after joining a growing actin filament

Back 15

ATP, ADP

Front 16

_____ and ______ prevent actin filament formation (they bind to the free actin subunits)

Back 16

thymosin and profilin

Front 17

_______ and ________ ______ (ARPs) encourage actin filament formation

Back 17

formins and actin-related proteins

Front 18

_____ ______ are a type of actin-binding protein that halps to control the behavior of actin filaments. These prevent depolymerization.

Back 18

capping proteins

Front 19

_____ ______ are another type of actin-binding protein that helps control the behavior of actin filaments. This one provides a starting point for filament growth.

Back 19

nucleating proteins

Front 20

“cell crawling” is mediated by ____ ______, 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)

Back 20

actin filaments

Front 21

common protrusions driven by actin are _______ (“false feet”) of amoebae

Back 21

pseudopods

Front 22

motor proteins in the ______ _____ interact with actin filaments

Back 22

myosin family

Front 23

two myosin subfamilies exist: _____ and_____?

Back 23

myosin-I and myosin-II

Front 24

myosin-I proteins consist of a ____ _____ domain that interacts with the actin filament, and a ______ ____ that carries cargo

Back 24

single head, single tail

Front 25

myosin-I molecules move from the ______ to _____ end of the actin filament

Back 25

negative to positive

Front 26

myosin involved in muscle contraction belongs to the _______ subfamily

Back 26

myosin-II

Front 27

myosin-II molecules are ______ of myosin molecules

Back 27

dimers

Front 28

Each dimer has ____ ____ and a ______ _____

Back 28

two heads, rod-like tail

Front 29

clusters of myosin-II dimers are called _______ ______

Back 29

myosin filaments

Front 30

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

Back 30

contractile force

Front 31

the skeletal muscle fibers are made of several _______

Back 31

myofibrils

Front 32

The myofibrils are made up of contractile units called ______

Back 32

sarcomeres

Front 33

each sarcomere contains actin filaments which are ____ filaments, and myosin filaments which are _____?

Back 33

thin, thick

Front 34

each actin filament is anchored on its plus (+) end by structures called ______?

Back 34

Z discs

Front 35

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

Back 35

T tubules

Front 36

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

Back 36

tropomyosin

Front 37

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

Back 37

troponin

Front 38

in the first stage of Energy production electrons are shuttled along the ______ _____ ______?

Back 38

electron-transport chain

Front 39

The electron transport chain pumps protons on one side of the membrane which generates an ________ _______

Back 39

electrochemical gradient

Front 40

in stage two of Energy production: the protons flow back through the membrane via an enzyme called ___ ______, which produces ATP from ADP + inorganic phosphate (Pi)

Back 40

ATP synthasis

Front 41

generally, this process of linking chemical synthesis with membrane transport is called ______ ________

Back 41

chemiosmotic coupling

Front 42

with mitochondria, a single glucose molecule produces __ ATP

Back 42

36

Front 43

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

Back 43

porins

Front 44

the inner 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

Back 44

cristae

Front 45

the ______ is the large internal space of the mitochondria that is bordered by the inner membrane; it has several enzymes involved with the TCA cycle and other specialized energy-generating processes, and is where newly synthesized ATP are located

Back 45

matrix

Front 46

th__________ ______ is quite narrow, and is simply the space between the inner and outer membrane; the ATP leaving the matrix first passes into this space

Back 46

intermembrane space

Front 47

in non-photosynthetic eukaryotes, ‘food’ arrives to the matrix (inside) of the mitochondrion where it is oxidized to form electron carrier molecules ____ and _____ ?

Back 47

NADH and FADH2

Front 48

this specific chemiosmotic mechanism is known as _________ ____________?

Back 48

oxidative phosphorylation

Front 49

ATP synthase is a multi-subunit protein complex with an enzymatic ‘_____ _____’ (F1) that extends from the inner mitochondrial membrane into the matrix

Back 49

Head unit

Front 50

as protons shuttle through the ______ ______ _______ (F0), they drive the rotation of the head unit, which physically squeezes ADP and Pi together to from ATP

Back 50

transmembrane proton carrier

Front 51

like mitochondria, chloroplasts have an _____and _____ _____?

Back 51

inner and outer membrane

Front 52

chloroplasts inner and outer membrane create an ______ ______?

Back 52

intermembrane space

Front 53

the space contained by the inner membrane is called the ______ (analagous to the matrix of mitochondria)

Back 53

stroma

Front 54

these enzymes are found in the_____ ______ of disc-like sacs called thylakoids.

Back 54

thylakoid membrane,

Front 55

these enzymes are found in the thylakoid membrane of disc-like sacs called _______?

Back 55

thylakoids

Front 56

thylakods exist is stacks called
_____?

Back 56

grana

Front 57

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

Back 57

photosystems

Front 58

each photosystem contains an ______ ______ and a ______ _____?

Back 58

antenna complex, reaction center

Front 59

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

Back 59

chlorophyll

Front 60

when a special chlorophyll molecule (P680) in the reaction center of __________ __ is excited by energy from the antenna, an electron is liberated

Back 60

photosystem II (PSII)

Front 61

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

Back 61

photolysis

Front 62

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

Back 62

stroma, photophosphorylation

Front 63

the special chlorophyll (P700) of ___________ _____ also absorbs light energy and loses an electron in the same way as photosystem II, except the lost electron from P700 is replaced by the electron from P680 rather than through photolysis

Back 63

photosystem I (PSI)

Front 64

these reactions of the photosystems are known as the _____ _______, which ultimately result in ATP (from PSII) and NADPH (from PSI)

Back 64

light reactions

Front 65

the ATP and NADPH produced from the light reactions are used to drive ______ _______ – the production of sugar from CO2

Back 65

carbon fixation

Front 66

this process involves a series of enzymes that operate what is known as the______ _____

Back 66

Calvin Cycle

Front 67

The most important enzyme in the Calvin Cycle is the ________

Back 67

Rubisco

Front 68

from ____ energy at the reaction center of PSII, _____ was split (photolysis) and ______ was generated as a by-product (the light reactions)

Back 68

light, water, oxygen

Front 69

_____ _____ was fixed into _____ by Rubisco and other enzymes of the Calvin Cycle (the dark reactions), which were driven by ATP (from PSII) and NADPH (from PSI)

Back 69

Carbon dioxide, sugar

Front 70

recall that during oxidative phosphorylation in the mitochondria, electrons are donated to the electron transport chain via ____

Back 70

NADH

Front 71

the electrons carried by NADH were generated via controlled _____ of food (e.g. glucose)

Back 71

Oxidation

Front 72

breaking down compounds is referred to as ________

Back 72

catabolism

Front 73

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

Back 73

glycolysis

Front 74

the overall process of glycolysis breaks down___ _____ (a six-carbon sugar) to ___ _____molecules (pyruvate is a three-carbon compound)

Back 74

one glucose,two pyruvate

Front 75

this production of ATP without the mitochondria is known as ______ __________?

Back 75

substrate-level phosphorylation

Front 76

one glucose molecule also generates___ NADH molecules

Back 76

2

Front 77

there are three main stages of glycolysis:

Back 77

1. energy investment (steps 1-3) where ATP is consumed
2. cleavage of six-carbon sugar to three-carbon molecules (steps 4-5)
3. energy production (steps 6-10)

Front 78

after glycolysis, pyruvate enters the _______ where it is converted to _____ ____

Back 78

mitochondria, acetyl CoA

Front 79

the_____ _____ ____ is also referred to as the Krebs cycle and the tricarboxylic acid (TCA) cycle

Back 79

citric acid cycle

Front 80

it occurs in the _______ ______ (recall, glycolysis occurs in the cytoplasm)

Back 80

mitochondrial matrix

Front 81

(just study this)

Back 81

The citric acid cycle begins by adding the acetyl group (two carbons) of acetyl CoA to oxaloacetate (four carbons) to give citric acid (a.k.a. citrate; six carbons)citric acid is enzymatically converted back to oxaloacetate (completing the cycle) by giving off carbon as CO2

Front 82

(just study)

Back 82

each cycle of the citric acid cycle, releases two CO2 molecules, three NADH, one FADH2 (similar to NADH) and one GTP (similar to ATP)

Front 83

a process called ________ involves the production of more complex molecules from simple ones (recall, catabolism involves the breakdown of molecules; i.e. the opposite of anabolism)

Back 83

anabolism

Front 84

notice how glycolysis and the citric acid cycle are central to ______ (combined process of anabolism and catabolism)

Back 84

metabolism