Chapter 5. Chem 132

Front 1

Myoglobin transports O2 through

Back 1

muscles

Front 2

Hemoglobin transports O2 in

Back 2

blood

Front 3

Myoglobin consists of ___helixes

Back 3

8 alpha helices

* lacks B structure entirely

*Labeled A-H

Front 4

Hemoglobin is a _____whose 4 subunits resemble myoglobin

Back 4

tetrameric

Front 5

Heme is a _____group

Back 5

prosthetic group : allows protein to carry some function

*covalently bonded to polypeptide chain

Front 6

The central Iron of Heme is

- ____possible coordination points

- liganded by 4 ____atoms

-Proximal His____ binds to Fe

-Distal His ____ binds to O2

Back 6

-6

-N

-F8

-E7

Front 7

O2 binding to myoglobin:

Dissociation constants

Back 7

Kd= [Mb][O2]/ [MbO2]

-High Kd= Mb delivers O2

-Low Kd= Mb doesn't release O2 efficiently

Front 8

FRACTIONAL SATURATION (Y)

Back 8

the proportion of myoglobin molecules that have bound O2

[Bound Mb]= [MbO2 =[pO2]

[Total Mb] = [Mb]+[MbO2] =K+pO2

Front 9

Hyperbolic curve indicates

Back 9

As [O2] increases, more and more O2 molecules bind to the heme groups until at high concentrations, all mb have bonded

Front 10

p50

Back 10

marks 50% saturation with O2

[Mb]=[MbO2]=Kd

Front 11

Hb and Mb are only ____identical in primary sequence

Back 11

18%

Front 12

Mb and Hb are similar in their

Back 12

-Secondary structure

-Tertiary structure

=indicate a common origin

Front 13

Oxygen binds _____to Hb

Back 13

Cooperatively:

Binding of O2 to on unit induces easier binding to other subunits.

Front 14

Sigmoidal curve of Hb binding indicates

Back 14

Cooperativity: one subunit binds to O2, other 3 will bind at the same time.

Front 15

Cooperative binding of Hb is due to

Back 15

Conformational shift: The four globin units undergo conformational changes when they bind to O2

Front 16

In deoxyhemoglobin

Back 16

O2 not present

Front 17

In oxyhemoglobin

Back 17

O2 binds= the Fe moves into the center of porphyrin ring=rotates aB units

Front 18

Bohr Effect

Back 18

the decrease of Hb's O-binding affinity when pH decreases

Front 19

Bohr Effect:

When pH increases

Back 19

O2 binding affinity increases

Favors binding

Front 20

Bohr Effect:

When pH decreases

Back 20

Favors dissociation of O2

Front 21

2,3 biphosphoglycerate (BPG)

Back 21

-in Hb cells

- 3 (-) charges

- stabilizes deoxy state of Hb

-decreases Hb O2 affinity

Front 22

Microfilaments are composed of

Back 22

globular ACTIN subunits associated in a double chain

Front 23

ATP binds at the _____ end of microfilaments

Back 23

(-) end

Front 24

Polymerization of microfilaments

Back 24

a reversible process that under goes shrinking and growing= generates movement

*subunits add more rapidly to (+) end

Front 25

Actin polymerization is driven by

Back 25

ATP hydrolysis

ATP--> ADP

*catalyzed by F-Acton not G-Actin

Front 26

Dimers

Back 26

formed by a and B tubulin

Front 27

Microtubules are

Back 27

-globular proteins

-assemble and disassemble

-thicker

Front 28

(+) end vs (-) of microtubules

Back 28

(+):

- grows faster

-dissasembles faster

(-):

anchors to organelles

Front 29

Function of microtubules in mitosis

Back 29

link replicated chromosomes at two points . DISASSEMBLY of the microtubules with action of motor proteins draw chromosomes apart

Front 30

Intermediate filaments are

Back 30

long lasting fibrous proteins consisting of coiled a helices

Front 31

Structure of Intermediate filaments :

Collagen

Back 31

3 left handed Gly rich helical polypeptides

Front 32

Intermediate filaments don't require ____for assembly

Back 32

Nucleotides

Front 33

Keratin structure

Back 33

coiled dimers associated in a staggered antiparallel arrangment

Front 34

Keratin fibers crosslink through

Back 34

disulfide bonds

Front 35

Collagen is a ____helix q

Back 35

triple

Front 36

Function of collagen

Back 36

structural support. Helps hold cells together

Front 37

Collegen is stabilized through h

Back 37

Hbonds

Front 38

Myosin if a _____protein

Back 38

motor protein

Front 39

Collagen is covalently ____linked

Back 39

Covalently bonds formed between side chains

Front 40

Myosin muscle contraction is driven by

Back 40

ATP hydrolysis

Front 41

Kinesin trasports cargo by moving

Back 41

along MICROTUBULE track

Front 42

Myosin has

Back 42

two heads and a long tail

Front 43

ATP binds to ____in Myosin

Back 43

heads

Front 44

Movement of Myosin is due to

Back 44

Myosin head releasing and rebinding to another actin subunit

Front 45

ATP hydrolysis in Myosin steps

Back 45

1) Myosin head bounds to actin

2) ATP binds= alter myosin to release actin

3) ATP-> ADP = increases Myosin affinity to actin

Front 46

Kinesin is composed of

Back 46

2 heads, a tail, and two light chains (vesicle cargo region)

Front 47

Kinesin has high processivity:

Back 47

Many cycles must occur before motor dissociates from track .