Protein Function

Question 1

Classes of proteins:

Answer 1

• structural
• contractile
• defense
• transport
• signaling
• enzymatic

Question 2

Examples of structural proteins:

Answer 2

• hair

- cell cytockeleton

Question 3

Examples of contractile proteins:

Answer 3

• muscle

- motile cells

Question 4

Examples of defense proteins:

Answer 4

• antibodies

- membrane proteins

Question 5

Examples of transport proteins:

Answer 5

• hemoglobin

- membrane proteins

Question 6

Example of signaling protein:

Answer 6

hormones

Question 7

Enzymatic proteins regulate:

Answer 7

the speed of biochemical reaction

Question 8

Fibrous protein differs from globulin proteins b/c…

Answer 8

they are usually elongated/fibrous in form

Question 9

Examples of fibrous proteins:

Answer 9

• alpha keratins
• fibroin
• collagen
• elastin

Question 10

Alpha keratins are the major proteins in…

Answer 10

• hair
• fingernails
• skin

Question 11

Alpha keratins are the ______ filament protein

Answer 11

intermediate

Question 12

Alpha keratins are predominately what shape?

Answer 12

alpha-helical

- twists together in left-handed coil

Question 13

Every 4th residue of the alpha helix of alpha keratins is…

Answer 13

hydrophobic (makes one side hydrophobic)

- hydrophobic regions stick together

Question 14

Fibroin:

Answer 14

fibers spun by silk worms and spiders

Question 15

Fibroin have long regions of…

Answer 15

antiparallel beta sheet

Question 16

Common sequence of fibroin:

Answer 16

• gly-ala or gly-ser

- allows for close packing

Question 17

Collagen:

Answer 17

abundant matrix material in bone, tendons, and skin

Question 18

Tropocollogen:

Answer 18

triplet helix made of left-handed helices w/ 3.3 residues per turn

Question 19

Every 3rd residue of collage is a…

Answer 19

glycine (central residue)

- usually followed by proline/hydroyproline

Question 20

Hydroxylation of proline requires…

Answer 20

vitamin C

Question 21

Deficiency of vitamin C causes…

Answer 21

weak tendons due to inability to hydroxylation proline

Question 22

What increases the toughness of collagen?

Answer 22

cross linking of lysine side chains (decreases elasticity)

Question 23

Old bones and skin have more…

Answer 23

cross-links and are more brittle

Question 24

Elastin is found in…

Answer 24

• blood vessels

- ligaments

Question 25

Elastin is more elastic than...

Answer 25

collagen

Question 26

Elastin is rich in:

Answer 26

- glycine - alanine - valine

Question 27

Structure of elastin is...

Answer 27

mostly random coil

Question 28

Elastin will cross-link via...

Answer 28

lysines

Question 29

Actin:

Answer 29

G-actin monomers come together to form fibrous protein F-actin (has myosin binding sites)

Question 30

Myosin:

Answer 30

- alpha helical tails and globular heads - tails tend to aggregate - heads tend to bind actin

Question 31

Sarcomere:

Answer 31

basic repeating pattern of muscle myofibril

Question 32

A band:

Answer 32

overlap of thick and thin filaments

Question 33

I bands:

Answer 33

thin filaments only