proteins

Question 1

Proteins-

Answer 1

Building blocks of cells

Constitute most of the cell’s dry mass

Execute nearly all of cell’s functions

Question 2

Enzymes

Answer 2

catalyze covalent bond formation or breakage

Question 3

Structural proteins-

Answer 3

mechanical support in cells and tissues

Question 4

Transport proteins-

Answer 4

carry small molecules or ions

Question 5

Motor proteins-

Answer 5

generate movement in cells and tissues

Question 6

Storage proteins-

Answer 6

store small molecules or ions

Question 7

singnal proteins-

Answer 7

carry signals from from cell to cell

Question 8

Receptor proteins-

Answer 8

detect signals and transmit them

Question 9

Receptor proteins-

Answer 9

detect signals and transmit them

Question 10

Gene regulatory proteins-

Answer 10

bind to DNA to switch genes on/off

Question 11

Special-purposeproteins-

Answer 11

highly variable functions.

Question 12

variety of functions possible because of the huge number of diffrent shapes they adopt.

Answer 12

the most structurally complex and functionally sophisticated molecules known.

Question 13

High molecular weight

Answer 13

(10-1000 kD), 30-10,000 AA long

Question 14

Polymers of subunits(monomers) held togerther by covalent bonds-

Answer 14

polypeptides

Question 15

Subunits attached via a -

Answer 15

dehydration reaction

Question 16

synthesis requires metabolic energy from

Answer 16

ATP or GTP

Question 17

Long polymers are flexible and can fold into-

Answer 17

three dimensional configurations

Question 18

determined primarily by

Answer 18

non-covalent bonds

Question 19

proteins-

Answer 19

macromolecules composed of one more flexible chains of amino acids (polypeptides) held together by peptide bonds.

Question 20

polypeptide

Answer 20

a single chain of amino acids

Question 21

protein

Answer 21

functional molecule composed of one or more polypeptides.

Question 22

glycoprotein-

Answer 22

a protein covalently linked to ne or more oligosaccharides

Question 23

lipoprotein

Answer 23

a protein covalently linked to one or more lipids

Question 24

Polypeptides have a backbone formed from -

Answer 24

repeating sequences of atoms linked by peptide bonds and side chains of amino acids( the parts of amino acids not involved in peptide bond formation.

Question 25

there are _____ diffrent amino acids

Answer 25

20

each has a diffrent chemical property

Question 26

three dimensional conformation of proteins is determined by its amino acid sequence and interactions between atoms.

Answer 26

• within the same molecule ( intramolecular interactions)
• with ohter molecule ( intramolecular interactions) like proteins and phospholipids
• small molecules in the enviroment ( water, inorganic ions, small ligands, ect)

Question 27

Most interactions within the same molecule are in the form of weak,non-covalent bond.

Answer 27

* ionic bonds

* hydrogen bonds

*van der waals forces

some interactions are in the form of covalent disulfidee bonds (-S-S-)

Question 28

Each protein normally folds into a

Answer 28

single stable confermation

Question 29

Folding in cells assisted by molecular chaperones-

Answer 29

bind to partly folded chains and help to fold, in crowded cell enviroment prevent association with other molecules until folding is complete, recognize products of mutated genes.

Question 30

Two families of molecular chaperones:

Answer 30

• hsp70-acts early during initial folding of the polypeptide
• hsp60-forms a barrel- like cage into which micfolded proteins are placed and the folding is corrected

Question 31

improper folding

Answer 31

seen in many diseases

Question 32

improperly folded proteins can form aggregates and accumulate -

Answer 32

some storage and neurodegenerative diseases.

Question 33

prions-

Answer 33

misfolding forms of proteins that can convert properly folded proteins into the abnormal configuation( PrP in scapie, BSE,CJD)

Question 34

Prions structure is complex,comes in a cariety of complicated shapes:globular, fibrilar, can form filamentws, sheets, rings, spheres

Answer 34

Several diffrent models have been developed to illustrate the three dimensional configuration of proteins: backbone, ribbon, wire and space filing

Question 35

Although the overall conformational pattern of each protein is unique-

Answer 35

two reular folding patterns are often present in parts of them: σ helix and ß sheet

Question 36

-result form hydrogen bonds forming between

Answer 36

N-H and C=O groups in the polypeptide backbone—> protein chain adopts a regular,repeating form (motif)

Question 37

amino acid side chains -

Answer 37

are not involved

Question 38

Can be illustrated -

Answer 38

showing all atoms in the polypeptide backbone, backbone atoms only or cartoon symbols used to represent the σ helix and the ß sheet in ribbon drawings of proteins.

Question 39

σ helix-

Hydrogen bonds formed between every 4th peptide bond (C=0 of one peptide bond and N=H of another bond)

Answer 39

• Helix with one complete turn every 3.6 amino acids

Question 40

σ helix-

Short regions of σ helix abundant in cell membrane proteins crossing lipid bilayer-

Answer 40

( non polar side chains face lipid and hyrophilic backbone faces interior of the helix)

Question 41

2 σ helixes can form a

Answer 41

Coiled-coil