chapter 3- proteins

Question 1

what are the 5 most common chemical elements that make up proteins

Answer 1

carbon, hydrogen, oxygen, nitrogen, sulphur

Question 2

what is the monomer from which proteins are made

Answer 2

amino acids

Question 3

what is the general structure of an amino acid

Answer 3

a central carbon atom bonded to a hydrogen atom, an r group, carboxyl group and a amine group (hydroxyl group??)

Question 4

how many amino acids are commonly found in cells

Answer 4

20

Question 5

how many non essential AAs are there and what does this mean

Answer 5

5, our bodies are able to make them from other AAs

Question 6

how many essential AAs are there and what does this mean

Answer 6

9, means that they can only be obtained from what we eat

Question 7

a further … AAs are said to be….. meaning

Answer 7

6, conditionally essential meaning they are only needed by infants and growing children

Question 8

what is a peptide bond

Answer 8

a covalent bond between two amino acids resulting from a condensation reaction

Question 9

what is a dipeptide

Answer 9

a molecule formed by the condensation of two AAs

Question 10

what is a polypeptide

Answer 10

a polymer formed by the condensation of many AAs (3+)

Question 11

what is a proteins primary structure

Answer 11

the sequence of amino acids that makes up the polypeptide of a protein

Question 12

what is a proteins secondary structure

Answer 12

the particular folding/conformation/shape of a chain of AAs in the polypeptide(s) of a protein

Question 13

what is a proteins tertiary structure

Answer 13

the particular folding of a whole polypeptide chain as determined by the AAs that make up the polypeptide

Question 14

what is a proteins quaternary structure

Answer 14

a number of polypeptide chains linked together and sometimes associated with non protein groups to form a protein

Question 15

what is a conjugated protein

Answer 15

a protein that contains non protein prosthetic groups attached by covalent, ionic or hydrogen bonds

Question 16

what is haemoglobin and its structure

Answer 16

a protein enabling transport of oxygen in the blood, it has a quaternary structure and 4 prosthetic ahem groups which are able to bind to oxygen

Question 17

what do peptide bonds form between

Answer 17

individual amino acid molecules between the carbon and hydrogen

Question 18

what is the reaction called which forms a peptide bond and a water molecule

Answer 18

condensation reaction

Question 19

peptide bond and adds to water back into the amino acids

Answer 19

hydrolysis

Question 20

what is a dipeptide

Answer 20

2 amino acids joined together by a peptide bond

Question 21

what is a polypeptide chain

Answer 21

3 or more amino acids joined together

Question 22

how many peptides are in a protein

Answer 22

a protein consists of 1 or more polypeptide chains folded into a specific 3d shape

Question 23

why is the structure of a protein important

Answer 23

because it plays an important role in the overall structure and function of the protein

Question 24

what is the primary structure of proteins

Answer 24

refers to simple long chains with NO intramolecular BONDS or interactions, specific order of AAs

Question 25

what is the secondary structure of proteins

Answer 25

what is the secondary structure of proteins

Question 26

what is the tertiary structure of proteins

Answer 26

hydrophilic or phobic interactions, hydrogen, ionic and disulphide bonds (or bridges) that hold the molecules together in shape

Question 27

what is the quaternary structure of proteins

Answer 27

same as tertiary but have 2 or more separate polypeptide chains interlinked

Question 28

what are the 2 structures in a secondary level structure of proteins

Answer 28

alpha helix or beta pleated sheet

Question 29

alpha helix structures always make......proteins

Answer 29

globular

Question 30

beta pleated sheet structures always make.....proteins

Answer 30

fibrous

Question 31

name 3 fibrous proteins

Answer 31

keratin elastin collagen

Question 32

what is a peptide bond

Answer 32

it is the bond that forms between the amine group of 1 amino acid and the carboxyl of another amino acid to form a dipeptide

Question 33

Scientists call the non-amino acid part in a globular protein the

Answer 33

prothetic group

Question 34

A globular protein is known as conjugated if it contains a/an…

Answer 34

prosthetic group

Question 35

are fiberous proteins soluble or insoluble in water

Answer 35

insoluble

Question 36

what type of proteins contain lots of hydrophobic side groups and what does this allow them to do

Answer 36

fibrous, have lots of structural functions

Question 37

a scientist analysed and recorded all of the chemical elements in one particular amino acid which elements did the scientist record

Answer 37

C, H, O, N

Question 38

which is correct: a) a glucose molecules contains 5 OH groups and has a C:O ratio of 1:1 b) glucose molecules contain 6 OH groups and has a a C:H ratio of 1:2

Answer 38

A

Question 39

if 2 amino acids on a tlc had different r groups and their spots have travelled different distances what can be suggested about the chemical properties of their r groups

Answer 39

they different in terms of polarity, charges and functional groups the one that travelled the least is more polar

Question 40

chromatography: why a pencil and not a pen