Topic 1 - 1.24 Proteins :3

Question 1

what monomers are proteins made up of

Answer 1

amino acids

Question 2

what are groups are amino acids made up of

Answer 2

Carboxyl group (-COOH), amino group(NH2) and an R group(either glycine which is -H or cysteine which is CH2-SH)

Question 3

what elements are proteins made of

Answer 3

nitrogen, oxygen, hydrogen, carbon and sometimes sulphur

Question 4

How many naturally occurring amino acids are there

Answer 4

20

Question 5

what is formed when 2 amino acids bond and what bond is formed

Answer 5

dipeptide, peptide bonds between carboxyl and amino acid

Question 6

what other bonds except for peptide bonds can form between amino acids

Answer 6

depends on R group
disulfide, ionic and hydrogen bonds

Question 7

Describe charges in an amino acid structure and how they help bonds form

Answer 7

the oxygen from the carboxyl group has a slightly negative charge while the hydrogen in the amino group has slightly positive charges.
this means they are attracted to eachother forming hydrogen bonds.

Question 8

when and how do disulfide bonds form

Answer 8

when 2 cysteine molecules (R group) in a polypeptide are close together
oxidation reaction between 2 sulphur containing groups… strong covalent bond knows as a disulfide bond.

Question 9

what protein structure are disulfide bonds usually present in

Answer 9

tertiary structure

Question 10

What are salt bridges

Answer 10

ionic bonds between strongly positive and negative amino acid side chains

Question 11

Describe the primary structure of a protein

Answer 11

linear sequence of amino acids in a polypeptide

> > helps determine final 3 dimensional shape of the protein molecule

Question 12

Describe the Secondary structure of a protein

Answer 12

hydrogen bonds cause polypeptide to twist and fold into shape

examples-alpha helix or beta pleated sheets

Question 13

Describe the tertiary structure of a protein

Answer 13

3 dimensional shape of a polypeptide chain
first folds into secondary structure(hydrogen bonds)
chain continues folding into tertiary structure
active site of enzymes depends on tertiary structure

Question 14

Describe the quaternary structure of a protein

Answer 14

the three dimensional arrangement of more than one tertiary polypeptide

> > > shows how individual sub units are arranged to form a larger 3 dimensional structure.

Also shows us the position of any prosthetic group

Question 15

Outline the structure of fibrous proteins and its properties

Answer 15

they have little/ no tertiary structure.
long parallel polypeptide chains, occasional cross linkages
insoluble in water+ very tough

found in connective tissue in tendons
keratin
matrix of bones

Question 16

collagen is a fibrous protein outline its structure and properties for its function

Answer 16

made up of 3 polypeptide chains
primary structure= repeating sequences of glycine with 2 other amino acids(proline and hydro proline)
the 3 alpha chains are arranged in a unique triple helix held by hydrogen bonds

Question 17

what is osteogenesis imperfecta

Answer 17

collagen triple helix does not form properly therefore bone lacks tensile strength , therefore it is brittle and breaks easily

Question 18

What protein structure do globular proteins have

Answer 18

triple or quaternary

Question 19

what are conjugated proteins

Answer 19

protein molecules joined with a prosthetic group

Question 20

what prosthetic group to lipoproteins have and what properties does it give them

Answer 20

lipid phosphate group
important for the transport of cholesterol in the blood.
lipid part allows it to combine with the lipid cholesterol

Question 21

what prosthetic group do glycoproteins have and what properties does it give them

Answer 21

carbohydrate
helps them hold loads of water (slippery and viscous)and makes it harder for proteases to break them down

Question 22

identify 2 lipoproteins and their similarities/ differences

Answer 22

LDL-> low density lipoproteins
»>
HDL-> high density lipoproteins»> contain more protein than LDLs

Question 23

Test for proteins

Answer 23

Option 1. add 5% potassium or sodium hydroxide solution AND 1% (w/v) copper sulfate solution

Option 2. Biuret reagent (contains 2 chemicals above already mixed.) when reagent is added solution goes from blue to purple indicating the presence of protein