Lesson 4 - Proteins

Question 2

what are amino acids

Answer 2

the building blocks of proteins, consisting of an amino group and a carboxyl group attached to a carbon atom and an R group that varies between amino acids

Question 3

what are peptide bonds

Answer 3

a bonds formed by condensation reactions between amino acids

Question 4

what are dipeptide bonds x

Answer 4

2 amino acids joined by a peptide bond

Question 5

what are polypeptides

Answer 5

long chains of amino acids joined by peptide bonds

Question 6

what are fibrous proteins

Answer 6

proteins that have long, parallel polypeptide chains with occasional cross-linkages that form into fibres, but with little tertiary structure

Question 7

what are disulfide bonds

Answer 7

a strong covalent bond formed as a result of an oxidation reaction between sulfur groups in cysteine or methionine molecules, which are close together in the structure of a polypeptide

Question 8

what are globular proteins

Answer 8

large proteins with complex tertiary and sometimes quaternary structures, folded into spherical shapes

Question 9

what is haemoglobin

Answer 9

a large conjugated protein involved in transporting oxygen in the blood, and gives the erythrocytes their red colour

Question 10

what is collagen

Answer 10

strong fibrous protein with a triple helix structure

Question 11

what is denaturing

Answer 11

the loss of the 3D shape of a protein as a result of changes in pH or temperature

Question 12

what is the prosthetic group

Answer 12

a molecule that is added in a conjugated protein

Question 13

what is a glycoprotein

Answer 13

a protein with a carbohydrate prosthetic group

Question 14

what is protease

Answer 14

a protein-digesting enzyme

Question 15

what is a lipoprotein

Answer 15

a protein with a lipid prosthetic group

Question 16

which elements are proteins made up of

Answer 16

carbon, hydrogen, oxygen, nitrogen (& sulfure)

Question 17

how many different types of amino acids are there

Answer 17

20

Question 18

what is the R group

Answer 18

another atom or group of atoms bonded to the central atom

Question 19

how is a protein formed

Answer 19

amino acids join together by a condensation reaction where 1 molecule of water is lost. A strong peptide bond is formed between the 2 amino acids, forming a dipeptide. The R group is not involved. More amino acids join to form a polypeptide. When the polypeptide folds or coils, it forms a protein

Question 20

what are the 4 types of bonds between amino acids

Answer 20

• peptide bonds
• hydrogen bonds
• disulfide bonds
• ionic bonds

Question 21

how is a hydrogen bond formed

Answer 21

in amino acids, when negative charges on the oxygen of the carboxyl groups and positive charged on the hydrogen atoms of the hydroxyl group come close together, the opposite charges attract, forming a weak hydrogen bond.

Question 22

how is a disulfide bond formed

Answer 22

when 2 cysteine molecules are close together in a polypeptide. An oxidation reaction takes place between the 2 sulfur-containing groups, resulting in a strong disulfide bond

Question 23

what is the nature of hydrogen bonds

Answer 23

break easily, but are very common

Question 24

what is the nature of disulfide bonds

Answer 24

stronger than hydrogen bonds, and occur less often

Question 25

how is an ionic bond formed

Answer 25

form between strongly positive and negative amino acid side chains in protein molecules.

Question 26

what is the nature of ionic bonds

Answer 26

strong, but rarely occur

Question 27

which protein is hair made out of

Answer 27

keratin

Question 28

how does blow drying or straightening affect the protein keratin

Answer 28

it breaks the hydrogen bonds and reforms them temporarily in a different way, until the hydrogen bonds reform in their original places

Question 29

how does perming affect the protein keratin

Answer 29

it breaks the disulfide bonds between the polypeptide chains, and permanently reforms them, until cut

Question 30

what is the primary structure

Answer 30

the linear sequence of amino acids in a peptide

Question 31

what is the secondary structure

Answer 31

folding or coiling of the polypeptide chain, such as an alpha-helix or beta-pleated sheets

Question 32

what is the tertiary structure

Answer 32

the 3D folding of the secondary structure

Question 33

what is the quaternary structure

Answer 33

the 3D arrangement of more than one tertiary polypeptide

Question 34

what is the function of collagen

Answer 34

gives strength to tendons, ligaments, bones and skin, as it is very strong

Question 35

what is the structure of collagen

Answer 35

It's made up of 3 polypeptide chains. The primary structure of the chains is repeating sequences of glycine with proline and hydroxyproline. The 3 alpha-chains are arranged in a triple helix, held together by many hydrogen bonds

Question 36

what are collagen fibres

Answer 36

collagen molecules held together with fibrils

Question 37

what is the genetic disease osteogenesis imperfecta

Answer 37

where the collagen triple helix may not form properly. As a result, the bone lacks tensile strength, becoming brittle and breaking easily

Question 38

what is the role of globular proteins

Answer 38

important in the immune system (antibodies), form enzymes and hormones, and maintain the structure of the cytoplasm

Question 39

explain how the structure of hemoglobin makes its job

Answer 39

it is the iron that enables the haemoglobin to bind and release oxygen molecules

Question 40

what is the function of glycoprteins

Answer 40

the carbohydrate prosthetic group helps them hold on to a lot of water, and makes it harder for proteases to break them down

Question 41

what is the function of lipoproteins

Answer 41

important in the transport of cholesterol the blood, as it enables it to combine with the lipid cholesterol

Question 42

what are the 2 types of lipoproteins

Answer 42

Low-Density Lipoproteins (LDLs) High-Density Lipoproteins (HDLs)

Question 43

what is the difference between LDLs and HDLs

Answer 43

HDLs contain more proteins and are smaller than LDLs,