5

Question 1

Proteins are …

Answer 1

polymers

Question 2

The monomers of … are amino acids.

Answer 2

proteins

Question 3

A … is formed when two amino acids join together.

Answer 3

dipeptide

Question 4

A … is formed when more than two amino acids join together.

Answer 4

polypeptide

Question 5

Proteins are made up of one or more …

Answer 5

polypeptides

Question 6

All amino acids have the same general structure - a … group (-COOH) and an amino group (-NH2) attached to a carbon atom.

Answer 6

carboxyl

Question 7

The difference between amino acids is the … group they contain.

Answer 7

variable

Question 8

All amino acids contain the elements carbon, oxygen, hydrogen and … Some also contain sulfur.

Answer 8

nitrogen

Question 9

Amino acids are linked together by … bonds to form dipeptides and polypoptides.

Answer 9

peptide

Question 10

A molecule of water is released during the reaction - it’s a … reaction.

Answer 10

condensation

Question 11

The reverse of this reaction adds a molecule of water to break the peptide bond - it’s a … reaction.

Answer 11

hydrolysis

Question 12

The four … levels of protein are held together by different kinds of bonds.

Answer 12

structural

Question 13

Primary structure - the … of amino acids in the polypeptide chain. Different proteins have different sequences of amino acids in their primary structure. A change in one amino acid may change the structure of the whole protein.

Answer 13

sequence

Question 14

Secondary structure - the polypeptide chain doesn’t remain flat and straight. … bonds form between the -NH and -CO groups of the amino acids in the chain. This makes it automatically coil into alpha or beta pleated sheet.

Answer 14

hydrogen

Question 15

Condensation reactions … a water molecule. Hydrolysis reactions use one.

Answer 15

form

Question 16

An R group is an amino acid’s variable group. It’s also called an amino acid’s “… chain”.

Answer 16

side

Question 17

Tertiary structure - the coiled or folded chain of amino acids is often coiled and folded further. More bonds form between the different parts of the … chain.

Answer 17

polypeptide

Question 18

Tertiary structure - Ionic bonds - these are … between negatively charged R groups and positively charged R groups on different parts of the molecule.

Answer 18

attractions

Question 19

Tertiary structure - disulfide bonds - whenever … molecules of the amino acid cysteine come close together, the sulfur atom in one cysteine bonds to the sulfur in the other cysteine, forming a disulfide bond.

Answer 19

two

Question 20

Tertiary structure - disulfide bonds - whenever … molecules of the amino acid cysteine come close together, the sulfur atom in one cysteine bonds to the sulfur in the other cysteine, forming a disulfide bond.

Answer 20

two

Question 21

Tertiary structure - Hydrophobic and hydrophilic interactions - when … R-groups are close together in the protein, they tend to clump together. This means that hydrophilic R-groups are more likely to be pushed to the outside, which affects how the protein folds up into its final structure.

Answer 21

hydrophobic

Question 22

Tertiary structure - hydrogen bonds - these weak bonds form between slightly positively-charged hydrogen atoms in some R-groups and slightly negatively-charged atoms in other R-groups on the … chain.

Answer 22

polypeptide

Question 23

Tertiary structure - ionic bonds - attractions between negatively charged … groups and positively charged R groups on different parts of the molecule.

Answer 23

R

Question 24

Tertiary structure - disulfide bonds - whenever two molecules of the amino acid … come close together, the sulfur atom in one … bonds to the sulfur in the other cysteine, forming a disulfide bond.

Answer 24

cysteine

Question 25

Tertiary structure - hydrophobic and hydrophilic interactions - when hydrophobic R groups are close together in the ..., they tend to clump together. This means that hydrophilic R groups are more likely to be pushed to the outside, which affects how the protein folds up into its final structure.

Answer 25

protein

Question 26

Tertiary structure - hydrogen bonds - these weak bonds form between slightly postively-charged hydrogen atoms in some R groups and slightly negatively-charged atoms in other R groups on the ... chain.

Answer 26

polypeptide

Question 27

For proteins made from a single polypeptide chain, the ... structure forms their final 3D structure.

Answer 27

tertiary

Question 28

Some proteins are made of several different polypeptide chains held together by bonds. The ... structure is the way these polypeptide chains are assembled together.

Answer 28

quaternary

Question 29

The quaternary structure tends to be determined by the tertiary structure of the individual ... chains being bonded together. Because of this, it can be influenced by all the bonds mentioned. For proteins made from more than one ... chain, the quaternary structure is the protein's final 3D structure.

Answer 29

polypeptide

Question 30

... proteins are round and compact. In a ... protein, the hydrophilic R groups on the amino acids tend to be pushed to the outside of the molecule. This is caused by the hydrophobic and hydrophilic interactions in the protein's tertiary structure. This makes globular proteins soluble, so they're easily transported in fluids.

Answer 30

globular

Question 31

Example - haemoglobin is a globular protein that carries oxygen around the body in red blood cells. It's known as a ... protein - this means that it's a protein with a non-protein group attached. The non-protein part is called a prosthetic group. Each of the polypeptide chains in haemoglobin has a prosthetic group called haem group contains iron, which oxygen binds to.

Answer 31

conjugated

Question 32

Insulin is a hormone secreted by the pancreas. It helps to regulate the blood ... level. Its solubility is important - it means it can be transported in the blood to the tissues where it acts.

Answer 32

glucose

Question 33

An insulin molecule consists of two polypeptide chains, which are held together by ... bonds. When they're in the pancreas, six of these molecules bind together to form a large, globular structure.

Answer 33

disulfide

Question 34

... is an enzyme that catalyses the breakdown of starch in the digestive system. It is made of a single chain of amino acids. Its secondary structure contains both alpha-helix and beta-pleated sheet sections. Most enzymes are globular proteins.

Answer 34

amylase

Question 35

... proteins are tough and rope-shaped. They're also insoluble and strong. They're structural proteins and are fairly unreactive (unlike many globular proteins).

Answer 35

fibrous

Question 36

Fibrous proteins - ... - found in animal connective tissues, such as bone, skin and muscle. It is a very strong molecule. Minerals can bind to the protein to increase its rigidity.

Answer 36

collagen

Question 37

Fibrous proteins - ... - ... is found in many of the external structures of animals, such as skin and hair. It can either be flexible (skin) or hard and tough (nails).

Answer 37

keratin

Question 38

Fibrous proteins - ... - ... is found in elastic connective tissue, such as skin, large blood vessels and some ligaments. It is elastic, so it allows tissues to return to their original shape after they have been stretched.

Answer 38

elastin