PROTEINS

Question 1

Just like carbohydrates, proteins are ______

Answer 1

Polymers

Question 2

Amino acids are _____ in proteins

Answer 2

Monomers

Question 3

What makes a dipeptide?

Answer 3

A DIPEPTIDE is formed when TWO amino acids join together.

Question 4

What makes a polypeptide?

Answer 4

A POLYPEPTIDE is formed when MORE THAN TWO amino acids join together.

Question 5

What makes a protein?

Answer 5

PROTEINS are made of ONE OR MORE POLYPEPTIDES

Question 6

What is an amino acid general structure?

Answer 6

A carboxyl group (-COOH) and an amine group (-NH3) attached to a carbon atom with a variable group R.

Question 7

All amino acids contain what chemical elements?

Answer 7

carbon, oxygen, hydrogen, nitrogen and some contain sulfur.

Question 8

What bond holds amino acids together?

Answer 8

Amino acids are linked together by PEPTIDE BONDS to form dipeptides and polypeptides

Question 9

A molecule of WATER is RELEASED during the reaction- it’s a _______ reaction

Answer 9

condensation

Question 10

The reverse of a condensation reaction is adding a molecule of water to BREAK the peptide bond-it’s a ______ reaction

Answer 10

hydrolysis

Question 11

What is the PRIMARY structure of amino acids?

Answer 11

This is the SEQUENCE of AMINO ACIDS in the POLYPEPTIDE CHAIN.

Different proteins have DIFFERENT SEQUENCES of amino acids in their primary structure

A change in just one amino acid may change the structure of the whole protein.

Question 12

what is the SECONDARY structure of amino acids?

Answer 12

The polypeptide chain doesn’t remain flat and straight.

HYDROGEN BONDS form between nearby amino acid in the straight chain.

This makes it automatically COIL into an ALPHA (a) HELIX or FOLD is a BETA(B) PLEATED SHEET-this is the secondary structure.

Question 13

What is the TERTIARY structure of amino acids?:

Answer 13

The coiled or folded chain of amino acids is often COILED or FOLDED FURTHER.

MORE BONDS form between different parts of the polypeptide chain.

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

Question 14

What is the QUATERNARY STRUCTURE of amino acids?

Answer 14

Some proteins are made of SEVERAL DIFFERENT POLYPEPTIDE CHAINS held together BY bonds.

The QUATERNARY STRUCTURE is the way these polypeptide chains are assembled together

E.G. HAEMOGLOBIN is made of four polypeptide chains, bonded together.

For proteins made from MORE THAN ONE polypeptide chain, the quaternary structure is the proteins FINAL 3D STRUCTURE.

Question 15

COMPUTER MODELLING can create _____ of proteins

Answer 15

3D interactive images

Question 16

This is really handy for INVESTIGATING the ______ in a protein molecule.

Answer 16

different level of structure

Question 17

What bond(s) hold the primary structure?

Answer 17

Held together by the PEPTIDE BONDS between amino acids.

Question 18

What bond(s) hold the secondary structure?

Answer 18

Held together by HYDROGEN BONDS?

Question 19

What bond(s) hold the tertiary structure?

Answer 19

Held together by Ionic bonds, Disulphide bonds, Hydrophobic and hydrophilic interactions and Hydrogen bonds.

Question 20

What is an ionic bond?

Answer 20

These are attraction between NEGATIVELY-CHARGED R groups and POSITIVELY-CHARGED R groups on different parts of the molecule.

Question 21

What is a Disulphide bond?

Answer 21

Whenever two molecules of the amino acid CYSTEINE come close together, the SULFUR ATOM in one cysteine bonds to the sulfur atom in the other cysteine, forming a disulphide bond.

Question 22

What are hydrophobic and hydrophilic interactions?

Answer 22

When HYDROPHOBIC (water-repelling) R groups are close together in the protein, they tend to CLUMP TOGETHER.

This means that Hydrophilic (water-attracting) R groups are more likely to be pushed to the outside, which affects how the protein FOLDS UP into its final structure.

Question 23

What are hydrogen bonds?

Answer 23

These weak bonds form between POSITIVELY CHARGED HYDROGEN ATOMS in some R groups and SLIGHTLY NEGATIVELY-CHARGED atoms in other R groups on the polypeptide chain

Question 24

What bonds hold the Quaternary structure?

Answer 24

This tends to be determined by the TERTIARY STRUCTURE of the individual polypeptide chains being bonded together

Question 25

What happens when you heat a protein to very high temperatures?

Answer 25

Heating a protein to a HIGH TEMPERATURE will break up its ionic and hydrophobic/hydrophilic bonds interactions and hydrogen bonds. In turn, it will cause a change in the proteins 3D shape.

Question 26

Why are globular proteins round?

Answer 26

In a globular protein, the HYDROPHOBIC R GROUPS on the amino acids tend to be pushed to the OUTSIDE of the molecule. This caused by the HYDROPHOBIC and HYDROPHILIC INTERACTIONS in the proteins tertiary structure.

Question 27

(Globular protein) Having hydrophobic r groups outside the molecule makes the protein ______

Answer 27

Soluble, so they are EASILY TRANSPORTED in fluids.

Question 28

Globular proteins have a range of functions in living organisms such as Haemoglobin. What is Haemoglobin?

Answer 28

Haemoglobin is a globular protein that carries OXYGEN around the body in RED BLOOD CELLS. It's known as a CONJUGATED PROTEIN this means its a protein with a NON-PROTEIN GROUP attached. The non-protein part is called a PROSTHETIC GROUP. Each of the four polypeptide chains in haemoglobin has a prosthetic group called HEAM. A heam group contains IRON, which oxygen binds too.

Question 29

Globular proteins have a range of functions in living organisms such as Insulin. What is Insulin?

Answer 29

Insulin is a hormone secreted by the PANCREAS. It helps to regulate the BLOOD GLUCOSE LEVEL. Its SOLUBILITY is important-it means it can be TRANSPORTED in the BLOOD to the tissues where it acts. An insulin molecule consists of two POLYPEPTIDE CHAINS, which are held together by DISULPHIDE BONDS.

Question 30

Globular proteins have a range of functions in living organisms such as Amylase. What is Amylase?

Answer 30

Amylase 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 sheets sections. MOSTNZYMES are GLOBULAR PROTEINS.

Question 31

What are Fibrous proteins?

Answer 31

Fibrous proteins are INSOLUBLE and STRONG. They're STRUCTURAL proteins and are fairly unreactive (unlike many globular proteins).

Question 32

Fibrous protein is TOUGH and ROPED SHAPED, such as collagen. What is collagen?

Answer 32

Collagen is 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, e.g in the bone.

Question 33

Fibrous protein is TOUGH and ROPED SHAPED, such as Keratin. What is Keratin?

Answer 33

Keratin is found in many of the EXTERNAL STRUCTURES of animals, such as skin, hair, nails, feathers and horns. It can either be FLEXIBLE (as it is in the skin) or HARD AND TOUGH (as it is in nails)

Question 34

Fibrous protein is TOUGH and ROPED SHAPED, such as Elastin. What is Elastin?

Answer 34

Elastin found in ELASTIC CONNECTIVE TISSUE, such as skin, large blood vessels and some ligaments. It is Elastic, so it allows tissues to return to its original shape after it has been stretched.

Question 35

Describe the general structure for an Amino acid.

Answer 35

Amino group(NH2) attached to a carbon with a hydrogen and variable R group. Carbon attached to a Carbonyl group(-COOH)

Question 36

Name the bonds that join amino acids together in proteins.

Answer 36

Peptide bonds

Question 37

What is a conjugated protein?

Answer 37

Conjugated protein means its a protein with NON-PROTEIN GROUP attached. The non-protein protein part is called a PROSTHETIC GROUP.

Question 38

Suggest which of the following proteins is most abundant in a tortoises shell Collagen, Elastin, Alpha-amylase, Keratin

Answer 38

Keratin

Question 39

HSA is a globular protein, which transports other molecules such as fatty acids around the bloodstream. The molecule consists of 585 amino acids, several of which are cysteine. Describe the bonds that could be present in the tertiary structure of HSA and suggest how its structure makes it suited for its role of transporting molecules in the blood.

Answer 39

The tertiary structure may contain IONIC BONDS. These are attractions between negatively charged R-groups and positively charged R-groups on different parts of the molecule. It may also contain DISULPHIDE BOND, which forms when the sulfur atom in two nearby cysteine molecules bond. There may also be hydrogen bonds, which are weak bonds between slightly positively charged hydrogen atoms in some R groups, and slightly negatively charged atoms in other R groups in the polypeptide chain. The tertiary structure will also contain Hydrophobic and Hydrophilic interaction. Hydrophobic R groups clump together, meaning the hydrophilic R groups are more likely to be pushed to the outside This will make HSA SOLUBLE in water, which makes it suited for transporting molecules in the blood.