Proteins (2.1.1)

What elements do proteins contain?
Carbon, hydrogen, oxygen, nitrogen and sometimes sulphur.
1 of 26
What is a polymer?
A long chain of monomers joined together to make a large macromolecule.
2 of 26
What is the general structure of an amino acid?
Each amino acid is made up of an amino group (NH2), a variable R group, and an acid group (COOH).
3 of 26
How do plants obtain nitrogen to make amino acids?
They take up nitrates from the soil and use the nitrogen from this to make amino acids and proteins.
4 of 26
How do animals obtain nitrogen to make amino acids?
Consume protein in diet, digest it into amino acids, absorb these into the bloodstream, where they are carried to cells.
5 of 26
How are amino acids joined together?
By a condensation reaction between the acid group of one, and the amino group of another. This releases a water molecule and forms a covalent bond. This new bond is a peptide bond.
6 of 26
Where are proteins made?
At the ribosomes/RER. It is controlled by the DNA/genetic code in the nucleus, which instructs the ribosomes on which proteins to make.
7 of 26
What is the primary protein structure?
The unique sequence of amino acids in the initial polypeptide chain produced.
8 of 26
Why does the primary structure affect the final structure of the protein?
Different amino acids have different R groups which will affect how the polypeptide chain twists and folds into its final shape. Different R groups allow different bonds to form as the protein structure develops.
9 of 26
Do proteins function at the primary level?
No, first they must be built up into at least the secondary structure.
10 of 26
What are the two arrangements for secondary protein structure?
Alpha helix (spiral) and beta pleated sheet (zig zag).
11 of 26
How is the secondary protein structure held?
They're held together by hydrogen bonds between the amino acids. The hydrogen bonds collectively hold the structure in place.
12 of 26
What is the tertiary protein structure?
The alpha helices and beta sheets can be folded further to give a protein with a specific shape. These structures are held in place by several types of bond.
13 of 26
What types of bond hold the tertiary structure in place?
Hydrogen bonds. Ionic bonds- between oppositely charged R groups. Disulphide bonds- One amino acid contains sulphur. When 2 cysteines are close in polypeptide strong covalent bonds form. Hydrophilic/phobic interactions.
14 of 26
What are hydrophilic/hydrophobic interactions?
Some amino acids have hydrophobic R groups which stay towards the centre of the protein. Others have hydrophilic R groups and are found around the edges. Affects final shape.
15 of 26
What important molecules do tertiary structures form the basis of?
Enzymes. Some hormones. Membrane proteins (channels and carriers)
16 of 26
Why is the functioning of a tertiary protein greatly affected by temperature?
Temperature goes up, more k.e & molecules vibrate. The hydrogen bonds in a tertiary protein break easily. If the temperature increases a lot, all of the bonds holding structure will break. Protein loses its specific 3D shape & no longer functions.
17 of 26
What is a quaternary protein?
Contains more than one polypeptide chain.
18 of 26
Give an example of a quaternary protein and its structure.
Haemoglobin is made up from 4 polypeptide chains, each with an non-protein haem group- prosthetic group. It has 2 alpha and 2 beta chains.
19 of 26
What are globular proteins?
Very precise shape due to hydrophilic/hydrophobic interactions. Form anitbodies, enzymes, membrane proteins and some hormones. They're often partially soluble.
20 of 26
What is the function of haemoglobin?
To carry oxygen from the lungs to the respiring tissues. It is the haem group which picks up the oxygen. They have a high affinity for it when concentration is high, but release it into tissues.
21 of 26
What are fibrous proteins involved in?
Providing structural strength in organisms.
22 of 26
What are globular proteins involved with?
Metabolic processes in organisms.
23 of 26
Where does collagen provide mechanical strength?
Makes up outer layer of artery walls. Tendons are made from collagen. Bone structure, contains collagen. Makes up cartlidge and connective tissue.
24 of 26
What are fibrous proteins?
Long fibres, that are large and not water-soluble. They tend to have structural roles in the body. Eg: keratin found in hair, collagen found in skin.
25 of 26
Give an example of a fibrous protein and its structure.
Collagen is a fibrous protein. Every 3rd amino acid of p.p chain is glycine- is small & allows 3 chains to fit closely together. Made of 3 polypeptide chains wound around each other. Many H-bond to make larger collagen fibrils, then collagen fibres.
26 of 26

Other cards in this set

Card 2


What is a polymer?


A long chain of monomers joined together to make a large macromolecule.

Card 3


What is the general structure of an amino acid?


Preview of the front of card 3

Card 4


How do plants obtain nitrogen to make amino acids?


Preview of the front of card 4

Card 5


How do animals obtain nitrogen to make amino acids?


Preview of the front of card 5
View more cards


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Biological molecules resources »