Proteins

Question 1

what are proteins

Answer 1

proteins are polymers made up of amino acids joined together by peptide bonds.

Question 2

what type of reaction joins two amino acids

Answer 2

condensation

Question 3

what is the bond between two amino acids called

Answer 3

peptide bond

Question 4

what reaction breaks the bond between two amino acids

Answer 4

hydrolysis

Question 5

what is the primary structure of the protein?

Answer 5

the sequence of the amino acids in the protein chains

Question 6

two types of secondary structure that can appear in a protein

Answer 6

1. coiled structure called alpha helix
2. a flatter folded structure called beta beta-plated sheet

Question 7

what bonds hold the secondary structure together.

Answer 7

hydrogen bonds

Question 8

tertiary structure of a protein

Answer 8

the overall 3D shape of the protein

Question 9

strength of hydrogen bond

Answer 9

individual bonds are weak but often many H bonds are formed and collectively they provide stability.

Question 10

strength of an ionic bond

Answer 10

stronger than H bonds

Question 11

disulfide

Answer 11

very strong

Question 12

hydrophobic/hydrophilic interactions

Answer 12

weak interactions

Question 13

properties of globular proteins

Answer 13

compact
water-soluble
spherically shaped

Question 14

why are globular proteins soluble?

Answer 14

hydrophobic R groups at the centre of the protein and hydrophilic on the outside/surface so water molecules can interact with surface

Question 15

how does globular proteins’ solubility enable them to carry out their function?

Answer 15

they can carry out important metabolic reactions in an aqueous environment

Question 16

Examples of globular proteins

Answer 16

haemoglobin
enzymes
peptide hormones
antibodies

Question 17

T/F haemoglobin has a quaternary structure

Answer 17

TRUE

Question 18

T/F haemoglobin does not have a prosthetic group

Answer 18

FALSE - the haem group is a prosthetic group

Question 19

T/F haemoglobin is a simple protein

Answer 19

FALSE-haemoglobin is a conjugated protein because it contains a prosthetic group.

Question 20

Describe what a conjugated protein is

Answer 20

a conjugated protein has a permanent non-protein component called a prosthetic group

Question 21

why is haemoglobin described as a conjugated protein?

Answer 21

has 4 haem groups as part of its structure

Question 22

how does solubility helop globular proteins

Answer 22

insulin has to be transported in the blood to target cells, so it is important that it is soluble.

Question 23

how does a very specific 3D shape help globular proteins.

Answer 23

insulin has to bind to receptors on target cells therefore its 3D shape is very important

Question 24

what is transcription

Answer 24

the first stage of protein synthesis

Question 25

what happens during transcription

Answer 25

DNA - mRNA

Question 26

what is translation

Answer 26

the second stage of protein synthesis

Question 27

what happens during translation

Answer 27

mRNA- Protein

Question 28

role of transcription

Answer 28

to produce short single-stranded sections of mRNA using DNA as a template

Question 29

Process of transcription

Answer 29

1. DNA helicase unwinds and unzips the DNA - breaking hydrogen bonds between nucleotide bases 2.pre-mRNA forms using complementary base pairing with the template strand of DNA 3. RNA polymerase catalyses the formation of phosphodiester bonds in the pre-mRNA

Question 30

Why is collagen such a strong molecule

Answer 30

it is made up of three polypeptides wound together in a strong rope like structure

Question 31

describe and explain why collagen is a fibrous protein

Answer 31

- triple helix structure - long polypeptide chains - structural role , stability within phospholipid bilayer - no tertiary structure - high number of hydrophobic R groups makes it insoluble

Question 32

why are fibrous proteins insoluble?

Answer 32

high number of hydrophobic R groups

Question 33

what are fibrous proteins?

Answer 33

long strands of polypeptide chains that have cross-linkages due to hydrogen bonds

Question 34

why are fibrous proteins suited for structural role?

Answer 34

- insoluble - organised structure due to repetitive sequence

Question 35

examples of fibrous proteins

Answer 35

keratin elastin collagen

Question 36

what are globular proteins

Answer 36

proteins that are compact spherical and soluble in water

Question 37

why do globular proteins form a spherical shape when folding into their tertiary structure

Answer 37

- their non-polar hydrophobic r groups are orientated towards centre of the protein - polar hydrophilic R groups are on outside of protein

Question 38

what does the prosthetic heam group contain in haemoglobin?

Answer 38

iron which is able to reversibly combine with an oxygen molecule

Question 39

how much oxygen can a haemoglobin carry

Answer 39

it has 4 heam groups so 4 oxygen molecules.