types of protein

Question 1

state some features of globular proteins

Answer 1

-soluble in water
-spherical shape
-complementary to a specific molecule
-hydrophilic R groups on the surface
-irregular amino acid sequence
-contain prosthetic grouups-conjugated proteins
- have a functional role-in cellular processes
-temperature ,pH sensitive

Question 2

state features of fibrous proteins

Answer 2

-insoluble in water
-elongated shape, form long strands
-regular amino acid sequence
-have structural functions,provide strength and support to tissues
-strong and tough
-unreactive
-flexible

Question 2

what are the two types of protein

Answer 2

-globular proteins
-fibrous proteins

Question 3

describe how globular protein fold into their tertiary structure

Answer 3

when a protein folds into their tertiary structure ,the hydrophobic R group clumb together on the inside of the protein,away from the aqueous environment and hydrophilic R groups are pushed on the outside of the protein,allowing globular protein to be soluble in water

Question 3

state 3 example of globular proteins

Answer 3

-catalase
-haemoglobin
-insulin

Question 3

state 3 examples of fibrous proteins

Answer 3

-collagen
-elastin
-keratin

Question 3

what is a conjugated petein

Answer 3

-its a globular protein that contains a non-protein component known as a prosthetic group

Question 4

what is a prosthetic group

Answer 4

a non-protein component that forms a permanent feature of a protein

Question 4

what are the 3 different types of prosthetic groups

Answer 4

-lipids and carbohydrates can acts as prosthetic groups,they combine with proteins to form lipoproteins and glycoproteins

-metal ions like iron ions in haemoglobin

-molecules deprived of vitamins can act as prosthetic groups

Question 4

what is a cheat code for how you compare proteins

Answer 4

SSAFES
-S for shape
-S for structure
-A for amino acid sequence
-F for function
-E for examples
-S for solubility

Question 4

compare fibrous and globular proteins

Answer 4

shape:
globular proteins have a spherical shape whereas fibrous proteins have an elongated shape,form long strands

function:

globular proteins are water soluble,allowing them to perform functions within the body such as enzymes, transport proteins and hormones,whereas fibrous proteins are insoluble in water so pervorm more structural roles in the body ,providing strength and support to tissues

-amino acid sequence ; regular amino acid sequence in fibrous proteins and irregular in globular proteins

examples:
haemoglobin,catalase and insulin for globular VS collagen,elastin and keratin for fibrous

solubility:globular proteins are water soluble,whereas fibrous protein are not

Question 5

how does the structure of globular proteins affect their function

Answer 5

the spherical shape allows them to bind to complementary molecules and perform specific functions like catalysing a reaction

Question 5

how does the structure of fibrous proteins affect their function

Answer 5

-elongated shape,forming strong and tough strands allows them to provide strength and support to tissues

Question 6

compare haemoglobin and elastin

Answer 6

haemoglobin is a globular protein whereas elastin is a fibrous protein

shape:
haemoglobin has a spherical shape whereas elastin has an elongated shape and it forms long strands

structure:
haemoglobin is a quaternary protein ,it consists of 4 polypeptide chains,2 sets of 2 identical subunits,2 alpha and 2 beta subunits
-haemoglobin is also a conjugated protein,it contains 4 prosthetic haem groups,one for each of its subunits

Elastin is also a quaternary protein,but it is not a conjugated protein and does not contain prosthetic haem group.Elastin is made of stretchy molecules called tropoelastin.They make elastin flexible and give it the ability to streach and recoil to its original size.
Elastin also has cross-linked structure which makes it very strong

amino acid sequence:
elastin has regular amino acid sequence whereas haemoglobin does not

function:
haemoglobin is water soluble so its function is of a transport protein,it binds to ,carries and transports oxygen molecules from the lungs to each cell in the body via the bloodstream- the Fe2+ ions within the haem group bind reversible with oxygen molecules to form oxyhaemoglobin,allowing the oxygen to be transported around the body

Elastin on the other hand is not water soluble so has a more structural role in the body.It is contained within arterial walls to provide it with strength and support, and flexibility ,allowing them to stretch and recoil to its original size without breaking

elastin also present in aleveoli in lungs

solubility:
haemoglobin has hydrophilic R groups on its surface so its soluble whereas elastin is insoluble due the many hydrophobic R groups

Question 6

compare keratin and insulin

Answer 6

insulin is a globular protein whereas keratin is a fibrous protein

shape

insulin has a spherical shape,complementary to specific cell-surface receptors
whereas keratin has an elongated shape,form long strong ,tough inflexible strands

structure: insulin is made of 2 polypeptide chains,held together by disulphide bonds
keratin also contains many disulphide bonds between Rgroups containing sulfur,this makes it strong and inflexible

amino acid sequence: insulin has an irregular amino acid sequence whereas keratin has a regular amino acid sequence, large part of it consisting of cysteine amino acids

function: insulin is soluble in water,allowing to have an important role as a hormone,(as hormones are transported in the blood which is largely mad of water)it is involved in the regulation of blood glucose concentration in the body

whereas keratin has a more external structural role, Keratin strengthens and provides support to hair,nails and skin

keratin can be flexible ,but in the skin,not in the hair and nails ,there its inflexible

solubility: insulin is soluble in water as has hydrophilic R groups on its surface,whereas keratin is insoluble due the many hydrophobic R groups

Question 7

compare catalase and collagen

Answer 7

catalase is a globular protein whereas collagen is a fibrous protein

shape
catalase has a spherical shape that is complementary to a hydrogen peroxide molecule,whereas collagen has an elongated shape,forms long strands

structure:catalase is quartenary protein it is also a conjugated protein,has 4 haem groups

collagen is made of 2 beta polypeptide chains which overlap each other to form a triple helix.The two polypeptide chains are held together by hydrogen bonds and as well as covalent bonds form between separate collagen molecules which makes collagen very strong

-collagen is flexible

amino acid sequence:
collagen has a regular amino acid sequence, consisting of proline and glycine , whereas catalase has an irregular amino acid sequence

function:
catalase is water soluble which allows it to act as an enzyme,it catalyses the breakdown of hydrogen provide into harmless water and oxygen-does that by providing an alternative pathway with lower activation energy

On the other hand collagen is insoluble in water so has a structural role in the body,it’s a connective tissue that forms skin and tendons,it gives them strength and support as well as flexibility

solubility: catalase is soluble in water as has hydrophilic R groups on its surface, collagen is not soluble due to the many hydrophobic R groups present

Question 7

what enables haemoglobin to transport oxygen around the body

Answer 7

each ahem group contains Fe2+ ions they bind to the oxygen molecule reversibly forming oxyhaemoglobin,and allowing oxyegn to be transported around the body through the bloodstream

Question 7

how many molecules can haemoglobin carry at once? Explain why.

Answer 7

each haem group can carry 1 oxygen molecule, haemoglobin has 4 haem groups so can carry 4 oxygen molecules at once

Question 7

what makes collagen strong

Answer 7

-two polypetide chains overlap

-hydrogen bonds hold the two polypeptide chains together

-covalent bonds form between collogan molecules

Question 7

what makes elastin flexible and able to stretch and recoil

Answer 7

consists of stretchy molecules called tropoelastin

Question 7

what determines the flexibility of a meterial

Answer 7

the number of disulphide bonds ,the fewer the disulphide bonds the more flexible the material

Question 8

what causes the unpleasant smell when you burn your hair

Answer 8

comes from the large number of sulfur atoms contained in the protein which makes up the hair-keratin

Question 9

what is hydrogen peroxide and why is it harmful

Answer 9

by product of metabolism and if left to accumulate it causes damage to the cells