Biological Molecules Flashcards
1
Q
Carbohydrates
A
Molecules that only contain the elements hydrogen, carbon and oxygen
- formula is Cx(H2O)y
2
Q
Globular proteins
A
- soluble in water
- hydrophilic R groups are on the outside of the protein
- hydrophobic R groups are in the centre of the protein
- spherical in shape
3
Q
Conjugated proteins
A
- type of globular protein
- protein that contains a non-protein component (prosthetic group)
- there are different types of prosthetic groups
- lipids and carbohydrates can combine with proteins to form lipoproteins or glycoproteins
- metal ions & minerals can be derived from vitamins also form prosthetic groups
4
Q
Haemoglobin
A
- found in red blood cells
- binds to oxygen reversibly
- binds to oxygen in the lungs and releases it in body tissues
- it’s a quaternary protein so contains 4 polypeptide chains with 2 alpha and 2 beta subunits
- each subunit contains a haem group which contains the Fe 2+ ion
- this ion is where the oxygen binds to reversibly
- one HB molecule can bind to 4 oxygen molecules
- when oxygen binds to HB , the structure slightly changes to make it easier for oxygen to bind
5
Q
Insulin
A
- a hormone that is carried in the bloodstream
- plays a role in blood glucose regulation
- 2 polypeptide chains linked together by disulfide bonds
- insulin carries out its role by binding to specific receptor molecules
- a receptor is a protein found on the CM of target cells
- the shape of insulin fits perfectly into its receptor
- if the shape changes slightly, it could prevent it from binding effectively
6
Q
Catalase
A
- type of enzyme that is specific to a particular reaction or type of reaction
- quaternary protein so has 4 polypeptide chains that each have a haem group
- the presence of the Fe 2+ ions allows catalase to interact with hydrogen peroxide and speed up its breakdown
- hydrogen peroxide is a common by product of metabolism and its accumulation is damaging to cells
- catalase stops its accumulation
7
Q
Fibrous proteins
A
- formed from long insoluble molecules
- high proportion of amino acids with hydrophobic r groups
- amino acid sequences are quite repetitive which leads to very organised structures reflected in the roles FP have
- FP tend to make strong, long molecules which are not folded into 3D shapes
8
Q
Keratin
A
- present in nails, skin and hair
- has a large proportion of the sulphur containing amino acid cysteine
- many strong disulfide bonds
- degree of disulfide bonds determines the flexibility
9
Q
Elastin formation
A
- formed by many tropoelastin molecules aggregating via interactions between hydrophobic areas
- structure is stabilised by cross-linking covalent bonds, involving the amino acid lystine
- the structure still has some flexibility
10
Q
Tropoelastin
A
- can stretch and recoil without breaking
- contains alternate hydrophobic and lysine rich areas
11
Q
Elastin
A
- found in elastin fibres
- made by linking many soluble tropoelastin protein molecules
- present in the walls of blood vessels and alveoli
- confers strength and flexibility to the skin and other tissues and organs
- gives these structures the flexibility to expand and return back to its normal size
12
Q
Collagen
A
- a connective tissue found in skin tendons, ligaments & the nervous system
- 3 polypeptide chains wound together in a triple helix structure to formo a tough rope-like protein
- flexible
- stable; contains high proportions of the AAs proline and hydroxyproline, where the R groups in these amino acids repel each other
13
Q
Tropocollagen
A
- every amino acid in the polypeptide chains is glycine (a small amino acid)
- it’s small size allows the 3 protein molecules to form a closely packed triple helix
- HBs form between the polypeptide chains, which forms long quaternary proteins with staggered ends
- allows proteins to join end to end, forming long fibrils called tropocollagen
- these cross-link to form strong fibres
