proteins 2

Question 1

what Is N linked glycosylation

Answer 1

• amide of an asparagine
• site Asn-x-Ser/Thr
• occurs in ER lumen

Question 2

what is O linked glycosylation

Answer 2

• hydroxyl group of serine or threonine
• glycosylated in the golgi lumen

Question 3

what does oligosaccharyltransferase do

Answer 3

• glycosylates proteins in the ER lumen

Question 4

what are the stages of glycoprotein degradation

Answer 4

• endocytosis to lysosome from cell surface
• proteins degrades via proteases
• remove sugars by lysosomal glycosidases

Question 5

what occurs with lysosomal hydrolases deficiency

Answer 5

• lysosomal storage diseases
• undigested substrates in lysosomes
• defects often leads to nervous system defects causing changed cell signalling and decrease mitochondrial function and low ATP

Question 6

what are the causes and symptoms of inclusion cel disease

Answer 6

• recessive mutation causing hydrolytic enzymes missing - failed sorting in golgi so lysosomal hydrolases found in blood

symptoms - small, weak muscle tone, bone abnormalities, high mortality, slow growth, coarse facial features and overgrowth of gums

Question 7

what are glycosaminoglycans (GAGs) made from

Answer 7

• contains unbranched polysaccharides
• with amino sugars and acidic disaccharide repeats
• long and linear

Question 8

what are proteoglycans made from

Answer 8

• glycoproteins with GAGs
• up to 95% GAG in weight

Question 9

how are GAGs assembled on a protein

Answer 9

• tetrasaccharide added at serine in golgi
• repeats added one sugar at a time

Question 10

what are the functions of proteoglycans

Answer 10

• lubricants in connective tissue
• cell adhesion to extracellular matrix
• bind cell proliferation factors

Question 11

what are the stages of glycosaminoglycans degradation

Answer 11

• endocytosis
• remove sugars - lysosomal glycosides

Question 12

what are biogenic amines

Answer 12

• small organic nitrogen containing molecules
• synthesised from amino acids

Question 13

what are the classes of biogenic amines

Answer 13

• aromatic and hetrocyclic
• aliphatic - mono, di, tri, poly amines
• aliphatic volatile amines

Question 14

what are the functions of biogenic amines

Answer 14

• cell membrane stabilisation
• immune functions and inflammation mediators
• nucleic acid and protein synthesis
• hormones
• neural transmission

Question 15

what reactions make biogenic amines

Answer 15

• decarboxylation of amino acids
• amination and transamination of aldehydes and ketones

Question 16

what is the biogenic amine of serine

Answer 16

• sphingosine

Question 17

what is the biogenic amine of histidine

Answer 17

• histamine

Question 18

what is the biogenic amine of tryptophan

Answer 18

• serotonin and nicotinamide and 5-hydroxytryptamine (5-HP)

Question 19

what is serotonin used for

Answer 19

• relaxation, pleasure, memory

Question 20

what is nicotinamide used for

Answer 20

• vitamin B3
• coenzyme and energy production

Question 21

what biogenic amine does tyrosine make

Answer 21

• adrenaline and thyoxine

Question 22

what is adrenalin used for

Answer 22

• hormone
• fight or flight response
• neurotransmitter

Question 23

what is thyroxine used for

Answer 23

• thyroid gland hormone
• activated to triiodothyronine
• metabolic rate, muscle control, brain development, bone maintenance

Question 24

describe the catecholamine synthesis pathway

Answer 24

1) tyrosine
2) dihydroxyphenylalanine
3) dopamine
4) norepinephrine
5) epinephrine

Question 25

what is the rate limiting stage in catecholamine synthesis

Answer 25

• tyrosine hydroxylate - stage 1
• co-substrate - oxygen
• cofactor - tetrahydrobiopterin

Question 26

what causes IBS

Answer 26

increased monoamine oxidase activity —> oxidative stress —> vascular dysfunction

Question 27

what does monoamine oxidase A deficiency cause

Answer 27

• serotonin build up in the brain —> loss of impulse control
• avoid high thymine food

Question 28

what does vitamin B12 - folate deficiency cause

Answer 28

• required for FAD—> monoamine oxidases disfunction –> tiredness, disturbed vision, psycgological problems

Question 29

what does monoamine oxidases (MAO) do

Answer 29

• family of enzymes
• deaminates neurotransmitters
• requires prosthetic group - flavin adenine dinucleotide (FAD)