protein and amino acids Flashcards
what is protein a major component of
plant and animal tissue
amino acids are needed in every what
living cell
why do we need a constant supply of protein
as Our bodies constantly make, break down and use proteins so we need protein to replace what we use.
We don’t store amino acids. As although stored in protein the protein always has a function to carry out so isn’t stored
what is excess protein converted into
energy or fat
protein is important in energy gen
if theres not enough protein or in form of glucose in body them what happens to muscles
broken down causing wasting - PEM. This helps to provide our bodys the fuel they need.
Wasting weakens muscles including the heart
insulin is a protein needed as what
a hormone for homeostasis
what is excess protein converted into and used for
proteins converted to glucose to be used as energy. Or to create fatty acids, so is incorporated into our fat store
what is the structure of protein
Made of strings of amino acids linked with peptide bonds.
there are 20 amino acids
R group determines the identity and unique chemical properties of the amino acid
alpha carbon is the central one
Amine group is a nitrogenous group
Proline is only amino acid that rings around the central carbon
what are essential amino acids and how many are there
9
Essential as were unable to synthesis that amino acid so it must come from diet
All 20 amino acids are needed
what are non essential amino acids and how many are there
Non essential – don’t have to get them from the diet as we can biochemically synthesis them
there are 3
explain semi-essential amino acids an dhow many there are
8
Semi essential amino acids we can synthesis but we need something else from the diet, Often another Animo acid to synthesis them
Cystine can only be synthesised if we have methionine (an essential amino acid)
We can only synthesis tyrosine if there’s adequate amount of phenylalanine in diet, (an essential amino acid )
what is Phenylketonuria (PKU)
Autosomal recessive disorder.
Cannot metabolise Phe due to (virtually) absent phenylalanine hydroxylase.
Excess Phe builds up in blood affecting brain development.
Heel-prick blood test in UK
Treatment is a low protein diet (Phe-restricted)
how do peptide bonds form
between CO and NH of 2 amino acids
it produces the product of water
often known as dehydration synthesis of polypeptides
what is the breaking of polypeptide bonds called
hydrolysis
as adds water across the bond
what is an ex of the structure of insulin
Sulphydryl (-SH) groups of 2 cysteine molecules may be oxidised to form a disulphide bridge.
what are the functions of proteins
Enzymes (e.g. amylase) (Anything ending is ase is an enzyme)
Energy source
Transport (e.g. haemoglobin) (eg na/k, channels, etc are all proteins)
Hormones (e.g insulin - released into blood by pancreas) (not all hormones are proteins but lots are)
Movement (e.g. actin & myosin - allow for shape changes in muscles allowing contraction)
Structure (e.g. collagen)
Storage (e.g. ferritin - stores iron in body)
Immunity (e.g. antibodies- for immune response)
Growth, differentiation and gene expression
explain hormones in terms of protein function
Chemical messengers made in one part of the body which act on cells elsewhere, e.g. insulin
hormones can travel slow taking minuets to hours for response
explain immune function in term of protein function
Antibodies are blood proteins which attack and inactivate bacteria.
Antibodies circulate in fluids, destroying targets
We have immune cells which manufacture proteins
Nervous system acts fast in seconds,
explain structural functions of protein
Fibrin in blood (can turn to a solid to clot blood when needed)
Collagen gives skin and bone their elastic strength
Keratin gives hair and nails their strength
nitrogen in protein foods is measured using what method, explain the method
Kjeldahl method.
Developed in 1883 by Johan Kjeldahl
Method used for UK food tables
Digestion
Neutralisation
Titration
name some non amino nitrogen’s
cyanide, nitrate, nitrite, nitrogen gas, azo compounds
what some of the amino nitrogen’s
- Amino acids
most have nutritional value
some excreted (no value) - Peptides, e.g. carnosine
- Nucleic acids
purines, pyrimidines (may be subtracted)
(Some biological amines are derived from nucleic acids )
why do children need more protein
as are growing
explain plant protein compared to animal protein nutrition in the diet
Plant protein has less value then animal protein . As its easier to get all amino acids with eating animal protein. But you can achieve all amino acids with plant diet but need lots more plant material eaten
If a child needs 1 g/kg/day milk/egg protein, they need how much of mixed animal and plant protein, and how much of just plant protein
1.5 g/kg/day mixed animal and plant protein
OR
2.0 g/kg/day plant protein per day
what are the UK DRV requirements for protein based on
on recommendations of FAO/WHO/UNU expert consultation in 1985.
Values based on estimates of amount of high quality egg or milk protein required for N equilibrium.
egg and milk protein are of highest quality
whats the requirement of protein during pregnancy and lactation
Pregnancy: +6 g/day
Lactation:
+11 g/day for 0-6 months
+8 g/day for 6+ months
whats the requirements of protein in g per kg/day
0.75g protein per kg/day
