Bioenergetics - Protein

what are proteins?

large molecules made up of chains of amino acids

found in every cell of the body

how many different amino acids are there?

20 different types

how many essential and non essential amino acids are there

9 essential and 11 non essential

what is the structure of proteins 

made up of chains of amino acids - classified by the number of amino acids in the chain

how many amino acids are in a peptide

less than 50

how many amino acids in dipeptide, tripeptide and polypeptide

dipeptide = 2

tripeptide = 3

polypeptide = more than 10

how many amino acids in a protein

more than 50 - typically 100 to 10000

what are amino acids made up of

carbon, hydrogen, oxygen, nitrogen and sometimes sulphur

what is the amino acid structure

central carbon

carboxylic acid group (COOH)

amine group (NH2)

R group (changes for every amino acid)

how are peptide bonds formed 

carboxyl group (COOH) of one amino acid joins with amine (NH2) group of another amino acid in a condensation reaction

how are peptide bonds broken

through a process called hydrolysis

how is protein structure affected by DNA

a change in the genes DNA sequence can lead to a change in the amino acid sequence of the protein

what are the different levels of protein structure

primary

secondary

tertiary

quaternary

what is the primary protein structure 

the simplest level - a sequence of amino acids in a polypeptide chain

what is the secondary protein structure

alpha helix, beta pleated sheet and triple helix in collagen

what are the 5 important interactions in the tertiary structure

hydrogen bond

hydrophobic interactions

hydrophilic interactions

salt bridges

disulfide bonds

what is the quaternary structure of proteins 

overall shape when 2 or more polypeptides assemble to make a protein

what are individual peptide chains called

subunits

what are globular proteins

compact, spherical shapes for example enzymes and antibodies

what are fibrous proteins 

long and narrow fibre like shape 

what is protein denaturing

disruption of any bond that stabalises secondary, tertiary or quaternary structure

what factors cause a protein to denature

heat - above 50 degrees breaks hydrogen bonds

acids

bases

salts

mechanical agitation

what is the protein turnover amount?

200g to 400g daily 

whats the name for protein degradation

catabolism

whats the name for protein synthesis

anabolism

what are the functions of protein

structure and mechanical functions like strength

enzymes and hormones needed to speed up reactions

fluid balance

acid base balance

transport

immunity

energy

where are amino acids absorbed

absorbed into small intestine

what happens in amino acid absorption

transported from intestines to liver via portal vein

ocasionally they’re absorbed intact

what are amino acids needed for in the liver 

synthesise new proteins 

converted to energy, glucose or fat and released into blood

what is protein turnover

constant flux between making new protein and breaking down old protein

how to get increased muscle size

need muscle protein synthesis to exceed breakdown

what is the metabolic fate of amino acids 

protein turnover - released into amino acid pool or used in synthesis

gluconeogenesis - amino acids can make glucose when its limited 

energy production - amino acids used for energy when diet deficient

fat cells - can be converted to fatty acids and stored as triglycerides 

what happens in deamination?

amino group is removed and ammonium ion is released

what are the effects of having too much protein in the diet

hydration - nitrogen obtained from protein is excreted in urine so too much protein causes excessive urine and dehydration

may lack important amounts of other sources like carbs and vitamins

fatty protein sources increase risk cardiovascular disease

high in phosphorous which can harm kidneys

how are proteins metabolised 

when glucose and lipid reserves are too low, liver cells breakdown internal proteins and absorb additional amino acids from blood

amino acids are deaminated 

what is the process of deamination

carbon chains are broken down and converted to either glucose through gluconeogenesis or fatty acids and stored as triglycerides

negatives of protein catabolism

proteins harder to breakdown than carbs or lipids

ammonium ions are toxic to cells

proteins are very important structurally and functionally to cells

how long does it take for protein to be digested 

protein is digested at different rates 

whey protein is rapidly digested 

caesin forms a curd and takes longer to empty from the stomach

soy is fast but slower than whey

what are complete proteins

proteins that contain all the amino acids

examples of complete proteins

meat, fish and dairy

what are incomplete proteins 

have some of the amino acids but not all

examples of incomplete proteins

nuts, grains and legumes

what is the tertiary protein structure

alpha helix and beta sheets fold into a compact shape 

energy provided per gram

4 kcal