MHS Module 3 - lipoproteins and protein metabolism p4

explain what lipoproteins are

lipid-protein complexes containing large insoluble glycerides and cholesterol

name the 4 groups of lipoproteins

chylomicrons

very low density lipoproteins

low density lipoproteins

high density lipoproteins

explain chlymicrons

largest lipoproteins

produced by intestinal epithelial cells from fats in food

carry absorbed lipids into lymph and then into bloodstream

explain protein metabolism

body synthesises 100k-400k different proteins with different structures and functions, built from the same 20 amino acids

what must occur to proteins to be used as energy

converted into substances that cn enter the citric acid cycle

what steps does the covnersion include

transamination

deamination

urea cycle

removal of amino group requires coenzyme derivative of vitamin b6

explain transamination:

attaches amino group of amino acid to keto acid

converts keto acid to amino acid:

• leaves mitochondrion and enters cytosol

• available for protein synthesis

explain deamination:

prepares amino acid for breakdown in citric acid cycle

removes amino group and hydrogen atom

• generates toxic ammonium ion usually in liver cells

explain urea cycle

liver cells have enzymes that remove toxic ammonium cells by synthesising urea

urea is fairly harmless water soluble compound excreted in urine

explain how amino acids are used for ATP production

when glucose and lipid reserves are inadequate, liver cells break down internal proteins and absorb additional amino acids from blood

amino acids become deaminated; sending carbon chains to mitochondria

what are the 3 factors that make protein catabolism an impractical source of quick energy

proteins are more difficult to break apart than complex carbohydrates or lipids

one by-produce amnion ions is toxic to cells

proteins form the most important structural and functional components of cells

how does protein synthesis occurs

body synthesises half of amino acids needed to. build proteins

explain the synthesis of the 10 essential amino acids

eight are not synthesised, 2 are insufficiently synthesised

explain the synthesis of non-essential amino acids

amino acids made by the body on demand

requires lamination (addition of amino group)