beta oxidation Flashcards
what are fatty acids
carboxylic acids with hydrocarbon chains of varying length, saturated or unsaturated, carboxyl carbon is assigned carbon 1
eg. dodecanoic acid= 12 carbons
octadecanoic acid= 18 carbons
how to name unsaturated fatty acids
decanoic acid becomes decenoic (like alkene), position of double bond is indicated by a ∆ with ^number of lower carbon
18:1(∆^9)cis-9-octadecenoic acid
ratio is total number of carbons:number of unsaturated bonds
how does a bend in the structure of a hydrocarbon chain occur
a cis double bond will cause a bend as theres no rotational freedom across the double bond (cis is same side)
how does the presence of unsaturated fatty acids affect the membrane
all saturated fatty acids- packs into crystalline form, stabilised by many hydrophobic interactions
presence of one or more unsaturated fatty acids with cis double bonds- interferes with tight packing, results in less stable aggregates, more fluid membrane
what does large amounts of trans fatty acid contribute to
cardiovascular disease
where are trans fatty acids produced
by dairy animals in their stomach by microbial fermentation, obtained by eating dairy products and meat
what is cis and trans
cis= same side
trans=opposite
what are polyunsaturated fatty acids
fatty acids with more than 1 carbon double bond
how can polyunsaturated fatty acids also be named
carbon 1 is assigned to the methyl group at the opposite end of the carboxyl group but with ω infront like ω-3 ω-6 or just use the normal way lol
alpha is when carboxyl group is carbon 1
ω is when the methyl group is carbon 1
how are fats stored
as triglycerides
what (enzyme) activates fatty acids for beta oxidation
fatty acyl-CoA synthetase
how is fatty acyl CoA synthetase made
fatty acid–>fatty acyl adenylate–>fatty acyl CoA (all reversible and catalysed by fatty acyl CoA)
- carboxylate ion is adenylated by ATP and forms acyl adenylate and PPi which gets hydrolysed into two molecules of Pi
- thiol group (R-S-H) of CoA attacks acyl adenylate and displaces AMO and forms the thioester fatty acyl CoA
where are fatty acids oxidised
mitochondria
what carries activated fatty acids into mitochondrial matrix
(acyl) carnitine
name the 3 stages of fatty acid beta oxidation
beta oxidation, 8 aceytyl CoA going into citric acid/krebs cycle, respiratory chain (etc)
describe what happens in the first stage of beta oxidation
occurs in 4 steps repeated multiple times, removes 2 carbon units each cycle, produces one acetyl CoA per cycle
how does beta oxidation with fatty acids with odd number of carbons differ from even numbered ones
requires 3 extra reactions for the product left after the last cycle, uses propionyl CoA for carboxylation
what are some risk factors for biotin deficiency
total parenteral nutrition without biotin supplements, pregnancy, severe malnourishment
symptoms of biotin deficiency
skin rashes, brittle hair, hair loss, alopecia, anaemia, neurological symptoms
what vitamin complex is biotin part of
vitamin B complex
what is biotin
a coenzyme for 5 carboxylases, required for gluconeogenesis and synthesis of phosphoenol pyruvate from pyruvate and fatty acid oxidation
name a coenzyme part of vitamin B complex
coenzyme B12
what is vitB12
cobalt containing coenzyme, important role in brain and red blood cell development, only bacteria produces this
what are some risk factors of VitB12 deficiency
vegan diet, malabsorption syndromes, genetic deficiency of transport proteins in gut, pregnancy
syndromes of vitB12 deficiency
anaemia, neurological symptoms, extreme tiredness, depression, mouth ulcers
what happens to cis position double bonds at odd numbered carbons
need to be repositioned into trans by Δ3,Δ2-enoyl CoA isomerase
what 2 things can happen to acetyl CoA
enters krebs cycle or converts to ketone bodies in liver
why are fatty acids not a source of fuel for the brain
fatty acids cant cross blood brain barrier
what are ketone bodies. name the 3 compounds
compounds produced during the metabolism of fats
acetone, acetoacetate, beta-hydroxybutyrate
what are ketone bodies used for
once acetyl CoA is converted into ketone bodies in the liver, they transport to other tissues to be used as fuel for krebs cycle, acetone is volatile and exhaled
what increases the synthesis of ketone bodies
starvation
what is ketosis
increased ketone bodies in blood
what is ketoacidosis
ketosis and acidosis occurring together
how can ketone bodies cause acidosis
overproduction of acetoacetate and beta hydroxybutyrate during starvation/fasting/diabetes lowers pH in blood
what can extreme acidosis lead to
death and coma
