beta oxidation

Question 1

what are fatty acids

Answer 1

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

Question 2

how to name unsaturated fatty acids

Answer 2

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

Question 3

how does a bend in the structure of a hydrocarbon chain occur

Answer 3

a cis double bond will cause a bend as theres no rotational freedom across the double bond (cis is same side)

Question 4

how does the presence of unsaturated fatty acids affect the membrane

Answer 4

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

Question 5

what does large amounts of trans fatty acid contribute to

Answer 5

cardiovascular disease

Question 6

where are trans fatty acids produced

Answer 6

by dairy animals in their stomach by microbial fermentation, obtained by eating dairy products and meat

Question 7

what is cis and trans

Answer 7

cis= same side
trans=opposite

Question 8

what are polyunsaturated fatty acids

Answer 8

fatty acids with more than 1 carbon double bond

Question 9

how can polyunsaturated fatty acids also be named

Answer 9

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

Question 10

how are fats stored

Answer 10

as triglycerides

Question 11

what (enzyme) activates fatty acids for beta oxidation

Answer 11

fatty acyl-CoA synthetase

Question 12

how is fatty acyl CoA synthetase made

Answer 12

fatty acid–>fatty acyl adenylate–>fatty acyl CoA (all reversible and catalysed by fatty acyl CoA)

1. carboxylate ion is adenylated by ATP and forms acyl adenylate and PPi which gets hydrolysed into two molecules of Pi
2. thiol group (R-S-H) of CoA attacks acyl adenylate and displaces AMO and forms the thioester fatty acyl CoA

Question 13

where are fatty acids oxidised

Answer 13

mitochondria

Question 14

what carries activated fatty acids into mitochondrial matrix

Answer 14

(acyl) carnitine

Question 15

name the 3 stages of fatty acid beta oxidation

Answer 15

beta oxidation, 8 aceytyl CoA going into citric acid/krebs cycle, respiratory chain (etc)

Question 16

describe what happens in the first stage of beta oxidation

Answer 16

occurs in 4 steps repeated multiple times, removes 2 carbon units each cycle, produces one acetyl CoA per cycle

Question 17

how does beta oxidation with fatty acids with odd number of carbons differ from even numbered ones

Answer 17

requires 3 extra reactions for the product left after the last cycle, uses propionyl CoA for carboxylation

Question 18

what are some risk factors for biotin deficiency

Answer 18

total parenteral nutrition without biotin supplements, pregnancy, severe malnourishment

Question 19

symptoms of biotin deficiency

Answer 19

skin rashes, brittle hair, hair loss, alopecia, anaemia, neurological symptoms

Question 20

what vitamin complex is biotin part of

Answer 20

vitamin B complex

Question 21

what is biotin

Answer 21

a coenzyme for 5 carboxylases, required for gluconeogenesis and synthesis of phosphoenol pyruvate from pyruvate and fatty acid oxidation

Question 22

name a coenzyme part of vitamin B complex

Answer 22

coenzyme B12

Question 23

what is vitB12

Answer 23

cobalt containing coenzyme, important role in brain and red blood cell development, only bacteria produces this

Question 24

what are some risk factors of VitB12 deficiency

Answer 24

vegan diet, malabsorption syndromes, genetic deficiency of transport proteins in gut, pregnancy

Question 25

syndromes of vitB12 deficiency

Answer 25

anaemia, neurological symptoms, extreme tiredness, depression, mouth ulcers

Question 26

what happens to cis position double bonds at odd numbered carbons

Answer 26

need to be repositioned into trans by Δ3,Δ2-enoyl CoA isomerase

Question 27

what 2 things can happen to acetyl CoA

Answer 27

enters krebs cycle or converts to ketone bodies in liver

Question 28

why are fatty acids not a source of fuel for the brain

Answer 28

fatty acids cant cross blood brain barrier

Question 29

what are ketone bodies. name the 3 compounds

Answer 29

compounds produced during the metabolism of fats

acetone, acetoacetate, beta-hydroxybutyrate

Question 30

what are ketone bodies used for

Answer 30

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

Question 31

what increases the synthesis of ketone bodies

Answer 31

starvation

Question 32

what is ketosis

Answer 32

increased ketone bodies in blood

Question 33

what is ketoacidosis

Answer 33

ketosis and acidosis occurring together

Question 34

how can ketone bodies cause acidosis

Answer 34

overproduction of acetoacetate and beta hydroxybutyrate during starvation/fasting/diabetes lowers pH in blood

Question 35

what can extreme acidosis lead to

Answer 35

death and coma