beta oxidation Flashcards

1
Q

what are fatty acids

A

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 well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how to name unsaturated fatty acids

A

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 well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

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

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how does the presence of unsaturated fatty acids affect the membrane

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what does large amounts of trans fatty acid contribute to

A

cardiovascular disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

where are trans fatty acids produced

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is cis and trans

A

cis= same side
trans=opposite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are polyunsaturated fatty acids

A

fatty acids with more than 1 carbon double bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how can polyunsaturated fatty acids also be named

A

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 well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how are fats stored

A

as triglycerides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what (enzyme) activates fatty acids for beta oxidation

A

fatty acyl-CoA synthetase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

how is fatty acyl CoA synthetase made

A

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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

where are fatty acids oxidised

A

mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what carries activated fatty acids into mitochondrial matrix

A

(acyl) carnitine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

name the 3 stages of fatty acid beta oxidation

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

describe what happens in the first stage of beta oxidation

A

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

17
Q

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

A

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

18
Q

what are some risk factors for biotin deficiency

A

total parenteral nutrition without biotin supplements, pregnancy, severe malnourishment

19
Q

symptoms of biotin deficiency

A

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

20
Q

what vitamin complex is biotin part of

A

vitamin B complex

21
Q

what is biotin

A

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

22
Q

name a coenzyme part of vitamin B complex

A

coenzyme B12

23
Q

what is vitB12

A

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

24
Q

what are some risk factors of VitB12 deficiency

A

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

25
Q

syndromes of vitB12 deficiency

A

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

26
Q

what happens to cis position double bonds at odd numbered carbons

A

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

27
Q

what 2 things can happen to acetyl CoA

A

enters krebs cycle or converts to ketone bodies in liver

28
Q

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

A

fatty acids cant cross blood brain barrier

29
Q

what are ketone bodies. name the 3 compounds

A

compounds produced during the metabolism of fats

acetone, acetoacetate, beta-hydroxybutyrate

30
Q

what are ketone bodies used for

A

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

31
Q

what increases the synthesis of ketone bodies

A

starvation

32
Q

what is ketosis

A

increased ketone bodies in blood

33
Q

what is ketoacidosis

A

ketosis and acidosis occurring together

34
Q

how can ketone bodies cause acidosis

A

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

35
Q

what can extreme acidosis lead to

A

death and coma