lipid metabolism Flashcards by Maddi Clark

fatty acids

long carboxylic acids

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TAGs

3 FA on glycerol backbone via esterification bond

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cholestrol

4 ring structure and precursor of steroids
stabilizes membrane

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how does choleterol contribute to the plasma membrane at LOW temperatures

increases fluidity

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how does cholestrol contribute to the plasma membrane at high temps?

increase rigidity/ reduces fluidity

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eocosinoids

derived from arachadonic acid and function as prostaglandins to modulate inflammation

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sphingomylein

Sphingomyelin is composed of a sphingosine, a fatty acyl group and a phosphorylcholine head group (41). Its overall structure is roughly equivalent to replacing glycerol and a fatty acyl group in glycerophospholipid with sphingosine.

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saturated fatty acids

c-c bonds only

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structure of prostaglandins

unsaturated fatty acids with a cyclopentane and derived from arachadonic acid

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unsaturated fatty acids

at least one c=c bond present

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Z fatty acids

cis

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E fatty acids

trans

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omega notion for fatty acids

non-carbonyl end

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omega notion for fatty acids

non-carbonyl end

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which orientation do fatty acid unstaruated bonds prefer to orient

cis –> introduces unique bending of the FA chains and prevents proper stacking

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do unsaturated fatty acids have higher or lower melting points/boiling points

lower boiling point because of chain bending (cis bonds)

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do unsaturated fatty acids make the plasma membrane more or less fluid

more fluid

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hydrogenation of unsaturated fats

convert from unsaturated to saturated which produces trans fat

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trans fat is more likey to exsist in what phase at room temp?

solid because of tight packing and lack of cis double bonds

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what are lipids packaged into in the small intestine

chylomicrons

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chylomicron structure

largely fats, apoproteins, cholesterol, phospholipids

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where are chylomicrons released

lacteals which release them into the lymphatic system

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where are left over chylomicrons recycled

liver

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VLDL

liver produces very low density lipoproteins and also deliver FA to tissue

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chylomicron function

deliver lipids to cells and tissue in body

why are LDLs different from VLDLs and chylomicrons

VLDLs and chylomicrons primarily transport fatty acids to tissue, LDLs transport cholesterol

HDL

transport cholesterol and other lipids away from tissue for processing and secretion

what is cholesterol returned to the liver converted into

bile

adipocytes

fat cells that are primary storage of lipids

what metabolic activities involving lipids do epinephrine and glucagon trigger?

hydrolysis of TAGs via hormone sensitive lipase

albumnin

blood transport protein for lipids

endogenous pathway

describes path of LDLs from absortion in small intestine into chylomicrons and delivered to tissue

Reverse Transport Pathway

choleterol taken from tissue and processed in liver via HDLs

end product of fatty acid beta oxidation

acetyl coA (2 c subunits) - can be fed into TCA cycle

where does beta oxidation occur

mitochondrial matrix

carnitine shuttle

long chain fatty acids must be attatched to carnitine to transport into mit

carnatine shuttle steps

1. enzyme replaces Co-A with carnatine so acyl group is transferred into mitochondria' 2. acyl carnatine complex is transported into mitochondria 3. co-A group replaces carnatine which is displaced into cytoplasm

step 1 of beta oxidation

oxidation - form a c=c double bond - and produce an NADH enzyme: acyl coA dehydrogenase

step 2 of beta oxidaiton

hydration - add oh group across double bond enolyl coA hydratase

step 3 of beta oxidaiton

oxidation - nadh formed - previous water becomes c=0

step 4

thyolisis - nucleophilic of s-coA on carbon 3, lose acetyl coA enzyme: thiolase

how does oxidation of odd numbered unsaturated bonds occur>

via enzyme: enoyl coA isomerase which moves c3 to c3 double bond to allow for step one to occur

even numbered unsaturated beta oxidaiton

use enolyl coA isomerase and then proceed with beta oxidation as normal

odd numbered carbons fatty acid oxidation

only affects last oxidation each will produce an acetyl coA except last will be propinyl coA

end product of odd numbered beta oxidation

propinyl coA

what is propinyl CoA coverted into

succinyl coA via propinyl coA carboxylase

each oxidation cycle produces what

1 acetyl coA 1 NADH 1 FADH2

energy yield of 1 beta oxidation

total atp formula for beta oxidation

7n- 6

what does liver convert acetyl coA into

ketone bodies

function of ketone bodies

packaged by liver and sent to tissue that require energy after glucose has been depleted (during starvation )

step 1 of ketone synthesis

2 acetyl coA are combined to form acetoacetyl coA --> produce acetoacetate

acaetoacetate

first ketone body produced 2 acetyl coA conjoined with one coA removed

is acetoacetate a ketone body

yes

B- hydroxybutrayte

reduced acetoacetate

acetone

ketone body produced by cleaving acetoacetate

how are b-hydroxyacetate and acetone produced from acetoacetate respectively

1. reduction (NADH) 2. decarboxylation

ketogenesis

production of ketone bodies in liver in response to depleted glucose levels and induction of gluconeogenesis

ketoacidosis

build up of ketone bodies are acidic and cause drop in blood pH , side effect of diabetes - breath smells sweet in diabetics

diabetes mellitus

level of glucose in blood is too high and kidneys try to remove exccess glucose in urine

diabetes insipidus

blood glucose normal but kidneys cant properly concentrate urine

where does fatty acid synthesis occur

cytoplasm

before first step of fatty acid syntehsis

malonyl (3c) coA and an acetyl coA attatch to an acyl carrier protein of fatty acid synthase enzyme -

first step of fatty acid synthesis

condensation - nuc attack of acetyl and decarboxylate malonyl coA

step 2 of fatty acid synthesis

reduction - produce NADP+

dehydration

create c=c

reduction

produce another NADP+ - produce acyl - ACP

end product of fatty acid synthesis

palmitic acid (c16)

which electron carrier is required in fatty acid synthesis

NADPH for 2 reduction steps

where does cholesterol synthesis occur

takes place in cytosol

precursor of cholesterol synthesis

acetyl coA

rate limiting step of cholesterol synthesiss

formation of mevalonate (reduced form of 3 acetyl coA combined with nadph)

isoprene formation

after mevalonate is formed, 3 atp are invested to produce 2 isoprenes (5 c with double bond and phosphate)

squalene

intermediate of cholesterol synthesis 6 isoprene units condense

how is squalene converted into cholesterol

nadph

what is arachodonic acid modified to become

eocosinoids