Chapter 12

Question 1

lipolysis

Answer 1

fatty acid degradation via B- oxidation

• TG cycle
• peroxisomes
• ketone bodies

Question 2

fatty acid biosynthesis

Answer 2

• regulation
• membrane lipid metabolism
• isoprenoid metabolism

Question 3

what are 3 sources of fatty acids in animals

Answer 3

• dietary triacylglycerois –>chylomicrons
• triacylglycerols stored in adipose tissue and released in response to hormones (glucagon, eprinephrine) –> fatty acids –>albumin
• triacylglycerols synthesized in the liver from carbohydrates and exported –> VLDL particles

Question 4

“Digestion and aborption of triacylglycerols in small intestine”

fatty acids are important and efficient energy source for many cells

after triacylglycerol molecules are ingested, they are mixed with ____________

Answer 4

bile salts

Question 5

digestion and absorption of triacylglycerols in the small intestine _____________pathway

Answer 5

exogenous

Question 6

The ____________ is a mechanism that regulates the level of fatty acids available to the body for energy generation

Answer 6

triacylglycerol cycle

Question 7

triglycerides

-triglycerides are a highly concentrated store of energy

Answer 7

• 9kcal/g vs 4 kcal/g of glycogen

- glycogen is also highly hydrated, 2 g H2O/g

Question 8

Depending on the animals current metabolic needs, fatty acids may be:

Answer 8

• converted to triacylglycerols
• degraded to generate energy
• used for membrane synthesis

Question 9

dietary triacylglycerols must be broken down before being absorbed by the intestines

_____, which act as detergents, are used to solubilize the triacylglycerols

Answer 9

bile salts

Question 10

______________: hydrolyze the ester bond of the triacylglycerols while in the micelles

Answer 10

pancreatic lipases

Question 11

in the intestinal mucosal cells, the fatty acids and monoacylglycerides are resynthesize into triacylglycerides and packed into ________________

Answer 11

chylomicrons

Question 12

glycerol-3- phosphate or dihydroxyacetone phosphate reacts sequentially with three molecules of _________. Acyl-CoA molecules are fatty acid esters of CoASH

Answer 12

acyl CoA

Question 13

_______________ is an abbreviated version of gluconeogeneis. This is where glycerol-3-phosphate is synthesized from substrates other than glucose or glycerol

Answer 13

glyceroneogenesis

Question 14

when energy reserves are low, the body fat stores are mobilized in a process termed _____________.

• this occurs in adipose tissue during fasting, during vigorous exercise, and in response to stress
• fatty acid binding proteins are responsible for transporting the fatty acids into target organelles

Answer 14

lipolysis

Question 15

lipid –>degration

Answer 15

triacylglyceride (use of lipase) —> glycerol –> fatty acids

Question 16

lipolysis generates ____________ and _______

Answer 16

fatty acids and glycerol

Question 17

Breakdown of triacylglycerols

-the glycerol is absorbed by the liver and converted to ______ intermediates

Answer 17

glycoytic

Question 18

upon entering the cell cytoplasm, fatty acids are activated by attachment of _________

Answer 18

coenzyme A

Question 19

transport into mitochondrial matrix via carnitine linkage

Answer 19

1. acyl-CoA converted into acylcarnitine
2. carrier protein transfers acylcarnitine into matrix
3. acyl-CoA regenerated
4. Carnitine recycled to intermembrane space

Question 20

_________ is responsible for transporting acyl carnitine into the inner membrane of the mitochondria

Answer 20

acyl carnitine translocase

Question 21

what are the four steps of fatty acid degradation that are repeated?

Answer 21

1. OXIDATION of B carbon, catalyzed by ACYL COA DEHYDROGENASE
2. HYDRATION of trans-2-enoyl CoA by ENOYL COA HYDRATASE
3. OXIDATION of L-2-hydroxyacyl CoA by L-3-HYDROXYACYL DEHYDROGENASE
4. CLEAVAGE of the 3-ketoacyl CoA by THIOLASE forms acytl-CoA and a fatty acid chain two carbons shorter

Question 22

fatty acid degradation is also called ____________

Answer 22

B- oxidation

Question 23

The reaction for one round of B-oxidation is?

where NADHx2.5
where FADHx1.5

Answer 23

make 31 NADH total
Makes 15 FADH2 total
takes 2 ATP to do

106 ATP total generated

processing of the products of the complete reaction by cellular respiration would generate 106 molecules of ATP

Question 24

When does the generation of H2O occur?

Answer 24

it occurs when O2 is reduced in electron transport as well as formation of H2O in ATP synthesis reaction of oxidative phosphorylation

Question 25

the degradation of MONOUNSATURATED fatty acid occurs with what enyzme?

Answer 25

cis-delta- enoyl CoA isomerase

Question 26

POLYUNSATURATED fatty acid require isomerase and reductase. Which ones

Answer 26

``` Forexample Linoleoyl CoA uses: - cis-delta-enoyl coA isomerase -cis-delta-enoyl coA isomerase -2,4- dienoyl coA reductase ```

Question 27

odd-chain fatty acids yield ______ in the final thiolysis step. _______________ a biotin enzyme, adds a carbon to propionyl CoA to for methylmalonyl CoA Succinyl CoA, a citric acid cycle component, is subsequently formed from methylmalonyl CoA by __________ a vitamen B12 requiring enzyme

Answer 27

propionyl CoA propionyl carboxylase methylmalonyl CoA mutase

Question 28

alpha oxidation degradation of branched - chain fatty acids, takes place in the _________-

Answer 28

peroxisomes

Question 29

Ketone bodies are another fuel source derived from fats. Ketone bodiy synthesis takes place in the liver

Answer 29

ketone bodies-acetoacetate, 3-hydroxybutrate, and acetone-are synthesized from acetyl CoA in liver mitochondria and secreted into the blood for used as fuel b some tissues such as heart muscle

Question 30

the formation of ketone bodies involves what enzymes?

Answer 30

Enzymes: - thiolase - HMG CoA synthase - HMG CoA lyase - d-3-hydroxybutyrate dehydrogenase. - Acetoacetate spontaneously decarboxylates to form acetone.

Question 31

Ketone bodies acetoacetate breaks down into what components?

Answer 31

D-3- hydroxy butyrate acetone

Question 32

The uilization of D-3-hydroxybutyrate and acetoacetate as a fuel uses what enzymes?

Answer 32

dehydrogenase CoA transferase Thiolase To finally yield --> 2 acetyl CoA

Question 33

Why can’t Acteyl CoA be used to generate glucose in citric acid cycle?

Answer 33

Pyruvate (3 chain carbon) is the end product of glycolsysis, pyruvate later get converted to a Acetyl CoA (2 chain carbon) through an enzyme called pyruvatedehydrogenase... If it was to generate glucose then the reaction would have to be able to happen in reverse. However this isn't possible because there is no enzyme that does the opposite of pyruvatedehydrogenase. Therefore animals cannot convert fatty acids into glucose

Question 34

_________ results when insulin is absent

Answer 34

diabetic ketosis

Question 35

fatty acid synthesis takes place in three stages:

Answer 35

1. Transfer of acetyl CoA out of the mitochondria into the cytoplasm. Citrate is transported into the cytoplasm and cleaved into oxaloacetate and acetyl CoA. 2 .Activation of acetyl CoA to form malonyl CoA. 3. Repetitive addition and reduction of two carbon units to synthesize C16 fatty acid. Synthesis occurs on an acyl carrier protein.

Question 36

1. citrate shuttle ________ is synthesized in the mitochondrial matrix, whereas fatty acids are synthesized in the ________ Acetyl-CoA units are shuttled out of the mitochondrial matrix as citrate

Answer 36

acetyl-CoA is synthesized in the mitochondrial matrix, whearas fatty acids are synthesized in the cytosol. Acetyl-CoA units are shuttled out of the mitochondrial matrix as citrate

Question 37

The malate dehydrogenase and NADP^+ linked malate enzyme reactions of the citrate shuttle exchange ________ for ________

Answer 37

NADH for NADPH

Question 38

2. formation of malonyl coenzyme A formation of ________ is the committed step in fatty acid synthesis Acetyl-CoA carboxylase

Answer 38

malonly-CoA =commited step in fatty acid synthesis Acetyl-CoA Carboxylase -The carboxylation of acetyl-CoA to form malonyl-CoA is catalyzed by acetyl-CoA carboxylase, ACC - ACC is found in most organisms - Mammalian ACC contains two subunits each with a biotin cofactor

Question 39

Regulation of fatty acid synthesis - regulation of acetyl carboxylase - GLOBAL * +insulin * -glucagon * -epinphrine - LOCAL * + citrate * -palmitoyl CoA * -AMPl

Answer 39

know what are positive and negative regulators

Question 40

The remaining reactions of fatty acid synthetase takes place on the ___________

Answer 40

fatty acid synthetase multienzyme comlex (FAS)

Question 41

____________, a complex of enzymes, catalyzes the formation of fatty acids. Fatty acid synthesis occurs on the acyl carrier protein (ACP), a polypeptide linked to CoA. Intermediates are linked to the sulfhydryl group of the CoA attached to ACP. __________ and _____________ attach substrates to the ACP.

Answer 41

fatty acid synthase acetyl transacylase and malonyl transacyalse

Question 42

the intermediates in fatty acid synthesis are covalently linked to the _________

Answer 42

acyl carrier protein (ACP)

Question 43

Elongation in _______ the enzyme that are involved in elongation are separate proteins; In __________ the activities all reside on the same polypeptide

Answer 43

in bacteria in higher organisms

Question 44

fatty acid synthesis consists of _______,_______,__________-and_________-

Answer 44

condensation, reduction, dehydration, and reduction reactions

Question 45

fatty acid synthesis ___________ catalyzes the condensation of acetyl ACP and malonyl ACP to form acetoacetyl ACP the next three steps- reduction, dehydration, and another reduction-convert the keto group at carbon 3 to a methylene group (-CH2-) forming buyryl ACP __________ is the source of reducing power

Answer 45

B ketoacyl synthase NADPH

Question 46

acyl-malonyl ACP condensing enzyme forms ___________

Answer 46

acetoacetyl-ACP

Question 47

Elongation then ext three reactions are similar to the reverse of fatty acid degradation, except - -

Answer 47

- The NADPH is used instead of NADH and FADH2 | - The D–enantiomer of Hydroxybutarate is formed instead of the L–enantiomer

Question 48

the elongation cycle is repeated six more times, using malonl-coA each time to produce ____________ a thioesterase then cleaved the palmityl(C16) CoA from ACP

Answer 48

palmityl-ACP

Question 49

multifunctional fatty acid synthase. it is a functional enzyme that is composed of two identical chains the enzyme consists of two distinct compartments 1. The __________ compartment, which bind the acetyl and malonyl substrates and condenses them 2. the _________ compartment, which carrier out the reduction and dehydration activities required for elongation

Answer 49

1. selecting and condensing | 2. modification

Question 50

Elongation and unsaturated Fatty acid synthase cannot generate fatty acids long than ________ longer fatty acids are synthesized by enzymes attached to the endoplasmic reticulum these enzymes extend palmitate by adding two carbon units, using malonyl CoA as a substrate

Answer 50

C16 palmitate

Question 51

Membrane bound enzymes generate unsaturated fatty acids Enzymes bound to the endoplasmic reticulum introduce double bonds into saturated fatty acids mammals lack the enzymes that introduce double bonds beyond carbon ___________ ____ and ______ are essential fatty acids that must be obtained form the diet

Answer 51

carbon 9 linoleate and linolenate

Question 52

Desaturation of stearoyl CoA Desturase uses electron from ETS -cytochrome bs NADH is electron donor

Answer 52

General (may not be important)

Question 53

Regulation of intracellular fatty acid metabolism - both short- and long term regulatory processes are used - in _________ regulation, enzymes are regulated by allosteric effectors, covalent modification (AMPK), and hormones - _______ regulation is effected by alteration in gene expression

Answer 53

- in short-term regulation | - long term regulation

Question 54

AMPK- Master regulator 5′-AMP-activated protein kinase is activated by an increase in _________ ratio Switches anabolic pathways off and catabolic pathways on Shifts metabolism from energy-consuming processes to energy-generating processes

Answer 54

- AMP/ATP

Question 55

The liver is the primary site of cholesterol synthesis, although most tissues synthesize some cholesterol. Cholesterol synthesis occurs in 4 stages.

Answer 55

1. Formation of mevalonate from Acteyl-CoA 2. Isopentyl pyrophosphate is synthesized from mevalonate. 3. Six molecules of isopentyl pyrophosphate condense to form squalene. 4. Squalene cyclizes and is converted into cholesterol. Stage 1 occurs in the cytoplasm and stages 2 and 3 in the endoplasmic reticulum.

Question 56

1. Formation of HMG-CoA --> Mevalonate HMG-CoA reductase is a target for some ______________ 2. Formation of Activated isoprene pyrophosphate is a good ___________ in these nucleophillic substitution reactions 3. formation of squalene

Answer 56

cardiovascular drugs leaving group

Question 57

cholesterol degrades into ??????/

Answer 57

lanosterol, terosterone, estradiol, cortisol, aldosterone, vitamam D, cell membrane, bile salts`

Question 58

cholesterol homeostasis --> intricate regulation through

Answer 58

1. cholesterol 2. LDL receptor activity 3, bile acid synthesis

Question 59

regulation of cholesterol biosynthesis

Answer 59

insulin "high glucose" | glucagon "low glucose"

Question 60

_____________are a class of drug that lowers serum cholesterol levels by inhibiting HMG-CoA reductase, the rate-limiting enzyme of cholesterol biosynthesis ___________ also interfere with CoQ, a critical molecule in energy generation

Answer 60

statins

Question 61

Molecules in meat may increase heart disease risk? describe this study and is it true?

Answer 61

``` Gut flora (of meat eaters) converts carnitine and choline into trimethylamine and enzymatic oxidation converts this to heart harming molecule TMAO (trimethylamine N-oxide) Gut microbes do not produce TMAO directly. They convert phosphatidylcholine (a common component of animal products such as meat and eggs) into a foul-smelling gas called trimethylamine; the liver then converts this gas into TMAO. L-carnitine passed right through the guts of long-term vegans and vegetarians, leaving their blood practically TMAO-free. When researchers examined volunteers’ stool, they found different groups of bacteria in people who did and didn’t eat meat. ```