Fatty Acid Biosynthesis

Question 1

The process of fatty acid biosynthesis occurs similar to ___-____, though in ___.

Answer 1

• beta-oxidation

- reverse

Question 2

Important distinctions:

Fatty acid synthesis up to palmitate occurs in the _____, but beta oxidation occurs in ___ ___.

Answer 2

• cytoplasm

- mitochondrial matrix

Question 3

Important distinctions:

Fatty acids are built using an ____ ____ ____ (__), but beta oxidation uses ____.

Answer 3

• acyl carrier protein (ACP)

- CoA

Question 4

Important distinctions:

___ is used to ___ electrons in synthesis, but ___ or ___ are used to ___ electrons in oxidation in the mitochondrion.

Answer 4

• NADPH
• donate
• NAD+
• FAD
• accept

Question 5

Important distinctions:

A three carbon molecule, ___ donates ___ carbons to the growing fatty acid chain - a ___ ____ is lost in the process.

Answer 5

• malonyl-ACP
• two
• carbon dioxide

Question 6

Beta oxidations yield:

Answer 6

two carbon acetyl-CoA units.

Question 7

Synthesis of fatty acids longer than 16 carbons occurs in:

Answer 7

endoplasmic reticulum or mitochondrion

Question 8

Oxidation of fatty acids longer than 16 carbons begins in:

Answer 8

peroxisomes

Question 9

In fatty acid biosynthesis, a __-_____ intermediate is formed at:

Answer 9

• D-hydroxyl

- carbon #3

Question 10

In fatty acid oxidation, an _-_____ intermediate is formed at:

Answer 10

• L-hydroxyl

- carbon #3

Question 11

Acetyl-CoA carboxylase catalyzes the addition of a ___ ___ to ___-___ to form ___-___.

Answer 11

• carboxyl group
• acetyl-CoA
• malonyl-CoA

Question 12

Acetyl-CoA carboxylase is regulated ___ (inhibited by ___ -___ and activated by ___ ) and by ___ ___ (___ inhibits, ___ activates).

Answer 12

• allosterically
• palmitoyl-CoA
• citrate
• covalent modification
• phosphorylation
• dephosphorylation

Question 13

Fatty acid biosynthesis occurs in the ____ and the fatty acids are built on:

Answer 13

• cytoplasm

- a ‘carrier’ known as acyl carrier protein (ACP).

Question 14

To start the synthesis process, the __ is swapped for ___.

Answer 14

• Co-A

- ACP

Question 15

Acetyl-CoA gets into the cytoplasm from the mitochondrion by the:

Answer 15

citrate shuttle.

Question 16

Acetyl-CoA is linked to ____ in the mitochondrion to make ____, which is transported out and then citrate is cleaved to yield ____-___ and ____ in the cytoplasm.

Answer 16

• oxaloacetate
• citrate
• acetyl-CoA
• oxaloacetate

Question 17

Malonyl-ACP is the ___ ____ for fatty acid biosynthesis.

Acetyl-ACP is the ___ ___ for fatty acid biosynthesis.

Answer 17

• adding block

- starting block

Question 18

During fatty acid synthesis, _______ of malonyl-ACP yields a ___ ___ ___ to the growing fatty acid chain.

Answer 18

• decarboxylation

- two carbon addition

Question 19

The two carbons from malonyl-ACP go onto the:

Answer 19

carboxyl end of the growing chain.

Question 20

The numerous enzymes of fatty acid biosynthesis are contained in a:

Answer 20

multi-enzyme complex called fatty acid synthase

Question 21

Fatty acids up to 16 carbons long are synthesized in the:

Answer 21

cytoplasm by the fatty acid synthase.

Question 22

Synthesis of fatty acids longer than 16 occurs in the endoplasmic reticulum (or mitochondrion) catalyzed by:

Answer 22

enzymes called elongases.

Question 23

Enzymes that produce unsaturation in fatty acid biosynthesis are called:

Answer 23

-desaturases

Question 24

Desaturases employ an unusual electron transferring process initiated by:

Answer 24

donation of electrons from NADH and accepted by oxygen.

Question 25

Desaturases are found in:

Answer 25

the endoplasmic reticulum.

Question 26

Essential fatty acids are those that must be provided in the diet of an organism, because:

Answer 26

the organism cannot synthesize them.

Question 27

In mammals, ___ and ___ ___ are essential fatty acids because they cannot make ___ bonds closer to the end than the ___-_ position (oleic acid is an omega-9 fatty acid).

Answer 27

• linoleic
• linolenic acids
• double
• Delta-9

Question 28

Linoleic acid

Answer 28

-Delta 9,12 double bonds = omega 6 for an 18 carbon fatty acid

Question 29

Linolenic acid

Answer 29

-Delta 9, 12, 15 double bonds = omega 3 for an 18 carbon fatty acid

Question 30

Trans fatty acids are produced by:

Answer 30

partial hydrogenation of vegetable oil.

Question 31

Hydrogenation of vegetable oil _____ its double bonds, ____ its melting point.

Answer 31

• saturates

- raises

Question 32

This chemical treatment (hydrogenation) is done for fats/oils in many processed foods and a byproduct of this action is creation of:

Answer 32

fatty acids with trans (instead of the natural cis) double bonds.

Question 33

Trans fatty acids in fats (called trans fats) are associated with ____ LDLs, ____ HDLs and _____. The reason is not fully known.

Answer 33

• increasing
• decreasing
• atherosclerosis

Question 34

Prostaglandins are hormone-like compounds made from ___ ___ by action of an enzyme known as ___ ___.

Answer 34

• arachidonic acid

- prostaglandin synthase

Question 35

Prostaglandins form:

Answer 35

cyclic oxygen-containing compounds or cyclooxygenases (COX enzymes such as COX-1 and COX-2)

Question 36

Prostaglandins are involved in numerous physiological effects, including: (5 things)

Answer 36

control of vasodilation/constriction, uterine contractions, aggregation/stickiness of platelets, inflammation/pain, and maintenance of stomach tissue, among others.

Question 37

Inhibitors of COX enzymes are called __ ____. Aspirin and ibuprofen are non-steroidal drugs (called NSAIDs) that inhibit ____ and ____.

Answer 37

• COX inhibitors

- COX-1 and COX-2

Question 38

Prostaglandins produced by COX-2 enzymes appear to have a limited role in:
so inhibitors specific to them were sought.

Answer 38

stomach maintenance

Question 39

Examples include ___ and ___, but they also appear to have negative side effects on the ___.

Answer 39

• Celebrex
• Vioxx
• heart

Question 40

Arachidonic acid is produced from ___ ___ released from _____ by action of an enzyme known as _____ __ (__).

Answer 40

• linoleic acid
• glycerophospholipids
• phospholipase A2 (PLA2)

Question 41

PLA2 can be inhibited by _____, so action of these compounds can also prevent ______ formation indirectly.

Answer 41

• corticosteroids

- prostaglandins

Question 42

Corticosteroids are important for treatment of:

Answer 42

-severe inflammation or pain.

Question 43

Arachadonic acid can also produce:

Answer 43

Leukotrienes

Question 44

The pathway that leads Leukotrienes does not involve_____, so that pathway is called the _____ pathway to distinguish it from the cyclic pathway that leads to prostaglandins.

Answer 44

• cyclization

- linear

Question 45

Leukotrienes are involved in: (3 things)

Answer 45

mucus production, bronchial constriction, and play important roles in causing asthma attacks.

Question 46

Another class of molecules made from prostaglandins is the:

Answer 46

thromboxanes

Question 47

Thromboxanes help to make platelets:

Answer 47

“sticky”, favoring aggregation.

Question 48

Thus, taking aspirin reduces synthesis of prostaglandins, which in turn reduces amounts of _____, which reduces _____ of platelets, which makes it harder for blood to ___.

Answer 48

• thrombaxanes
• stickiness
• clot

Question 49

It is for this reason that people prone to clotting problems are advised to take:

Answer 49

aspirin daily.