MACRO Quiz (EXAM 4)

Biological Importance of Lipid Metabolism:

• Lipids perform several essential functions:

  • _______

  • _______ storage of _______

  • _______ of several important _______ and _______ molecules

• Lipid metabolism includes both the _______ and _______ of fatty _______ and/or more complex _______ molecules.

• The choice between synthesis and degradation reflects the level of energy stores available to the _______.

Biological membranes, Efficient, energy, Components, structural,  functional, synthesis, synthesis, fatty, lipid, body,

• ________ are an important source of carbon fuel (________):

  • ________

  • ________ Cycle, ________

• Important building blocks for membranes, hormones, and other lipid molecules (________):

  • Requires ________

  • Consumes ________

• Also, the Krebs Cycle, ETC occur in the ________

Fatty acids, catabolism, beta-oxidation, Krebs, ETC, anabolism, NADPH, ATP, mitochondria

STUDY

• Like carbohydrates, fatty acids are oxidatively cleaved to _______

• Acetyl-CoA feeds into _______ (Citric Acid Cycle & ETC)

• TCA intermediates (e.g., _______) serve as precursors to the _______ of other molecules, including fatty acids

acetyl-CoA, cellular respiration, citrate, biosynthesis

What’s the reducing agent for acetyl-CoA?

NADPH

Digestion of Lipids

1. Minimal digestion of lipids in _______

2. Fats are mainly converted to _______ and _______ in GI tract by _______ from pancreas

3. Bile from liver aids in _______ & _______

4. Free fatty acids and monoglycerides are absorbed by _______ cells; then _______ resynthesized, packaged as _______ (less readily mobilized), & released into _______ system

5. < 5% of _______ is excreted; it’s mainly stored in _______ cells till needed as fuel

Glycogen is more readily and easily mobilized

stomach, monoglycerides, fatty acids, lipase, digestion, absorption, intestinal epithelial, triglycerides, chylomicrons, lymph, fat, adipose

Preparation for Catabolism

• Before they can be used as fuel, stored fats must be hydrolyzed to ________ and ________

• Hormones (________, ________) initiate signal for lipase to break down triacylglycerols (TAG) —> _____ —> _____ —> _____ and _____

fatty acids, glycerol, glucagon, epinephrine, DAG, MAG, glycerol, fatty acids

• Fatty acids are _______ in blood plasma

• Must “bind” to _______ to circulate

• Ultimately metabolized (_______) to acetyl CoA —> feeds into _______

• Glycerol metabolized in liver (CAP) to _______ —> contributes to _______ or _______

not soluble, blood serum albumin, beta-oxidation, cellular respiration, glyceraldehyde 3-phosphate, glycolysis, gluconeogenesis

Overview of Beta-Oxidation:

• Fatty acids separate from albumin and diffuse across cell membrane, aided by _________

• On outer mitochondrial membrane, FAs linked to ______ by acyl-CoA synthetase, fueled by ATP; transported into the _________

• _________ (breakdown of acyl-CoA to acetyl-CoA) occurs in mitochondria

• Provides _________ for cellular respiration and synthesis of ATP

transport proteins, CoA, mitochondria, beta-oxidation, acetyl-CoA

Steps of Beta-Oxidation:

• Sequential breakdown of ______ to acetyl-CoA in mitochondrion

• Iterative 4-step process:

  • Decreases C-chain by _____ (Acetyl-CoA)

  • Yields _ FADH2 & _ NADH

• For a 16-C fatty acid:

  • _ rounds of b-oxidation yield:

    • _ Acetyl CoAs

    • _ FADH 2 (1 per round)

    • _ NADH (1 per round)

acyl-CoA, 2Cs, 1, 1, 7, 8, 7, 7

4 Steps of each “Round” of Beta-Oxidation:

1. __________ (oxidation) of acyl-CoA, reduction of FAD —> FADH2

2. __________ (addition of H2O)

3. ________ of beta-carbon, ________ of NAD+ —> NADH

4. Reaction w/________ —> 2C-shortened acyl-CoA + 1 acetyl-CoA

Dehydrogenation, Hydration, Oxidation, reduction, CoA-SH

STUDY

Overview of Fatty Acid Synthesis:

• Sequential buildup of fatty acids from ______

• _ carbon units added at a time

• Requires reducing agent, ______ (from ______)

• Acetyl CoA is located mainly in mitochondria w/no ______ out

• Acetyl CoA “transported” out of mitochondria as ______

acetyl-CoA, 2, NADPH, PPP, transporter, citrate

Transporting Acetyl-CoA out of Mitochondria:

• Acetyl CoA + oxaloacetate —> citrate, which can be _________ across mitochondrial membrane

• In the _________, citrate converted to acetyl- CoA + oxaloacetate

• Oxaloacetate reduced by _______ to _______

• Malate oxidized to _______ by _______; yields _ NADPH

• Pyruvate transported back into mitochondrion, converted back to _______, etc...

transported, cytoplasm, NADH, malate, pyruvate, NADP+, 1, oxaloacetate

Simplified Steps of Fatty Acid Synthesis:

• Acetyl-CoA (__) transferred ____________ (ACP) —> acetyl-ACP

• Acetyl-ACP activated by condensation with ______ (1C) —> malonyl-ACP (__)

• Malonyl-ACP (3C) condenses with another _________ (__)—> 4C acyl-ACP + CO2

• Several steps yield a ____ extended fatty acid-ACP

• All of the above are repeated many times to produce __________ of the desired length

2C, acetyl carrier protein, HCO3, 3C, acetyl-ACP, 2C, 2C-, fatty acids

Steps of Fatty Acid Synthesis:

• 4-step iterative process, repeated over multiple rounds to build up fatty acids _ carbons at a time:

1. _________ of acyl-CoA + malonyl-CoA —> beta-diketone + CO2

2. beta-diketone _______ by ______ —> beta-hydroxy-ketone + NADP+

3. beta-hydroxyketone _________ —> alpha, beta-unsaturated ketone

4. alpha, beta-unsaturated ketone _______ by ______ —> fatty acid-ACP + NADP+

2, Condensation, reduced, NADPH, dehydrated, reduced, NADPH

STUDY

Synthesis of Other Lipids:

• Acetyl-CoA is the precursor/building block for other lipids, as well, e.g., _________ and _________

cholesterol, steroid hormones

STUDY

Sample Problem

Quantitatively compare the ATP yield from the complete oxidation of glucose, a six-carbon carbohydrate, and hexanoic acid, a six-carbon fatty acid. Hexanoic acid is also called caproic acid and is responsible for the “aroma” of goats. If fats are better fuels than carbohydrates, why does the body use carbohydrates (glucose) as its primary source of energy/ATP?

37 ATPs total fro 1 C6-FA

Sample Problem Solved

STUDY

Biomedical Importance of the Metabolism of Nitrogen-Containing Compounds

• In normal adults, nitrogen intake = nitrogen excreted; exceptions:

  • Nitrogen intake _ Nitrogen excreted, during growth and pregnancy

  • Nitrogen intake _ Nitrogen excreted, may follow surgery, advanced cancer or other disorders

• Most Nitrogen in humans comes from _________, which are catabolized to urea through the _________

>, <, amino acids, Urea Cycle

Nitrogen-Containing Compounds:

• Amino Acids

  • _________

  • _________ (of other AAs & nucleotides)

• Nucleotides

  • Comprises nucleic acids (_________ & _________ bases)

  • _________

• Urea

  • the Waste product of _________ of _________

  • _________

Fuel, building blocks, purine, pyrimidine, Genetic code, catabolism, amino acids, Urea Cycle

Why is Nitrogen Unique?

• Our nutrients/fuels come mainly from plants (and animals that eat plants)

• Plants can readily synthesize C,H,O- containing compounds (_______) from environmental ____ and ____ (photosynthesis)

• But atmospheric ________ (___) is inert

glucose, CO2, H2O, Nitrogen, N2

Nitrogen (N2 ) Fixation

• __% of Earth’s atmosphere, but it’s __________, except under special conditions

• Nitrogen can be “fixed” in 3 ways:

1. __________ (Haber Process)

2. __________

3. __________

80, inert/unreactive, Chemically, Lightning, Nitrogen-fixing Bacteria

Nitrogen Assimilation in Plants

• ____ in soil is assimilated into amino acids by _____: picked up by a-ketoglutarate to give ________

• glutamate transfers ______ to other a-keto acids to generate an array of ___________ (___________), and regenerate a-ketoglutarate

NH4+, plants, glutamate, :NH3, alpha-amino acids, transamination

STUDY

Amino Acids in the Body:

• Unlike carbohydrates and fats, amino acids are _______; they’re _______:

• Used for the synthesis of _______ and/or _______

• Or catabolized to:

• _______ & processed through _______

• Carbon fuels & fed into the _______

not stored, either, proteins, nucleotides, Ammonium, Urea Cycle, TCA

STUDY

STUDY

KNOW THE IDEA, don’t memorize specific substrate names

STUDY

DON’T MEMORIZE GREEN AA

STUDY

Amino Acid Synthesis:

• Humans can synthesize __ amino acids from _____ or _____ intermediates (amino _ comes from glutamate)

• The other _ are “essential” amino acids that must be obtained from the ____

11, TCA, glycolysis, N, 9, diet

Purine & Pyrimidine Synthesis:

• The ______ bases of nucleotides (purines & pyrimidines) are synthesized, in part, from amino acids

amine

STUDY

• Amino acids are incorporated into ________ and ________

• ________ come from the PPP

• Nucleic acids (DNA & RNAs) are synthesized from ________

• ...nucleic acids carry the “code” for ________

pyrimidines, purines, Ribose sugars, nucleotides, protein synthesis