Biochemistry Final Module

In amino acid metabolism, alanine is broken down to make ___________.

pyruvate

In amino acid metabolism, glutamate and glutamine are broken down to make ___________.

a-ketoglutarate

In amino acid metabolism, aspartate is broken down to make ___________.

oxaloacetate

In amino acid metabolism, pepsin breaks down proteins in the ___________.

stomach

In amino acid metabolism, trypsin and chymotrypsin break down proteins and larger peptides in the ___________.

small intestine

In amino acid metabolism, aminopeptidase and carboxypeptidase A + B break down small peptides to amino acids in the ___________.

small intestine

Small peptides are broken down into individual amino acids by ______________ and _____________.

Aminopeptidase ; carboxypeptidase A + B

Amino acid breakdown from non-dietary proteins occurs in three places:

The liver, extra-hepatic tissue, and muscle

Glutamine transports 2 units of _____________.

ammonia

The glucose-alanine cycle converts pyruvate to ________________.

alanine

Glutamate picks up 1 ____________ in the liver.

amino group

Which steps of the urea cycle use ATP and how many are used in each step?

Step 1: 2 ATP

Step 2: 1 ATP

Step 1 of the urea cycle is catalyzed by what enzyme?

ornithine transcarbamoylase

Step 2 of the urea cycle is catalyzed by what enzyme?

argininosuccinate synthetase

Step 3 of the urea cycle is catalyzed by what enzyme?

arginase

Step 4 of the urea cycle is catalyzed by what enzyme?

argininosuccinase

Triacylglycerols are __________ lipids.

storage

Phospholipids and glycolipids are __________ lipids.

membrane

Fatty acids contain how many carbon atoms (range)?

4 - 36

Saturated fatty acids have ____ C=C bond(s).

0

Monounsaturated fatty acids have ____ C=C bond(s).

1

Polyunsaturated fatty acids have ____ C=C bond(s).

2+

How would you label a fatty acid that is 18 carbons long and has a double bond on carbon 9?

18: 1^Δ9

How would you label a fatty acid that is 18 carbons long and has double bonds on carbons 9 and 12?

18: 2^{Δ9, 12}

When numbering double bonds on fatty acids, start numbering from the __________ end.

carboxylic acid

What are triacylglycerols made of?

Three fatty acids attached to a glycerol molecule

What determines the surface properties of membrane lipids?

Head group substituents

What are membrane lipids made of?

Fatty acid chains, a glycerol molecule, and a phosphate group (varying substituents)

What membrane lipid has this head group?

Phosphatidic acid

What membrane lipid has this head group?

Phosphatidylethanolamine

What membrane lipid has this head group?

Phosphatidylcholine

What membrane lipid has this head group?

Phosphatidylserine

Cerebrosides contain ______ carbohydrate(s), while gangliosides contain ______ carbohydrate(s).

1 ; 2-4

What kind of lipid contains blood group determinants?

Glycosphingolipids

What kind of lipid is always made up of ring structures?

Sterols

What kind of fatty acid has a very high melting point?

Trans fatty acids

What kind of fatty acids are able to pack tightly together?

Saturated fatty acids

What kind of fatty acids are not able to pack together tightly and are usually kinked?

Unsaturated fatty acids

Do saturated or unsaturated fatty acids have a higher melting point?

Saturated

What is transbilayer diffusion?

When a lipid moves from one side of the membrane to the other

What is lateral diffusion?

What a lipid moves from one location to another on the same side of the membrane

What is the fluid mosaic model in membranes?

Proteins + lipids embedded in the membrane are free to move laterally within the plane of the membrane

What is oxidation of fatty acids and what does it provide?

“Burning” of fatty acids to provide energy

Why is fat good for energy?

Fatty acids have a lot of carbons that are reduced (electrons) and carry more energy

What molecules are used for short-term energy needs?

Glucose and glycogen

What molecules are used for long-term energy needs?

Fats

What does epinephrine release signal?

The body needs energy immediately

What does glucagon release signal?

The body is out of glucose

Where does B-oxidation of fatty acids occur?

The mitochondria

Can fatty acids diffuse freely across mitochondrial membranes?

Yes, if they are small (<12 carbons)

How are large fatty acids transported across mitochondrial membranes?

The carnitine transporter

How are fatty acids activated for transport?

By adding a good leaving group using fatty acyl-CoA synthetase

Adding Acyl-CoA to a fatty acids makes:

An activated fatty acid

Activated fatty acids are trans-esterified to _____________.

acyl carnitine

What is both the committed step and the rate-limiting step in B-oxidation?

Carnitine-mediated import

The carnitine shuttle links two pools of ___________ and ___________.

acyl-CoA and CoA

B-oxidation consists of _____ reactions per round.

4

What is removed with each round of B-oxidation?

One acetyl group (2C) as acetyl-CoA

In the 4 steps of one round of B-oxidation, what four kinds of enzymes are used in order?

1) Dehydrogenase, 2) hydratase, 3) dehydrogenase, 4) acetyltransferase

B-oxidation processes fatty acids that are at least _____ carbons long.

12

The number of acetyl-CoA molecules produced from fatty acid metabolism will always be ______ the amount of starting carbons.

half

There will always be ______ less rounds of fatty acid metabolism than the number of acetyl-CoA molecules produced.

one

7 rounds of fatty acid metabolism would result in _______ NADH and ______ FADH2.

7 ; 7

What must occur for monounsaturated fatty acids before they can undergo B-oxidation?

Cis C=C bond must be converted into a trans C=C bond through isomerization reaction

What must occur for polyunsaturated fatty acids before they can undergo B-oxidation?

They must be reduced and then undergo an isomerization reaction

Odd-numbered fatty acids have what molecule leftover after the last acetyl-CoA is removed?

Propionyl-CoA

Burning fat makes acetyl-CoA which is ultimately recycled to make ________.

ATP

When the body is starved, the liver turns on the process of _______________.

gluconeogenesis

Why is glucose necessary in the body?

For the brain to run all of its processes

The process of gluconeogenesis depletes _____________.

oxaloacetate

What cycle cannot be run without oxaloacetate?

The citric acid cycle

What molecule builds up when the citric acid cycle is not run?

acetyl-CoA

When there is a build-up of acetyl-CoA, __________ runs out.

free CoA

When there is no free CoA for the body to use, what process cannot be run?

B-oxidation

What can the liver produce to replenish CoA pools?

Ketone bodies

____________ is the first ketone body molecule made.

Acetoacetate

The presence of ___________ in the breath occurs with the creation of ketone bodies.

acetone

What molecule is the building block for fatty acid synthesis?

Malonyl CoA

Where does fatty acid synthesis take place?

In the cytosol (high NADPH concentration)

What does breakdown of ketone bodies create?

Molecules such as succinate, acetyl CoA, etc. that can be used in the citric acid cycle to create ATP

Fatty acid synthesis is a __________ reaction, whereas fatty acid breakdown is a ___________ reaction.

anabolic ; catabolic

The 4 reactions that happen in fatty acid degradation are:

Oxidation → Hydration → Oxidation → Cleavage

The 4 reactions that happen in fatty acid synthesis are:

Condensation → Reduction → Dehydration → Reduction

Acetyl-CoA + CO2 → ___________

Malonyl CoA

What regulates the rate limiting step in the formation of Malonyl CoA?

Acetyl-CoA carboxylase

Biotin acts as the carrier of ________.

CO2 (can be transferred to Acetyl CoA)

What is the active group in fatty acid synthesis?

A thiol

The fatty acid synthase enzyme involves ______ protein(s) and ______ active site(s).

1 ; 7

What protein will swing into each active site in fatty acid synthase?

The acyl carrier protein (ACP)

Fatty acid synthesis terminates at how many carbons?

16C

How many ATP are made during the synthesis of 1 fatty acid?

~106

How many ATP are used during the synthesis of 1 fatty acid?

~30

What inactivates fatty acid synthesis?

Phosphorylation

What allosterically activates fatty acid synthesis?

Citrate