BCM476 - exam 1

Ketogenic amino acids are degraded to which of the following metabolites?

Acetyl-CoA

These enzymes transfer an alpha-amino group from amino acids to alpha-ketoglutarate.

Aminotransferases

This is the cofactor required by phenylalanine hydroxylase.

Biopterin

A specific sequence of amino acids that indicates that a protein should be degraded.

Degron

This class of enzymes cleave most aromatic rings in biological systems.

Dioxygenases

This enzyme catalyzes an oxidative deamination and can utilize either NAD+ or NADP+.

Glutamate dehydrogenase

The manganese center of photosystem II converts ______ to ______.

H2O; O2

In the light reactions of photosynthesis, the cooperation between photosystem II and photosystem I creates a flow of electrons from H2O to the final acceptor, ______.

NADP+

In the overall equation for the Calvin cycle, two molecules of ____ and three molecules of ____ are consumed in incorporating a single CO2 molecule into a hexose.

NADPH; ATP

What is the side product of the light reactions?

O2

This product results when aspartate is transaminated with alpha-ketoglutarate.

Oxaloacetate

What are the special pairs in the reaction center of plants?

P700 and P680

Write a balanced reaction for photosystem I:

Pc(Cu+) + FDox + light --> Pc (Cu2+) + Fdred

This is the primary proteolytic enzymes the stomach.

Pepsin

This methyl group donor is the product of the first step of methionine degradation.

S-adenosylmethionine

A ____________ intermediate is formed between the carbonyl group of the ketose substrate and the e-amino group of a lysine residue of transaldolase.

Schiff base

What is the difference between synthase and synthetase?

Synthase is any enzyme that catalyses the synthesis of a biological compound but, unlike synthetases, does not make use of ATP as a source of energy while synthetase is any ligase that synthesises biological compounds using ATP as a source of energy

_____ plays a major role in the regeneration of ribulose 1,5-bisphosphate.

Transketolase and aldolase

This protein is used as a tag to identify proteins targeted for destruction.

Ubiquitin

This is the molecule that is formed from excess NH4+ by ureotelic organisms.

Urea

The half-life of a cytosolic protein is primarily determined by the

amino acid residue

Glutamate is the carbon skeleton precursor for the amino acids glutamine, proline, and _________.

arginine

In the urea cycle, free NH3 is coupled with carboxyphosphate to form

carbamic acid

In the first step of the urea cycle, CO2 and NH4+ are converted into carbamoyl phosphate (or __________).

carbonic acid

What class of enzymes cleaves most aromatic rings in biological systems?

dioxygenases and monooxygenases

In the urea cycle, the carbon skeleton of aspartate is preserved as

fumarate

The purpose of the pentose phosphate pathway is to

generate NADPH and synthesize 5-carbon sugars

What three amino acids make up glutathione?

glutamate, glycine, cysteine

Which amino acids are solely ketogenic?

leucine and lysine

Urea is synthesized in the:

liver

The C-terminal glycine of ubiquitin is covalently linked to ______ residues of the protein destined to be degraded.

lysine

Homocysteine is an intermediate in the synthesis of cysteine and ___________.

methionine

Sodium bicarbonate secreted from the pancreas

neutralizes the pH of food

Essential amino acids differ from nonessential amino acids in that:

nonessential amino acids are synthesized in simple reaction pathways compared to complex pathways for most essential amino acids

Which amino acid(s) are metabolites in the urea cycle, but are not used as building blocks of proteins?

ornithine and citrulline

The urea cycle is linked to gluconeogenesis through the TCA cycle intermediates fumarate and ________.

oxaloacetate

The cause of formation of ATP in both photophosphorylation and oxidative phosphorylation is:

pH gradient

The inhibitor of photosystem I is:

paraquat

In C4 plants, carbon dioxide is added to __________ (or ________) to form oxaloacetate, which is reduced to malate, which carries CO2 to the bundle-sheath cells.

phosphoenol-pyruvate or pyruvate

What prosthetic group do aminotransferases contain?

pyridoxal phosphate group

Serine dehydratase catalyses the conversion of serine into NH4+ and _______.

pyruvate

Where does the charge separation take place within each photosystem in chloroplasts?

reaction center

What is the name of the enzyme that is located on the stromal surface of the thylakoid membranes and catalyzes condensation of CO2 with the enediolate intermediate?

rubisco

In what part of the cell does the Calvin-Benson cycle occur?

stroma of the chloroplasts

The pathway of electron flow from H2O to NADP+ in photosynthesis is referred to as

the Z scheme of photosynthesis

What reaction can synthesize amino acids from alpha-ketoacids?

transamination reaction

Chorismate is a precursor to the amino acids:

tryptophan, tyrosine, and phenylalanine

Amino acid synthesis is generally regulated by

turnover, diet, and feedback and allosteric enzyme regulation

What does the bacteriopheophytin have in its center?

two protons