BCM 476 Exam 1 Study Guide

Degron

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

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

Acetyl-Coa

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

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

Dioxygenases

The purpose of the pentose phosphate pathway is to

Generate ATP & NADPH

The manganese center of photosystem II converts ____ to ____

H2O to O2

Which amino acid is solely ketogenic?

Leucine

Urea is synthesized in the

Liver

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

Lys

Homocysteine is an intermediate in the synthesis of cysteine and ____

Methionine

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

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

What is the side product of light reactions

O2

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

Ornithine & Citrulline

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

P700 and P680

The inhibitor of photosystem I is:

Paraquat

Complete the following reaction for photosystem I (be sure to balance the reaction with regard to the electrons)

Pc(Cu+ ) + Fdox + light à Pc (Cu2+) + Fdred

Pepsin

Primary proteolytic enzyme of the stomach

In C4 plants, carbon dioxide is added to _____ to form oxaloacetate, which is reduced to malate, which carries CO2 to the bundle-sheath cells

Pyruvate

Serine dehydratase catalyzes the conversion of serine into NH4 + and _____

Pyruvate

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

Urea

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

Aminotransferases

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

Dioxygenases

This class of enzyme cleave most aromatic rings in biological systems

Glutamate Dehydrogenase

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

Biopterin

This is the cofactor required by phenylalanine hydroxylase

S-adenosylmethionine

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

Oxaloacetate

This product results when aspartate is transaminated with alpha-ketoglutarate

Ubiquitin

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

Choose the reaction in which amino acids could be synthesized from alpha-ketoacids

Transamination reaction

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

Transketolase and aldolase

Amino acid synthesis is generally regulated by

Turnover, diet, and feedback and allosteric enzyme regulation

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

amino terminal residue.

In the first step of the urea cycle, CO2 and NH4 + are converted into _____

carbamic acid

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

fumarate

Sodium bicarbonate secreted from the pancreas

neutralizes pH of the food.

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

What prosthetic group do aminotransferases contain?

pyridoxal phosphate group

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

Chorismate is a precursor to the amino acids

tryptophan, tyrosine, and phenylalanine

What does bacteriopheophytin have in its center?

two protons