BioChem Exam 3 Quizzes

90% of chylomicrons are ___________________

Triacylglycerols

Arrange the following by increasing density:

1. LDL

2. VLDL

3. Chylomicrons

4. HDL

5. IDL

3<2<5<1<4

Among the important functions of apolipoproteins the _________________ is of primary importance.

stabilization of the lipoprotein micellar structure

HDL's are metabolized in the ____________________

liver

LDL __________________

delivers cholesterol to the tissues

Arrange the following by increasing particle size:

1.  LDL

2. VLDL

3. HDL

4.  Chylomicrons

3<1<2<4

Which of the following enzymes is principally responsible for hydrolysis of TAG's in chylomicrons and VLDL to free fatty acids for delivery to various tissues?

lipoprotein lipase

Lipoproteins can be characterized by their_____

electrophoretic mobility, size, & density

The rate limiting step in beta oxidation of fatty acids is_____________________

transfer of fatty acyl CoA into the mitochondria

The rate limiting step for cholesterol biosynthesis is _________________

the production of mevalonic acid by the action of HMG-CoA reductase

Exogenous xenobiotics are best described as…..

Substances derived from processes outside the body.

In general, xenobiotic transformations occur in the…..

liver

Xenobiotic substances are best characterized as……

Lipophilic compounds

Xenobiotic metabolism generally takes place in two phases the first of which is usually……

The introduction of a reactive group to be functionalized in phase two

The ultimate goal of xenobiotic metabolism is……

To facilitate excretion, to make the substance more hydrophilic, & to deactivate the toxin

True/False    Cytochrome c is largely responsible for oxidizing xenobiotic substances.

false

_____________ is most frequently used by the body to expedite excretion of xenobiotic substances.

Glucoronidation

Cytochrome P450 is an important player most commonly used by the body to modify xenobiotic substances by…….

Oxidation

True/False    Xenobiotic biotransformation always results in a non-toxic metabolite.

false

Aspirin is detoxified by _____________________

Hydrolysis

When glucose is in a straight-chain formation, it:

is one of a group of 16 stereoisomers.

All of the following are true of epimers EXCEPT:

they always have equal but opposite optical activities.

Aldonic acids are compounds that:

have been oxidized, and have acted as reducing agents

The formation of α-d-glucopyranose from β-d-glucopyranose is called:

mutarotation.

Ketose sugars may have the ability to act as reducing sugars. Which process explains this?

Ketose sugars undergo tautomerization.

Which of the following enzymes cleaves polysaccharide chains and yields maltose exclusively?

β-Amylase

Why is the α-anomer of d-glucose less likely to form than the β-anomer?

The β-anomer undergoes less neighboring group repulsion.

Which of the following is digestible by humans and is made up of only one type of monosaccharide?

Maltose

Andersen's disease (glycogen storage disease type IV) is a condition characterized by a deficiency in glycogen branching enzyme. Absence of this enzyme would be likely to cause all of the following effects EXCEPT:

glycogen devoid of α-1,4 linkages.

The cyclic forms of monosaccharides are:

1. hemiacetals.

2. hemiketals.

3. acetals.

1 and 2 only

The enzymes which catalyze the removal of an alpha amino group from an amino acid to form an alpha ketoacid are called______________

Aminotransferases

In mammals, urea is produced almost exclusively in the ______________.

Liver

Increased accumulation of ___________due to folic acid deficiency leads to many cardiovascular disorders.

Homocysteine

What molecule acts as the carrier for the assembly of carbon and nitrogen to form urea?

Ornithine

Which of these molecules provides the nitrogen in the production of urea?

Carbamoyl phosphate

The amino acids whose carbon skeleton is degraded into precursors for the formation of ketone bodies are called______________

Ketogenic amino acids

Melanin deficiency, often leading to albinism, is due to a defect in ________________metabolism.

Tyrosine

Endogenous proteins are mainly degraded in __________

Proteosomes

Ammonia is transported in the blood to the liver via_________

Glutamine

True/False     Phenylketonuria, a disease characterized by an accumulation of phenylalanine, may be caused by a deficiency of the coenzyme tetrahydrofolate.

False