Chapter 3 & MCQ's

Methemoglobin

"blue man syndrome" NADH cytochrome b5 reductase deficiency Treated by methylene blue. A brownish blue coloration (cyanosis) of the skin and mucous membranes and brown-colored blood. (chocolate blood)

Myoglobin

-A hemeprotein present in heart and skeletal muscle. -Functions both as a reservoir for oxygen and as an oxygen carrier. -monomer -Contains eight stretches of α-helix

A two year old child presents with metabolic acidosis after ingesting an unknown number of aspirin tablets. At presentation her blood is a PH of 7. Given that the aspirin has a pKa of 3 calculate the ratio of its ionized to un-ionized forms at pH of 7.0.

10,000 to 1.

Hemoglobin F

2 zeta+ 2 elipson= Hb Gower

Which of the following statements concerning the ability of acidosis to precipitate a crisis in sickle cell anemia cell?

Acidosis decreases the solubility of HbS

sickle cell anemia

An autosomal recessive disorder. Caused by a single nucleotide substitution in the gene for β-globin (βS), The resulting hemoglobin, α2βS2 (HbS). Can't contract malaria because of the life cycle of the RBC

80 year old man presented with impairment of higher intellectual function and alteration in mood and behavior. His family reports progressive disorientation and memory loss over the last 6 months. There is no family history of dementia. The patient was tentatively diagnosed with Alzheimer disease. Which one of the following describes Alzheimer?

Associated with the deposition of neurotoxic amyloid B peptide aggregates

In comparing the a-helix to the b-sheet, which statement is correct for only the B-Sheet?

Bsheets are stabilized by interchain hydrogen bonds

hyperbaric oxygen therapy

CO poisoning is treated with 100% oxygen at high pressure

2,3-BPG concentration is elevated in which diseases?

COPD hypoxia (hemoglobin may have difficulty receiving sufficient oxygen) chronic anemia (fewer than normal RBCs are available)

Which of the following statements concerning the hemoglobins is correct?

HbA is the most abundant hemoglobin in normal adults.

_____ transports H+ & CO2 to the lungs and tissues

Hemoglobin

What is the major Hemoglobin in adults?

Hemoglobin A

Why is hemoglobin C disease a nonsickling disease?

In HbC, the polar glutamate is replaced by polar lysine rather than by non polar valine as in HbS

B-Lysine 82 in HbA is important for the binding of 2,3 bisphosphoglycerate. In Hb Helinski, this amino acid has been replaced by methionine. Which of the following should be true concerning Hb Helinski?

It should have increase O2 affinity and decrease delivery of O2 to tissues.

A 67 year old man is presenting with 1 week history of angina and shortness of breath. He complained that his face and extremities has a blue color. His medical history included chronic stable angina treated with isosorbide dinitrate and nitroglycerin. Blood obtained for analysis was brown colored. Which one of the following is the most likely diagnosis?

Methamoglobinemia

Hemoglobin is found in

RBCs, and transports oxygen.

GLOBULAR HEMEPROTEINS

Specialized proteins that contain heme as a tightly bound prosthetic group.

Binding of CO2 stablizies what?

T or deoxy form of hemoglobin- results in the decrease in the affinity for oxygen.

Name the allosteric effectors

The pO2, the pH of the environment the pCO2 and the availability of 2,3-bisphosphoglycerate.

Which of the following statements concerning the peptide shown below is correct? VAL- Cys- GLU- SER- ASP- ARG- CYS

The peptide chain contains a side chain which can be phosphorylated.

Which of the following statements concerning protein structure is correct?

The primary driving force for protein folding is the hydrophobic effect.

Prosthetic group

a non-polypeptide group which is required for protein conformation and biological activity.

HbA2

a2 (alpha)2

HbA

a2B2

HbF

a2Y2

HbA1C

a2b2-glucose

Heme- Heme Interaction

binding of an oxygen molecule at one heme group increases the oxygen affinity of the remaining heme groups in the same hemoglobin tetramer. Although it is more difficult for the first oxygen molecule to bind to hemoglobin, the subsequent binding of oxygen occurs with high affinity

2,3-BPG decreases the O2 affinity of hemoglobin by

binding to deoxyhemoglobin but not to oxyhemoglobin.

How many molecules of O2 can hemoglobin bind?

can bind four O2 molecules

Hemoglobin

can transport H+ and CO2 from the tissues to the lungs.

what would be true about the extent of red blood cell sickling in individuals with HbS and hereditary persistence of HbF?

decreased

Variables that increase Sickle cell Anemia

decreased pO2, increased pCO2, decreased pH, dehydration, and an increased concentration of 2,3-BPG in RBC.

what type is Hemoglobin F

fetal hemoglobin HbA synthesis starts in the bone marrow at about the eighth month of pregnancy and gradually replaces HbF. HbF has a higher affinity for oxygen than does HbA as a result of HbF only weakly binding 2,3-BPG. (higher affinity because the fetus must pull O2 from the mother with out this fetus would die)

Hemoglobin can bind

four O2 molecules, one at each of its four heme groups.

Pseudogenes

genes not expressed.

A particular point mutation results in the disruption of the a-helical structure in a segment of the mutant protein. The most likely change in the primary structure of the mutant protein is...

methionine to proline

How many molecules of O2 can Myoglobin bind?

one molecule of O2.

Myoglobin can bind...

only one molecule of O2.

which one of the following statements concerning the titration curve for non-polar amino acids is correct?

point C represents the region where the net charge on the amino acid is zero. (middle of the curve)

In Myoglobin where are the polar amino acids located?

polar amino acids are located on the surface.

Carbon monoxide binding to Hb

results in CO tightly binding to hemoglobin

when does HbA2 appear?

shortly before birth It is composed of two α-globin chains and two δ-globin chains.

allosteric effectors regulate

the O2 binding properties of hemoglobin

The higher the oxygen affinity =

the lower the P50 = the more tightly oxygen binds

Hemoglobin A is

the major hemoglobin in adults (tetramer)

Which of the following statements concerning the binding of oxygen by hemoglobin is correct?

the oxygen affinity of hemoglobin increases as the percentage saturation increases.

Chromosome 16 contains

the ζ gene (Hb Gower 1) two genes for the α-globin chains.

Thalassemia

Β-thalassemia; β-globin chains is decreased or absent Α-thalassemia; α-globin chains is decreased or absent

Chromosome 11

β-globin chain the ε gene (Hb Gower 1), two γ genes (HbF), and the δ gene (HbA2).