Protein Biochemistry and Hemoglobin Ebook

Question 1

A very effective way to determine the molecular weight of a protein, the number of subunits in a purified protein, and to visualize many proteins simultaneously

Answer 1

SDS-PAGE

Question 2

One problem with antibody affinity chromatography is that sometimes the only way to elute the proteinmay be under harch conditions, resulting in a

Answer 2

Denatured, inactive protein

Question 3

A recombinant fusion protein is generated, in which an epitope is appended at either the N- or C-terminus of the coding region of the protein of interest. The proteins expressed can be easily identified in whole cell extracts and can be purified by immunoprecipitation using antibodies against the epitope

Answer 3

Epitope tagging

Question 4

Eliminates the need for conventional methods of protein purification and animal immunization to generate antibodies, which are often more tedious and time-consuming

Answer 4

Epitope tagging

Question 5

A plate-based assay designed for detecting and quantifying substances such as peptides, proteins, antibodies and hormones.

Answer 5

Enzyme-Linked Immunosorbent Assay (ELISA)

Question 6

Makes it possible to visualize the distribution and localization of specific cellular components within a cell or tissue.

Answer 6

Immunohistochemistry (IHC)

Question 7

Contain small amounts of purified proteins, which allow simultaneous determination of a great variety of analytes from small amounts of samples within a single experiment

Answer 7

Protein Microarrays (protein chips)

Question 8

Heme is considered to be a non protein molecule that is required for biological activity. In other words, Heme is a

Answer 8

Cofactor

Question 9

A monomeric protein (single polypeptide chain) with one heme group. It is found in muscle where it binds oxygen tightly until an oxygen-depleted state induces its release for metabolic oxidation.

Answer 9

Myoglobin

Question 10

A tetrameric protein with four polypeptide chains (two α-globins and two β-globins). It is found in high concentration in red blood cells and servers to
transport oxygen from the lungs throughout the body.

Answer 10

Hemoglobin

Question 11

The higher P50, the

Answer 11

Lower the affinity for oxygen

Question 12

Binding at one site affects the activity of an enzyme (or a transport protein) at another site.

Answer 12

Allostery

Question 13

Oxyhemoglobin does not bind

Answer 13

2,3-BPG

Question 14

Picked up along with oxygen in the lungs and delivered to tissues

Answer 14

Nitric Oxide

Question 15

Can be caused by exposure to oxidizing agents or by mutations in the hydrophobic pocket of Hb

Answer 15

Methemoglobinemia

Question 16

Two proteins are involved in keeping levels of methemoglobin in our blood down: cytb5 reductase reduces cytb5 which in turn reduces

Answer 16

Methemoglobin

Question 17

One of the major roles of fetal hemoglobins is to extract oxygen from the

-the reason it has ahigher affinity for oxygen than HbA

Answer 17

Maternal circulatory system in the placenta

Question 18

This change in affinity of HbF relative to HbA is due to a histidine to serine mutation in the

Answer 18

BPG binding site

Question 19

Glycation of the amino-terminus will remove a positive charge which will reduce affinity for

Answer 19

BPG

Question 20

Absence or decreased synthesis of functional α-globin or β-globin chains. These can be caused by splicing defects, deletions of genes, or altered regulatory elements.

-Loss of function mutations

Answer 20

Thalassemias

Question 21

Homozygous state with 2 defective genes

Answer 21

Thalassemia major

Question 22

Heterozygous state with 1 normal and 1 defective gene

Answer 22

Thalassemia minor

Question 23

In cases where α-globin gene expression is below 50% of normal, the β-globin forms β4 (HbH) tetramers which precipitate in red blood cells resulting in

Answer 23

Anemia

Question 24

Mutations have been found to cause disease through one of what four different effects on protein function?

Answer 24

1. ) Loss of function
2. ) Gain of function
3. ) Heterochronic expression
4. ) Ectopic expression

Question 25

The expression of a gene at the wrong time

Answer 25

Heterochronic expression

Question 26

The expression of a gene in the wrong place

Answer 26

Ectopic expression

Question 27

A loss of function due to deletion, leading to a reduction in gene dosage, is exemplified by the

Answer 27

α-thalassemias

Question 28

Many other types of mutations such as a premature stop codon or of a missense or other mutation can also lead to a complete loss of function. All of these classes of mutation, and others, are illustrated by the

Answer 28

β-thalassemias

Question 29

A group of hemoglobinopathies that result from a reduction in the abundance of β-globin, one of the major adult hemoglobin proteins in red blood cells

Answer 29

β-thalassemias

Question 30

Missense mutation that locks hemoglobin in its high oxygen affinity state, thereby reducing oxygen delivery to tissues. -Example of a gain of function mutation

Answer 30

Hemoglobin Kempsey

Question 31

Some mutations in hemoglobin regulatory elements lead to the continued expression in the adult of the γ-globin gene, which is normally expressed at high levels only in fetal life. Such γ-globin gene mutations lead to a phenotype called the

Answer 31

Hereditary persistence of fetal hemoglobin (HPFH)

Question 32

Thalassemias due to reduced or absent production of a globin mRNA because of deletions or mutations in regulatory or splice sites of a globin gene reduce

Answer 32

Transcription

Question 33

Thalassemias due to nonfunctional or rapidly degraded mRNAs with nonsense or frameshift mutations reduce

Answer 33

Translation

Question 34

The most common single-gene diseases in humans, and they cause substantial morbidity

Answer 34

Hemoglobinopathies

Question 35

Required for the gene expression of all genes in the β-globin cluster on chromosome 11

Answer 35

The locus control region (LCR)

Question 36

What is more likely to cause a disease, mutation of a β-globin gene, or mutation of an α-globin gene

Answer 36

β-globin gene mutation

Question 37

Why is a beta globin gene mutation more likely to result in a mutation?

Answer 37

A single β-globin gene mutation affects 50% of the β chains, whereas a single α-chain mutation affects only 25% of the α chains

Question 38

Because α chains are the only α-like components of all hemoglobins 6 weeks after conception, α-globin mutations cause severe disease in both

Answer 38

Fetal and postnatal life

Question 39

The hereditary disorders of hemoglobin can be divided into which three broad groups?

Answer 39

1. ) Structural variants 2. ) Thalassemias 3. ) Hereditary persistence of fetalhemoglobin

Question 40

Alter the globin polypeptide without affecting its rate of synthesis

Answer 40

Structural Variants

Question 41

``` Decreased synthesis (or, rarely, extreme instability) of one or more of the globin chains, resulting in an imbalance in the relative amounts of the α and β chains ```

Answer 41

Thalassemias

Question 42

Most variant hemoglobins result from

Answer 42

Point mutations

Question 43

The hemoglobin structural variants can be separated into which three classes?

Answer 43

1. ) hemolytic anemia 2. ) Altered oxygen transport 3. ) Varients that cause Thalassemia

Question 44

Due to a beta chain substitution of Glutamate 6 for lysine

Answer 44

Hemoglobin C

Question 45

Less soluble than HbA and tends to crystallize in red blood cells

Answer 45

HbC

Question 46

α-Thalassemias involve mutations that prevent the alpha subunits from being synthesized. as a result, be get tetrameric beta subunits such as

Answer 46

1. ) Fetal γ4 (Hb Bart's) | 2. ) β4 (HbH)

Question 47

Fetal γ4 (Hb Bart's) and β4 (HbH) are not capable of

Answer 47

Veleasing oxygen

Question 48

Infants with severe α-thalassemia and high levels of Hb Bart's suffer severe intrauterine hypoxia and are born with massive generalized fluid accumulation, a condition called

Answer 48

Hydrops fetalis

Question 49

The onset of β-thalassemia is not apparent until a few months after

Answer 49

Birth

Question 50

β-thalassemia results in hemoglobin being made up of four

Answer 50

Alpha subunits (leads to RBC destruction)

Question 51

In contrast to α-thalassemia, the β-thalassemias are usually due to single-base pair substitutions rather than to

Answer 51

Deletions

Question 52

When the β-thalassemia alleles allow so little production of β-globin that no Hb A is present, the condition is designated

Answer 52

β0 thalassemia

Question 53

What are some effective methods for treating βthalassemias?

Answer 53

Blood transfusion, Iron chelators, Bone marrow transplant

Question 54

Carriers of one β-thalassemia allele are clinically well and are said to have

Answer 54

Thalassemia minor

Question 55

Almost every type of mutation known to reduce the synthesis of an mRNA or protein has been identified as a cause of

Answer 55

β-thalassemia

Question 56

The majority of β-thalassemia patients with a decreased abundance of β-globin mRNA have abnormalities in

Answer 56

RNA splicing

Question 57

The only disease-modifying therapy aproved for sickle cell anemia

Answer 57

Hydroxyurea

Question 58

Increases total and fetal hemoglobin in children with sickle cell

Answer 58

Hydroxyurea

Question 59

The change in expression during development of the various globin genes

Answer 59

Globin switching

Question 60

Embryonic globin synthesis occurs in the

Answer 60

Yolk sac from 3rd to 8th week

Question 61

At about the 5th week, the major site of hematopoiesis begins to move from the yolk sac to the

Answer 61

Fetal liver | -Resulting in HbF

Question 62

What is the make-up of HbA2?

Answer 62

α2δ2

Question 63

The expression of the β-globin gene has been found to be only partly controlled by the promoter and two enhancers in the immediate flanking DNA. Another critical element has been identified as the

Answer 63

Locus Control Region

Question 64

What are two hemoglobinopathies that fall under the structural variant realm of hemolytic anemia?

Answer 64

Sickle Cell Anemia and HbC

Question 65

Oxygenated Hemoglobin C tends to

Answer 65

Crystallize

Question 66

Under deoxygenated conditions, sickle hemoglobin, HbS is only

Answer 66

1/5 as soluble as normal Hb

Question 67

Infants with severe α-thalassemia and high levels of Hb Bart's suffer severe intrauterine hypoxia and are born with massive generalized fluid accumulation, a condition called

Answer 67

Hydrops Fetalis

Question 68

Often result in hypochromic, microcytic red blood cells

Answer 68

Thalassemias

Question 69

The diagnosis of thalassemia minor can be supported by hemoglobin electrophoresis, which generally reveals an increase in the level of

Answer 69

HbA2

Question 70

Characterized as β-thalassemia where β alleles allow so little production of β chains that there is no functional HbA

Answer 70

β0-thalassemia (a thalassemia major)

Question 71

How many functional α chains are there in Hb Bart's?

Answer 71

0

Question 72

How many functional α chains are there in HbH (moderately severe hemolytic anemia)?

Answer 72

One

Question 73

The diagnosis of thalassemia minor (heterozygous) can be supported by hemoglobin electrophoresis, which generally reveals an increase in the level of

Answer 73

Hb A2 (α2δ2)

Question 74

Some deletions within the β-globin cluster do not cause thalassemia but rather a fascinating phenotype termed the

Answer 74

Hereditary persistence of fetal hemoglobin

Question 75

One group of defects, which accounts for the great majority of patients, impairs the production of β-globin alone and causes

Answer 75

Simple β-thalassemia

Question 76

What causes the complex β-thalassemias?

Answer 76

The β-glob in gene, as well as one or more other genes, or the LCR in the β-glob in cluster is removed

Question 77

Lead to a decrease in the abundance of the β-globin mRNA and include promoter mutants, RNA splicing mutants (the most common), mRNA capping or tailing mutants, and frameshift or nonsense mutations that introduce premature termination codons within the coding region of the gene.

Answer 77

Mutations causing simple β-thalassemia so

Question 78

Mutations in the β-globin gene that cause premature stop codons cause

Answer 78

β0 thalassemia

Question 79

Mutations resulting in defects to the 5' cap or 3' tail of β-globin mRNA cause

Answer 79

β+-thalassemia

Question 80

Start approximately 50 to 100 kb upstream of the β-globin gene cluster and extend 3' to varying degrees -Cause εγδβ- thalassemia

Answer 80

Deletions that remove the β-globin LCR

Question 81

Given to children with sickle cell to prevent pneumococcal disease

Answer 81

Penicillin Prophylaxis

Question 82

For HbSS (sickle cell), what affect do the following have on sickle cell aggregation? 1. ) Increased BPG 2. ) Low pH 3. ) Glycosylation

Answer 82

1. ) Increased sickling 2. ) Increased sickling 3. ) Decreased sickling

Question 83

In HbSS, anything that stabilizes the T-state (decreases affinity for oxygen) will

Answer 83

Increase Sickling

Question 84

If we have an individual that is heterozygous for beta thalassemia and heterozygous for sickle cell

Answer 84

Sickle cell band will be thicker than HbA band

Question 85

If we have an individual that is heterozygous for alpha thalassemia and heterozygous for sickle cell

Answer 85

Sickle cell band will be thinner than HbA