Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Harpers - Biochemistry > Ch 53 - Red Blood Cells > Flashcards

Ch 53 - Red Blood Cells Flashcards

1
Q

The packaging of hemoglobin and carbonic anhydrase inside specialized cells called _____________ greatly amplified the capacity of circulating blood to carry oxygen to and carbon dioxide away from peripheral tissues.

A

erythrocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Anemia, a deficiency in the level of circulating hemoglobin (______________), compromises health by reducing the ability of the blood to supply tissues with adequate levels of oxygen.

A

<120-130 g/L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

____________ help staunch the outflow of blood from damaged tissues.

A

Platelets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Hence, replacements are constantly being produced from precursor _________.

A

stem cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Stem cells possess a unique capacity both to produce unaltered daughter cells (__________) and to generate a diverse range of specialized cell types (__________).

A

self-renewal

Potency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Stem cells may be:

____________ - (capable of producing all the cells in an organism)
____________ - (able to differentiate into cells of any of the three germ layers)
____________ - (produce only cells of a closely related family)
____________ - (produce only one type of cell).

A

totipotent

pluripotent

multipotent

unipotent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Differentiation of hematopoietic stem cells is regulated by a set of secreted glycoproteins called _____________.

A

Cytokines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Stem cell factor and several colony stimulating factors collaborate with _______________ to stimulate the proliferation of hematopoietic stem cells in the bone marrow and their commitment to differentiate into one of several myeloid cell types.

A

interleukins 1, 3, and 6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Binding of _______________ directs myeloid progenitor cells to eventually differentiate into erythrocytes or platelets, respectively.

A

erythropoietin or thrombopoietin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

_____________ Are Devoid of Internal Organelles

A

Mature Erythrocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The structure and composition of red blood cells reflects their highly specialized function: to deliver the maximum quantity of ____________ possible to tissues and aid in the removal _____________, a waste product of cellular respiration, and ________.

A

oxygen

carbon dioxide

Urea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The interior of a red blood cell contains a massive concentration of hemoglobin, roughly one-third by weight (_______________ for an adult).

A

30-34 g/dL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

As a consequence, _________ are unable to reproduce.

A

enucleated red blood cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Their _____________ possesses a much higher ratio of surface area to volume than more spherical geometries.

A

disc-like configuration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

By minimizing the distance to be traversed, these factors promote efficient gas exchange between capillary walls and the rapidly moving (up to ______) erythrocytes.

A

2 mm/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Erythrocytes generate ATP exclusively via ___________.

A

Glycolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

True or False:

Red blood cells lack mitochondria, and hence the enzymes of the TCA cycle, electron transport chain, β-oxidation pathway, or ATP synthase.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Glucose enters red blood cells by ____________, a process mediated by the _______________, also known as glucose permease.

A

facilitated diffusion

glucose transporter (GLUT1)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The glycolytic pathway in red blood cells also possesses a unique branch, or shunt, whose purpose is to isomerize 1,3-bisphosphoglycerate (1,3,-BPG) to ____________________.

A

2,3-bisphosphoglycerate (2,3-BPG)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

2,3-BPG binds to and stabilizes hemoglobin in the _________.

A

T-state

21
Q

Conversion of 1,3-BPG to 2,3-BPG is catalyzed by ______________, a bifunctional enzyme that also catalyzes the hydrolysis of 2,3-BPG to the glycolytic intermediate 3-phosphoglycerate.

A

2,3-bisphosphoglycerate mutase

22
Q

A second enzyme, _____________, catalyzes the hydrolysis of 2,3-BPG to the glycolytic intermediate 2-bisphosphoglycerate.

A

multiple inositol polyphosphate phosphatase

23
Q

The activities of these enzymes are sensitive to _______, which insures that 2,3-BPG levels rise and fall at the appropriate times during the oxygen transport cycle.

A

pH

24
Q

It accounts for ∼2% of the protein of the membrane of the RBC.

A

GLUT1

25
Q

GLUT1 exhibits specificity for glucose and related d-hexoses (____________ are not transported).

A

l-hexoses

26
Q

The transporter functions at ∼_____% of its Vmax at the physiologic concentration of blood glucose, is saturable, and can be inhibited by certain analogs of glucose.

A

75%

27
Q

It is a member of a family of homologous glucose transporters found in mammalian tissues.

A

GLUT1

28
Q

GLUT1 is not dependent upon _______, unlike the corresponding carrier in muscle and adipose tissue.

A

insulin

29
Q

Its 492 amino acid sequence has been determined.

A

GLUT1

30
Q

It transports glucose when inserted into artificial liposomes.

A

GLUT1

31
Q

GLUT1 is estimated to contain ____ transmembrane helical segments.

A

12

32
Q

It functions by generating a gated pore in the membrane to permit passage of glucose; the pore is conformationally dependent on the presence of glucose and can oscillate rapidly (∼900 times/s).

A

GLUT1

33
Q

____________ facilitate CO2 transport.

A

Carbonic anhydrase

34
Q

True or False:

Like oxygen, the solubility of carbon dioxide in aqueous solution is low, much too low to accommodate more than a few percent of the CO2 produced by metabolically active tissues.

A

True

35
Q

However, the solubility of the hydrated form of CO2, carbonic acid (H2CO3) and its protonic dissociation product, bicarbonate (HCO3−), are relatively ________.

A

high

36
Q

The presence in erythrocytes of high levels of the enzyme ______________ enables them both to concentrate waste CO2 by catalyzing its rapid conversion to carbonic acid, and to reverse this process in order to facilitate its expulsion in the lungs.

A

carbonic anhydrase

37
Q

While red blood cells carry some CO2 in the form of hemoglobin-bound carbamates, roughly ____% is carried internally as dissolved bicarbonate.

A

80%

38
Q

The RBC is highly dependent upon ___________ as its energy source, for which its membrane contains high-affinity glucose transporters.

A

glucose

39
Q

___________, producing lactate, is the mode of production of ATP.

A

Glycolysis

40
Q

True or False:

Because RBCs lack mitochondria there is no production of ATP by oxidative phosphorylation.

A

True

41
Q

The RBC has a variety of transporters that maintain _________ and __________ balance.

A

ionic and water

42
Q

Production of ____________ by reactions closely associ-ated with glycolysis is important in regulating the ability of Hb to transport oxygen.

A

2,3-bisphosphoglycerate

43
Q

The pentose phosphate pathway of the RBC metabolizes about 5%-10% of the total flux of glucose) and produces NADPH. Hemolytic anemia due to a deficiency of the activity of ______________________ is common.

A

glucose-6-phosphate dehydrogenas

44
Q

________________ is important in the metabolism of the RBC, in part to counteract the action of potentially toxic peroxides. The RBC can synthesize ______ and the ______ required to return oxidized glutathione (G-S-S-G) to the reduced state GSH.

A 
Reduced glutathione (GSH)
GSH and NADPH
45
Q

The iron of Hb must be maintained in the ___________. Ferric iron is reduced to the ferrous state by the action of an NADH-dependent ____________________ involving __________ and ___________.

A

ferrous state
methemoglobin reductase system
cytochrome b5 reductase and cytochrome b5

46
Q

True or False:

While biosynthesis of glycogen, fatty acids, protein, and nucleic acids does not occur in the RBC, some lipids (eg, cholesterol) in the red cell membrane can’t exchange with corresponding plasma lipids.

A

False: Some lipids (eg, cholesterol) in the red cell membrane CAN exchange with corresponding plasma lipids.

47
Q

The RBC contains certain enzymes of nucleotide metabolism (eg, _____________, _____________ and ___________). Deficiencies of these enzymes are involved in some cases of hemolytic anemia.

A

adenosine deaminase
pyrimidine nucleotidase
adenylyl kinase

48
Q

When RBCs reach the end of their lifespan, the globin is degraded to _____________ (which are reutilized in the body), the iron is released from heme and reutilized, and the tetrapyrrole component of heme is converted to _____________, which is mainly excreted into the bowel via the bile.

A

Amino acids

Bilirubin

49
Q

Newly formed red blood cells retain portions of the __________, __________, _________, etc that were present in their nucleated precursors.

A

ribosomes, endoplasmic reticulum, mitochondria

Harpers - Biochemistry (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions