MIDTERM - HEMOGLOBIN METABOLISM Flashcards
iron bearing protein contained
within the erythrocytes .
hemoglobin
one gram of hemoglobin can carry
____ of oxygen
1.34 ml
The concentration of hemoglobin within RBCs is approximately ____ and its molecular weight is
approximately ____.
34 g/dL; 64,000 Daltons
what are the main function of hemoglobin
transport oxygen from lungs to tissue, carbon dioxide from tissue to lungs.
contributes to acid-base balance by binding and releasing hydrogen ions and
transport nitric oxide (a regulator of vascular tone)
a regulator of vascular tone
nitric oxide
Hemoglobin is the first protein whose structure was described
using _____.
x-ray crystallography
-
-
carbon, hydrogen, nitrogen
the ring of heme composed of carbon, hydrogen, and nitrogen is called as
protoporphyrin IX
what is the central atom found in the heme of the hemoglobin
ferrous iron
When the ferrous irons are oxidized
to the ferric state (Fe3+), they no longer can bind oxygen.
true or false
True
Oxidized hemoglobin is also called ___
methemoglobin
describe the globin strcture
The four globin chains comprising each hemoglobin molecule
consist of two identical pairs of unlike polypeptide chains, 141 to
146 amino acids each.
in globin structure, each globin chain is divided into how many helices and non helices
divided into eight helices separated by
seven nonhelical segments
Hemoglobin is a tetramer of four globin chains with a heme attached
to each globin chain.
true or false
true
globin chain alpha and its number of amino acids
141
globin chain beta and its number of amino acids
146
aside from globin chain alpha, what is the globin chain that has 141 amino acids as well?
globin chain zeta
how many amino acids do theta has?
unknown
the hemoglobin molecule can be describe as its
primary
secondary
tertiary
quaternary structures
the structure of hemoglobin that refers to the amino acid sequence of the POLYPEPTIDE CHAINS
primary structure
the structure of hemoglobin that refers to chain arrangements in HELICES and NON HELICES
secondary structure
the structure of hemoglobin that refers to the
arrangement of the helices into a PRETZEL LIKE CONFIGURATION
tertiary hemoglobin
The quaternary structure of hemoglobin, also called a _____, describes the complete hemoglobin molecule
tetramer
The complete hemoglobin molecule is SPHERICAL, has four heme groups
attached to four polypeptide chains, and may carry up to
four molecules of oxygen
true or false
true
A small percentage of Hb A is ____.
glycated
is a posttranslational modification formed by the nonenzymatic
binding of various sugars to globin chain amino groups over
the life span of the RBC
glycation
Heme biosynthesis occurs in the ____of bone marrow erythroid precursors,
mitochondria and cytoplasm
can mature rbc make hemoglobin?
nope, they will lose the capability to make as they lose mitochondria and ribosomes along the maturation process
how many enzymes do we have for heme synthesis
8
how many enzymes involve in hemem synthesis in both mitochondria and cytoplasm
each have 4 enzymes involve
the heme synthesis starts with the condensation of what substances
succinyl-coA and glycine
glycine and succinyl coenzyme A (CoA) is catalyzed by ___ to produced aminolevulinic acid (ALA)
aminolevulinate synthase
aminolevulinic acid (ALA)
–> in the cytoplasm, aminolevulinic acid dehydratase converts ALA to ___
porphobilinogen (PBG)
porphobilinogen (PBG)
–> it will then be converted into ______ through the enzyme ____
hydroxymethylbilane; hydroxymethylbilane synthase (PBG deaminase)
uroporphyrinogen III
–>will be converted into ____ through what enzyme
coproporphyrinogen III ; uroporphyrinogen III decarboxylase
hydroxymethylbilane
–> it will be converted into ___ through enzyme ____
uroporphyrinogen III; uroporphyrinogen III synthase
what are the products made along the heme synthesis under cytosol or cytoplasm?
porphobilinogen
hydroxymethylbilane
uroporphyrinogen III
coproporphyrinogen III
From coproporphyrinogen III, it will go back to mitochondria to continue and be converted into
protoporphyrinogen III
coproporphyrinogen III will be converted into protoporphyrinogen III through what enzyme
coproporphyrinogen III oxidase
protoporphyrinogen III will be converted into ___ by the enzyme ____
protoporphyrin IX ; protoporphyrin III oxidase
protoporphyrin IX will form a heme through what enzyme
ferrochelatase
where does the heme synthesis starts and ended?
mitochondria
in globin synthesis, which chromosome do alpha and zeta globin are coded?
short arm chromosome 16
in globin synthesis, which chromosome do epsilon, gamma, delta and beta globin gene cluster are coded?
short arm of chromosome 11
expect for which globin chain we do have a single genome per chromatid. In this 2 globin chain, they both have 2 copies per chromatid
alpha and gamma globins
Production of globin chains takes place in erythroid precursors from the PRONORMOBLAST through the circulating POLYCHROMATIC ERYTHROCYTES, but not in ____.
mature erythrocytes
Transcription of the globin genes to messenger ribonucleic acid (mRNA) occurs in the ___,
nucleus
Transcription of the globin genes to messenger ribonucleic acid (mRNA) occurs in the nucleus,
and translation of mRNA to the globin polypeptide chain occurs on ___
Ribosomes in the cytoplasm.
which globin chain produces more mRNA upon transcription? is it the alpha globin or the beta globin
alpha globin, but less efficient in translation
alpha globin makes more MRNA but the globin gene chain is much more efficient in translating,
Therefore, a and b chains are produced in
approximately _____ amounts. After translation is complete,
chains are released from the ribosomes in the cytoplasm.
equal
the alpha chain has what charge?
positive charge
b chain has what charge?
negative
arrange the highest affinity of a chain starting alpha
alpha chain
gamma chain
delta chain
in order to form a complete hemoglobin mob\lecule
Two heterodimers then combine
to form a ____.
tetramer
The two alpha and two beta chain will form ____ the major hemoglobin present from 6 months of age through adult hood
HB A
chains comprising the HB A2
Two alpha and two delta
Hb A2 comprises less
than ___ of total hemoglobin in adults.
3.5%
Hb F contains ___ chains.
two alpha and two gamma
These RBCs with Hb F are
called F or ___
A/F cells.
A third function of
hemoglobin involves the
___, ___- and ____ of nitric oxide.
binding, inactivation, and
transport