Ch. 10 - Hemoglobin Metabolism (Incom. start at Hb synthesis...) Flashcards
This is the first protein whose structure was described using x-ray crystallography.
Hemoglobin (Hb)
This molecule is a conjugated globular protein consisting of four heme groups and two heterogenous pairs of polypeptide chains.
Hemoglobin
The hemoglobin molecule has how many heme groups?
4
The hemoglobin molecule has how many heterogenous pairs of polypeptide chains?
2
This is the main cytoplasmic component of erythrocytes.
Hemoglobin (Hb)
This type of hemoglobin (Hb) is generated from RBCs through hemolysis; it has a short half-life, is rapidly salvaged and is catabolized or excreted renally.
Free (non-RBC) Hemoglobin (Hb)
What is the approximate concentration of hemoglobin within the RBCs?
34 g/dL
What is hemoglobin’s main function?
To transport oxygen from the lungs to the tissues.
Hemoglobin also modulates vascular dilation by transporting nitric oxide (NO) and transports _____ from the tissues to the lungs for exhalation.
Carbon dioxide
Heme consists of a ring of carbon, hydrogen, and nitrogen atoms called _____ with an atom of divalent ferrous iron (Fe2+) attached.
Protoporphyrin IX
Heme consists of a ring of _____, _____, and _____ atoms called protoporphyrin IX with an atom of divalent ferrous iron (Fe2+) attached.
Carbon
Hydrogen
Nitrogen
Heme consists of a ring of carbon, hydrogen, and nitrogen atoms called protoporphyrin IX with an atom of divalent _____ attached.
Ferrous iron (Fe2+)
Each heme molecule combines reversibly to how many oxygen molecules.
One
Each heme molecule combines (irreversibly/reversibly) to one oxygen molecule.
Reversibly
The four globin chains comprising each hemoglobin molecule consists of how many identical pairs of unlike polypeptide chains?
Two
The four globin chains comprising each hemoglobin molecule consists of two identical pairs of unlike polypeptide chains with how many amino acids each?
141 - 146
Each globin chain is divided into how many helices and nonhelical segments?
Eight helices
Seven nonhelical segments
This part of the globin chain is designated as A to H and contains subgroup numberings for the sequence of the amino acids in each helix and are relatively rigid and linear.
Helices
This part of the globin chain connects the helices, as reflected by their designations.
Flexible nonhelical segments
This hemoglobin structure refers to the amino acid sequence of the polypeptide chains.
Primary structure
This hemoglobin structure refers to the chain arrangements in helices and nonhelices.
Secondary structure
This hemoglobin structure refers to the arrangement of the helices into a pretzel-like configuration.
Tertiary structure
This hemoglobin structure describes the complete hemoglobin molecule.
Tertiary structure, or tetrameric molecule
Each globin chain contains a heme group that is suspended between the _____ and _____ helices of the polypeptide chain.
F and E
The iron atom at the center of the protoporphyrin IX ring of heme is positioned between two _____ radicals, forming a proximal histidine bond within F8.
Histidine
Globin chain amino acids in the cleft are (hydrophobic/hydrophilic) whereas amino acids on the outside are (hydrophobic/hydrophilic).
Hydrophobic
Hydrophilic
(T/F) The hemoglobin molecule is water soluble.
T
What is the shape of the complete hemoglobin molecule?
Spherical
How many heme groups and polypeptide chains does the complete hemoglobin molecule have?
4; 4
How many molecules of oxygen can the complete hemoglobin molecule carry?
4
(T/F) The complete hemoglobin molecule is composed of 4 alpha globin chains and two non-alpha globin chains.
F (2-alpha globin chains)
(T/F) Each heme group, attached to a globin chain, can carry multiple molecules of oxygen.
F (Only one molecule of oxygen per heme)
Heme biosynthesis occurs in the _____ and _____ of bone marrow RBC preursors.
Mitochondria
Cytoplasm
The production of globin chains takes place in _____ from the pronormoblast through the circulating polychromatic (polychromatophilic) erythrocytes.
RBC precursors
(T/F) The production of globin chains can take place in mature RBCs.
F
The combination of two a (alpha) and two B (beta) chains along with their four heme molecules forms what heemoglobin? This is the predominant hemoglobin in postnatal life.
Hemoglobin (Hb) A
This type of hemoglobin contains two alpha and two delta chains; the delta chains are inefficiently expressed; only small amounts of this Hb are found in the RBCs.
Hb A2
This type of hemoglobin contains two alpha and two gamma chains; in adults, this is distributed unevenly among RBCs.
Hb F; present in a few RBCs called F cells
