Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
16 Cards in this Set
- Front
- Back
|
What are the biological roles of myoglobin and hemoglobin?
|
Mb- stores oxygen in the muscle
Hb- red blood cells transport oxygen from lungs to tissues |
|
|
What is the structure of myoglobin?
|
Alpha helix with one domain and a single heme group
|
|
|
What is the function of the proximal and distal histidine in myoglobin?
|
Proximal histidine attaches the heme to the helix. Distal histidine stabilizes oxygen binding, blocks strong CO binding and acts as a proton scavenger to prevent Fe2 to Fe3.
|
|
|
What is the structure of hemoglobin?
|
Tetramer of 2 alpha helices and 2 beta, gamma or delta chains.
Adult: beta Fetal: gamma Adult minor: delta |
|
|
Why is the hemoglobin protein needed to bind heme to oxygen?
|
Free heme binds CO much tighter than O2. The protein hinders CO binding.
Free heme is oxidized by O2 and can't bind. Protein inhibits oxidation. |
|
|
What are the differences between the myoglobin and hemoglobin oxygen saturation curves? Why?
|
Myoglobin has a higher saturation at a lower level of oxygen pressure (tissues). This allows the tissues to pull oxygen off of the hemoglobin. At higher levels of oxygen saturation (lungs), the hemoglobin has a high saturation and can load oxygen.
|
|
|
How does oxygen cooperativily bind to hemoglobin?
|
When oxygen is not bound, the hemoglobin has a low affinity for oxygen. When one of the hemes binds oxygen, the other groups change conformation and have a higher affinity to fill all the hemes and hold them.
|
|
|
What are the three physiologic regulators for hemoglobin?
|
Bisphosphoglycerate
H+ CO2 |
|
|
Where does BPG preferentially bind? What is the result? When does this occur?
|
BPG binds to de-oxy hemoglobin. This causes a shift in the equilibruim to create less oxygenated hemoglobin by releasing oxygen to the tissues. This shifts the curve right during times of hypoxia
|
|
|
How do H+ and CO2 act as allosteric regulators?
|
H+ produced in the muscles during activity weakens O2 binding
CO2 produced during activity lowers O2 affinity by binding at N-terminal amines. |
|
|
How does altitude change Hb?
|
Increased altitude causes a decreased oxygen pressure, putting the oxygen saturation farther down on the curve. This causes less oxygen to be delivered to the tissues. This causes an increase in BPG to shift the curve right.
|
|
|
What is methemoglobinemia? What are the causes? How is it treated?
|
Abnormal amount of methemoglobin that contains Fe3 and binds, but cannot release O2.
Caused by drugs/chemicals, nitrate food, diarrhea in infants (metabolic acidosis), or genetic loss of cytochrome b5 reductase. Treated by methylene blue |
|
|
What happens to the hemoglobin curve in methemoglobinemia?
|
Hb curve shifts right because methemoglobin can't release oxygen. Results in cyanosis.
|
|
|
What are the environmental changes that cause hemoglobin right shift?
|
CADET face right
CO2 Acid/ Altitude DPG (BPG) Exercise Temperature |
|
|
What are the types genetic diseases that affect hemoglobin?
|
Loss of subunit -> thalessemia
Point mutation -> hemoglobinopathies (sickle cell) Quaternary structure -> heterozygous or homozygous |
|
|
What is the result of a defect in Hb kansas?
|
Unstable hemoglobin that has decreased cooperativity and oxygen affinity. Results in anemia.
|
