Chapter 17 (Metabolism and Exercise 3) Flashcards
What is actin
Complex of several proteins
5nm in diameter
2 micrometres in length
G-actin molecules link together to form chains which together are called F actin. (fibrous)
2 chains of G-actin intertwine around each other.
Also consists of Tronponin complex and tropomyosin.
What is troponin complex
Globular protein bound to G actin at regular intervals.
3 binding sites - one for myosin head, one for calcium ions, one for tropomyosin.
What is tropomyosin
Long thin molecule that lies within the groove between 2 chains of G actin.
What is myosin
10nm in diameter
2.5 micrometres in length.
Rod shaped
Has 2 bulbous heads - which contain an ATP binding site allowing the myosin head to have enzymatic function.
What is a sarcomere
A contractile unit of proteins.
2.5 - 3 micrometres long.
Defined by 2 Z lines at each end.
What is the sarcoplasmic reticulum function?
Stores and regulates release of Ca 2+ ions vital for muscle contraction.
What is a triad?
T-tubule (transverse) with sarcoplamsic reticulum on either side.
site of excitation - contraction coupling.
(2 terminal cisternae and 1 T tubule)
Haemoglobin information
Respiratory
Pigment
two different types Adult haemoglobin Fetal haemoglobin. Globular proteins Quaternary structure produced from 2 different genes. Have 4 prosthetic groups (haem groups)
Erythrocytes information
Immature RBC produced in bone marrow of long bones.
Become specialised via differentiation.
What is a haem group
Each haemoglobin (Fe2+) can bind to 4 oxygen molecules.
What is a respiratory pigment.
a molecule that can bind reversibly to oxygen.
Function of haemoglobin
transport oxygen to cells for aerobic respiration.
Definition of association
Binding of an oxygen molecule to 1 haem group to form oxyhaemoglobin.
Cooperative binding
1st oxygen binds to haemoglobin.
causes allosteric effect
causes second haem group to be exposed, so increases the binding ability.
second oxygen to bind to second haem group faster than first.
causes further allosteric effect….
Fetal haemoglobin information? (compared to adult Hb)
Has higher affinity
Haem exposed more
o2 binds more readily
2 alpha and 2 gamma ppcs.
What is myoglobin
only 1 ppc with 8 alpha helices.
1 haem group so 1 Fe 2+
can only bind 1 oxygen
Function of myoglobin
Acts as an oxygen store within skeletal muscle
Only gives up oxygen at very low partial pressures of oxygen.
How is carbon dioxide transported in the blood?
Aqueous solution in plasma
As bicarbonate ions dissolved in plasma.
Combined with amine group of 4 ppc. in each Hb molecule.
- forms carbaminohaemoglobin.
SHOW PERCENTAGES!!!
Effect of carbon dioxide on curve?
- Binds irreversibly with Hb.
- Forms carboxyhaemoglobin.
- Less Hb can form oxyhaeoglobin.
- O2 carriage in blood decreases.
Effect of temperature on curve?
- Hyperthethermia ( raised body temp)
- Shifts curve right
- Incr temp weakens association between O2 and Fe2+, so disrupts ionic and hydrogen bonds within Hb.
- Hb loses quaternary structure
- This promotes release of Oxygen from oxyhaemoglobin.
- Saturation falls.
INCREEASE IN TEMPERATURE DECREASES AFFINITY OF HB FOR O2.
Effect of pH on curves?
- Decrease in pH
- result of H2CO3 or lactic acid (dissociates to form H+)
- Shift dissociation curve to right as H.Hb is formed. (haemoglobinic acid)
- Which promotes release of o2, so percentage saturation falls.
- Decreases affinity of Hb for O2.
DECREASE IN PH DECREASES AFFINITY FOR HB FOR O2.
Myoglobin on graph
- Has higher affinity than adult haemoglobin
- Hyperbolic shape
- At any PO2, will have a higher saturation level than aHb.
- Binding is not cooperative (only one haem group)
Fetal haemoglobin on graph.
- Shifted adult haemoglobin to left.
- At any given partial pressure of oxygen, more oxygen is offloaded from maternal adult haemoglobin and is taken up by fetal haemoglobin.
