Mass Transport Flashcards
What type of molecule is hemoglobin?
Protein
How many polypeptide chains make up a haemoglobin molecule?
Four
What does haemoglobin transport?
Oxygen
What is the primary structure of haemoglobin?
Order of amino acid sequence in polypeptide chains
What is the secondary structure of haemoglobin?
Coiling of polypeptide chains into a helix
What is the tertiary structure of haemoglobin?
Folding polypeptide chains into precise shape.
What is the quaternary structure of haemoglobin?
Linking of the four polypeptide chains. Each polypeptide chain also also has an associated haem group.
What ion does haem group contain?
Iron (Fe2+)
How many oxygen molecules does each iron ion combine with?
one per ion
How many oxygen molecules can a molecule of haemoglobin carry in humans?
four
What is the name given to the process by which haemoglobin binds to oxygen?
Loading
Association
What is the name given to the process by which haemoglobin releases oxygen?
Unloading
Disassociation
What does affinity mean with respect to haemoglobin?
Affinity is the relative attraction of haemoglobin to oxygen
If haemoglobin has high affinity, what does this mean?
Easier to take in oxygen, harder to lose
If haemoglobin has low affinity, what does this mean?
Harder to take in, easier to lose
How does haemoglobin change its affinity for oxygen?
It will change shape when in the presence of certain molecules (e.g. carbon dioxide). If present, the carbon dioxide changes its shape, so the oxygen no longer fits as well, and is easily disassociated.
What do we mean by partial pressure?
Pressure exerted by a single component of a mixture of gases
What does a dissociation curve represent?
Relation between partial pressure of oxygen and oxygen saturation of haemoglobin
What shape does the oxygen dissociation curve take?
Sigmoidal (S)
Why does the oxygen dissociation curve increase slowly to begin with>
Difficult for first oxygen molecule to bind
Why does the oxygen dissociation curve increase sharply after a slow beginning?
First oxygen to bind changes the quarternary structure, making the binding of subsequent molecules easier
Why does the oxygen dissociation curve increase slowly at the end of the graph?
Easier for molecules to bind, but the likelihood of the fourth oxygen molecule finding an empty binding site is less likely.
What is the name of the increase in ease of binding for oxygen molecules?
Positive cooperativity
If an oxygen dissociation curve is shifted to the left, how does that affect the affinity for oxygen?
Increases oxygen affinity
If an oxygen dissociation curve is shifted to the right, how does that affect the affinity for oxygen?
Decreases oxygen affinity
What effect does carbon dioxide have on the affinity of hemoglobin?
Higher carbon dioxide concentration, the lower the affinity
What effect does a higher concentration of carbon dioxide have on the oxygen dissociation curve?
Right shift
What effect does a lower concentration of carbon dioxide have on the oxygen dissociation curve?
Left shift
What name is given to the shifting of the dissociation curve due to carbon dioxide?
Bohr effect
Why does carbon dioxide cause the haemoglobin to lose oxygen more readily?
Dissolved carbon dioxide is acidic.
Low pH causes the haemoglobin to change shape
Why do large organisms require a transport system?
Need to transport nutrients over a greater distance
Why are specialist exchange surfaces required in large organisms?
Larger organisms require a large number of nutrients. This requires a greater surface area
What happens to the SA:Vol ratio as the size of organisms increases?
Decreases
What are the main features of all transport systems?
- Suitable medium
- Closed system of branching vessels
- Way of controlling the direction of mass transport
- Mechanism to control mass flow of water
How do animals move their transport medium around the body?
Muscular contraction
How do plants move their transport medium?
Passive process E.G evaportation
Name the blood vessel that carries blood to the heart muscle.
Coronary artery
How is the heart described?
Double pump
What does the left side of the heart deal with?
Oxygenated blood from lungs
What does the right side of the heart deal with?
Deoxygenated blood from body
What are the two chambers that each pump has?
Atrium Ventricle
What is the structure and role of the atria?
- Thin-walledq
- Elastic
- Stretches so blood can enter
What is the structure and the role of the ventricle?
- Thick muscular walls
- Pumps blood a good distance
Why is the heart a double pump system?
As the blood flows through the capillaries of the lungs, there is a drop in pressure. This decreases the speed the blood moves through the rest of the body
What valve separates the left atrium and ventricle?
Left atrioventricular valve
What valve separates the right atrium and ventricle?
Right atrioventricular valve
Which chamber has the thickest wall and why>
Left ventricle
Has the pump the blood through the aorta at high pressure all round the body
What supplies the blood to the heart?
Coronary arteries
What happens if the coronary arteries are blocked?
Heart attack
muscles have no oxygen so die as they can not respire aerobically
Blood moves in one direction as it passes the heart, give two ways in which this is achieved
- Valves stop backflow
- Pressure gradient
Explain how the highest blood pressure is produced in the left ventricle.
Stronger contractions
What is the contraction of the atria known as>
Atrial systole
What is the relaxation of the heart called?
Diastole
What is the contraction of the ventricles called?
Ventricular systole
How do the atrioventricular valves close?
As ventricles contract, the ventricular pressure exceeds atrial pressure
Where are the semi lunar valves?
Aorta and pulmonary artery
How do the semi-lunar valves close?
When elastic walls of the arteries recoil, causing the pressure to exceed that of the relaxed ventricle, the blood is forced through the artery.
What are pocket valves?
Valves in vein
How do pocket valves close?
When skeletal muscles contract and the veins are squeezed, the valves only allow blood to flow toward the heart.
How do you calculate cardiac output?
Heart rate X stroke volume
What are the four types of blood vessels?
Arteries
Veins
Capillaries
Aterioles
What is the second most inner layer found in both arteries and veins called?
Elastic layer
What is the adaptations of arteries which allow them to withstand high pressure?
Thick elastic tissue which allows it to expand
Name three substances that are found within the tissue fluid
Glucose
Amino acid
fatty acids
Explain the role of the heart in the formation of tissue fluid.
Contraction of ventricles produces high blood pressure
Forces water out of blood capilaries
Describe and explain four ways in which the structure of capillary adapts it for exchange of substances between blood and surrounding tissues.
- Small diameter, gives large SA: Vol ratio
- Narrow lumen, reduces flow rate giving more time for diffusion
- Single-cell thick, reduces diffusion distance
- Flattened cells, reduces diffusion distance.
How does water move up the stem?
- Cohesion
- Tension
How is water lost through a leaf?
Lost through the stomata
How is water lost through the stomata?
Diffusion
Humidity of the atmosphere is lower than that inside the leaf
How does water move through the cells of a leaf?
- Mesophyll cells lose water through evaporation
- Lowers water potential
- Causes movement of water via osmosis from neighbouring cells due to water potential difference
How does water move up the stem in the xylem?
- Water evaporates from the mesophyll
- Hydrogen bonds between water molecules cause cohesion
- Loss of water draws up new water molecules
What is the evidence of cohesion-tension theory?
- Changes in diameter of tree trunks based on the rate of transpiration.
Where does the energy come from to drive the process of transpiration?
The sun
Does sucrose affect water potential and if so how does the plant combat this?
Lowers water potential in phloem sieve tubes, water moves from the xylem to sieve tubes
What is a potometer?
Equipment that measures movement of water into plant
What is it that moves in a potometer?
Water
Observed by trapping an air bubble that is drawn through a capillary tube
Why is the plant investigated, cut underwater?
As to not get air trapped in xylem vessels
What is measured when using a potometer?
Movement of a trapped air bubble along a capillary tube and the time is taken. Then the volume of water taken in the plant and the time taken to calculate the rate of uptake.
Do humid conditions increase or decrease rate of water loss?
Decreases rate of water loss
How does sucrose enter the sink from the phloem?
Active transport
How is sucrose moved from the source to the sieve elements?
1 - Diffuses down the concentration gradient by facilitated diffusion into companion cells
2 - H+ ions actively transported out of companion cells
3 - H+ ions and sucrose molecules are transported into sieve tube elements by co-transport
How is sucrose moved through the sieve elements?
1 - Sucrose that moves in at the source decreases water potential
2 - Water moves in from the xylem
3 - At the sinks, sucrose moves into the respiring cells, as does water
4 - This creates a hydrostatic pressure difference, so the sucrose solution is forced from source to sink
Is translocation active or passive?
Active
Active transport
Describe how high pressure is produced in the leaves.
Water potential becomes lower
water enters phloem via osmosis
increased volume means an increased pressure
In a woody stem, what lues just under the bark?
The phloem
What happens in a ringing experiment?
Complete ring of bark and phloem removed from stem
What would you observe after a ringing experiment?
Swollen region in bark above the ring of ripped stem.
What happens to the parts of the plant above and below the stripped area of bark in a ringing experiment?
Non-photosynthetic parts below ring die, those above stay alive
How does removing the phloem affect the plant and what does it mean?
- Sugars accumulate above the ring causing swelling
- ## Interruption of sugars causes parts below the ring to dieThis shows the phloem and not the xylem is involved in the movement of sugars.
What is an isotope?
Element with the same number of electrons and protons but a different number of neutrons
What are radioactive isotopes used for in-plant investigations?
To trace the movement of isotopes and substances they become.
What can be used to identify the presence of radioisotopes?
X-ray film
This will be blackened when exposed to radiation
