Download absorption of glucose in the ileum

Important points to note:
1) We will complete our
practical 3 table and graph in
the lesson tomorrow.
2) We will have our test on cell
membranes and movement
across them (35 marks)
tomorrow
4) You will need to make notes
on the lesson today for
homework- power point on
jgrundy.edublogs.org
What do you think
this is?
5) Extra animations and
extension reading for today's
lesson are also on the blog
6) Homework: read through p97
and 98 on ORT and answer
questions
Movement of molecules and ions against
concentration gradients by co-transport.
Learning Objective:
In order to be successful in this lesson you must be able to:
explain the process of co-transport in the context of absorption of glucose (and
amino acids) in detail.
Movement of molecules and ions against
concentration gradients by co-transport.
describe the
adaptations of
small intestine
epithelial cells
to absorption
define what is
meant by cotransport
PROGRESS
explain the process
of co-transport in
the context of
absorption of
glucose (and amino
acids).
In active transport ATP is used to:
• Directly move molecules
• Co-transport: move individual molecules using
a concentration gradient that has already
been set up
M1.
(a) 2 marks for correct answer 0.2
Accept concentration ÷ time
1 mark for 6 / 30;
2
(b) 1. (Uptake) decreases / slower, then no
further uptake / uptake stops;
2. (Decreases) to 20 - 22 / no uptake after 20 /
22 minutes;
2. Accept: (only) 1.6 (arbitrary units) absorbed /
(only) drops to 8.4
Is for correct use of data from graph
2
(c) 1. Stops / reduces / inhibits respiration;
1. Accept: inhibits respiratory enzymes
2. No / less energy released / ATP produced;
2. Ignore: less energy produced/ made
3. (ATP / energy needed) for active transport;
3. Accept ref to Na+ pump / description of active
transport
Ignore consequences of less Na+ in cell
3
(3)
M2.
(a) (i) absorbed by diffusion;
no energy/ATP available / active transport
requires energy/ATP;
2 max
(disqualify energy made)
(allow energy reference in either (i) or (ii))
(ii) absorbed by active transport;
1
(b) (absorption by) diffusion no longer
occurs / diffusion/movement
of ions equal in both directions;
because no concentration/diffusion gradient
/ reached equilibrium;
2
(c) malonate fits into/blocks active site of
enzyme / complementary to active site;
(prevents fitting neutral)
competes with substrate / is a competitive
inhibitor / prevents substrate
forming enzyme-substrate complex;
2
Movement of molecules and ions against
concentration gradients by co-transport.
describe the
adaptations of
small intestine
epithelial cells
to absorption
define what is
meant by cotransport
PROGRESS
explain the process
of co-transport in
the context of
absorption of
glucose (and amino
acids) in detail.
Inside the ileum...
1. By what process
do the products of
digestion pass across
the wall of the small
intestine into the
blood?
2. Explain
how the
microvilli aid
the process
Coeliac disease is a disease of the human digestive system. In coeliac disease, the
structures labelled Z are damaged.
Although people with coeliac disease can digest proteins they have low concentrations
of amino acids in their blood.
Explain why they have low concentrations of amino acids in their blood
Suitable explanation given e.g.
Reduced surface area;
(So) less absorption;
Cell membranes damaged;
(So) Fewer carrier / channel proteins;
Carrier / channel proteins damaged;
So less absorption
.
(2 marks)
The need for active transport.....
Describe diffusion:
Movement of molecules and ions against
concentration gradients by co-transport.
describe the
adaptations of
small intestine
epithelial cells
to absorption
define what is
meant by cotransport
PROGRESS
explain the process
of co-transport in
the context of
absorption of
glucose (and amino
acids) in detail.
The (very clever) co-transport
system
P 95 + 96 define co transport and explain the process of co-transport in the context of
absorption of glucose (and amino acids) in detail.
Task:
In pairs produce an A3 presentation to help your explain the process of co-transport in
the ileum to your peers.
You must:
• Define co- transport
• Explain the process of co-transport in the context of absorption of glucose (and amino
acids) in detail.
• Make it easy to understand
• Use key terms accurately
There are lots of different molecules
and ions involved in this process.
How might they affect the water
potential inside the lumen/ cells/
blood?
Active or passive?
• Sodium ions move out of the epithelial cell
• Sodium ions move into the epithelial cell
• Glucose molecules move into the epithelial
cell.
Cholera and diarrhoea
Cholera is a water-borne disease. It is caused by a bacterium. The bacterium
produces a toxin which acts on the epithelial cells of the small intestine and causes
changes in membrane permeability. The cholera toxin affects the movement of
ions through the intestinal wall. It causes the loss of chloride ions from the blood
into the lumen of the small intestine. This prevents the movement of sodium ions
from the lumen of the small intestine into the blood. The resulting high
concentration of ions causes diarrhoea.
Sodium ions normally enter the blood from cells of the intestinal wall against a
concentration gradient. Describe how. (3 marks)
The high concentration of ions in the small intestine of a person with cholera causes
diarrhoea. Explain why. (2 marks)
Cholera and diarrhoea
Cholera is a water-borne disease. It is caused by a bacterium. The bacterium
produces a toxin which acts on the epithelial cells of the small intestine and causes
changes in membrane permeability. The cholera toxin affects the movement of
ions through the intestinal wall. It causes the loss of chloride ions from the blood
into the lumen of the small intestine. This prevents the movement of sodium ions
from the lumen of the small intestine into the blood. The resulting high
concentration of ions causes diarrhoea.
Sodium ions normally enter the blood from cells of the intestinal wall against a
concentration gradient. Describe how. (3 marks)
Active transport;
Using ATP;
Carrier proteins;
The high concentration of ions in the small intestine of a person with cholera causes
diarrhoea. Explain why. (2 marks)
Water potential lowered in small intestine;
Osmotic loss of water;
QWC First mark only credited if water potential is clearly
linked to intestine or blood
Co-transport
•
•
•
•
http://www.sciencephoto.com/media/526810/view
http://149.142.237.182/na_glucose_cotransport_animation.html
http://highered.mheducation.com/olc/dl/120068/bio04.swf
http://web.archive.org/web/20060619033256/http://w3.uokhsc.edu/human_physiology/cot
ransport.htm
•
http://www.abpischools.org.uk/page/modules/cellbiology/biology6.cfm
Oral rehydration therapy
• http://www.thealevelbiologist.co.uk/topics/aq
a-as-topics/cholera
• http://bigpictureeducation.com/biologybehind-cholera