Download Active Transport

A student investigated the effect of pH on the activity of the enzyme amylase.
She set up the apparatus shown in the diagram.
The tubes were made from Visking tubing. Visking tubing is partially permeable.
She added an equal volume of amylase solution and starch to each tube.
•
She added a buffer solution at pH2 to tube A.
•
She added an equal volume of buffer solution at pH8 to tube B.
After 30 minutes, she measured the height of the solutions in both tubes.
After 30 minutes,
the solution in
tube B was higher
than the solution
in tube A.
Explain why the
solution in tube B
was higher.
1.
Starch hydrolysed / broken down / glucose
/ maltose produced;
1. Neutral: Sugar produced
2. Lower water potential;
3. Water enters by osmosis;
3
Active Transport
Learning Objective:
In order to be successful in this lesson you must be able to:
interpret data to identify when a substance is being actively transported.
Active Transport
explain the
process of
active
transport
Compare and
contrast active
transport and
facilitated diffusion
PROGRESS
interpret data to
identify when a
substance is being
actively
transported.
Active transport
Active transport
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
List the ways in which passive
transport differs from active transport
• Metabolic energy in the form of ATP is needed
• Substances are moved against a
concentration gradient
• Carrier protein molecules are involved
• The process is selective
Give two ways in which active transport is different from facilitated diffusion.
1 ...................................................................................................................
......................................................................................................................
2 ...................................................................................................................
......................................................................................................................
1. Uses energy / ATP;
2. Against concentration gradient / low to high concentration;
3. Does not use channel proteins / only uses carrier proteins;
Assume “it” refers to active transport.
1. Facilitated diffusion is passive - neutral
2. Along / across concentration gradient - neutral
Accept up/down concentration gradient
Accept AT does not need concentration gradient.
2 max
Active Transport
explain the
process of
active
transport
Compare and
contrast active
transport and
facilitated diffusion
PROGRESS
interpret data to
identify when a
substance is being
actively
transported.
Direct transport of a molecule:
•
https://highered.mheducation.com/sites/9834092339/student_view0/chapter5/pr
imary_active_transport.html
Design a flowchart to describe the process of active transport
1. Carrier proteins span the
plasma membrane and bind to
the molecule or ion to be
transported on one side of it
The molecule or ion is then
released to the other side of
the membrane.
On the inside of the cell/
organelle, ATP binds to the
protein, causing it to split into
into ADP and a phosphate
molecule. The protein molecule
changes shape and opens to the
opposite side of the membrane.
The phosphate molecule is released from
the protein which causes the protein to
revert to its original shape, ready for the
process to be repeated. The phosphate
molecule then recombines with the ADP
to form ATP during respiration.
The molecule or ion
binds to receptor
sites on the carrier
protein.
Sodium-potassium pump
•
https://highered.mheducation.com/sites/9834092339/student_view0/chapter5/s
odium-potassium_exchange_pump.html
M4.
(a) cell has lower water potential than external medium;
so, water enters by osmosis;
2
(b) (i) active transport;
by specific carrier proteins/pumps;
2
(ii) sodium ions transported more into vacuole (than to outside);
because more sodium carrier proteins/pumps in vacuole membrane;
or
vacuole membrane less permeable to sodium ions/allows slower
sodium ion diffusion (back out);
membrane has fewer sodium channels;
2 max
[6]
Active Transport
explain the
process of
active
transport
Compare and
contrast active
transport and
facilitated diffusion
PROGRESS
interpret data to
identify when a
substance is being
actively
transported.