Guided notes covering material from Topic 1.4 of the updated IB Biology syllabus for 2016 exams. Notes sequence and prompts are based on the Oxford IB Biology textbook by Allott and Mindorff.
Guided notes covering material from Topic 1.4 of the updated IB Biology syllabus for 2016 exams. Notes sequence and prompts are based on the Oxford IB Biology textbook by Allott and Mindorff.
1.Define the term selectivity permeable2. A. Name 3 types of p.pdffashioncollection2
1.Define the term selectivity permeable
2. A. Name 3 types of passive transport
B. Does passive transport require cellular energy (e.g ATP) in order to occur
3.Define diffusion
4. A.Why does cell require substances to diffuse across the plasma membrane?
B. Give 2 examples of substances that must diffuse across the plasma membrane.
5. A. Name 5 factors that can affect diffusion across the plasma membrane
B. Which molecule would cross the cell membrane more easily- O2 (molecular oxygen) or
sodium ions? Why? Pre-Lab: Read the Introduction to this lab below. Complete the Pre-Lab
Questions to be turned in at the beginning of your next lab. Living organisms and cells are
constantly exchanging materials with their surroundings in order to stay alive. We take in food
molecules for energy and building materials for our tissues and organs and eliminate waste. We
take in oxygen when we breathe in and eliminate the waste product carbon dioxide when we
breathe out. The cells of our body are surrounded by bodily fluids, which are mostly water but
also contain many different molecules. So, the cell, like our bodies, must control or regulate what
goes in and out. Cells do that by controlling what crosses the cell or plasma membrane. In other
words, the plasma membrane is selectively permeable. Once the plasma membrane, they must
move through the cytoplasm rapidly enough to allow the cell to function. There are a number of
different ways that molecules can cross the selectively permeable plasma membrane, based on
the size and the chemical nature of the molecules. Some molecules move by a process called
passive transport. Remember that all molecules are constantly moving and the direction of this
movement is random; this molecular movement is referred to as Brownian motion. In passive
transport, molecules move from high concentration to low concentration
Solution
1. Selective permeable mean that a membrane allows only specific molecules to pass through it
and do not let others to pass. This can be through active or passive transport.
2. A. Passive transport includes transfer of molecules through the cell membrane without the
need of energy. This includes : Osmosis, Diffusion and Facilitated diffusion.
B. Passive transport does not require energy as it is down the concentration gradient..
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Answer the following questions about molecule movement across a membr.pdfarihantcomputersddn
Answer the following questions about molecule movement across a membrane. a. How is
osmosis similar to simple diffusion of CO_2 across a membrane? How is it different? If an
aquaporin is involved, how does this change your answer? b. Compare and contrast carrier
proteins and channel proteins. Include information about both structure and mechanism of
transport. c. Compare and contrast indirect and direct active transport. Give a specific example
for each type of transport.
Solution
5a: Osmosis is the movement of water molecules down the concentration gradiant through a
semipermeable membrane. Both osmosis and simple diffusion of CO2 across a membrane occur
down the concentration gradiant and are passive transport. However, osmosis transports
hydrophilic water molecules while simple diffusion transports hydrophobic non polar CO2
molecules. If an aquaporin is involved, the proces would be called as facililated diffusion which
refers to transport of polar, charged, hydrophilic molecules down the concentration gradiant with
the help of membrane transport proteins.
5b: Carrier proteins are the transporter proteins that are actually the integral membrane proteins
serving in transport of ions across the membrane. These proteins have ion binding sites and
exhibit changes in shape to transport the ions. Channel proteins are the integral membrane
proteins that form the hydrophilic channels for transport of polar, charged and hydrophilic
substances across the membrane. They do not undergo the shape change.
5c: Direct active transport couples the exergonic chemical reaction for increasing the solute/ion
concentration on one side of the membrane. The indirect active transport includes coupling of
favorable downhill movement of one solute to the unfavorable uphill movement of other
substance. For ex: sodium potassium pump couples ATP hydrolysis with uphill movement of
sodium (direct active transport). Downhill movement of sodium coupled with uphill movement
of glucose (indirect active transport)..
This presentation include different kind of transport mechanism of different material inside the cell and outside the cell including Passive transport and Active transport mechenism.
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2. Learning Objectives
1.Describe the properties of a cell.
2.Identify the components common to all cells.
3.Compare and contrast the cells that characterize the three domains of life.
4.Explain how the chemical structure of phospholipids enables them to form a bilayer in water.
5.Explain why a biological membrane has selective permeability.
6.Identify different functions of membrane proteins.
7.Compare and contrast the ways that molecules move across membranes.
8.Explain the relationship between diffusion and concentration gradients.
9.Explain how processes of passive transport work including Osmosis and Diffusion
10.Explain how mechanisms of active transport work including the Sodium-Potassium Pump
11.Explain how larger objects/molecules cross membranes including: Exocytosis and Endocytosis
12.Predict when each of these transport mechanisms might be in use
13.Identify the functions of the organelles in eukaryotic cells.
14.Describe how organelles interact in carrying out a cell’s function.
15.Compare and contrast the structure and function of cytoskeletal proteins
16.Compare and contrast different cell junctions in animal cells.
17.Explain the function of plasmodesmata in plant cells.
5. Section 4.5
This image is a concentration gradient of black pixels, with high
concentration at the top and low concentration at the bottom.
At the top, the black pixels are
abundant and close together.
High concentration
of black pixels
Low concentration
of black pixels
At the bottom, the black pixels
are sparse.
“Gradient” Describes a Difference
Between Neighboring Regions
6. Section 4.5
The balls within this box have the same concentration gradient as
the black pixels did.
High concentration
of balls
Low concentration
of balls
This arrow points down
the concentration gradient
since it starts at high
concentration and ends at
low concentration of balls.
Concentration Gradients Have a
Tendency to Dissipate
7. Movement across membranes
• Passive Transport
– does not require input of
energy
– leads to equilibrium
– Simple diffusion
– Facilitated diffusion
– Osmosis
• Active Transport
– requires energy input
– can concentrate
substances
8.
9. Section 4.5
In simple diffusion, particles move from high concentration to low
concentration—that is, they move down their concentration gradient.
Low concentration areas
High concentration areas
Figure 4.15
Passive Transport Does Not Require Energy
10.
11. Section 4.5
Facilitated diffusion is passive transport that requires membrane
proteins.
Table 4.2
Passive Transport Does Not Require Energy
12. Membrane Proteins Transport Ions
and Polar Molecules
Section 4.5
The hydrophobic tails of phospholipids repel hydrophilic substances.
Therefore, ions (such as Cl- and Na+) and polar substances must pass
through a protein channel to cross the membrane.
Table 4.2
Return to AP
13. Section 4.5
Osmosis, the
diffusion of water
down its
concentration
gradient, is also a
type of passive
transport.
Figure 4.16
Passive Transport Does Not Require Energy
20. Active Transport Requires Energy
Section 4.5
In active transport, the cell uses energy and a transport protein to move
a substance against its concentration gradient.
Table 4.2
26. Membrane Transport Summary
Is the substance
nonpolar?
Yes
No
Is the substance
moving down its
concentration
gradient?
Yes
No
Is the substance
very large?
No
Yes
Is the substance
entering or
leaving the cell?
Exocytosis
Facilitated
diffusion
Simple diffusion
Active
transport
Entering Endocytosis
Leaving
Section 4.5
