1. Topic-
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| The Cell Membrane and Membrane Transport |
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2. Content-
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Subject Matter:
Labeling the composition of the cell membrane.
Learning the key functions of the cell membrane and certain materials
that can pass through the membrane.
Definitions:
Diffusion: process by which the collisions between molecules cause
them to continually spread apart from each other
Active transport: transport of molecules through the cell membrane
with the use of energy molecules
Passive transport: transport through the membrane without the use
of energy.
Osmosis: specific transport of water through the cell membrane that
enables cell to maintain proper water equilibrium. |
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3. Goals: Aims/Outcomes-
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1. Students will learn the key functions of the cell membrane.
2. Students will learn about certain materials that are able to pass
through the cell membrane, and others that cannot.
3. Students will learn the difference between the types of transport
between the cell membrane
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4. Objectives-
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1. Through learning the difference between the types of transport,
students will understand the importance of cellular respiration.
2. Students will understand that molecules will GENERALLY go from
areas of high concentration to areas of low concentration.
3. Students will understand the importance of cells having a cell
membrane. |
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5. Materials and Aids-
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PowerPoint
Animations
Interactive activities |
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6. Procedures/Methods-
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A. Introduction-
1. Cell membrane or plasma membrane is one of the vital parts of
a cell that encloses and protects the constituents of a cell. It separates
the interior of a cell from outside environment. It is like a covering
that encloses the different organelles of the cell and the fluid that
harbors these organelles. To be precise, cell membrane physically
separates the contents of the cell from the outside environment, but,
in plants, fungi and some bacteria, there is a cell wall that surrounds
the cell membrane. However, the cell wall acts as a solid mechanical
support only. The actual function of cell membrane is the same in
both cases and it is not much altered by the mere presence of a cell
wall. The cell membrane is made of two layers of phospholipids and
each phospholipid molecule has a head and a tail region. The head
region is called hydrophilic (attraction towards water molecules)
and the tail ends are known as hydrophobic (repels water molecules).
Both layers of phospholipids are arranged so that the head regions
form the outer and inner surface of the cell membrane and the tail
ends come close in the center of the cell membrane. Other than phospholipids,
cell membrane contains lots of protein molecules, which are embedded
in the phospholipid layer. All these constituents of the cell membrane
work jointly to carry out its function.
2. Cell membrane anchors the cytoskeleton (a cellular 'skeleton' made
of protein and contained in the cytoplasm) and gives shape to the
cell.
Cell membrane is responsible for attaching the cell to the extracellular
matrix (non living material that is found outside the cells), so that
the cells group together to form tissues.
Another important cell membrane function is the transportation of
materials needed for the functioning of the cell organelles. Cell
membrane is semi permeable and controls the in and out movements of
substances. Such movement of substances may be either at the expense
of cellular energy or passive, without using cellular energy.
The protein molecules in the cell membrane receive signals from other
cells or the outside environment and convert the signals to messages,
that are passed to the organelles inside the cell.
In some cells, the protein molecules in the cell membrane group together
to form enzymes, which carry out metabolic reactions near the inner
surface of the cell membrane. Read more on how do enzymes work.
3. Explain why certain materials can and cannot pass through the cell
membrane.
The proteins in the cell membrane also help very small molecules to
get themselves transported through the cell membrane, provided, the
molecules are traveling from a region with lots of molecules to a
region with less number of molecules.
3. Materials that can pass through the cell membrane:
oxygen
water
nutrients
waste
carbon dioxide
Materials that cannot:
large molecules
polar (charged molecules/ can only pass through with assistance through
a different kind of transport)
cellular organelles
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B. Development-
1. Show model of the cell membrane and explain each constituent.
2. Show animation for various kinds of transport into and out of the
cell membrane.
3. Quick intro to cellular respiration. |
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C. Practice-
1. Worksheet
2. Ask questions regarding material
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D. Independent Practice-
1. Small lab activity to show transport through the membrane through
the use of onions, water, saline solution, glucose, starch, and indicator
solutions
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E. Accommodations (Differentiated Instruction)-
1. Additional lecture notes for those in need
2. Various seating accommodations
3. Group activity |
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F. Checking for understanding-
1. Quiz on material
2. Homework assigned
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G. Closure-
Prep next lesson: bridge from transport to cellular respiration,
which synthesizes energy molecules
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7. Evaluation-
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1. Grade quiz and homework
2. Rate student understanding throughout the lesson as a whole
3. Establish a review to be done at the beginning of the next class. |
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