2.B.1
·
Discuss how cell membranes separate the internal
environment of the cell from the external environment of the cell.
·
Cell membranes consist of proteins,
lipids and Cholesterol and that regulate what can go in and what can go out. The lipids and cholesterol do not allow things
that are hydrophilic into the cell while proteins help move large substances
that cannot pass the membrane, into the membrane.
·
Cells are selectively permeable. Discuss each
point below and how it allows the cell to be selectively permeable.
o
Discuss the following structures and the role
the play in the cell membrane: phospholipids, embedded proteins, cholesterol, glycoproteins
and glycolipids
·
Phospholipids are a key component of the cell
membrane that has both a hydrophobic and hydrophilic regions. The hydrophilic
or “head” of the Phospholipid is faced towards water environments on the
outside a d internal environments.
Temperature can affect phosphate movement.
·
There are three types of Embedded
Proteins. There is
internal membrane proteins that are connected into the phospholipid layer,
trans membrane proteins that connected across the whole membrane and allow
substances across the membrane, and Peripheral proteins that are bound to the
membranes surface. Membrane proteins
help transport substances, signal other cells, and join the cell to the
cytoskeleton and intercellular joining.
·
Cholesterol molecules increase firmness and
integrity to keep the membrane regulated from becoming too fluid or firm.
·
Glycolipids:
are located on the outside of the cell membrane and help Cells to recognize
other cells.
·
Glycoproteins: are located on the outside of the
cell membrane and assist in
recognizing other cells, but are more common than a glycolipid.
·
Discuss the properties of a phospholipid
(hydrophobic/phallic, polar/non, and fatty acids/phosphates.
·
A phospholipid is divided into two
regions. The hydrophobic area that is phosphate and allows water to pass
through it. The hydrophilic area is
lipid and does not allow water to pass through it.
·
Embedded proteins – how do they allow transport?
· Embedded proteins allow transport by giving a passage for substances
that cannot pass through the membrane. The transport protein allows certain
molecules that are hydrophilic to pass through the tunnel.
·
Discuss which molecules can easily pass through
the membrane and which can’t. Why?
·
Molecules that are hydrophilic can
pass through the membrane easily because the phosphate that attract these
certain type of molecules while other molecules cannot pass through because
they are not attracted to those hydrophilic molecules and need the help of
proteins to force there way in
·
Cell walls are a structural boundary that
provides extra barrier for some organisms.
o
Discuss the cell wall of plant cells,
prokaryotes and fungi, and what they are composed of.
o
Cell walls provided structure to a
cell as well as a permeability barrier.
Plant cells are composed of cellulose and are on the outside of the cell
membrane. Prokaryotic cell wars are composed of peptidoglycan. Fungal cell
walls are made of chitin.
o
2.B.2
·
Passive transport does not require the input of energy;
the net movement of molecules is from high to low. Discuss the following
factors relating to passive transport.
o
Discuss how primary transport allows for export
of waste.
o Passive transport allow for the export of waste by diffusing the molecules
from high concentration to low concentration areas.
o
Discuss how membrane proteins play a role in facilitated
diffusion of charged/polar molecules in the membrane. Use the examples of
glucose and Na/K transport
· Proteins play a role in facilitated diffusion by allowing charged
molecules and polar molecules out and into the membrane. The example of the
glucose transport is that electrochemical gradients help power a protein transport
channel and allows for the channel to change its shape to move glucose
molecules to the inside of the cell.
o
Discuss the following solutions and their effect
on a cell. hypotonic, hypertonic, and isotonic.
o
A Hypotonic state is when there is more solute on the
outside than inside the cell and can cause a cell to become shriveled and
plasmolysis.
o
A Hypertonic state is when there is
more solute on the inside than the outside and can cause a cell to explode;
o
In Isotonic, the cell is at
equilibrium and there is a same about of solute outside and inside
o
Discuss water potential and the formula for
solving for it.
o Water potential is defined as the potential energy of water transfer and
the formula solves where the water will flow either in or out of a cell.
· 
o TP is
the pressure potential of the water while Solute potential is solution
potential. The solute potential of regular water is 0.
·
Active transport requires free energy to move
molecules against their concentration gradient from areas of low to high.
Discuss the following factors relating to active transport:
o
Discuss where the free energy used in active
transport comes from.
o
The free energy is found in the form
of ATP
o
Discuss the membrane proteins needed for active
transport.
o
The membrane proteins need for
active transport is a protein pump
o
Explain how molecules are moved against their
concentration gradient. Use the example of the Sodium Potassium Pump.
o
Molecules are used to move against the consentration gradient
from a area of low concentration to a area of high concentration. In the Sodium
Potassium pump, ATP powers the pump to change its shape to move the sodium and
potassium against the gradient and move the Ions into or out of the cell.
o
Discuss the difference between endocytosis and
exocytosis.
§
What happens in each?
§
In Endocytosis the cell membrane
surrounds itself around a concentration of molecules and consumes it
§
In Exocytosis the membrane fuses
molecules inside and force molecules out.
o
Discuss the difference between pinocytosis and
phagocytosis.
o Pinocytosis is when a cell consumes dissolved particles and is also know
as cell drinking.
o Phagocytosis is when a cell engulfs solid particles and material’s into
the cell and is also known as “cell eating”
2.B.3
·
Discuss how internal membranes facilitated cell
process by minimizing competing interactions by describing the activities of
the lysosome.
·
Inside of a lysosome, the organelle
contains thousands of enzymes that break down broken cell material and
macromolecules. If there was no membrane around the lysosome then the cell
would die from all the chemical reactions released from the enzymes.
·
Membranes and membrane bound organelles in
eukaryotic cells processes. Discuss each of the following and how they
compartmentalize: ER, mitochondria, chloroplast, Golgi, and nuclear envelope.
·
The ER is divided into two parts,
the Rough ER and the Smooth ER. The rough ER is located near the nucleus and
its job is to synthesize proteins from the ribosomes that are embedded on it.
The smooth ER detoxifies a cell, creates
phospholipids and regulates metabolism
·
The mitochondria creates ATP for
plant and animal cells using the process
of glycolysis, transition, the Krebs cycle and the electron transport
chain
·
The Chloroplast creates sugar for
plant cells through the process of photosynthesis.
·
The Golgi apparatus ships proteins
across the cell to where they need to be.
·
The nuclear envelope contains DNA,
allows RNA to pass in and out of the nucleus and creates ribosomes
·
Discuss how prokaryotic cells function since
they have no membrane bound organelles.
·
Enzymes inside of prokaryotes float
around inside of the cell.
