2B Review

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.