Lecture 3 study guide Flashcards
Assume Na+ is being transported across a membrane via facilitated diffusion. What condition would allow for the most transport of Na+ across that membrane?
Na+ will be electrically repelled by K+ and there is a very small concentration gradient. There is very little kinetic energy driving diffusion of Na+
- a larger concentration gradient will provide greater kinetic energy to drive diffusion and Na+ will be electrically attracted to the Cl-; this will create a large electrochemical gradient
under a microscope you view a cell with an extensive SER present. What could indicate this?
the cell is involved in detoxifying things
peroxisomes —-
are able to detoxify substances by enzymatic action
- Discuss how cell structure relates to function and discuss specific examples of this relationship in human cells
- The structure of the cell is specific to the kind of cell that it is, and is optimized for its specific function, to allow the cell to perform specific tasks.
- One example is the heart: It has 4 hollow chambers and the structure allows the heart to function and let the heart pump blood to the body.
- Bone cells: They don’t have the right structure for nerve impulse conduction.
describe the function and composition of the plasma membrane
- Consists of the phospholipid bilayer (2 layers) surrounding the cell, is selectively permeable, is composed of phospholipids (a water loving head and two water fearing tails), and cholesterol (that provides structural support).
describe the major roles of lipids in the plasma membrane
contribute to the shape, rigidity, and tension. Also signal, identify, traffic, maintain cellular architecture, and store energy in specific membranes.
describe the major roles of carbohydrates in the plasma membrane
Cell recognition and adhesion, cell protection, make up 1-5% of chemical composition, and even cell differentiation sometimes.
describe the major role of proteins in the plasma membrane
selective transport of molecules, cell to cell recognition, chemical signaling from outside and inside the cell to tell proteins where to go, acting as enzymes, providing help with the cell’s shape, and overall interaction.
what are desmosomes
Are mechanical anchoring and are very strong, good for areas of the body that have a lot of mechanical stress on them. Act like a zipper to lock things in place.
example of a desmosome
the heart
the muscles
what are gap junctions
These are communicating junctions that leave a small gap or opening between cells so that electrical signals and ions or other things that need to move quickly from cell to cell can easily get through. These are communicating junctions that leave a small gap or opening between cells so that electrical signals and ions or other things that need to move quickly from cell to cell can easily get through. Ex: heart, anywhere else that needs quick movement.
example of gap junctions
Ex: heart, anywhere else that needs quick movement.
what are tight junctions
An impermeable junction in which things are not allowed through. Where you are trying to block things from passing through.e
examples of tight junctions
stomach lining, bladder lining
describe passive transport
passive transport does not require an input of energy (merely kinetic energy); therefore, the molecules are free to pass in and out of the cell freely
- the seesaw method
define concentration gradient
- molecules tend to move down their concentration gradient
- the difference in concentration of a substance between two areas
describe the active transport
- Active transport requires and input of energy (ATP), and the body powers this process by taking ATP from the body for the process. It also allows movement against its concentration gradient.
how can substances be moved across the plasma membrane against their concentration gradient
- If the substance has the rights to cross like in facilitated diffusion, then specific molecules can be ferried across into the cell or out of the cell.
- a substance can move freely through with a gap junction, with a tight junction it needs permission to more through.
solute pump
the sodium potassium pump. When you bring in 2 Potassium for every 3 Sodium that is taken out. Is an active form of transportation and helps stabilize the resting membrane potential.
vesicular transport
endocytosis -> in
- the taking in of matter by a living cell by invagination of its membrane to form a vacuole.
exocytosis -> out
- a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.
define electrochemical gradient
the combined differences in concentration and charge, which affects the diffusion of ions (charged particles).
- there is a electric/electro gradient and a chemical gradient. This is a combination of both
explain how the electrochemical gradient influences the movement of substances across the plasma membrane
- Allows the cells to control individually how and in what direction ions move across the membranes in and out of the cells
electrical vs. chemical gradient
electrical - the difference in charge across the membrane
chemical - the difference in solute concentration across the membrane
define membrane potential
the measurement of the difference in charge across the membrane
