semi-impermeable:
selectively permeable:
What types of molecules are permeable:
impermeable:
Semi-impermeable meaning it is kind of able to penetrate through the membrane freely.
Selectively permeable meaning only specific molecules can make it through the membrane.
???
Concentration gradient:
How is it different from an electrochemical gradient?
The high amount of particles within or outside the membrane.
Electochemical gradient focuses on the charge of the outside the membrane.
What does it mean for a molecule to move up or down its concentration gradient? What is the difference between simple and facilitated diffusion?
It means that it diffuses through the membrane to attempt in achieving equilibrium.
Simple diffusion doesn’t require energy. Whereas, facilitated diffusion does need energy.
- What is Osmosis? (lecture) Why and how does water flow across a cell membrane?
Osmosis is the diffusion of water over a membrane layer. It flows through Aquaporins in order to help the concentration and electrochemical gradients at healthy levels for the cell.
- What do the terms hypertonic, hypotonic, and isotonic mean?
Hypertonic suggests a high level of particles in a solution comparative to something else. Hypotonic suggests a lower level of particle concentration in a solution. Isotonic suggests equilibrium.
If a cell placed in a solution swells and bursts which of the following could be said?
The solution is hypotonic
What is osmolarity and how is it determined (page 954)
Solute concentration expressed as the number of moles in solute per liter of solution.
Explain how a plant cell depends on osmosis for maintaining structure and what happens to a plant cell when placed in hypertonic, hypotonic, and isotonic solutions? Use the term Turgor or osmotic pressure in your explanation
The flow of water into a plant cell allows it to become turgid(osmotic pressure) and in its normal state. The cell prefers a Hypotonic solution.
- Name at least two different protein types by which facilitated diffusion occurs. Which do you think allows for faster diffusion?
Channel proteins(gated) and carrier proteins. Because the channel protein would be open constantly while the ligand is bound, it would most likely be faster(ion channel 100 million ions per second). Carrier Proteins require conformational change in the protein and aren’t ever constantly open.
- What is the difference between passive and active transport? Can channels do both? Can carriers do both?
Passive= no energy. Active= needs energy
- Using the Na+/K+ pump (Na+/K+-ATPase) as an example explain how ATP hydrolysis can drive active transport.
when 3 Na+ have found their way to the pump ATP delivers and allows conformational change in the protein to release and open the protein to 2 K+ molecules. This drives active transport
- Where is the energy for Cotransport (secondary active transport) derived from? Why are ion gradients especially useful for driving secondary active transport mechanisms? What do the terms symport and antiport refer to?
Secondary transport is not driven by phosphates but by other molecules such as Calcium. DAG is an example of Calcium mediated secondary transport.
- Transport proteins work great for many types of small organic molecules like ions, amino acids, and sugars. However the cell often ingests large macromolecules that would be as big, or bigger than the transport proteins themselves. Describe three mechanisms by which large macromolecules and food particles can be taken into a cell and then compare and contrast their similarities and differences.
Exocytosis,
- Two types of signaling mentioned in your book occur only when cell are in direct contact with each other. Which two are they and what are some the key words that go with each.
Animal: direct contact signaling. Plant cells: Plasmodesmota
- There are at least 3 types of signaling that occur between cells that are not in direct contact with each other. What are the 3 types? Classify each as either long distance or localized. Then classify each type as general (to all cells) or specific (single cells).
Long distance, Local signaling,
- Suppose you had to match the different types of cell signaling with forms of human communication as follows. A telephone call, shouting from your back porch, a radio or television broadcast, a handshake, a kiss. Briefly justify each of your responses.
qwer
- Describe the three stages of cell signaling as proposed by Earl Sutherland.
Reception, Transduction, Response.
- What is a ligand? Why is it important in cell communication?
Any molecule that binds to the receptor molecule. It is important because cells are able to identify specific ligands and respond according to the information provided.
- (lecture) What is the Kd of a receptor. Does having a high Kd mean that the receptor binds the ligand tightly or loosely? Name a situation in which you might want a high Kd. Name a situation in which you might want a low Kd.
dissociation constant. Depends on if it is a Large Kd(loose) or Small Kd(tight). Tight binding would be for testosterone development (long term0. Loose binding would be helpful with acetylcholine (short term)
- Name the four types of receptors discussed in the book and compare and contrast their location in the cell, their structure, and their mode of transmitting signals.
G protein Receptor PLASMA MEMBRANE;
- Describe the mechanism by which a G protein coupled receptors receives and transmits a signal.
PLASMA MEMBRANE Ligand binds to g protein receptor. This allows for the g protein to be released and alpha separate promoting a signal.
- Describe the mechanism by which a Receptor Tyrosine Kinase (enzyme-linked receptor) receives and transmits a signal.
PLASMA MEMBRANE Tyrosine Kinase is a dimer that needs two different ligands to be bound then they dimer is comes together. It then phosphorylates itself and then phosphorylates other proteins.
- What is a Kinase?
A protein that phosphorylates.
Describe the mechanism by which an Ion channel receptors receives and transmits a signal.
PLASMA MEMBRANE; When the ligand
binds to the receptor and the gate opens, specific ions can flow through the channel and rapidly change the concentration of that particular ion inside the cell. This change may directly affect the activity of
the cell in some way.
