Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
30 Cards in this Set
- Front
- Back
|
What are 4 concentration dependent transport mechanisms?
|
1) Osmosis
2) Simple diffusion 3) Facilitated diffusion 4) Active transport |
|
|
What is simple diffusion?
|
-molecule moves from high concentration to low concentration
-no energy required -concetration reaches equilibrium |
|
|
What is facilitated diffusion?
|
-channel protein (permease) binds to molecule causing a conformational change
-no energy required -concentration reaches equilibrium |
|
|
What is active transport?
|
-molecule moves against the conc gradient (for more in cell usually)
-energy required -NO equilibrium |
|
|
What are three types of active transport mechanisms?
|
-simple transport
-group translocation -ABC transport |
|
|
What is simple transport (not diffusion)?
|
-molecule is not altered
-energy required in form of protonmotive force |
|
|
What is group translocation?
|
-molecule is chemically altered during transport
-ATP required when a phosphate froup is added |
|
|
What is ABC transport?
|
-ATP-binding cassette is located in the periplasm of Gram- bacteria
-requires binding protein and energy ATP |
|
|
How many alpha helices do transmembrane proteins contain?
|
-12
|
|
|
What are three types of simple transporters (the actual proteins)
|
-Uniporter
-Antiporter -Symporter |
|
|
How does a Uniporter transport molecules?
-Antiporter? -Symporter? |
-one molecule in one direction
-co-transports two molecules in opposite directions at same time -co-transports two molecules in same direction at same time |
|
|
Where did transporters evolve from? What evidence is there of this?
|
-all evolved from one possible common transporter
-they all show similar similarities in structure even though there are hundreds of them! |
|
|
What happens during group translocation?
|
-molecule is chemically altered during transport
*The transported molecule is altered during the process, so the cell in not fighting a conc gradient! |
|
|
Give a common example of group translocation.
|
-phosphotransferase system: transports some sugars (glucose, mannose, fructose). Requires ATP as source of added phosphate group
|
|
|
What is ABC transport stand for?
How does it get its energy? |
ATP-Binding Cassette Transport
-Coupled to ATP hydrolysis as energy source |
|
|
In Gram- bacteria, where are transporting proteins located?
How about Gram+? |
-in periplasmic space
-anchored to cytoplasmic membrane |
|
|
What happens during ABC transport?
|
-transported molecule binds to a transporting protein
-this interacts with a membrane-spanning protein |
|
|
How do prokaryotes move?
How about microbial eukaryotes? |
-flagella
-pseudopod, cilia, flagella |
|
|
What is flagellum?
|
-a long filamentous structure attached to the cytoplasmic membrane
|
|
|
Where are flagella located on the bacterium?
What is each type known as? |
1) monotrichous (polar): at one end of cell
2) amphitrichous: both ends of cell 3) lophotrichous: many (tuft) at one end of cell 4) peritrichous: around entire periphery of cell |
|
|
What are the three parts of a bacterial flagellum?
|
1) filament
2) hook 3) basal body |
|
|
How do flagella grow?
|
-flagellin molecules pass through channel in filament and incorporated at terminus, thus growing from tip
|
|
|
Describe the filament part of a flagella.
|
-rigid, helically-shaped polymer of identical protein subunits known as flagellin
|
|
|
Describe the hook of the flagella.
|
-a different protein that connects the filament to the motor portion (basal body)
|
|
|
Describe the basal body
|
composed of a rod that passes through two (G+) or four (G-) rings that anchor flagellum to membrane
-surrounding the inner ring are the motor (mot) proteins and the switch (Fli) proteins |
|
|
How do flagellum move bacteria?
|
-they spin like a propeller
-increasing or decreasing rate of rotation affects speed and direction -CCW is a run, CW is a tumble |
|
|
Where does energy for teh basal body "motor" come from?
|
-derived from protonmotive force
|
|
|
What are eukaryotic flagella composed of?
|
-microtubules (bundles of tubulin)
-dynein (motor) |
|
|
How does the flagella move a eukaryote?
|
-in a whip-like motion caused by microtubule sliding
|
|
|
How does cilia work?
|
-since it's shorter and more numerous than flagella, they beat like oars
|
