Set 2 Wilson Biology

Front 1

What are the three types of cytoskeleton?

Back 1

-actin filaments/microfilaments
-intermediate filaments
-microtubles

Front 2

How do actin filaments assemble and disassemble?

Back 2

by noncovalent, reversible, addition/loss of actin monomers at the ends of the filaments

Front 3

What is treadmilling?

Back 3

assembly at one end of the filament (the plus end) and disassembly at the
opposite end (the minus end)

Front 4

What is the main functions of cytoskeleton?

Back 4

cell structure and movement

Front 5

What are stress fibers? What do they do?

Back 5

bundles of actin filaments that help keep cells elongated

Front 6

What are microvilli? What do they do?

Back 6

stable actin bundles projecting from the cell surface which increases the cell’s surface area

Front 7

What are focal adhesions? What do they do?

Back 7

places where the actin cytoskeleton attaches to the cell membrane

Front 8

What are micotubules made of?

Back 8

tubulin dimers (one molecule of alpha tubulin and one of beta tubulin)

Front 9

What is dynamic instability?

Back 9

switching between growth and shortening at microtubule ends

Front 10

What mechanisms do micotubules use?

Back 10

-dynamic instability
-treadmilling

Front 11

What are centrosomes?

Back 11

where microtubles are organized in cells.
also called Microtubule Organizing Centers (MTOCs)

Front 12

What are centrioles?

Back 12

barrel shaped arrangements made of 9 sets of triplet microtubules

Front 13

Where are centrosomes found in animal cells? What do centrosomes consist of?

Back 13

-they are found near the nucleus
-they consist of a stable pair of centrioles that is surrounded by an ill-defined “pericentriolar matrix”

Front 14

What are the organizational states of microtubles?

Back 14

-mitotic spindles
-cilia
-flagellae (different than prokaryote flagellae)

Front 15

What are cilia and flagellae?

Back 15

Long cell projections used for swimming movement and moving materials across the cell surface

Front 16

How do cilia and glagellae move?

Back 16

Dynein motor proteins do the work. They are enzymes that use ATP to create movement they make microtubules slide past each other which causes bending.

Front 17

What are examples of intermediate filaments?

Back 17

-nuclear lamins (support the nucleus, attachment points for the DNA)
-keratin filaments (supports skin, hair)
-neurofilaments (support long processes in neurons)

Front 18

What are the types of cell membranes? What do they do?

Back 18

-plasma membrane that encases
all cells
-endomembrane system encases internal stuctures

Front 19

What does the plasma membrane do?

Back 19

-contains and holds the contents of the cell (separates the contents from the outside world)
-selectively blocks passage of some molecules from one side to the other, and permit passage of others

Front 20

What are 3 mechanisms that allows the transport of molecules across membranes?

Back 20

1. passive diffusion
2. carrier mediated diffusion
3. active (ATP-dependent) transport

Front 21

Passive Diffusion

Back 21

-the molecules do not become concentrated on either side
-the flow is with the concentration gradient
-no energy (ATP) required
-no carrier proteins

Front 22

What kinds of molecules can be passively diffused across cell membranes?

Back 22

-water (because of its small size- passes through imperfections in the lipid bilayer)
-lipid-soluble uncharged molecules (e.g., uncharged lipids/fats, nucleosides)

Front 23

What kinds of molecules can not be passively diffused across cell membranes?

Back 23

-Most water-soluble molecules
-Molecules carrying positive or negative charges (sugars, amino acids, proteins, peptides, nucleic acids)

Front 24

What is carrier mediated diffusion?

Back 24

Transported molecules are helped by “receptor proteins” or “carriers” in the membrane that can bind to the molecule.
-no energy required
-transport can occur in either direction with the concentration gradient-passage occurs in either direction

Front 25

What is active transport?

Back 25

-carriers use ATP to “pump” molecules against their concentration gradients
-transport only goes one way

Front 26

What are the 3 classes of active transport?

Back 26

-Uniportors: transport one substance in one direction
-Symportors: transport two different substances in the same direction
-Antiportors: transport two different substances in opposite directions

Front 27

What does it mean for an active transport channel to be gated?

Back 27

channels will only open if certain chemical or voltage difference is present across membrane

Front 28

What is endocytosis?

Back 28

The process by which complex molecules, large particles, bacterial cells, and water can enter cells

Front 29

How does endocytosis work?

Back 29

-A membrane vesicle (part of the plasma membrane) forms around a particle or a bacterium
-Membrane vesicle is brought into the cell

Front 30

What are the 3 kinds of endocytosis?

Back 30

-Phagocytosis: large particles and small cells are engulfed inside vesicles
-Pinocytosis (or ”cell drinking”): cells take up water into vesicles
-Receptor-mediated endocytosis: a specialized form of endocytosis for taking certain kinds of macromolecules into cells.

Front 31

How does receptor mediated endocytosis work?

Back 31

-the macromolecule binds to a receptor on the cell surface forming a coated pit
-a protein called clathrin coats the inside surface of the plasma membrane at the coated pit
-A clathrin-coated vesicle forms around the macromolecule (clathrin forms a shell-like structure)
-The vesicle moves into the cell cytoplasm and then becomes uncoated—releasing its contents

Front 32

What is exocytosis?

Back 32

Processes by which complex molecules packaged into vesicles in cells fuse with the plasma membrane and are dumped out of the cell

Front 33

What is the endomembrane system?

Back 33

Dense network of closed membrane tubules, closed vesicles, and closed sacs