Bio test #2

Different types of cells.......

are permeable to different types of particles

where can diffusion happen?

inside or outside of the cell

what is the cell membrane?

it is the outer boundary of the cell and is its gatekeeper.

for any cell to survive it must have what?

it must be in osmotic balance with its watery environment

What is the function of the cell wall?

it provides cell structure and protection to the cell

What does the cell membrane do?

it regulates what goes in and out of the cell, provides a boundary and outer structure of the cell

what does the cholesterol in the cell structure do?

it restricts the movement of the phospholids and keeps the bilayer strong

what are the other membranes?

most cell parts have their own membranes inside the cell. they all vary in what they allow in or out of their boundary

water will always do what?

move from a greater area of concentration to an area of lesser concentration

what is passive transport?

natural osmotic movement in and out of cells, it requires no energy expanded from the cell

how much energy is required to move water from an area of greater concentration to that of lesser concentration?

none, which makes it passive transport

What passes easily through the membrane (selective permeability)

particles soluble in lipids

what diffuses easily?

particles such as ions or compounds in solution

what makes the bulk of the outer cell membrane's boundary?

phospholipids

what has a cell wall?

plants and certain bacteria

What is another name for the cell membrane?

plasma membrane

what are channel proteins?

pores in the membrane. they use their polarity to attract or repel substances (simplest type)

to move things in and out of the cell, some transport proteins act like what?

pumps

what are the types of active transport?

pumps, endocytosis, receptor-aided endocytosis, phagocytosis and exocytosis

in nature there is a tendency toward.....

randomness

what does not diffuse easily?

solids

what is osmosis?

the *diffusion* of *water* into and out of cells across a selectively permeable membrane.

what is diffusion?

the *random movement* of particles from an area of high concentration to an area of low concentration.

what is the middle lamella?

the area between 2 cell walls where cell division begins

What are the current models of the membrane?

the fluid mosaic model

what are the functions of the protein in the bilayer?

the phopholipids bilayer forms the cell's outer boundary. Its properties allow it to act as a barrier across which most particles cannot pass.

what are membrane proteins?

the plasma membrane also contains proteins scattered throughout the bi-layer, appearing as large bumps throughout the bi-layer. Components of the layer are constantly moving.

what is endocytosis (a.p.)

the process by which the cell *engulfes* and then takes in substances from its environment

what is exocytosis?

the process by which the cell moves waste substances out of the cell

the proteins do what?

the proteins *regulate which particles pass through*, other proteins *act as enzymes* and *take part in chemical reactions* and may also *act as markers* in recognizing other cells. Some of these markers *aid in fighting disease*.

what is facilitated diffusion?

the use of transport proteins to aid in the passage of particles across the plasma membrane

what do transport proteins do?

they aid ions and large insoluble particles across the cell membrane (selective)

what and where are these polar heads and fatty acid tails found?

they face outside of the cell as well as inside of the cell. this arrangement keeps the membrane together with little energy required because of the attraction between polar heads and the water environment inside of the cell , and outside

what are carrier proteins?

they fit a substance into it and then release it. the shape of the carrier protein changes at first, then goes back to normal

what is pumps? (active transport)

transport proteins that act as pumps against concentration gradient

what is receptor-aided endocytosis?

when *specific molecules* of a substance outside the cell first link up with proteins called receptors in the plasma membrane. a vesicle forms and brings the substance inside the cell.

what is phagocytosis?

when cell eating (solid chunks of material) and *pinocytosis* cell drinking (liquid droplets) are taken in

active transport is required when?

when moving substances from *lesser* to greater concentration

What is selective permeability?

when only certain substances are able to pass in and out of the membrane

what is dynamic equilibrium?

when particles move but are already equally distributed (osmotic balance occurs)

when does osmotic balance occur?

when the water moving in the cell and the water moving out of the cell is equal

what is the structure made up of?

2 layers (bilayers) of molecules called phopholipids and cholesterol.

why is it referred to the fluid mosaic model?

Because the parts of the layer are always moving around (*fluid*). the layer is made up of many parts put together (*mosaic*) it is a representation of the cell membrane (*model*)

What is an example of selective permeability?

CO2 produced in respiration moves out of the cell and glucose, used in repiration moves into the cell

what is the cell wall?

a layer surrounding the membrane

phospholipids contain what?

a polar phosphate head and a non-polar fatty acid tail

what is the cell wall composed of?

cellulose and a complex carbohydrate

what are the types of transport proteins?

channel proteins and carrier proteins

What are the types of passive transport?

diffusion, osmosis, and facilitated diffusion

what is active transport?

energy needed from the cell to transport some substances in or out.

some carrier proteins act like.....

gates for the cell membrane