Honors Biology Review 8.2 and 8.3; Cell Structure and Function

The cell membrane is composed of a phospholipid bilayer, the heads of the phospholipid face outside and the tails face inwards

Describe the structure and properties of the cell membrane

the heads are faced outward because they are polar and hydrophilic and the tails face outwards and are hydrophobic, the heads face outward because its facing where the water is

Explain how and why the phospholipids are arranged within the cell of a membrane

because it is constantly moving and is made up of many parts

Why is the term "fluid mosaic" used to describe the cell membrane

it makes sure the phospholipids are still able to move and keeps them together

Discuss the role of cholesterol within the cell membrane

it allows active transport to occur, it also allows for levels to be where they need to be, and allows for materials to be where they need to be

How does the cell membrane maintain homeostasis

the cell wall and vacuole provide structure and the cell wall keeps the vacuole and cell membrane from exploding from too much water

How do the cell wall and the vacuole support cell structure

B. Without

The term "passive transport" refers to the movement of materials across a membrane ________ energy input from a cell

a. with

b. without

random molecular movement

Complete the following statement: the driving force for diffusion is...

"down" means moving from a place with high concentration to low concentration while "against" means moving from a place with low concentration to high concentration

distinguish between "down the concentration gradient" and "against the concentration gradient"

they move from a place with high concentration to low concentration; this is because of osmosis

When viewing a diagram of cellular transport, explain the movement of particles and water - where do they move and why

Compare: they all require no cell energy and go from high to low concentration

Contrast:

Diffusion: anything can pass through

Osmosis: only water passes through to where more solute is

Facilitated diffusion: only certain things can pass through

Compare and contrast cell transport mechanisms: diffusion, osmosis, facilitated diffusion

Isotonic: concentration is the same in the intracellular and extracellular environments

Hypertonic: Concentration is high inside the cell and concentration is low in the extracellular area

Hypotonic: Concentration is low inside the cell and the concentration is high in the extracellular area

Distinguish between isotonic, hypertonic, and hypotonic intracellular and extracellular environments

the blood cell will have a hypertonic reaction and all the liquid inside the cell will leave and the cell will look shriveled up.

A hypertonic salt solution has a higher concentration of solutes than a blood cell. Explain what happens when a blood cell is placed in a hypertonic salt solution.

It will look shriveled up because it loses water. You might be able to see visible gaps between the cell wall and the cell membrane under a microscope because the cell membrane has loss volume.

Consider a cell that has undergone plasmolysis. Describe what the cell looks like and why the cell has this appearance.

Pumps choose what goes through the cell (active transport)

Channels don't use ATP, and lets things pass through freely.

How do transport proteins that are pumps differ from those that are channels?

an aquaporin is a transport channel for water. Water is a polar substance and the tails of phospholipids (hydrophobic) stop water from going through. This is the reason where aquaporins come into play (hydrophilic)

What's the purpose of aquaporins? Why is an aquaporin necessary?

facilitated moves with the concentration gradient and requires no energy to function. On the other hand active transport moves against the concentration gradient and requires energy to be used.

How do facilitated diffusion and active transport differ?

they require energy

How do endocytosis and exocytosis differ from diffusion?

It (White Blood cells) consume bacteria and viruses

Explain the role of phagocytosis in the immune system.

the nerve impulses stop.

What might happen if vesicles in your neurons were suddenly unable to fuse with the cell membrane?

the cell membrane is selectively permeable and chooses what goes in and out of the cell based on size, polarity, concentration, and more. It being selectively permeable allows for homeostasis to be maintained so the cell doesn't shrivel or explode.

explain how the cell membrane chooses what goes in and out of the cell?

1. Diffusion

2. Facilitated Diffusion

3. Osmosis

What are the 3 passive transport mechanisms?

it is the movement of cells across the cell membrane requiring no energy

explain passive transport

1. Molecular transport

2. endocytosis

3. Exocytosis

endo and exocytosis are both bulk transport

what are the 3 main types of active transport?

it binds to a target molecule and uses chemical energy (ATP) to move a substance against the gradient

how does molecular transport work?

it is the process of taking material into the cell by the cell engulfing them in a membrane

It eats the molecules and pinches off the cell membrane to transport the cells to a different area

What is endocytosis?

It is the release if substances outside of a cell

It fuses with the cell membrane and all of the contents in the cell are forced out

What is exocytosis?

neurotransmitters are expelled by exocytosis and the impulses are sent to the next nerve

what is the role of exocytosis for transmission of nerve impulses?