Cell Transport

Cellular transport

The way in which molecules move in and out of the cells through the cellular membrane

What do all cells have?

A cell membrane

Cell membranes functions

Controls what enters and exits the cell to maintain homeostasis and provides protect protection and support for the cell

Structure of the cell membrane

Phospholipid bilayer: two layers of phospholipids, phosphate head, fatty acid tails, and proteins embedded in the membrane

Are phosphate heads polar or nonpolar? (Water loving or water fearing)

Polar

Are Fatty acid tails polar or non-polar? (Water loving or water fearing)

Nonpolar

The fluid mosaic model

The membrane is fluid with the molecules moving and the membrane itself being able to bend, the membrane is made of multiple macromolecules piece together like a tile mosaic

Cell membranes also have __________ in it

pores

Selectively permeable

Allow some molecules in and keeps out certain size/shaped molecules

The pores in the cell membrane are ______________ ________________

Selectively permeable

Passive transport

Cell doesn’t use energy

Active transport

Cell does use energy

3 types of passive transport

Diffusion, facilitated diffusion, and osmosis

3 types of active transport

Protein pumps, endocytosis, and exocytosis

How do molecules move and spread out in passive transport?

They move randomly and molecules spread out from an area of high concentration to a area of low concentration

The concentration gradient

The concentration gradient is why passive transport occurs

Diffusion (passive transport)

Random movement of particles from an area of high concentration to an area of a low concentration

What happens to the molecules in diffusion?

They will move around, but will stay spread out and continue until equilibrium is reached (All molecules are evenly spaced.)

facilitated diffusion

Cellular transport from an area of high concentration through a transport protein that is selective in what we can pass through (larger molecules, usually) to a low concentration

Osmosis

Diffusion of water through a selectively permeable membrane and water moves from a high to low concentration

solute

particles dissolved in water

Solvent

In mixed solutions, water moves differently than particles dissolved in water

What does ocean certification do to calcium carbonate?

It degrades and dissolves them

The 3 solutions of osmosis

Hypotonic, hypertonic, or isotonic

Hypotonic

The solution outside of the cell has a lower concentration gradient of solute in a higher concentration gradient of water than inside the cell (low solute; high water)

Hypotonic results

Water moves from the solution to inside the cell, sell swells and bursts open

Cytolysis

Cell swells and bursts open

Hypertonic

The solution has a higher concentration gradient of solute (outside the cell) and a lower concentration of water than inside the cell (high solute; low water)

Hypertonic result

Water moves from inside the cell into the solution: the cell shrinks

Plasmolysis

Cell shrinks

Isotonic

The concentration of solute in the solution (outside the cell) is equal to the concentration of solute inside the cell

Isotonic result

Water moves equally in both directions and the cell remains the same size (dynamic equilibrium)

How do bacteria and plants deal with osmotic pressure?

They have several walls that prevent them from over expanding

Turgor pressure

The pressure exerted implants on the cell wall

How do animals deal with osmotic pressure?

They’re bathed in blood, and kidneys keep the blood isotonic by removing excess salt and water

How do molecules move in active transport?

Actively move to where they are needed, and from an area of low concentration to an area of high concentration

Protein pumps

Transport proteins that require energy to do work

Example of protein pumps

Sodium/potassium pumps are important in nerve responses

What do proteins do to move molecules and what does it require?

Protein changes shape to move molecules, and it requires energy

Endocytosis

Taking bulky material into a cell

What does endocytosis use to work?

Energy

Explain endocytosis

Cell membrane in folds around food particle, forms food vacuole, and digest food, and this is how white blood cells eat bacteria

Exocytosis

Forces material out of the cell in bulk by the membrane surrounding the material fusing with the cell membrane

What does exocytosis change and require?

The cell changes shape and it requires energy

Example of exocytosis

Hormones or wastes released from the cell