Basic Cell Structure The Cell Membrane The outside

Basic Cell Structure The Cell Membrane • The outside of all cells are surrounded by a membrane made of phospholipids. • Nickname: “The gatekeeper”

Membrane Structure • There are proteins “stuck” in the membrane that help get things into and out of the cells. • They also help to get messages into the cell.

Proteins in Membrane

The Membrane is a lipid bilayer.

Cell Membrane • Selective Permeability –membrane’s ability to allow SMALL molecules through and keeps LARGE molecules OUT. Helps maintain HOMEOSTASIS.

How do molecules get into and out of a cell?

Transport through the membrane Two types – Passive Transport • Energy NOT required – Active Transport • Energy is required

• Movement of molecules from higher concentration lower concentration • Always higher to lower! • No energy input required! Diffusion

Osmosis: Diffusion of water through a cell membrane

Solutions – Higher concentration of solutes = HYPERTONIC. – Lower concentration of solutes is HYPOTONIC. – Equal solute concentrations are ISOTONIC.

3 types of Solutions

What types of solution? Hypertonic Or Hypotonic

Facilitated Diffusion Energy is NOT required to move substances across the membrane. Protein

Facilitated Diffusion High Concentration Cell Membrane bilayer Low Concentration Glucose molecules Protein channel

Active Transport • Energy is required. • Need ATPthe universal energy molecule. • Low to high

Some molecules are too large to get through any type of protein. 1. Endocytosis • Into 1. Exocytosis • Out of

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Inside of the cell Exocytosis Outside of the cell

What is rate of transport? How many molecules can cross the membrane in a given amount of time

Effects on Transport Rate of Transport Large Size Small Hot Temp. Cold High Concentration Low Decreases Increases Decreases

Compare/ Contrast Passive Transport Active Transport

Types of Cellular Transport • 1. Diffusion 2. Facilitated Diffusion 3. Osmosis • Weeee! !! Passive Transport cell doesn’t use energy high low Active Transport cell does use energy 1. Protein Pumps 2. Endocytosis 3. Exocytosis This is gonna be hard work!! high low