Chapter 7: Cell Membrane (plasma membrane)

Review: the Characteristics of Life

Try to come up with as many characteristics you can. Living things… Reproduce. Have genetic material. Grow and develop. Use materials and energy. Respond to their environment. Maintain homeostasis. Change over time. Are made up of units called cells.

What is a cell? Smallest unit of living tissue collected

together surrounded by a barrier that separates it from the surroundings.

All living things are made up of cells.

Here is a neat animation of relative size of cells and other ‘objects’.

Cell Theory The cell theory states:

All living things are composed of cells. Cells are the basic units of structure and

function in living things. New cells are produced from existing

cells.

“Pro” versus “Eu” Cells fall into two broad categories,

depending on whether the contain a nucleus (controls cell’s activities). Prokaryotic

Does not contain Eukaryotic

Does Contain

Review If a cell of an organisms contains a

nucleus, the organism is a (an) A. plant B. eukaryote C. animal D. prokaryote

Review In many cells, the structure that controls

the cell’s activities is the A. cell membrane B. organelle C. Nucleolus D. Nucleus

Review the Biomolecules Four main biomolecules found in living

things: Proteins

Various functions throughout cells/organism. Lipids

Fats, steroids, oils. Doesn’t mix with water. Function: store energy.

Carbohydrates Function: main source of energy.

Nucleotides Function: store genetic information DNA or RNA

Cell Boundaries The cell MEMBRANE regulates what

enters and leaves the cell and also provides protection and support. All cells have membranes. Also phospholipid bilayer

Cell Membrane

Cell Membrane The cell membrane is made up of

two layers called the “lipid bilayer”. The heads of the lipids are on the

outsides. They are hydrophilic (hydro = water;

philic = loving). The tails of the lipids are on the

insides. They are hydrophobic (phobic =

fearing/hating) Studded throughout the

membrane are proteins with various functions.

Lipids

made of alcohol and carbon

Tails are fatty acid chains

Slight movement to allow water and substances to pass through membrane (simple diffusion no energy)

Cell Membrane as a “mosaic” Carbohydrate chain

(glyco)- act like chemical identification cards allowing individual cells to identify one another Glycoproteins Glycolipids

Proteins channels and pumps – help move material across the membrane Integral protein

(channel) Peripheral protein

Lipids bilayer- gives the membrane a flexible structure that forms a strong barrier

Polar vs. Non-polar

POLAR/NONPOLAR Polar means that the substance has positive or negative

poles. Non-polar does NOT have positive or negative poles. Polar things like other polar things. Water

is polar!!!!!!!!! Non-polar things like other non-polar

things. Oil is non-polar!!!!!! Selectively permeable- Some molecules can cross the

membrane without assistance, most cannot.

Review Cell membranes are constructed mainly

of A. lipid bilayers B. protein pumps C. carbohydrate gates D. free-moving proteins