Cell Structure and Function I. Cell Theory 1. All living things are made of cells. 3. New cells are...

Cell Structure and Function I

Cell Theory

• 1. All living things are made of cells.• 3. New cells are produced from existing

cells• 2. Cells are the basic unit of structure and

function in living things.

Cell Exploration

• Light Microscopes– Living organisms can be

seen– Light limits the resolution

so extremely small things like proteins and viruses cannot be observed

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Cell Exploration

• High resolution video technology– Allows scientists to see time elapsed

movies of cells as the grow, divide and develop.

– http://www.cellsalive.com/mitosis.htm

Cell Exploration

• Transmission Electron Microscopes (TEMs)

– Can see more detain and extremely small structures

– Beams of electrons must pass through ultra-thin sliced samples therefore no living things can be seen

Cell Exploration• Scanning Electron Microscope

(SEMs)– Beams of electrons scanned

over the surface of a specimen– Produces a 3D image– Samples must be

chemically preserved and removed of all water so no living things can be seen.

Prokaryotes vs. Eukaryotes• Prokaryotes

(bacteria) have no nucleus and very few organelles. DNA is not contained

• Eukaryotes (protists, fungi, plants and animals) larger,more complex,DNA is inside the nucleus

Plant Cells Vs. Animal Cells• Both plant and animal cells contain

a variety of organelles. Some structures are specific to either plant cells or animal cells only.– Only plant cells contain:

•Cell wall•Chloroplasts•Large central vacuoles

– Only animal cells contain:•Centrioles

Smooth ER vs. Rough ER• Rough ER - ribosomes on the ER make

proteins, the ER modifies the proteins• Smooth ER - makes lipids

Mitochondria vs.

Chloroplasts

• Mitochondria make energy from chemicals (food molecules)

• Chloroplasts make energy from light through photosynthesis

Cytoskeleton• Network of

protein filaments

• Maintains shape

• Involved in cell movement

Prokaryotes Eukaryotes

Cell membraneContain DNA

NucleusEndoplasmic reticulum

Golgi apparatusLysosomesVacuoles

MitochondriaCytoskeleton

DNA is free

floating

Cell Structure and Function II

Cell Wall

• Provides support and protection for plant cell walls

• Made of porous cellulose so it does not regulate what enters and leaves

Cell Membrane• Regulates what enters and leaves the

cell and provides support and protection

• Structure – lipid bilayer with embedded proteins

Diffusion through Cell Boundaries

• Particles move from an area of high concentration to an area of lower concentration

• No energy is required

Osmosis• Diffusion of water through a selectively

permeable membrane

Is this really Osmosis???

Isotonic"ISO" means the same

• Concentration of solutes (salts) is the same inside and outside of cell.

• Water flows in and out in equal amounts

• No effect on cell

Hypertonic“Hyper” means more

• Concentration of solutes is more outside the cell than inside

• Water flows out of cell• The cell shrivels and may

die.

• This is why it is dangerous to drink sea water

• This is also why "salting fields" was a common tactic during war, it would kill the crops in the field, thus causing food shortages.

Hypotonic "HYPO" means less

• Concentration of solutes is less outside the cell than in.

• Water flows in

• The cell swell with water and becomes “turgid”

Active Transport• Carried our by protein pumps

found in the membrane• Energy is required

Facilitated Diffusion• Molecules move through

protein channels. • No energy required

Endocytosis

• Cell takes material into cell by infolding of the cell membrane

• Phagocytosis – eating – cell engulfs large particles

• Pinocytosis – drinking – cell takes in liquid• www.endocyte.com/ animation/animation.htm

Exocytosis• Cell releases large amounts of material

Cell Specialization• The cells in multicellular organisms can

develop in different ways to perform different tasks.

Levels of Biological

Organization

• Organism• Organ system• Organ• Tissue• Cell• Organelle• DNA• Atoms