Chapter 3Cell Structure

MicroscopesMagnification: makes an image large.Resolution: measures clarityCompound Light Micro.: uses light to pass through specimen. Can view living specimens, Max power 2000xElectron microscopes: use electrons to see. Can not view living specimens, Max power 200,000x three types;

TEM: transmission electron microscope; very thin slice of specimen stained with a metal, electron beam directed at it. 2D.

SEM: scanning electron microscope; specimen still coated with metal (not sliced). Electron beam again, but bounce off instead of absorb. 3D

STM: needle like probe measures the voltage caused by electrons leaking or tunneling form surface of specimen. Can view individual atoms. 3D

Cell featuresCell theory: developed by many scientist consists of 3 parts

1. all living things are made of one or more cells2. cells are the basic units of structure and function of

organisms3. all cells arise from existing cells.

Surface area to volume relationships- Very important in movement of material into or out of a cell- Small cells can exchange more readily than large cells- The math:And you have to complete math lab page 56, analysis 1-3. Due 9/15

Prokaryotes- Single celled organism- Lacks nucleus and other internal compartments- Don’t carry out specialized functions- Very very small- Been around for at least 4 billion years- Bacteria is an example

Characteristics- Can be found everywhere- Do have cytoplasm (jelly like filling inside membrane or cell wall)- Single circular (loop) of DNA- Has a cell wall (structure and support)- Some have a capsule (allows them to stick to anything)- Many have flagella (whip and nae nae like structures that allow them to move)

Eukaryotes (you)- Roughly 2.5 billions years old- Has a nucleus- Multiple organelles (structures that carry out specific functions in the cell)- Very complex- Can have flagella or cilia for movement

The cytoskeleton- The internal framework of the cell (provides transport, information transfer,

and anything else cell needs)- Made up typically of protein fibers- 3 different types

- Actin fibers: typically just beneath the cell membrane, major role in determining the shape of cell.

- Microtubules: act as highway system. Transports everything- Intermediate fibers: helps keep things where they need to be.

The Cell Membrane- Fluid like layer of phospholipids

- Phospholipid: a two part structure (head, polar and two tails, non-polar).

- Selectively permeable- Bi-layer, made up of phospholipids

- Ions are repelled, must have a “gate” to pass through bi-layer- Some fats and other non-polar compounds can pass through

with out “gates”- Membrane proteins

- Proteins are located all over the membrane- Are capable of moving around in the membrane- Made up of several different types:

Hydrophilic: water lovingHydrophobic: repels water

1.Cell surface marker: acts as a road sign (what type of cell) made up of a carbohydrate and a protein.

2.Receptor proteins: bind specific substances to cell (like puzzle pieces) shape is everything!!

3.Enzymes: take part in biochemical reactions.4.Transport proteins: move substances in and out

of the cell.

Cell OrganellesThe City Analogy

1.Cell membrane: City Border2.Cell Wall: City Wall3.Cytoplasm: lawns4.Endoplasmic reticulum: public

transportation5.Ribosomes: factories6.Golgi Bodies: Post office or UPS7.Chloroplasts: Solar panels8.Nuclear membrane: city hall

fence with guard9.Mitochondria: Power plant

10.Nucleus: City Hall/town hall11.DNA: original blue prints12.RNA: copies of blue prints

(specific parts)13.Nucleolus: vault of records14.Lysosomes: waste

disposal/recyclers15.Vacuole: water towers, or

retaining ponds16.Chromosomes: rolled up blue

prints17.Proteins: lumber, bricks, etc…

Assignment!!! Due 9/16

Draw a picture, by hand, of a city listing all the parts of a city and their corresponding cell part! Does not have to be in color.

Does not have to be a Picasso!!! Not being graded for creativity, or artistic abilities!!!

Cell OrganellesNucleus- Found in cytoplasm of eukaryotes- Not in prokaryotes- Contains DNA (our hereditary information)- Has nuclear pores (allows RNA to leave)- Nucleolus holds DNARibosomes- Where proteins are made- Both free (in cytoplasm) and attached (in rough ER)Endorplasmic Reticulum (ER)- System of internal membranes that move proteins and other substances

through the cell.- Rough ER, has its own ribosomes attached.- Smooth ER, lacks ribosomes, makes lipids, aids in breaking down toxins.- Proteins leave ER via vesicles (small membrane bound sacs)

Golgi apparatus- Receives the newly made proteins- Set of flattened membrane bound sacs- Package and distribute modified proteins.Lysosomes- Small spherical organelles that contain digestive enzymes- Break down and “digest” waste materials

Very important, see page 64, which is the process of production, packaging, and distribution of proteins via the ER, Golgi app., and lysosomes.

Mitochondria- Harvest energy from organic compounds to make ATP- ATP main energy currency of the cell- Has its own DNAChloroplasts- Use light energy to make carbohydrates.- Found in plants, algea, and seaweed- Has its own DNACentral Vacuole- Takes up much of a plants cell volume- Stores water- May contain ions, nutrients, or waste- Makes cells rigid (plants wilt when CV is not full)