Bio Test #1

Cells

Discovered in 1665

Schleiden and Schwann proposed the cell theory.

Cell Theory

1. All organisms are composed of cells.
2. cells are the smallest living things.
3. Cells arise only from pre-existing cells.


1. cells today represent a continuous line of descendants from previous cells.

Cell Size

* Limited
* Small for diffusion of substances

Rate of Diffusion affected by…

Surface area, Temperature, Concentration Gradient, Distance

Surface area to volume Ratio

* small cells have advantage.
* size increase, volume increase faster than surface area.
* overcome limitations by being long and skinny (neurons)

Microscopes

help to see cells not visible to the naked eye.

two types: light and electron microscopes

Resolution

minimum distance two points can be apart and still be distinguished as two separate points.

(Must be 100u apart)

Structure Similarities

1. DNA location (nucleus or nucleoid)
2. Cytoplasm (Semifluid matrix)
3. Ribosomes (synthesize proteins)


1. Plasma Membrane (Phospholipid Bilayer)

Prokaryotic Cells

* simplest organism
* lack membrane bound nucleus.
* contain ribosomes.
* cell wall outside of plasma

membrane
* two domains archaea & bacteria

Bacteria Cell Walls

Protect, maintain shape and prevent excess uptake or loss of water.

composed of peptidoglycan

Flagella

* present in some prokaryotic cells
* used for locomotion (rotary motion)
* 1+ or none

Eukaryotic Cells

* membrane-bound nucleus
* more complex
* compartmentalization
* cytoskeleton for support and cell structure

Endomembrane System

* membranes throughout cytoplasm
* divides cells into compartments where diff cell function occur.
* fundamental distinction between eukaryotes and prokaryotes

Endoplasmic Reticulum

Has the RER and SER

RER and SER depends on cells function

Rough Endoplasmic Reticulum (RER)

* attachment of ribosome to membrane
* synthesis of protein to be secreted, sent to lysosomes or plasma membrane

Smooth Endoplasmic Reticulum

* fewer bound ribosomes
* variety of functions
* synthesis, store Ca^2+ and detoxification

Golgi Apparatus

* flattened stacks of interconnected membranes (Golgi bodies)
* packages, distributes molecules synthesized at one location and used at another
* cis and trans faces
* vesicles transport molecule to destination

Lysosomes

* membrane bound digestive vesicles
* from Golgi apparatus
* enzymes catalyze breakdown of macromolecules.
* destroy cells or foreign matter by phagocytosis.

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