Microscope and Cell structures

Midterm 2

Robert Hooke

First person to look at a plant through a microscope

Cellulae

Tiny compartments (Cell)

Cell theory

All living things are composed of cells and all cells come from other cells

Light Microscope

Earliest type of microscope

Visible light passes through a sample and glass lenses

Light is bent to magnify

Magnification

The increase in an objects image size

Resolution

The measure of the clarity of an image

The ability to distinguish two nearby objects

Electron Microscope

Focuses beams of electrons

Electromagnets bend the electron path and magnify the image

Scanning EM

Study the detailed architecture of a cell

Usually coated with a thin film of gold

Elections excite the gold atoms

Transmission EM

Election beam passed through a very thin section of specimen

Stain containing heavy metals coat certain types of cellular structure

Microscope limitations

Election microscopy can not be used to look at live samples (must be dead cells )

Light microscopy, many parts of a cell and some full microorganisms are too small

Surface to volume ratio

Large calls have more volume than small cells but have much smaller surface area

Prokaryotic cell

The first cells to evolve and lived before eukaryotic cells evolved

Example; bacteria and archaea (small, simple cell structure )

Eukaryotic cell

Evolved from prokaryotic cells

Example: all higher life forms such as plants, animals and fungi (larger, more complex cells )

Distinction of eukaryotes

Membrane enclosed nucleus which houses most of the DNA

Have many membrane enclosed organelles

Plasma membrane

Forms a flexible boundary between the living cell and its surrounding (allows things to pass through)

Ribosome

Machinery for protein synthesis

Cytosol

Aqueous solution that fills the cell

DNA

One or more chromosomes

Cytoplasm

The entire contents of the inside of the cells

Phospholipid

A layer that keeps things in and out

Consist of polar phosphate + head group and two non-polar tails that are attached to the phosphate head group

Membrane protein

Channels, receptors and enzymes

Nucleoid

Region of the cell where the chromosome is coiled

Cell wall

Rigid, chemically complex shell surrounding the plasma membrane

Capsule

Sticky outer coat around the cell wall

Glues the cells to surfaces or to other cells

Flagella

Long projection that propels a cell through its environment