Hidden world

Microbes

Organisms that are only visible using a microscope

Cellular microbes

Bacteria, archaea, protists, fungi

Acellular microbes

Viruses

Original replicating molecule

Fulfilled both enzymatic & hereditary function

Ribozymes

RNA strands that have no free nucleotides to pair, folds and pairs with own bases

All organisms descended from

Luca

What separated first

Bacteria and archaea

What led to increase in o2 in earths atmosphere

Evolution of photosynthetic bacteria (Cyanobacteria)

How eukaryotes formed

Archaea cell merged with bacterial cell

How did great oxygenation event occur

Build up of o2 by Cyanobacteria

What happens after great oxygenation event

1st multicellular eukaryotes evolve, then 1st photosynthetic eukaryotes

How does refraction occur

Light refracts when passing from one medium to another

What determines direction and magnitude of bending

Refractive indices of two media forming the interface

What do convex lenses do

Focus light at a specific point (focal point)

What is focal length

Distance between centre of lens and the focal point

Strength of lens is related to focal length

Short focal length = greater magnification

Resolution

Ability of lens to distinguish two distinct points

Fixation

How organisms firmly attach to microscope slide

Heat fixation

Preserves overall morphology but not internal structures (bacteria & archaea)

Chemical fixation

Protects fine cellular substructure and morphology (larger more delicate organisms)

What do dyes do

Make internal and external structures of cell more visible by increasing contrast with background

Phase contract microscope

Converts differences in cell density into detected variations in light intensity

Fluorescence microscope

Excitation with light of specific wavelength causes fluorescent protein to emit longer wavelength light