Exam 1

Microboe

microorganism - is a microscopic organism It is usually a single-celled organism, or it can exist as acolony of cells

who discovered Microorganism

Antonie van Leeuwenhoek in ~1670 when he built the fist microscope

prokaryotic microbes

Bacteria and Archaea

Eukaryotic microbes

fungi, algae and protozoa

are viruses the most abundant microbe? (T/F)

true

prokaryotic cell

Eukaryotic Cell

Bacteria

single-celled prokaryotic organisms

Very ancient, first living cells were prokaryotic and resembled bacteria

ENORMOUS GENE DIVERISTY

phylogenetically

unicellular

Bacteria shape

many shapes, most commonly spherical, rod like, spirals, and so on

Archaea

organization is between Bacteria and Eukarya

Many can survive in extreme environments

Extremophiles

cannot cause disease

phylogenetically

unicellular

Archaea grow above 100 C (T/F)

True

Bacteria and Eukarya membrane lipids are ether linked (T/F)

False

Why can archaea survive in harsh environments?

Because ether bonds are more chemically and physically resistant than ester bonds, archaea membranes are more stable.

Fungi

Many different types, yeasts are the most common fungal microorganisms

fungal cells contain chitin.

They are abundant (human skin and human gut) to fermenters of carbohydrates (wine, beer, etc)

can cause human diseases

unicellular and Multicellular (more abundant)

phylogenetic

chitin

A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls.

Algae

many unicellular microalgae

Photosynthetic

Many clades, phylogenetically not a single group

Protozoa

Heterotrophic single-cell eukaryotic organisms

Not a single phylogenetic group

Most are motile

Many cause disease in humans: Amoeba, Trypanosoma, Plasmodium

Viruses

The most numerous "organisms" on Earth

Are not cells but rather packages of nucleic acids and proteins, sometimes with lipid and carbohydrate envelopes

they require the invasion of a living cell to proliferate (pathogenic)

Bacteriophages

Viruses that specifically infect bacteria.

are viruses of bacteria

features of microorganisms

Proliferate quickly, can recover populations VERY quickly

Can adapt to many different conditions

Very fast evolution

- horizontal Gene transfer

- High mutation rates

- Short time scale for natural selection

Can find a way to live in almost any environment

Deinococcus radiodurans

extremely resistant to DNA damage (present in nuclear reactors and nuclear waste)

Has extraordinary capacity to survive high levels of ionizing radiation and the double-strand DNA breaks that result from exposure to this type of radiation

Bacteria

How do Deinococcus radiodurans live?

Mainly due to the presence of multiple genomecopies in each cell.

When their genome gets damaged by radiation, the genom repairs due to the multiple genome copies they have.

Genome organization in eukaryotic

multiple linear chromosomes

much larger total genome size than most prokaryotes

Lots of non-coding regions

Each gene tends to be regulated separately (no operons)

Introns interrupt open reading frames

operons

In prokaryotic cells, a cluster of genes under control of a promoter.

Genome organization in prokaryotic

Larger chromosomes

- Most are circular but can also be linear

- Linear chromosomes have strands often linked at the ends by hairpins for exonuclease protection

Smaller plasmids

- Can be either circular (moreoften) or linear

endosymbionts

Organelles originated from prokaryotes (e.g., chloroplasts from Cyanobacteria) that were engulfed by eukaryotic cells. Over time, they became endosymbionts and lost the majority of their original genomes.

chloroplasts

Eukaryotic organelle that originated from Cyanobacteria (prokaryotic).

Cyanobacteria

Taken up by Eukaryotic cell.

Genome of mitochondria and chloroplasts

Similar to their prokaryotic ancestors, the genomes are circular.

Their genomes encode the essential machinery needed for protein synthesis, including ribosomes and a minimal set of tRNAs.

High gene density

High gene density

The DNA is highly compact, meaning a large proportion of the genome codes for functional proteins with very little wasted space.

Horizontal gene transfer

The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms.

Much more prevalent in unicellular organisms

- Easy to accomplish

Allows rapid adaptation to new environment

- Acquisition of antibiotic resistance genes