BI276 - microbes

office hours: tues/thurs - 7 to 8pm

microbiology

the study of microorganisms

functions of the cell

motility, differentiation, intercellular communication, and horizontal gene transfer

what do cells have in common?

cytoplasmic membrane, cytoplasm, ribosomes, cell wall

cytoplasmic membrane

seperates the inside of the cell from the outside

cytoplasm

an aqueous mixture of macromolecules, small organic molecules, various inorganic ions, and ribosomes - “the inside of the cell”

common macromolecules

proteins, lipids, nucleic acids, and polysaccharides

cells and microbes can be viewed as

genetic coding devices (RNA/DNA) and biochemical catalysts

ribosomes

the structures responsible for protein synthesis

cell wall

a releatively permeable strucutre outside the cytoplasmic membrane that lends structural strength to a cell

Cell walls are typically found in plant and animal cells. True or False?

False, they are typically found in plant calls but not animal cells

microorganism

an organism usually requiring a microscope to be seen consisting of a single cell or cell cluster, including the virus

how big are microbes?

size varies

types of microorganisms

viruses, bacteria/archae, and protozoa/algae/fungi

common microorganisms

bacteria, fungi, protozoa, microscopic algae and viruses

where do we encounter microbes?

food, skin, body, soil, freshwater

characteristics of a microbe

diverse in form/function, inhabit every environment that supports life, many single-celled (but can still be multicellular), live in microbial communities

phtotrophic bacteria

bacteria can conduct photosynthesis

the importance of microorganisms

oldest form of life and largest mass of living material on earth

microorganisms carry out major processes for _______________

biogeochemical cycles ex. nitrogen, carbon, potassium cycles

examples of other life forms require microbes to survive

humans harbor E. coli

Microorganisms are described as UBIQUITOUS. what does this mean?

they can live in places unsuitable for other organisms such as soil, water, air, food, and common surfaces

what tools help study microorganisms?

microscopy, culture, medium, growth, and colony

culture

cells grown in/on nutrient medium

medium

liquid/solid mixture containing all required nutrients

growth in microorganisms

increase in cell number resulting from cell division

colony

visible cluster; contains millions or billions of cells

how was this obtained?

streak plating

pure culture

a colony with only ONE species

All microbial life descended from one common ancestor. T or F?

True, LUCA

the 3 domains of life

bacteria, archaea, and eukarya

the two fundamental cell types

prokaryotic and eukaryotic

organelles

assortment of membrane-enclosed cytoplasmic structures (commonly found in eukaryotic cells)

what does LUCA stand for?

last universal common ancestor

DNA genome

full set of genes in a cell - “the living blueprint”

gene

a segment of DNA that encodes a protein or RNA molecule

what are the 3 lineages which rose from LUCA

archaea, eukarya, bacteria

chromosomes

strucutures in which prokaryotic cells and eukaryotic cells are organized into

how is nucleoid formed?

the chromosome aggregates within the prokaryotic cell

where is the nucleoid commonly found?

in prokaryotic cells

plasmids

small circles of DNA distinct from that of chromosomes

enzymes

proteins that have catalytic activity, carry out reactions that supply energy and perform biosynthesis within the cell

microbial taxonomy

kingdom, phylum, class, order, family, genus*, and species*

when are enzymes synthesized?

during gene expression in the sequential process of transcription and translation

transcription

the process by which the information encoded in DNA sequences is copied into an RNA molecule

translation

the process whereby the information in an RNA molecule is used by a ribosome to synthesize a protein

DNA replication

microbial growth requires replication of the genome through this process, followed by cell division

the processes in which ALL CELLS carry out

transcription, translation, and DNA replication

which taxonomy is important in classifying microbes?

genus and species

what is the criteria for writing scientific names

italicized, genus is capitalized, species is lower case
ex. staphylococcus aureus - S. aureus

characteristics of bacteria

prokaryotes, usually undifferentiated single cells, long, 80+ phylogenetic lineages

the only 2 lineages defined as prokaryoes

bacteria and archaea

smallest known microbe

circovirus - 20nanometers

largest shown bacterium

epulopiscium - 700 nanometers

characteristics of archaea

prokaryotes, five well described phyla, historically associated with EXTREME ENVIRONMENTS but not all extremophiles, lack known parasites or pathogens of plants, 12+ phyla

characteristics of eukarya

plants, animals fungi, first were unicellular, 6 kindgoms, presentation varies

characteristics of viruses

obligate parasites that only replicate within host cell, NOT CELLS, do not carry metabolism, small genomes of double-stranded or single stranded DNA or RNA

how do viruses make genomes?

hijacking host cell and making proteins

how are viruses classified?

structure, genome composition, and host specificity

what are in bacteria cell wall?

peptidoglycan

how do bacteria reproduce?

via binary fission - NOT SEXUAL

what do bacteria use for energy?

they use organic chemicals, inorganic chemicals, or photosynthesis

examples of organic chemicals

carbon

peptidoglycan cell walls in archaea

not present

specific examples of archaea

methanogens (carry out metabolism), extreme halophiles, extreme thermophiles

extreme halophiles

live in high SALT environments

the 2 cell lineages which are eukaryotes

fungi and protozoa

what are these?

fungi - hyphae present

cell walls in fungi

made of chitin

what do fungi use for energy?

organic chemicals

are fungi unicellular or multicellular?

both

molds and mushrooms are multicellular organisms consisting of what?

masses of mycelia which are composed of filaments called hyphae

are yeasts multicellular or unicellular?

unicellular

what is this?

protozoa

why are viruses classified as Acellular?

they lack cytoplasm, cell membrane, and organelles

characteristics of protozoa

eukaryotes, unicellular, and motile via psuedopods, cilia, or flagella

how do protozoa get energy?

absorb or ingest organic chemicals

what do viruses consist of?

DNA or RNA core surrounded by a protein coat. This is enclosed in a lipid envelope

under what condition does a virus replicate?

only when they are in a living host cell

are animal parasites eukaryotic or prokaryotic?

eukaryotic

are algae prokaryotic or eukaryotic?

eukaryotes

what do algae cell wall consist of?

cellulose

how do algae gain energy?

photosynthesis

what do algae produce?

molecular oxygen and organic compounds

history of life on earth. When did the first cells appear?

earth is 4.6 billion years old but the first cells appeared between 3.8 and 4.3 billion years ago

what wsa the first cell linage that came about?

bacteria/archaea - 4 billion years ago

when did each cell lineage appear?

bacteria/archaea → phototrophic bacteria → cyanobacteria → eukarya → animals → vascular plants → mammals → humans

the atomosphere was anoxic until 2.6 billion years ago. True or False?

True, the atmosphere had no oxygen until 2.6 billion years ago

only anaerobic metabolisms where around when the atmosphere was anoxic. True or false?

True

intercellular communication

they are “aware” of their neighbours and can respond accordingly

the resolution of the human eye

human eye has difficulty resolving objects less than 100um in diameter

what limits prokaryotic cell size?

prokaryotic cells rely on DIFFUSION for transport

when was the first anoxygenic phototroph introduced?

approximately 3.6 billion years ago

when was the first cyanobacteria introduced?

the first oxygenic phototrophs where introduced 2.6 billion years ago

when were plants and animals introduced?

approximately 0.5 billion years ago

what makes up a significant fraction of earth’s biomass?

total carbon

extremophiles

live in habitats too harsh for other life forms ex. hot springs, glaciers, high salt, high acidity

microbial ecology

how microbes affect animals, plants, and entire global ecosystems

major cellular sources of carbon

plant cell walls, protein, RNA, DNA, membranes, peptidoglycan (many plant contributions)

major cellular sources of nitrogen

protein

carbon’s global biomass is just over _________ microbal and just under _______ plant based

20%; 80%