Bio 114 Bacteria Archaea and Protists

Bacteria and Archaea

• Most are unicellular

• all are prokaryotic

• lack a membrane bound nucleus (nucleoid)

• lack other membrane bound organelles (mitochondria)

How many RNA polymerase subunits do bacteria and archaea have ?

Bacteria: Just one type - 5 subunits

Archaea: just one type - 13 subunits

Bacteria vs Archaea Peptidoglycan differences

bacteria: majority have peptidoglycan

• helps maintain cell shape and integrity

• some lineages lost peptidoglycan

Archaea: absent and a lack

• use several other cell wall components (s-layer)

First amino acid incorporated during translation for Bacteria vs Archaea

Bacteria: formylmethionine

Archaea: methionine

Histones associated with DNA for Bacteria vs Archaea

Bacteria: no

Archaea: yes

Genetic Variation through Gene Transfer

Lateral Gene Transfer allows for..

acquisition of traits not otherwise available via binary fission

3 types of genetic variation through lateral gener transfer

Transformation

• when bacteria/archaea naturally take up DNA from the environment released by cell lysis or secreted

Conjugation

• genetic information transferred by direct cell - cell contact, includes event called plasmid transfer

transduction

• viruses pick up DNA from one prokaryotic cell and transfer it to another cell

Prokaryote Horizontal Gene Transfer

• Transformation: DNA taken up from the environment

• Conjugation: DNA transferred by direct cell-to-cell contact

• Transduction: DNA transferred by viruses (bacteriophage virus)

Prokaryote Morphological Diversity varies in..

1. size

2. shape

3. motility

Prokaryote Morphological Diversity: Cell Composition

Single Circular Chromosome (DNA strand) (most)

• plasmids (independent auxiliary genetic elements (most))

Ribosomes (membrane-less bound organelles)

• Synthesizes proteins

Cell Wall (like some eukaryotes)

• Allows water to enter via osmosis

• Flagellum for movement

Prokaryote Morphological Diversity: Membrane, Cell Wall, Capsule

1. Inner (plasma) membrane

2. Cell Wall

   1. rigid structure, prevent dehydration

   2. Bacteria: Peptidoglycan (polymer consisting of sugars and amino acids)

   3. Archaea: No peptidoglycan (Cell wall variable)

3. Outer Membrane

   1. Bacteria: Peptidoglycan

      1. gram positive:

         1. single layer cell wall + thick

         2. outer membrane not present

         3. purple stain

      2. gram negative:

         1. double layer wall and thin

         2. outer membrane present

         3. pink stain

4. Capsule

   1. Polysaccharide (sugary) secretion

      • Aid in attachment, dehydration, protection

      from immune cells

      • Missing in some bacteria

Prokaryote Metabolic Diversity

Two Nutritional Needs:

1. Acquiring chemical energy to make ATP (adenosine triphosphate)

2. Obtaining molecules with C-C bonds to be used for synthesis of lipids, proteins, DNA, RNA, and other large complex compounds

   
   

Prokaryote Metabolic Diversity: Source of Energy

What are the different ways for Adenosine Triphosphate (ATP) production?

1. phototrophs: light used to excite electrons

   1. ATP is made by photophosphorylation

2. Chemoorganotrophs (chemical carbon feeders): oxidize organic molecules with high potential energy (carbohydrates, lipids)

   1. ATP is made by cellular respiration or fermentation pathways

3. Chemolithotrophs (chemical rock feeders): oxidize inorganic molecules with high potential energy H2, CO2, Fe2+, NH4+) with O2 as electron acceptor

   1. ATP is made my cellular respiration

Prokaryote Metabolic Diversity: Source of C-C Bonds

what are the different ways for obtaining carbon-carbon blocks:

1. Autotrophs ( self-feeders): synthesize their own from simple starting materials (CO2 and methane)

2. Heterotrophs (other-feeders): absorb ready-to-use compounds from other organisms

what is cyanobacteria?

lineage of photosynthetic bacteria and were first to preform oxygenic photsynthesis.

once oxygen was common in oceans, cell could only carryout out…before this conly ___ respiration was possible

aerobic respiration

anaerobic

oxygen is

highly EN

an efficient electron acceptor

• more energy released in ETC w/ oxygen as ultimate acceptor than is released with other acceptor substances

all organisms require Nitrogen (n) to..

synthesize proteins and nucleic acids

molecular nitrogen (n2) is abundant in the atmosphere but most organisms can’t use it directly, what do they do?

obtain N fro ammonia NH3 or Nitrate NO3-

nitrogen fixation

certain bacteria and archaea are only organisms capable of converting N2 to NH3

nitrogen cycle

driving movement of nitrogen atoms through ecosystems around globe

eukaryotes

diverse and range single celled organisms the size of bacteria to multicellular organisms the size of sequoia trees and blue whales

Eukaryotes share fundamental features that distinguish them from bacteria and archaea like having ___, more ___, and ____

• Have organelles (ex. mitochondria and ER)

• more extensive cytoskeleton (protein filaments through cytoplasm)

• Nuclear envelope

Ediacaran (or vendian) period

• Pre cambian

• complex but enigmatic fossils

• community of slow moving, small, benthic (bottom of water) or upright organisms

• filter feeding, microbe glazing

The Cambrian Explosion

first animals earl sponges to more larger, bilateral, more complex animals in fossil record

In the Ediacara…

1. cyanobacteria crust or mat on top of sediment

2. little/no disturbance of sediment lower

3. organisms wewre microbial grazers, some filter feeders

fauna

refers to all animal life present

what triggered the cambrian explosion?

1. developmental (intrinsic)

   1. new genes, new bodies:Gene

      duplication and diversification

      increased the number of Hox genes

      in animals; allowed larger, more

      complex bodies to evolve; opened

      up new possibilities

   2. lateral gene transfer

      1. involved in biomineralization from bacteria to sponge

2. environmental (extrinsic)

   1. higher oxygen levels: threshold level made aerobic respiration more efficient. allowed for larger and more active animals

   2. ozone layer: reduced the amount of UV reaching the surface

   3. seawater calcium concentration

      1. volcanic activity, erosion; minerals became available for shell production

3. ecological changes (extrinsic)

   1. evolution of predation: exerted selection for prey defense ( shells, exoskeletons, rapid movement)

   2. new niches beget more new niches: increased mobility allowed the exploitation of new resources

   3. increase size and diversity of plankton: plankton large enough to produce droppings and corpses, food for decomposers. spongers also filter and release wastes.

   4. ediacaran mass extinction: followed by adaptive radiations

The nuclear envelope was ___ because it 1. 2. Also, it gave early eukaryotes a novel way to ___

• separates transcription and translation

• enables complex mrna processing, such as splicing and capping, to occur before the mRNA is exported for protein synthesis

• control egen expression

What is the origin of mitochondria?

• host ancestral cell engulfs an aerobic bacterium

• fails to digest it

• bacterium lives and reproduces in host cell

• eventually them become dependent

what is the origin of chloroplasts?

• Chloroplasts have bacteria-like characteristics

• Chloroplasts have circular DNA with genes similar to those in

cyanobacteria

• Peptidoglycan in cell wall

• Extant endosymbiotic cyanobacteria live in cells of protists and

animals

endosymbiosis leading to photosynthesis first occurred in the common ancestor of the ___ which gave rise to all of its subgroups __ ____ _ ____

plantae, primary endosymbiosis of cyanobacteria

chloroplasts also occur in __ __ __. in these species, the chloroplasts are surrounded by more than _ _____.

foure protist lineages

2 membranes

Evolution of endosymbiosis in protista

• single origin or primary endosymbiosis

• possibly at least 3 occasions of secondary endosymbiosis

multicellularity:

• refers to organisms with more than one cell

• arose independently in 7 eukaryotic lineages

How did multicellularity arise?

• colonial model

• coenocytical model

origins of multicellularity in Eukaryotes colonial model:

1. each cell exists and reproduces as an individual

2. then, cells derived benefit from aggregation and cooperation

3. then, the evolution of separate somatic and germ cell lines

4. finally, cells arrange to form interior/exterior polarity

origins of multicellularity in Eukaryotes coencytical model:

1. each cell exists and reproduces as an individual

2. then, cells form coenocytes by incomplete cell division

3. then, membranes form between nuclei, create separate cells

4. then, cells differentiation to form cell types, including germinal ( a single cell/cytoplasmic mass containing several nuclei)

Multicellularity has given rise to increasing ____ ____ and ____ ______ __ _____

structural complexity

greater division of labor

multicellularity has given rise to

• larger size

• increasingly elaborate genetic developmental programs giving rise to massive cellular diversity

  • greater functional specialization

  • emergence of complex cell-cell interaction networks

why not just one big cell?

• single cells rely on diffusion; less effective as surface area to volume ratios decrease with increasing size

  • multicellular organisms consists of small cells that absorb and excrete substances via specialized transport systems

• multicellularity may allow improved metabolic efficiency

  • different cells specialized for specific functions

Eukaryotic protists:

• include all eukaryotic taxa not including plants, animals, or fungi

• composed of 7 monophyletic groups

  • unikonta (one tailed flagellum)

  • bikonta (two tailed flagellum)

• most unicellular

Protists are important for what 3 reasons?

1. they are important medically

   1. malaria

2. they are important ecologically

   1. harmful algal blooms

      1. harmful to humans

3. they are critical to understanding the evolution of plants, fungi, and animals

   1. key role in food chains, and in the global carbon cycle