Micro Quiz IV

The original environment on Earth was

anoxic (without oxygen)

Prokaryotes that turned the atmosphere from anoxic to oxic

Cyanobacteria (lived in water)

In early earth ____ was dominant

RNA

The Central Dogma of Molecular Biology

DNA to RNA to protein

In early earth Lipid membranes formed and

separated the reactions happening from the environment

Archaea main difference

it has a cell membrane which allows it to grow in extreme environments

First evolved organisms were

phototrophs

phototrophs

used light (photo) as their energy source

aerobic respiration uses ____

O₂ as the terminal electron acceptor

Enzymes that can remove Reactive oxygen species ROS from cells evolved into

aerobic microorganisms

facultative anaerobes

Microorganisms that grow with or without oxygen but grow better in the presence of oxygen

The mitochondria came from

a Gram-negative aerobic bacteria

How many genes does the mitochondria have?

37 (mtDNA)

Scientists look for these silent mutations in

marker genes

Marker genes

genes that every cell needs for survival – such as the ribosome’s

small subunit (SSU) rRNA

Who created the Tree of Life?

Carl Woese (By looking at these genetic changes in the SSU rRNA)

Vertical Prokaryotic Gene Transfer

moving genetic material from parent to daughter cells

• via cell division

Horizontal Prokaryotic Gene Transfer

moving genetic material from one living cell to another

• Via transformation or transfection

biovars

differ biochemically and physiologically

morphovars

differ morphologically

serovars

differ in antigenic properties

serotypes

a distinct subgroup within a single species of microorganism (like a bacterium or virus) that is classified based on the specific antigens found on its surface

E. coli O157:H7

causes outbreaks linked to spinach and salads (yearly); linked to cookie dough (2009) and Taco Bell (2006)

E. coli O26

linked to the outbreak at Chipotle (2015)

E. coli O21

caused an outbreak linked to flour (2015)

Pneumocystis jirovecii

an important microorganism that helped identify AIDS

Eukarya

18S rRNA

Bacteria and Archaea

16S rRNA

Viruses are classified

according to their nucleic acid

Autotrophs

get their carbon from inorganic carbon such as CO₂

Heterotrophs

get their carbon from organic material

The Calvin Cycle

Two G3P: make one glucose (C6) via the reversal of glycolysis

Ten G3P: regenerate a total of five RuBP (C5) via the regeneration step

the most abundant protein on Earth

RuBisCO

The Calving Cycle uses

18 ATP molecules + 12 NADPH + 6 CO2 are used to make ONE glucose! (C6H12O6)

the Calvin cycle occurs in the

caboxysome

Reverse TCA

Used by green sulfur and green non-sulfur bacteria

Cost: 3 CO2 → 1 pyruvate → 1 G3P → cell material

Ferredoxin

non-heme iron-sulfur proteins that act as electron donors

erredoxin enzymes that do carboxylation

Succinyl-CoA (α-ketoglutarate)

b) Acetyl-CoA (pyruvate)

Hydroxypropionate

Described mainly in Chloroflexus (green non-sulfur bacteria)

Cost: 2 CO₂ → glyoxylate (C4) → cell material

Phototrophy

the use of light for energy

Photosynthesis

the conversion of light energy into chemical energy

Oxygenic photosynthesis

makes oxygen (have chlorophyll)

Anoxygenic photosynthesis

does not make oxygen (have bacteriochlorophyll)

light absorbed by microorganisms is between

300 and 900nm

Chlorophyll contains

a tetrapyrolle ring with Mg2+ in the center

Four types of chlorophyll:

a, b, c and d

(a and b are the most common)

Bacteriorhodopsin

A pigment that associates with a transmembrane protein that works as a proton pump

Bacteriorhodopsin absorbs green light (500-650nm) and makes bacteria appear

purple

Chloroplast

• contain thylakoid membranes arranged in stacks (grana)

• both light reactions and dark reactions occur here

Carotenoids

• can absorb high-energy blue light (440-490nm)

• Light can cause ROS (reactive oxygen species), such as singled oxygen (¹O₂)

Chemolithotrophy

the use of inorganic compounds for energy (such as Hydrogen sulfide (H2S), elemental sulfur (S0), ammonia (NH3), nitrate (NO2-), ferrous iron (Fe2+), and hydrogen (H2) )

Chemolithotrophs: Hydrogen

• facultative chemolithotrophs

• Can happen with or without oxygen

• H₂ is normally made during fermentation

Chemolithotrophs: Sulfur

• acid tolerant

• has 2 parts

• Electrons can travel through the ETC and arrive at O2

- Forms a pmf → ATP

• Carbon fixation depends on a reversal of the ETC

Chemolithotroph: Iron

• Will create iron deposits due to the low yield of energy per molecule

• Must remove iron from the environment to have the reaction move forward

Chemolithotroph: Nitrogen

• Oxidation of nitrogen compound is known as nitrification

• Most nitrifiers are also autotrophs

• 2 steps

Anammox

done by strict anaerobic bacteria Plantomycete