Ch. 8: Microbial Metabolism Flashcards
metabolism
used to describe all of the chemical reactions inside a cell
the 2 metabolic pathways
- anabolic
- catabolic
anabolism
refers to endergonic reactions (require energy) involved in biosynthesis, converting simple molecular building blocks into more complex molecules
catabolism
refers to exergonic reactions (spontaneous & release energy) that break down complex molecules into simpler ones
chemotroph classifications
- chemoautotrophs
- chemoheterotrophs
phototroph classifications
- photoautotrophs
- photoheterotrophs
autotrophs
organisms that convert inorganic CO2 to organic carbon compounds
heterotrophs
rely on more complex organic compounds as nutrients that are initially provided by autotrophs
phototrophs
get energy from light for electron transfer
chemotrophs
obtain energy for electron transfer by breaking chemical bonds
the 2 types of chemotrophs
- organotrophs
- lithotroph
organotroph
chemotrophs that obtain energy from organic compounds
- example: humans, fungi
lithotroph
chemotrophs that get energy from inorganic compounds
- unique to micro world
chemoautotrophs
- energy source: chemical
- carbon source: inorganic
- examples: hydrogen, nitrogen, sulfur, iron, & carbon monoxide-oxidizing bacteria
chemoheterotrophs
- energy source: chemical
- carbon source: organic compounds
- examples: all animals, most fungi, protozoa, bacteria
photoautotrophs
- energy source: light
- carbon source: inorganic
_ examples: all plants, algae, cyanobacteria, green & purple sulfur bacteria
photoheterotrophs
- energy source: light
- carbon source: organic compounds
- examples: green & purple nonsulfur bacteria, heliobacteria
oxidation reactions
reactions that remove electrons from donor molecules, leaving them oxidized
reduction reactions
reactions that add electrons to acceptor molecules, leaving them reduced
redox reactions
oxidation & reduction occur together, name for the pair of reactions
electron carriers
molecules that bind to & shuttle high energy electrons between compound pathways
nicotinamide adenine dinucleotide (NAD)
nicotine adenine dinucleotide phosphate (NADP)
flavine adenine dinucleotide (FAD)
NAD+/NADH
ATP
energy currency of cell, used to fulfil any energy need of the cell
ADP
formed when 2nd phosphate added to AMP
high-energy phosphate bonds
bonds between phosphate groups
dephosphorylation
loss of a phosphate group; energy released to drive endergonic reactions
catalyst
a substance that helps speed up a chemical reaction
enzymes
proteins that serve as catalysts for biochemical reactions inside cells
activation energy
energy needed to form or break chemical bonds & convert reactants to products
substrates
chemical reactants to which an enzyme binds
active site
location within the enzyme where the substrate binds
induced fit
active site modification in presence of substrate along with simultaneous formation of the transition state
2 types of helper molecules
- cofactors
- coenzymes
cofactors
inorganic ions such as iron & magnesium that help stabilize enzyme conformation & function
coenzymes
organic helper molecules that are required for enzyme action
apoenzyme
an enzyme lacking a necessary cofactor or coenzyme & is active
competitive inhibitor
molecule similar to a substrate; can compete with substrate for binding to the active site by blocking the substrate from binding
noncompetitive (allosteric) inhibitor
bind to enzyme at allosteric site; location other than active site
conformational change
reduces affinity of enzyme for substrate
feedback inhibition
involves use of a pathway product to regulate its own further production
glycolysis
most common pathway for the catabolism of glucose producing energy, reduced electron carriers, & precursor molecules for cellular metabolism
Krebs Cycle
occurs in cytoplasm of prokaryotes (mitochondrial matrix of eukaryotes)
oxidative phosphorylation
electron transport system (ETS)
last component involved in process of cellular respiration that comprises series of membrane associated protein complexes & associated mobile accessing electron carriers
aerobic respiration
final electron acceptor in ETS is an oxygen molecules (O2) that becomes reduced to water
anaerobic respiration
serves as possible alternative to aerobic respiration & uses an inorganic molecule other than oxygen as final electron acceptor
4 classes of electron carriers
- cytochromes
- flavoproteins
- iron sulfur proteins
- quinones
proton motive force
chemiosmosis
flow of hydrogen ions across membrane
ATP synthase
membrane bound enzyme complex
2 types of fermentation
- lactic acid
- alcohol
lactic acid fermentation
fermentation by some bacteria like those in yogurt other sourced products
homolactic fermentation
when lactic acid is the only fermentation product
heterolactic fermentation
produces mixture of lactic acid, ethanol, and/or acetic acid & CO2
alcohol fermentation
produces ethanol
photosynthesis
biochemical process by which phototrophic organisms convert solar energy into chemical energy
light dependent reactions
energy from sunlight is absorbed by pigment molecules in photosynthetic membranes & converted to stored chemical energy
light independent reactions
chemical energy produced by light dependent reactions is used to drive the assembly of sugar molecules using CO2
chloroplasts
where photosynthesis takes place in eukaryotes
thylakoids
stacked disk shaped photosynthetic structures
granum
stack of thylakoids
stroma
space surrounding granum
photosynthetic pigment
embedded in thylakoid membrane
photosystems
photosynthetic pigments within the photosynthetic membranes, comprised of light harvesting complex
light harvesting complex
consists of multiple proteins & associated pigments that each may absorb light energy & become excited
reaction center
contains pigment molecule that can undergo oxidation upon excitation, where an electron is given up; light energy then converted to excited electron
photophosporylation
example of oxidative phosphorylation; used to generate ATP by chemiosmosis
noncyclic photophosphorylation
cyclic photophosphorylation
if cells need ATP greater than need for NADPH, may bypass production of reducing power with this
calvin benson cycle
biochemical pathway used for fixation of CO2
3 stages of calvin benson cycle
fixation, reduction, regeneration
RuBisCO
enzyme said to be most plentiful enzyme on earth, composing 30%-50% of total soluble protein in plant chloroplasts
