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energy The capacity to do work or cause change Kinetic energy is actively performing work,
Potential energy is stored (ability to perform work based on location/arrangement)
1st law of thermodynamics – energy conservation
Endergonic reactions – consume energy Exergonic reactions – release energy
Energy conversions
Cell takes PE of chemicals (in electrons/bonds) and eventually converts them to cellular work (KE)
Endergonic/exergonic reactions are usually coupled so that the energy can either be used immediately or stored (ATP) for later use
2 types of metabolism
_________________ - biosynthesis building complex molecules from simple ones requires energy (ATP) - endergonic
_________________ - degradation breaking down complex molecules into simple ones generates energy (stored as ATP) - exergonic Example - glycolysis
Enzymes
Needed to keep pace (speed up reactions) Reaction involves either breaking a
molecule apart or brining one together Catalyze reactions without becoming
products or being consumed in the reaction
Act upon ______________ to form _________________
Lower _________________ so reaction rate increases
Enzyme - structure
Simple enzymes – consist of protein aloneConjugated enzymes or holoenzymes –
contain protein and nonprotein molecules apoenzyme –protein portion cofactors – nonprotein portion
metallic cofactors – iron, copper, magnesium coenzymes - organic molecules - vitamins
Control of enzyme activity1. _________________ inhibition –
substance that resembles normal substrate competes with substrate for active site
2. _________________ inhibition – enzymes are regulated by the binding of molecules other than the substrate on the active site
• Enzyme _____________– inhibits at the genetic level by controlling synthesis of key enzymes
• Enzyme _____________– enzymes are made only when suitable substrates are present
Things that affect enzymes
Temperature, pH, pressureEnzymes have optimal T and pH for
activityCan be denatured by extreme
temperatures or pH (changes protein structure)
Roles of enzymes: Pathogenesis Produced by pathogenic microbes--make
microbe a better pathogen (evade host response, destroy host tissues)
Examples: Hemolytic enzymes (hemolysins) Elastase, collagenase (destroy connective tissue) Lecithinase C (destroys cells) Penicillinase (inactivates penicillin – antibiotic
resistance)
Note: names end in -________
Types of enzymes (location, quantity)
_______enzymes – transported extracellularly, where
they break down large food molecules or harmful
chemicals; cellulase, amylase, penicillinase
________enzymes – retained intracellularly & function
there
_________________– always present regardless of
substrate concentration (glycolysis enzymes)
_________________– produced in presence of
substrate, prevents cell from wasting resources
Types of reactions catalyzed by enzymes
Synthesis or _________________ reactions – _________________ reactions to form covalent bonds between smaller substrate molecules, require ATP, release one molecule of water for each bond
_________________ reactions– _________________ reactions that break down substrates into small molecules, requires the input of water
Transfer reactions by enzymes
1. Aminotransferases – convert one type of amino acid to another by transferring an amino group
2. Phosphotransferases – transfer phosphate groups, involved in energy transfer
3. Methyltransferases – move methyl groups from one molecule to another
4. Decarboxylases – remove carbon dioxide from organic acids
5. Oxidation-reduction (redox)reactions – transfer of electrons (may involve _________________ )
REDOX reactions The process by which electrons are transferred
between atoms is called an oxidation/reduction reaction (redox) – we can track movement of e- by following H transfers
_________________ = loses e- (donor becomes oxidized; reducing agent)
_________________ = gains e- (acceptor becomes reduced; oxidizing agent)
Occurs as a paired reaction
“LEO says GER” or “OIL RIG”
Cellular respiration is one big redox reaction!
Redox reactions involve electron transfersO I L R I G (Oxidation is Losing; Reduction is Gaining)
Redox reactions
Involve electron transfers (energy transfers) always occur in pairs electron donor + electron acceptor = redox pair process salvages electrons & their energy.
released energy can be captured to _________________ ADP or another compound
Electron donor + Electron acceptor
NOTE: electron transfers involve a hydrogen atom (proton + electron) = ____________________ and involves an electron carrier
Redox reactions
Electron carriers resemble __________ that are loaded and
unloaded with electrons and hydrogen most carriers are __________, NAD, FAD, NADP,
coenzyme A & compounds of the respiratory chain
donor acceptorshuttle
Redox reactions
_____________________________
Overview of cell respiration – electrons are removed from glucose and eventually used to make ATP
The path that electrons take on their way down from glucose to oxygen involves many stops
NADH
Figure 6.6
1/2
(from food via NADH)
2 H 2 e
Energy forsynthesis
of
Electro
n tran
spo
rt chain
2 e
2 H
1/2
ATP – the energy shuttle 3 part molecule consisting of
adenine – a nitrogenous base ribose – a 5-carbon sugar 3 phosphate groups
_________________ _________________ _________________
_____________ of glucose by ATP
How does ATP “give” energy?ATP transfers energy to compounds that are going to be catabolized (or going to do work) by donating the high energy phosphate
How is ATP regenerated?ATP used for Energy must be regenerated (ADP + Pi)
1. substrate-level phosphorylation
2. oxidative phosphorylation
3. photophosphorylation