CHAPTER 3 - BROCK BIOLOGY

metabolism

a series of biochemical reactions neeeded to sustain life

catabolism and anabolism

metabolism is consist of _______ and ________

catabolism

breaking down complex molecules to release energy

anabolism

synthesizing cellular material

exergonic reactions

• releases free energy and can perform work

• free energy is negative

endergonic reactions

• require an energy input to proceed

• free energy is positive

bioenergetics

transformation of energy during metabolism characterized by electron flow within the cell

phototrophs

obtain energy from light

chemotrophs

obtain energy from chemical reactions

chemoorganotrophs

use organic chemicals such as glucos and acetate

chemolithotrophs

use inorganic chemicals

heterotrophs

use organic compounds for carbon

autotrophs

use carbon dioxide as their carbon source

redox reactions

transfer electrons from electron donor to an electron acceptors

oxidized

electron donor is

reduced

electron receptor is

reduction potential

measures a substance’s affinity for electrons

strong electron donors

more negative values indicate

strong electron acceptors

more positive values indicate

NAD+/NADH

act as vital soluble coenzyme electron carrier that shuttles electron between different enzymatic reactions within the cell

nucleotide adenine dinucleotide

what is NAD

catabolic pathways

exergonic processes in which cells generate free energy by transforming reactant into product

anabolic pathways

endergonic process in which the synthesis of cellular material from simple precursors requires an input of energy

reducing power

ability to donate electrons during electron transfer

G0’=-nFE’0

equation for standard free-energy change

greater
reduction potential
donor
acceptor
free energy
release

the _______ the difference in ______________ between the _______ and _______, the more _______ is _______ for the cell

adenosine triphosphate

an energy-rich phosphate compound and serve as the primary energy currency, coupling exergonic catabolic reactions to endergonic anabolic reactions

substrate-level phosphorylation

atp is synthesied directly from energy-rich metabolic intermediates

oxidative phosphorylation

electron transport generates an electrochemical gradients called the proton motive force to drive atp synthesis

photophosphorylation

lgiht energy creates a pmf to power qtp synthesis in phototrophic organisms

enzyme

biiological catalysts that accelerate reactions by lowering the activation energy barrier without changing the reaction equilibrium

substrate

bind to a specific region on the enzyme

active site

substrate bind to a specific region on the enzyme called the ________ to form an enzyme-substrate complex

prosthetic groups and coenzyme

example of nonprotein helper

prosthetic groups

tightly and permanently bound

coenzyme

loosely and transiently bound

Glycolysis

The universal pathway oxidizing glucose to pyruvate

Embden meyerhof parnas pathway

Other called for glycolysis

Consumes 2 atp and no redox changes

What does Stage I in glycolysis do?

Produces 4 atp abd 2 nadh

What does stage ii in glycolysis do?

2 atp, 2 nadh, 2 pyruvate

What is the net yield per glucose

Glycolysis

Lacks redox balance on its own and requires coupling with respiration or fermentation to regenerate NAD+

Citric acid cycle

Pyruvate is decarboxylated to acetyl-CoA, which combines with oxaloacetate to form citrate

Krebs cycle

Other called for citric acid cycle

Glyoxylate cycle

Used by chemoorganotrophs growing on two-carbon (C2) compounds like acetate

Isocitrase lyase and malate synthase

Glyoxylate cycle bypasses decarboxylation steps using enzymes ??? To regenerate oxaloacetate

Anaerobic catabolism

Electron donor

Electeo acceptor

Fermentation is a form of ___________________ where organic compounds serve as both _______________ and ____________, achieving redox balance without an external electro acceptor

Substrate-level phosphorylation

The energy conservation of fermentation relies entirely on _______________

respiration

a form of aerobic or anaerobic catabolism in which an electron donor is oxidized using an external electron acceptor

electron chemical gradient

As electrons flow through the electron transport chain, protons are pumped to the outer surface of the cytoplasmic membrane, creating an ________________.

atp synthase

a reversible multi-protein motor consisting of a cytoplasmic catalytic complex and a membrane-integrated rotor

38 atp

Complete aerobic respiration of one glucose yields up to ________ (vastly outperforming fermentation)

oxidative phosphorylation

Uses the flow of protons down their electrochemical gradient to drive the mechanical rotation that synthesizes ATP from ADP + Pi via _____________

calvin cycle

used to fix carbon by reducing CO2, present in many autotrophs inclusding oxygenic phototrophs and most chemolithotrophic bacteria

rubisco

the first step in calvin cycle is catalyzed by the enzyme _________

ribulose biphosphate carboxylase

other called for enzyme rubisco

18 atp and 12 nadph

synthesizing one hexose molecule via the calvin cycle requires a total of ___________

nitrogen fixation

a process that many bacteria and archaea used to form ammonia from gaseous dinitrogen

nitrogenase

nitrogen fixation fix atmospheric nitrogen into ammonia, using the enzyme _________

polysaccharides

synthesized from activated hexose forms like uridine diphosphoglucose (UDPG) or adenosine diphosphoglucose (ADPG)

gluconeogenesis

cells synthesize glucose by running glycolysis in reverse, when glucose is unavailable

pentose phosphate pathway

this pathway produces pentoses for nucleic acid synthesis and serves as the primary direct source of NADPH for biosynthetic reductions

glycolysis
citric acid cycle

the carbon skeletons for amino acid synthesis are derived almost exclusively from intermediates of ________ or the _________

inosinic acid

precursor of purines

uridylate

precursor of pyrimidines

lipids

In Bacteria and Eukarya, ______ are assembled by attaching fatty acids to glycerol.

hydrophobic isoprenoid

phytanyl

In Archaea, membrane lipids use _______________ chains (such as ______ ) linked to glycerol instead of fatty acids.