Ch 13 (Book) Catabolism, Gluc Breakdown, TCA Cycle Flashcards
4 organic carbon sources for catabolism
carbohydrates (sugars)
lipids
peptides
aromatic molecules
carbohydrate examples
cellulose of plant cell walls
starch from potatoes
pectin of fruit
polysaccharides are ________ to products that enter central catabolic pathways like ________
hydrolyzed, glycolysis
which two polysaccharides are most widely digested
starches
pectins
out of numerous choices of substrate, why are certain ones chosen?
availability
energy efficiency
catabolic repression
the process of prioritized catabolism of substrates
ex. glucose over lactose for E. coli
sources of lipids
milk
animal fat
nuts
what are lipids catabolized to
glycerol
FA
glycerol
a 3 carbon sugar that enters catabolism as a glycolysis intermediate
could break down to acetate
how do FA enter catabolism
form acetyls by fatty acid degradation pathway
acetyls enter TCA cycle or fermentation
how are peptides catabolized
broken into aa that are decarboxylated or deaminated
lignin
an aromatic that makes up trees
broken down by fungi and soil bacteria to acetyl CoA –> TCA
in fermentation are all the e- from organic substrates returned to organic products?
yes
in respiration are the e- transferred to an inorganic electron acceptor?
yes
photoheterotrophy
bacteria gain energy from light and use organic carbon sources for catabolism/biosynthesis
fermentation
partial breakdown of organic food without transferring e- to a terminal e- acceptor
ethanol, lactate, acetate
respiration combines what 2 things
catabolic breakdown of organic molecules and e- transfer to a terminal e- acceptor
anaerobic respiration
use of a terminal electron acceptor other than O2
what are the only polysaccharides human enzymes can digest?
starch
lactose
sucrose
how can humans/animals digest other polysaccharides
symbiotic relationship with microbes that can
ex. human gut microbes
3 pathways to form pyruvate
glycolysis (embden-meyerhof-parnas EMP)
entner-doudoroff (ED)
pentose phosphate pathway
products of glycolysis
glucose –> 2 ATP, 2 NADH, 2 pyruvate
products of ED pathway
1 ATP, 1 NADH, 1 NADPH, 2 pyruvate
sugar acids from intestinal mucous – essential for enteric bacteria to colonize intestine
PPP pathway products
1 ATP, 2 NADPH
which steps in glycolysis are irreversible
the ones that consume ATP
substrate-level phosphorylation
transfer of a phosphate from an organic substrate to make ATP
enzymes of catabolism are regulated at the level of ________ of the enzyme, and by ________ regulation
transcription, allosteric
why is allosteric regulation needed
so intermediates don’t build up
to make sure the cell doesn’t spend more energy than it has
which step is most importantly regulated in glycolysis
fructose-6-P –> fructose 1,6-bisphosphate by phosphofructokinase
activated by ADP, inhibited by ATP
amphibolic
if a pathway can do catabolism and anabolism
how do ED bacteria help humans
prevent pathogen colonization
stimulate the immune system
key intermediate in PPP
ribulose-5-P
intermediates from PPP can be used in what biosynthesis
aa
vitamins
purines –> DNA/RNA
or can reenter glycolysis
how does fermentation complete catabolism
recycle NADH + H+ to NAD+
ex. 2 molecules of lactic acid, 2 molecules of ethanol + 2 CO2, or 1 lactic acid, 1 ethanol, 1 CO2
mixed-acid fermentation
can also form acetate, formate, lactate, succinate
what is acetyl coA structure
acetyl group esterified to CoA
can acetyl coA be converted to fermentation products
yes, many pathways
what types of food products does fermentation yield
ethanol –> beer/wine
lactate –> cheese and yogurt
butyric acid –> butter
phenol red broth test
test for fermentation
red pH indicator that turns yellow at below pH 6.8
tricarboxylic acid cycle (TCA) Krebs Cycle
generates NADH and FADH2 which donate e- to a terminal electron accepton in the ETC
pyruvate dehydrogenase complex (PDC)
converts pyruvate to acetyl CoA
removes CO2 and moves 2e- to NAD+
what do some memb proteins in the ETC do with the energy
pump protons out to generate a gradient
how many ATP do you get from NADH and FADH2
NADH: 3
FADH2: 2
oxidative phosphorylation
electron transport and ATP generation
glyoxylate bypass
modified TCA cycle used by some bacteria to catabolize FA –> acetyl CoA
