BHS 150.1 – Biochemistry II
Notetaker: Kim Powell
Date: 2/1/2013, 2sndhalf
Page1
start on pg. 263
REVIEW:

Insulin is present after a meal; goal is to store nutrients

insulin works through receptor tyrosine kinase
◦
receptor tyrosine kinase phosphorylates a phosphatase
◦
phosphatase removes phosphate group from glycogen synthetase, glycogen phosphorylase,
and pyruvate kinase
▪

***both pyruvate kinase and glycogen synthetase are activated when de-phosphorylated.
Glycogen phosphorylase is inhibited when dephosphorylated.
Glucagon works through metabotropic receptor
◦
G-protein stimulates adenylate cyclase to make cAMP and activate a family of protein
kinases
FOCUS ON THREE ENZYMES: glycogen synthease, glycogen phosphorylase, and pyruvate kinase:
Glycogen Synthetase
Fed State (insulin high
and glucagon low)
Glyocogen
Phosphorylase
ACTIVATED/ glycogen INACTIVATED/
production stimulated glycogen degradation
inhibited
Fasting State (glucagon INACTIVATED/
high and insulin low)
glycogen production
inhibited
Pyruvate Kinase
ACTIVATED/glycolysis
stimulated
ACTIVATED/ glycogen INACTIVATED/
degradation stimulated glycolysis inhibited
FED STATE (postprandial state):
Glucose (from
carbohydrates)

Glucokinase traps
glucose

liver provides itself
energy through the
kreb's cycle and
electron transport
chain

starts to make
glycogen
Muscle

Brain
Liver
RBCs
Other
tissue
Amino acids (from
proteins)
Fatty acids

Used to make
proteins

As glycogen synthetase
enzyme becomes
saturated, production
of triglycerides is
stimulated; lots of acetl
CoA/malonyl CoA
present
Muscle can use
glucose for energy or
and store excess as
glycogen

Muscle takes up
amino acids to
repair muscles
after exercise

Muscle can use fatty
acids for energy

Brain prefers glucose
as its energy source,
lots of glucose goes to
the brain

Used to make
proteins
neurotransmitte
rs

Aren't used by brain
during fed state

brain is insulinindependent

RBC can ONLY use
glucose for energy

Aren't used by RBCs

exclusively anaerobic
glycolysis produces
lactate which gets sent
to the liver for
glucoeogenesis

Can use glucose right
after eating but they
use a variety- aren't

Can use fatty acids but
they use a variety-

Use amino acids
to make
neurotransmitte
very picky
rs
aren't very picky

Adipos
e tissue
Most fats are put into
storage in adipose
tissue
◦
dietary are
delivered from
chylomicron
◦
triglycerides from
liver are delivered
via VLDL
FASTING STATE:
Glucose (from
carbohydrates)
Liver


Glycogen broken down
into glucose so that
brain and RBC can get
glucose

Used in
gluconeogenesis
Fatty acids

Liver uses fatty acids to
make ketone bodies

ketone bodies made
from acetyl coA (can be
used by muscle but
NOT by liver)
when it runs out of
glycogen, it starts
gluconeogenesis using
lactate from RBCs,
glycerol from fatty acid
breakdown, and amino
acids from muscles

Insulin is gone, can't
take up glucose

they use their stores of
glycogen
Brain

Uses glucose from
quick store of glycogen
RBCs

RBC can ONLY use
glucose for energy

exclusively anaerobic
Muscl
e
Amino acids (from
proteins)


◦
3-hydroxybutyrate
◦
acetone (breathedoff)
Proteins are
broken down to
provide amino
acids for liver to
do
gluconeogenesis

Uses fatty acids as
primary fuel source

also use 3
hydroxybutyrate made
by liver (using an
enzyme to break them
back into acetyl coA
Not being used
for energy

Not being used for
energy

Aren't used by RBCs
glycolysis produces
lactate which gets sent
to the liver for
glucoeogenesis
Other
tissue

Aren't using glucose
because insulin isn't
present
Adipo
se
tissue

Starts to break down to
release triglycerides
into bloodstream

Kidney excretes
urea when
amino acids are
broken down

Can use fatty acids but
they use a varietyaren't very picky
◦
Starts releasing
triglycerides (for
muscle)
STARVING STATE (2-3 days without food):
Glucose (from
carbohydrates)
Liver
Muscle

Glucose levels
are stability
low

glucagon levels
aren't still
rising, they
have plateaued

liver is
glycogen
depleted and
it's using
gluconeogensis
using lactate
and glycerol

Depleted their
glycogen stores
Amino acids (from
proteins)
Fatty acids

Less are
available
because muscle
isn't being
broken down

Used almost
exclusively to
make ketone
bodies to be fed
to the brain

Decrease in
breakdown to
protect heart
and other
important

Being used
predominantly
by muscle
muscles

Brain

RBCs
Brain wants
glucose but
liver isn't
providing it
easily because
muscles can't
keep degrading
and providing
amino acids for
gluconeogenesi
s

Still using
glucose
because they
can't use
anything else

Not used for
energy
Not used for
energy
Adipose tissue

Brain starts
using ketone
bodies; they
become
primary energy
source

ketone bodies
are easier to
extract acetyl
coA from than
fatty acids

Not used for
energy

Degrade
quickly to make
fatty acids
available for
muscle and
liver
Diabetes vs. starving state:

Uncontrolled diabetics are in “starvation” mode even though they have lots of glucose.
◦
Diabetes you have low insulin (same as starvation) but HIGH levels of glucose. The high
levels of glucose cause damage
▪
lots of fatty acids= clogging arteries
▪
no insulin, can't store glucose, so glycogen stores are depleting and liver starts making
glucose
▪
glycolysis isn't going on, so we aren't storing glucose as fatty acids.
▪
glucose is being excreted
▪
glucose damages the retina in 3 ways:

absorption of water leads to macular edema

neovascularization because vessel walls are being glycated

lens swells, cornea swells
▪
nerves are glycated which leads to an increase in pain
▪
ketone bodies are still being made by the liver and leading to acidic problems and
eventually ketoacidosis.
CLICKER QUESTIONS:
1. Insulin binds to a receptor tyrosine kinase which:

dephosphorylates the metabolic enzymes

phosphorylates the metabolic enzymes

phosphorylates another kinase to phosphorylate the metabolic enzymes

phosphorylates a phosphatase that dephosphorylates the metabolic enzymes
2. During fasting, what are some of the sources of carbons for gluconeogenesis (choose 3):

amino acids from protein degradation

ketone bodies made by the liver

glycerol from triglyceride breakdown

glycogen from the liver stores

lactate from glucose metabolism