Transcript Ch 4: Cellular Metabolism

PROTEIN
POLISAKARIDA
PENTOSA
ASAM
AMINO
GLISEROL
AS. LEMAK
GLUKOSA
MOLEKUL
PEMBANGUN
Tahap II
ASETIL-KoA
SIKLUS ASAM
SITRAT
H2O
BIOMOLEKUL
Tahap I
HEKSOSA
PIRUVAT
ASETIL-KoA
LIPID
CO2
PRODUK
PEMECAHAN
UMUM
Tahap III
PRODUK
KATABOLISME
SEDERHANA
Metabolism
• Definition ?
• Metabolic pathways = network of
linked reactions
• Basic feature: coupling of exergonic
rxs with endergonic rxs. (direct vs. indirect coupling)
• Metabolism
– Catabolism (ATP production)
– Anabolism (Synthetic pathways
Potential Energy
heat (~ 70% of energy
used in physical exercise)
Kinetic Energy
WORK
Bioenergetics
• The study of energy in living systems
(environments) and the organisms (plants and
animals) that utilizing them.
Biochemical Pathways
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How Cells Use Energy
• Adenosine Triphosphate (ATP) is the
molecule in cells that supplies energy.
– Five-carbon sugar (ribose)
– Adenine (nucleotide base)
– Chain of three phosphate groups
• Most energy exchanges in cells involve
cleavage of the outermost phosphate
bond, converting ATP into ADP and
inorganic phosphate.
ATP-ADP Cycle
Carbohydrates
• Carbohydrates are the most abundant organic molecules in
nature
– Photosynthesis energy stored in carbohydrates;
– Carbohydrates are the metabolic precursors of all other
biomolecules;
– Important component of cell structures;
– Important function in cell-cell recognition;
– Carbohydrate chemistry:
• Contains at least one asymmetric carbon center;
• Favorable cyclic structures;
• Able to form polymers
Carbohydrate Nomenclature (I)
• Carbohydrate Classes:
– Monosaccharides (CH2O)n
• Simple sugars, can not be broken down further;
– Oligosaccharides
• Few simple sugars (2-6).
– Polysaccharides
• Polymers of monosaccharides
9
Carbohydrate Nomenclature (II)
• Monosaccharide (carbon numbers 3-7)
– Aldoses
• Contain aldrhyde
1
2
• Name: aldo-#-oses (e.g., aldohexoses)
3
Memorize all aldoses in Figure ?
– Ketoses
• Contain ketones
• Name: keto-#-oses (ketohexoses)
CHO
H
OH
H
OH
4
H
OH
5
6
H
OH
CH 2OH
1
CHO
2
H
O
3
H
OH
4
H
OH
5
6
H
OH
CH 2OH
Monosaccharide Structures
Axis
Axis
a
Conformation
of monosaccharide
e
e
e
a O
a
e
e
Oe
a
a
a
a
Boat
Chair
H
HO 2HC
HO
HO
OH
HO
H
OH
H
H
e
e
e
e
a
Conformation
of glucose
a
a
CH 2OH
OH
O
H
H
H
OH
 -D-glucopyranose
OH
H
OH
H
Disaccharides
• Simplest oligosaccharides;
• Contain two monosaccharides linked by a
glycosidic bond;
• The free anomeric carbon is called reducing end;
• The linkage carbon on the first sugar is always C1. So disaccharides can be named as sugar-(a,)1,#-sugar, where a or  depends on the anomeric
structure of the first sugar. For example, Maltose
is glucose-a-1,4-glucose.
Strutures of Disaccharides
Note the linkage and reducing ends
6 CH 2OH
O
OH 5
1
3
OH
O 4
3
2
HOH
1
OH
1
OH 3
4
OH 3
OH
1
2
OH
4
O
3
OH
Maltose (glucose-a-1,4-glucose)
4
OH 3
OH
1
CH 2OH
O
5
HOH
1
2
2
OH
6 CH 2OH
O
5
HOH
1
Cellobiose (glucose- -1,4-glucose)
6 CH 2OH
O
3
OH
Lactose (galactose- -1,4-glucose)
5
OH
O 4
2
OH
6 CH 2OH
O
5
OH
4
2
6 CH 2OH
O
5
O
5
OH
4
6 CH 2OH
6 CH 2OH
OH
1
2
2
O
3
OH
O
OH 5
CH 2OH
46
OH
Sucrose (glucose-a-1,2-froctose)no reducing end
Polysacchrides
•
•
•
•
Also called glycans;
Starch and glycogen are storage molecules;
Chitin and cellulose are structural molecules;
Cell surface polysaccharides are recognition molecules.
• Glucose is the monosaccharides of the following
polysacchrides with different linkages and banches
– a(1,4), starch (more branch)
– a(1,4), glycogen (less branch)
– a(1,6), dextran (chromatography resins)
– b(1,4), cellulose (cell walls of all plants)
– b(1,4), Chitin similar to cellulose, but C2-OH is replaced
by –NHCOCH3 (found in exoskeletons of crustaceans,
insects, spiders)
Overview of Glucose
Catabolism
• Cells catabolize organic molecules and
make ATP two ways:
– Substrate-Level Phosphorylation
• Glycolysis
• Krebs (TCA) Cycle
– Oxidative Phosphorylation
• Electron Transport Chain
Overview of Glucose Catabolism
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Overview of Glucose Catabolism
•
Glycolysis
– Biochemical pathway that
produces ATP by substratelevel phosphorylation.
• Yields a net of two ATP
molecules for each
molecule of glucose
catabolized.
– Every living creature is
capable of carrying out
glycolysis.
– Most present-day organisms
can extract considerably
more energy from glucose
through aerobic respiration.
•Net reaction
C 6 H12 O 6  2 Pi  2 ADP  2 NAD  
2C 3 H 4 O 3  2 ATP  2 NADH  H  
Glucose priming
Cleavage and
rearrangement
P
P
Krebs Cycle
•
•
After pyruvate has been
oxidized, acetyl- CoA feeds into
the Krebs cycle.
Krebs cycle is the next step of
oxidative respiration and takes
place in mitochondria. Occurs
in three stages:
– Acetyl-CoA binds a fourcarbon molecule and
produces a six-carbon
molecule.
– Two carbons are removed
as CO2.
– Four-carbon starting
material is regenerated.
• Cycle is also known as
– Tricarboxylic acid (TCA)
cycle
– Citric acid cycle
COOH
CH2
HO C COOH
CH2
COOH
citric acid
pyruvate (3C)
CO2
acetyl coenzyme A (2C)
oxaloacetate (4C)
FADH
citrate (6C)
NADH
NADH
GTP
CO2
a-ketoglutarate (5C)
succinate (4C)
CO2
NADH
Krebs Cycle
Krebs Cycle
• Generates two ATP molecules per molecule of
glucose.
• Generates many energized electrons which can be
directed to the electron transport chain to drive
synthesis of more ATP:
– 6 NADH per molecule of glucose
– 2 FADH2 per molecule of glucose
Glycolysis
Bioenergetics
• KREBS CYCLE
– Takes place in Mitochondrion when oxygen is
present
– Pyruvic acid from glycolysis is trimmed to a 2 carbon
compound
• Remaining carbon from glucose => CO2
– Hydrogens transferred
• NAD+ => NADH
• FAD => FADH
– Products of kreb cycle
• 3 NADHs
• 1 FADH2
• 2 ATP
Electron Transport System
Electron Transport System
Energy
• Capacity to perform work.
• Two examples:
1. Kinetic energy
2. Potential energy
Kinetic Energy
• Energy in the process of doing work.
• Energy of motion.
• Examples:
1. Heat
2. Light energy
SUN
Potential Energy
• Energy that matter occupies because of it’s
location, arrangement, or position.
• Energy of position.
• Examples:
1. Water behind a dam
2. Chemical energy (gas)
GAS
Question:
• What is ATP?
Answer:
• adenosine triphosphate (ATP)
• Components:
1. adenine:
nitrogenous base
2. ribose: five carbon sugar
3. phosphate group: chain of three
adenine
phosphate group
P
ribose
P
P
Answer:
• Works by the direct chemical transfer of a
phosphate group.
• This is called “phosphorylation”.
• The exergonic hydrolysis of ATP is coupled
with the endergonic processes by transferring
a phosphate group to another molecule.
Hydrolysis of ATP
• ATP + H2O 
ADP + P (exergonic)
Adenosine triphosphate (ATP)
P
P
P
Hydrolysis
(add water)
P
P
+
P
Adenosine diphosphate (ADP)
Dehydration of ATP
ADP + P
 ATP + H2O (endergonic)
Adenosine triphosphate (ATP)
P
P
P
Dehydration synthesis
(remove water)
P P +
P
Adenosine diphosphate
(ADP)