Transcript Krebs Cycle - WordPress.com

Starter:
What is the equation for cellular respiration?
Glucose
energy (ATP)
+
O2
CO2 + water +
Starter:
What are the energy carriers in cellular
respiration?
How many net ATP come out of glycolysis?
Cellular Respiration:
Harvesting Chemical
Energy
Metabolism
There are chemical reactions going on in all
living organisms that are essential for the
growth and repair of the body and for nutrition
and release of energy in a useable form. These
processes are both breakingdown(catabolism)and building-up
(anabolism)processes, and combined, they are
called the metabolism of the body.
The Metabolic Pathway of Cellular Respiration
Cellular respiration is an example of a metabolic pathway
It is a complex energy release process, controlled by
enzymes, that breaks down the complex molecules one step
at a time, releasing energy in small controlled amounts
All of the reactions involved in cellular respiration can be
grouped into three main stages:
1. Glycolysis
2. The
Krebs cycle
3. Electron
transport
This is what happens in the process of burning:
fire
fuel
+
+
air
energy
wastes
(wood)
in the form
heat and
water vapour
light
and
CO2
The complex food molecules contain so much energy
that the cell would be unable to handle it if it was all
released at once, as in burning.
Firstly, let's get to know the players....
Energy Carriers
1. ATP - Adenosine Triphosphate
2. NADH - Nicotinomide Adenine
Dinucleotide
3. FADH2- Flavin Adenine Dinucleotide
ATP
W is the nitrogenous base (adenosine)
X is the ribose sugar, together W and X
make up Adenosine.
Y is a phosphate group,
and Z is the high energy bond between
the phosphate groups. When Z is
hydrolyzed, energy is released that can be
used by the cell.
ATP consists of a base, in this case adenine (red), a ribose (magenta) and a phosphate chain (blue).
A Road Map for Cellular Respiration
Cytosol/
Cytoplasm
Mitochondrion
High-energy
electrons
carried
by NADH
High-energy
electrons carried
mainly by
NADH
Glycolysis
Glucose
2
Pyruvate
Krebs
Cycle
Electron
Transport
Figure 6.7
Stage 1: Glycolysis
A molecule of glucose is split into two
molecules of pyruvate
These molecules then donate high
energy electrons to NAD+, forming NADH
Glycolysis makes some ATP directly
when enzymes transfer phosphate groups
from fuel molecules to ADP
2 Pyruvate
Glucose
Figure 6.8
Stage 2: The Krebs Cycle
The Krebs cycle completes the breakdown of sugar
In the Krebs cycle, Pyruvate from glycolysis is first
“prepped” into a usable form, Acetyl-CoA
Acetic
acid
Pyruvate
CO2
Coenzyme
1
A
2
The Krebs cycle extracts the energy of sugar by
breaking the acetic acid molecules all the way down
to CO2
The cycle uses some of this energy to make ATP
The cycle also forms NADH and FADH2
Kreb's Cycle
1
Output
Input
2
Acetic acid
2 CO2
Kreb's
Cycle
ADP
3 NAD+
FAD
3
4
5
6
The Kreb's Cycle Animation
Stage 3: Electron Transport/Respiratory
Chain transport releases the energy
Electron
your cells need to make the most of their
ATP
The molecules of electron transport
chains are built into the inner membranes
of mitochondria
The chain functions as a chemical machine
that uses energy released by the “fall” of
electrons to pump hydrogen ions across the
inner mitochondrial membrane
These ions store potential energy
When the hydrogen ions flow back
through the membrane, they release
energy
The ions flow through ATP synthase
ATP synthase takes the energy from this flow
and synthesises ATP
Electron Transport Animation
Protein
complex
Electron
carrier
Electron
flow
Inner
mitochondrial
membrane
Electron transport
chain
ATP synthase
Figure 6.12
Adding Up the ATP from Cellular Respiration
Cytosol
Mitochondrion
Glycolysis
Glucose
2
Pyruvate
2
AcetylCoA
Krebs
Cycle
Electron
Transport
Maximum
per
glucose:
by direct
synthesis
by
direct
synthesis
by
ATP
synthase
Figure 6.14
The Versatility of Cellular Respiration
Cellular respiration can “burn” other kind
of molecules besides glucose
Diverse types of carbohydrates
Fats
Proteins
Food
Polysaccharides
Sugars
Glycerol
Fats
Fatty acids
Proteins
Where Carbs,
Protein and Fat
enter...
Amino acids
Amino groups
Glycolysis
AcetylCoA
Krebs
Cycle
Electron
Transport
Figure 6.13
FERMENTATION: ANAEROBIC HARVEST OF FOOD
ENERGY
Some of your cells can actually work for short
periods without oxygen
For example, muscle cells can produce ATP
under anaerobic conditions
Fermentation - the anaerobic harvest of
food energy
Fermentation in Human Muscle Cells
Human muscle cells can make ATP with
and without oxygen
They have enough ATP to support activities
such as quick sprinting for about 5 seconds
A secondary supply of energy (creatine
phosphate) can keep muscle cells going for
another 10 seconds
To keep running, your muscles must generate
ATP by the anaerobic process of fermentation
Glycolysis is the metabolic pathway
that provides ATP during fermentation
Pyruvate is reduced by NADH, producing
NAD+, which keeps glycolysis going
In human muscle cells, lactic acid is a byproduct
Fermentation
2 ADP+ 2
2 ADP+ 2
Glycolysis
2 NAD+
Glucose
(a) Lactic acid fermentation
2 Pyruvate
+ 2 H+
2
NAD+
2 Lactic
acid
Fermentation in Microorganisms
Various types of microorganisms
perform fermentation
Yeast cells carry out a slightly different
type of fermentation pathway
This pathway produces CO2 and ethyl
alcohol
The food industry uses yeast to produce various food
products
Figure 6.16
Activity:
Using Limewater complete an
experiment to test one of the
products from anaerobic
respiration