Transcript Citric Acid (Krebs) Cycle

Clicker Question
Which of the following was not a President of the United
States?
a.
b.
c.
d.
e.
James K. Polk
Henry Clay
Benjamin Harrison
Gerald Ford
Herbert Hoover
ATP
ATP=Adenosine Triphosphate, an organic molecule
produced in cell respiration that provides accessible
energy for cells to do work.
Consists of 1 adenosine molecule bonded to 3 phosphate
groups.
ATP
ATP loses a phosphate and becomes ADP
(adenosine diphosphate); an exergonic reaction
(energy is released).
Fig. 5.4
Cell Respiration
A series of chemical reactions in which food (glucose) is
combined with oxygen to release energy that cells can use
to do work.
Cell Respiration
A series of chemical reactions (more than 24) in which food
(glucose) is combined with oxygen to release energy that
cells can use to do work.
The same way you breathe air into your lungs, cells breathe
in oxygen too.
All eukaryotic organisms (including plants) use cell
respiration.
Cell Respiration
Cell Respiration
Specifically, each molecule of glucose can create 32
molecules of ATP.
Cell Respiration
Cell respiration is an aerobic process, meaning that it
requires oxygen.
Cell Respiration
Redox (oxidation-reduction) reaction: A chemical reaction
in which electrons are transferred between substances.
Oxidation: The loss of electrons in a chemical reaction.
Reduction: The gain of electrons in a chemical reaction
(reduction in electrical charge).
Cell Respiration
Clicker Question
When a substance gains electrons in a chemical reaction, is
it…
a. Reduced
b. Oxidized
c. Neither
Cell Respiration
3 Stages:
1. Glycolysis
2. Citric Acid (Krebs) Cycle
3. Electron Transport Chain
Cell Respiration
Fig. 6.6
Hershey’s Kiss Ingredients
Sugar; milk; chocolate; cocoa butter; lactose; milk fat; soy
lecithin; vanillin; artificial flavor; PGPR; emulsifier.
Clicker Question
What kind of molecule is lactose?
a.
b.
c.
d.
e.
Monosaccharide
Disaccharide
Carbohydrate
A and C
B and C
Cell Respiration
3 Stages:
1. Glycolysis
2. Citric Acid (Krebs) Cycle
3. Electron Transport Chain
Glycolysis
-Takes place in the cytoplasm of cells
-2 ATP molecules are used to split glucose in half
-Energy released from splitting is used to make 4 ATP
molecules.
-At the end of glycolysis, the glucose molecule has been
transformed into 2 molecules of pyruvic acid.
Clicker Question
What is the relative concentration of H+ and OH- ions in a
solution of pyruvic acid?
a. H+ is greater
b. OH- is greater
c. They’re both about equal
Cell Respiration
3 Stages:
1. Glycolysis
2. Citric Acid (Krebs) Cycle
3. Electron Transport Chain
Mitochondria (singular: mitochondrion)
Fig. 4.20
Citric Acid (Krebs) Cycle
-Occurs inside the mitochondria
-Pyruvic acid broken down to release more energy (2 more
molecules of ATP)
-Hydrogen and its electrons are transferred to the
molecules NADH and FADH2.
-Carbon dioxide is formed as a by-product.
Clicker Question
What is a molecule?
a. A chemical compound in which atoms are ionically
bonded to each other
b. A chemical compound of acids and bases
c. A chemical compound in which the atomic number
doesn’t change
d. A chemical compound in which atoms are covalently
bonded to each other
Cell Respiration
3 Stages:
1. Glycolysis
2. Citric Acid (Krebs) Cycle
3. Electron Transport Chain
Electron Transport Chain
-The final stage of cell respiration, releasing enough energy
to produce 28 of the 32 total ATP molecules formed for
every initial molecule of glucose.
-Also produces water as a product.
-Electrons carried by NADH and FADH2 “bounce” down a
chain of molecules and provide the energy to make ATP.
What happens when your cells can’t “breathe?”
-Cells can continue to make ATP for short amounts of time
without oxygen.
-Anaerobic capture of food energy is called fermentation,
and it relies on glycolysis.
-In fermentation, electrons are added to pyruvic acid to
form lactic acid.
Fermentation
-Fermentation is used to produce many foods, such as
cheese, sour cream, and yogurt.
-To make alcohol, yeast (a microscopic fungus) is added to
sugar in the absence of oxygen, and the yeast produce
alcohol as a waste product instead of lactic acid.
You know that ride at the carnival where you stand in a circular room
that spins so fast that the force pins you against the wall and the floor
drops out? That’s what Carlos Castro, an engineering professor at The
Ohio State University, did to ants to see how much pressure their
necks could withstand before their heads popped off. Turns out they
can take quite a lot—up to 5,000 times their own body weight, in fact.
The experiment sounds brutal, but the ants were anesthetized and
donated their heads to a good cause—this research may one day help
scientists design robots that can carry huge amounts of weight, either
on Earth or in space. Castro’s goal was to figure out not only how
much pressure ants’ necks could withstand, but also to examine how
the unique structure of an ant’s neck joint allowed it to carry such a
massive load.
Interview Activity
Interview your partner about their paper topic and take as
detailed notes as possible. Ask them things like:
1. What is your paper topic?
2. Where did you find your topic?
3. Why did you choose that topic?
Photosynthesis
Autotroph: An organism that makes its own food using
photosynthesis.
Examples: Plants, algae, cyanobacteria.
Photosynthesis
Fig. 7.1
Photosynthesis
Photosynthesis
Photosynthesis
Symbiosis: A close relationship between organisms in which
they depend on each other.
Photosynthesis
Symbiosis: A close relationship between organisms in which
they depend on each other.
Why does Al Gore love plants so much?
Photosynthesis
Fig. 7.2
Photosynthesis
Fig. 7.2
Clicker Question
True or False: Plants have mitochondria:
a. True
b. False
Clicker Question
Which of the following organelles have DNA?
A.
B.
C.
D.
Nucleus
Chloroplast
Mitochondria
All of the above
Photosynthesis
There are 2 stages:
1. Light Reactions
2. Calvin Cycle
Light Reactions
-Occur inside the thylakoid membranes.
-Chlorophyll (a pigment, or light-absorbing molecule) inside
the thylakoids absorbs sunlight.
-Energy from the sun is captured and used to split water
into hydrogen and oxygen.
-Energy from the sun is also used to produce ATP molecules
and to transfer electrons from water (now split) to the
molecule NADPH.
Why do plants look green?
-Because of pigments (light-absorbing molecules),
especially chlorophyll.
-Sunlight occurs as radiation waves, kind of like waves in the
ocean. It travels through space as a wave.
-Different kinds of radiation have different size wavelengths,
which is the distance between the crest of 2 neighboring
waves.
The electromagnetic sprectrum
Fig. 7.4
Why do plants look green?
-Chloroplasts contain the pigments chlorophyll a, which
absorbs blue-violet and red light, and chlorophyll b, which
absorbs blue and orange light.
-Chlorophyll a and b do not absorb light in the green part of
the spectrum very well.
Carotenoids
Fig. 7.7
Clicker Question
What are the end products of the light reactions?
a.
b.
c.
d.
e.
Oxygen
ATP
Glucose
Carbon dioxide
Oxygen and ATP
Photosynthesis
There are 2 stages:
1. Light Reactions
2. Calvin Cycle
The Calvin Cycle
-Carbon dioxide (CO2) enters the chloroplast, and is
converted into glucose using the energy from ATP and the
electrons carried by NADPH.
-Several enzymes act as catalysts in the chemical reactions
of the Calvin Cycle.
Photosynthesis
Fig. 7.3
Clicker Question
Leaves appear green because
a. They eat a lot of lime popsicles
b. They contain the pigment chlorophyll, which absorbs
green light
c. They contain the pigment chlorophyll, which reflects
green light
d. They contain carotenoids, which reflect green light.
Where will our fuel come from?
Bioethanol
-Starch in wheat, corn, beets, and other food crops is
converted to glucose and then fermented into ethanol by
microorganisms.
-Ethanol can be burned and used as a fuel (most gasoline
for cars nowadays contains 15% ethanol).
-Bioethanol can also be made from cellulose, specifically
wood and grass.
Scenario
The U.S. federal government has decided to draft new
legislation concerning energy sources. The government is
considering several policy options and has invited
lobbyists from the hydrogen fuel cell, bioethanol, and
fossil fuel industries to present their proposals.
Green Team: House of Representatives
Red Team: Senate
Blue Team: Fossil fuel industry, wants to maintain status
quo on energy sources.
Yellow Team: Wants 25% of all energy to come from
biofuel by 2050.
White Team: Wants 25% of all energy to come from
hydrogen fuel cells by 2050.