Unit 4 Cell Energy Slides 18-19

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Whatdoesthemitochondriadoand
whatdoesithavetodowithcellenergy?
•It’sthepowerhouse
ofthecell,of
course!!
Why?
•Itproducesan
energymolecule
calledATP
ATP
Adenosine Triphosphate (ATP) One of the principal chemical
compounds that living things use to
store and release energy
ATP
Made up of:
1.Adenine
2.5-carbon sugar called ribose
3.Three phosphate groups (The key
to ATP's ability to store and release
energy.)
ATPvs.ADP
Adenosine Diphosphate – ATP minus one
phosphate group
vATP – contains three phosphate groups
(tri = three)
vADP – contains two phosphate groups
(di = two)
Adenosine
Triphosphate
Adenosine
Diphosphate
ATP and Energy
vATP is used by all types of cells as their
basic energy source.
vEnergy is released when a phosphate is
removed.
PHOTOSYNTHESIS
WHICH ORGANISMS GO
THROUGH PHOTOSYNTHESIS?
•
Plants
Autotrophicorganisms–
onesthatcansynthesize
theirownfood
PhotosyntheticBacteria
(ex.Cyanobacteria)
SomeProtists
(ex.Algae)
PHOTOSYNTHESIS
• Photosynthesis - Process by which plants and some other organisms
use light energy to convert water and carbon dioxide into oxygen and
high-energy carbohydrates such as sugars and starches.
PHOTOSYNTHESIS
Needed (Reactants):
Light
Water
Carbon dioxide
Given Off (Products):
Sugars
Oxygen
CHLOROPHYLL
• Photosynthesis also
requires chlorophyll, a
molecule located in
chloroplasts.
• Chlorophyll Principal pigment of
plants and other
photosynthetic
organisms; captures
light energy
CHLOROPYLL
• Plants gather the sun's
energy with light-absorbing
molecules called pigments.
• The plants' principal
pigments are called
chlorophyll.
– Chlorophyll does not absorb
light well in the green region of
the spectrum therefore green
light is reflected by leaves (this
is why plants look green).
What is the main product of
photosynthesis?
Sugar, but there are other products
as well.
CHLOROPLAST VOCABULARY
• Thylakoids - Saclike photosynthetic membrane found in
chloroplasts. (where chlorophyll is found)
• Stroma – Colorless, liquid portion of the chloroplast
– Outside the thylakoid membranes in chloroplasts
Chloroplast
TWO SETS OF REACTIONS IN
PHOTOSYNTHESIS
1. The Light-Dependent Reactions
2. The Light-Independent Reactions
(aka-Calvin Cycle)
Thesetwo
chemical
reactions
work
together!
LIGHT DEPENDENT REACTIONS:
WHY DOES IT REQUIRE LIGHT?
• The sunlight breaks each water molecule into :
• electrons
• H+ ions (released into thylakoid membrane)
• Oxygen atoms (released into the air)
WHAT ARE BIG PLAYERS IN THE LIGHT
DEPENDENT AND CALVIN CYCLE?
• Enzymes such as ATP synthase (synthesizes ATP from ADP) and another
known as a reductase
+
Reactants:Water+CarbonDioxide+Energy(Light)
Products:Oxygen+Glucose
FACTORS AFFECTING
PHOTOSYNTHESIS
1.
Water
Ø
2.
Temperature
Ø
3.
A shortage of water can slow or even stop photosynthesis.
Photosynthesis depends on enzymes that function best between 0°C and
35°C. (32-95oF)
Intensity of Light
Ø
Increasing light intensity increases the rate of photosynthesis...but a plant
will reach a maximum rate.
CELLULAR
R E S P I R AT I O N
( R E S P I R AT I O N F O R S H O R T )
ALL CELLS NEED
ENERGY
•
•
•
1. Organisms obtain energy from food
2. Glucose is main source of food for cells
3. Cells break chemical bonds of glucose;
energy released (between the C-C
bonds)
RESPIRATION
CELLULAR RESPIRATION
• Cellular Respiration - Process that releases energy by
breaking down glucose and other food molecules in
the presence of oxygen
CELLULAR RESPIRATION
Requires (Reactants):
1. Glucose
2. Oxygen
Gives Off (Products):
1. Water
2. Carbon Dioxide
3. Energy
CELLULAR RESPIRATION- MULTISTEP
PROCESS
• If cellular respiration took place in just one
step:
– All of the energy would be released at once
– Most would be lost in the form of light and heat.
• Instead, a living cell has to release chemical
energy in food molecules a little bit at a time.
– Must trap those little bits of energy by using them
to make ATP.
3 STAGES OF CELLULAR
RESPIRATION
1. Glycolysis
2. Krebs Cycle
3. Electron
Transport Chain
•
Each stage captures
some of the chemical
energy available in
food molecules and
uses it to produce ATP.
FIRST STAGE: GLYCOLYSIS
• Glycolysis –A molecule of
glucose is broken into two
molecules.
• Occurs in the cytoplasm
• (glucose is too BIG to go through the
mitochondrion’s membrane)
– Does not require oxygen
(anaerobic)
Products of Glycolysis
•2 ATP
AT THE END OF GLYCOLYSIS
• 90% of the chemical energy that was
available in glucose is still unused
• Oxygen is required for the final steps of
cellular respiration due to chemical
properties.
–Therefore, cellular respiration is aerobic
(requires oxygen).
SECOND STAGE: KREBS CYCLE
• Krebs Cycle – products
of glycolysis are broken
down into carbon
dioxide in a series of
energy-extracting
reactions
• Occurs in the
mitochondrion
• Produces about 2 ATP
THIRD STAGE: ELECTRON
TRANSPORT CHAIN
• The electron transport chain
extra products from the Krebs
cycle to convert ADP into
ATP
• Oxygen serves as the final
electron acceptor.
– Occurs in the mitochondrion
– Produces about 34 ATP
ATP PRODUCED IN
EACH STEP OF
AEROBIC RESP.
• Glycolysis: produces 2 ATP
molecules per glucose
molecule
• Krebs Cycle and Electron
Transport: ~34 ATP
molecules per glucose
molecule
• Total = ~36 ATP
We say that cellular respiration is
aerobic, but what happens if the cell
is in an anaerobic environment?
What can the cell do to produce
energy and not die?
AFTER GLYCOLYSIS, IF NO OXYGEN
IS PRESENT – CELL WILL ENTER
ANAEROBIC RESPIRATION
Glycolysis (produces 2 ATP)
Anaerobic
(no oxygen)
Fermentation
(Anaerobic
fermentation)
(produces 2 ATP)
Aerobic
(oxygen)
Krebs Cycle (produces 36 ATP)
ANAEROBIC RESPIRATION
• Fermentation - Releases energy from food
molecules by producing ATP in the absence of
oxygen.
– Anaerobic - Does not require oxygen
– Occurs in the cytoplasm (cytosol)
2 TYPES OF FERMENTATION
1.Alcoholic Fermentation –
• produces CO2 and alcohol
• carried out by yeast (and other microorganisms)
• makes bread rise and helps to make beer/wine
2. Lactic Acid Fermentation –
• produces lactic acid
• Produced in animal muscle cells during rapid exercise
• Bacterial cells can do this too (helps make cheese,
sour cream, and yogurt)
EXERCISE: QUICK ENERGY
• Muscles only contain enough ATP for
a few seconds of intense activity
• Then, muscle cells produce their ATP
by lactic acid fermentation.
– Produces lactic acid, which
requires oxygen debt (must
repay after the race with plenty
of heavy breathing)
EXERCISE: LONG-TERM ENERGY
(LONGER THAN 90 SECONDS)
• Cellular Respiration is the only
way to generate a continuing
supply of ATP
• Releases energy slowly (why
athletes must pace themselves)
– Body stores energy in muscle
and other tissues in the form of
the carbohydrate glycogen
(usually enough to last for 15 20 min.)
Photosynthesis vs.Respiration
Photosynthesisandcellularrespirationtakeplacein
oppositedirections!
Photosynthesis:Uselightenergytobuildasugar.
carbondioxide+water+lightenergy →sugars+oxygen
Respiration:Breakdownsugartoreleaseenergy.
oxygen+sugars →carbondioxide+water+energy
Heterotroph
Heterotroph - Organism that obtains energy from the
foods it consumes; also called a consumer
• Only do aerobic or anaerobic respiration
Autotroph
Autotroph - Organism that can capture energy from
sunlight or chemicals and use it to produce its own food
from inorganic compounds; also called a producer.
• Do photosynthesis AND cellular respiration
Photosynthesis:BuildGlucose(storesenergy)
Respiration:BreakDownGlucose(releasesenergy)
Doplantshavemitochondria?
YES!!
Sodotheydo
cellular
respiration?
YES!!!
Photosynthesis vs.Respiration
PhotosynthesisOccursIn:
o Plants
o Algae
o Somebacteria
CellularRespirationOccurs
In:
o Alleukaryotes
o Someprokaryotes
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