Cells and Energy

1
Cells and Energy

• Chapter 4

2
Preview Vocabulary

• Metabolic processes take one of two directions
• They synthesize/anabolize (build up material and
  store energy).
• or
• They hydrolyze/catabolize (break material down
  and release energy).
• Chemosynthesis and photosynthesis are
  synthesizing processes that capture the energy
  needed for life and store it in sugars.
• Cellular respiration and fermentation are
  catabolic processes that break down sugars and
  deliver energy to sustain life.

3
AKS Standards 8d - explain the role of cell
organelles in maintaining homeostasis and cell
reproduction for both prokaryotic and eukaryotic
cells 8l - analyze and explain the storage and
release of energy through the process of
photosynthesis and respiration (GPS) 10a -
relate the complexity and organization of
organisms to their ability for obtaining,
transforming, transporting, releasing and
eliminating the matter and energy used to sustain
the organism (GPS)
4
The chemical energy used for most cell processes
is carried by ATP.

• ATP stands for Adenosine Triphosphate
• ATP is a molecule made up of adenosine and three
  negatively charged phosphate groups.
• The energy carried by ATP is released when a
  phosphate group is removed from the molecule.
• The bonds holding the 3rd group in ATP is
  unstable and very easily broken.
• When the 3rd phosphate is removed, energy is
  released and ATP becomes ADP, or adenosine
  diphosphate.
• ADP is a lower-energy molecule.

5
The ATP Cycle

• The breakdown of ATP to ADP and the production of
  ATP from ATP can be represented by a cycle.
• ATP ? ADP releases energy.
• ADP ? ATP requires energy.

6
Types of Phosphorylation

• To make ATP, you must PHOSPHORYLATE and ADP
  molecule.
• This means that you must add a PHOSPHATE (P) to
  ADP to make ATP.
• Phosphorylation can occur in THREE WAYS
• Substrate Level Phosphorylation directly
  transferring a phosphate group to ADP using an
  enzymeas seen in glycolysis and the Krebs cycle.
• Oxidative Phosphorylation using the power of a
  concentration gradient where oxygen is the
  terminal electron acceptor to phosphorylate ADP
  into ATP...as seen in the electron transport
  chain of the mitochondria.
• Photophosphorylation using the power of sunlight
  to phosphorylate ADP into ATP.as seen in the
  photosynthesis light reactions.

7
Types of Phosphorylation
?SUBSTRATE LEVEL PHOSPHORYLATION
OXIDATIVE PHOSPHORYLATION?
?PHOTOPHOSPHORYLATION
8
Ways of Obtaining Energy

• Heterotrophs obtain energy by breaking down
  carbon compounds (food) in the presence or
  absence of oxygen.
• Animals, fungi, and some protistans are
  heterotrophs.
• Carbohydrates 4 energy calories per mg
• Lipids 9 energy calories per mg
• Protein 4 energy calories per mg
• Autotrophs use chemical energy to build their
  own food molecules.
• Plants and most algae photosynthesize, many
  bacteria chemosynthesize.
• Photosynthesis converts light energy into carbon
  compounds.
• Chemosynthesis converts chemical energy into
  carbon compounds.

9
AKS Standards 8d - explain the role of cell
organelles in maintaining homeostasis and cell
reproduction for both prokaryotic and eukaryotic
cells 8l - analyze and explain the storage and
release of energy through the process of
photosynthesis and respiration (GPS) 10a -
relate the complexity and organization of
organisms to their ability for obtaining,
transforming, transporting, releasing and
eliminating the matter and energy used to sustain
the organism (GPS)
10
Photosynthetic organisms are producers.

• Photosynthesis is the process whereby light
  energy is converted to chemical energy and carbon
  is fixed into organic compounds.
• In the presence of light, plants transform carbon
  dioxide and water into carbohydrates and release
  oxygen.
• 6 CO2 6 H2O light ? C6H12O6 6 O2
• carbon dioxide water light ? sugar oxygen
• Plants then use the sugars to produce complex
  carbohydrates such as starches.

COMMON MISCONCEPTION Plants DO NOT get energy
from photosynthesis. Rather, they use light
energy to build sugars. They then use the sugars
to build ATP via cellular respiration (just like
animals).
11
Photosynthesis in plants occurs in chloroplasts.

• Chloroplasts are membrane-bound organelles found
  in the leaves photosynthetic organisms.
• Chlorophyll is the green pigment molecule in
  chloroplasts that is directly involved in
  photosynthesis.

Thylakoids have membranes that contain
chlorophyll (where light is absorbed). Grana
stacks of thylakoid. Stroma fluid surrounding
thylakoids where Calvin cycle occurs.
12
The reactions of photosynthesis occur in two main
stages.

• http//www.mhhe.com/biosci/bio_animations/02_MH_Ph
  otosynthesis_Web/
• Light-Dependent Reactions
• Capture energy from sunlight and use this energy
  to produce ATP and NADPH.
• ATP and NADPH are the energy required to power
  the Calvin cycle.
• Occur within and across the thylakoid membranes.
• This is the photo phase uses light.
• Light-Independent Reactions
• Also called the dark reactions or the Calvin
  cycle.
• Use the ATP and NADPH produced by the light
  reactions to build simple sugars.
• Occurs in the stroma of the chloroplast.
• This is the synthesis phase builds sugars.

13
Calvin Cycle (Dark) Reactions -take place in
stroma -use ATP and NADPH produced in light
reactions to convert CO2 into simple
sugars -return ADP, inorganic phosphate, and
NADP to the light reactions
Light Reactions -carried out by molecules in
thylakoid membranes -convert light E to chemical
E of ATP and NADPH -split H2O and release O2 to
the atmosphere
14
Overview of Light-Dependent Reactionshttp//www.s
umanasinc.com/webcontent/animations/content/harves
tinglight.html
15
Overview of Light-Independent Reactionshttp//hig
hered.mheducation.com/sites/0070960526/student_vie
w0/chapter5/animation_quiz_1.html
16
AKS Standards 8d - explain the role of cell
organelles in maintaining homeostasis and cell
reproduction for both prokaryotic and eukaryotic
cells 8l - analyze and explain the storage and
release of energy through the process of
photosynthesis and respiration (GPS) 10a -
relate the complexity and organization of
organisms to their ability for obtaining,
transforming, transporting, releasing and
eliminating the matter and energy used to sustain
the organism (GPS)
17
Cellular respiration makes ATP by breaking down
sugars.

• Animals eat other organisms for food, but food is
  not a direct source of energy for cells.
• Instead, all organisms break down molecules from
  food to produce ATP.
• Because it occurs in the presence of oxygen,
  cellular respiration is known as aerobic
  respiration.

COMMON MISCONCEPTION Animals are NOT the only
organisms that use cellular respiration. All
living organisms use some type of respiration
(aerobic or anaerobic) to produce ATPthis
includes bacteria, protistans, fungi, plants, and
animals!!!
18
OVERVIEW OF CELLULAR RESPIRATION

• The chemical formula for cellular respiration is
• 6O2 C6H12O6 ? 6 CO2 6 H2O Energy
• oxygen glucose ? carbon dioxide water
  ATP
• The reactants of cellular respiration are
• oxygen (O2) glucose (C6H12O6)
• The products of cellular respiration are
• carbon dioxide (CO2) and water (H2O)
• The 4 main stages of cellular respiration are
• Glycolysis
• Intermediate Step
• Krebs Cycle (Citric Acid Cycle)
• Electron Transport / Oxidative Phosphorylation

19
Cellular respiration occurs in mitochondria.

• Mitochondria are membrane-bound organelles found
  in the cells of organisms that perform cellular
  respiration.
• Mitochondria have a double membrane that serves
  to compartmentalize the reactions of cellular
  respiration.

Christae folds created by convoluted inner
membrane, increases the surface area for the
electron transport chain. Matrix aqueous
solution in the center of mitochondria where
chemical reactions of Krebs cycle
occur. Inner-Membrane Space area where a
hydrogen ion gradient is established using energy
from electron transport chain gradient powers
the production of ATP from ADP and Pi.
20
The Players for Cellular Respiration

• Mitochondria site of cellular respiration in
  cells.
• Glucose energy source broken down to release
  ATP.
• NADH FADH2 coenzymes that shuttle electrons
  from Glycolysis The Krebs Cycle to the Electron
  Transport Chain.
• Glycolysis begins the breakdown of glucose into
  two molecules of pyruvate.
• Intermediate Step converts pyruvate from
  glycolysis into Acetyl CoA for entry into Krebs
  cycle
• Krebs Cycle completes the breakdown of glucose.
• CO2 waste product of cellular respiration.
• O2 required for aerobic respiration.
• Electron Transport Chain establishes a
  concentration gradient of hydrogen across the
  inner membrane gradient powers production of
  ATP.

21
Cellular respiration occurs in four main
stages.http//www.sumanasinc.com/webcontent/anima
tions/content/cellularrespiration.htmlhttp//www.
mhhe.com/biosci/bio_animations/MH01_CellularRespir
ation_Web/index.html

• Glycolysis
• Takes place in cytoplasm of cell just outside the
  mitochondria.
• Begins the breakdown of glucose into 2 molecules
  of pyruvate.
• Produces 2 ATP, 2 NADH, and 2 pyruvate
• Intermediate Step
• Takes place just inside the mitochondria.
• Converts pyruvate from glycolysis into acetyl
  CoA, which can enter the Krebs cycle.
• Produces 2 NADH and 2 acetyl CoA releases
  carbon-dioxide waste
• Krebs (Citric Acid) Cycle
• Takes place in the matrix of the mitochondria.
• Completes the breakdown of glucose.
• Produces 2 ATP, 6 NADH, and 2 FADH2, releases
  carbon dioxide waste
• Electron Transport
• Occurs across the inner membrane of the
  mitochondria.
• Uses electrons donated from NADH and FADH2 to
  establish a hydrogen ion gradient across the
  inner membrane which is used to power the
  production of ATP.
• Produces approximately 34 ATP

22
Glycolysis occurs in the cytoplasm.
Intermediate step occurs just inside the
mitochondria.
Krebs cycle occurs in the matrix of the
mitochondria.
Electron transport occurs across the inner
membrane of the mitochondria concentration
gradient occurs in inner-membrane space.
23
Overview of Glycolysishttp//highered.mcgraw-hill
.com/sites/0072507470/student_view0/chapter25/anim
ation__how_glycolysis_works.html
24
Intermediate Step Converts Pyruvate into Acetyl
CoA
25
Overview of Krebs (Citric Acid) Cycle
http//highered.mheducation.com/sites/0072507470/s
tudent_view0/chapter25/animation__how_the_krebs_cy
cle_works__quiz_1_.html
26
Overview of Electron Transport Chain
http//highered.mheducation.com/sites/0072507470/s
tudent_view0/chapter25/animation__electron_transpo
rt_system_and_atp_synthesis__quiz_2_.html
27
Cellular respiration and photosynthesis are like
mirror images.
28
AKS Standards 8d - explain the role of cell
organelles in maintaining homeostasis and cell
reproduction for both prokaryotic and eukaryotic
cells 8l - analyze and explain the storage and
release of energy through the process of
photosynthesis and respiration (GPS) 10a -
relate the complexity and organization of
organisms to their ability for obtaining,
transforming, transporting, releasing and
eliminating the matter and energy used to sustain
the organism (GPS)
29
Respiration in the Absence of Oxygen (Anaerobic
Respiration)

• When oxygen is NOT present, glycolysis is
  followed by a different pathway called
  fermentation.
• Fermentation releases energy from food molecules
  in the absence of oxygen
• Because fermentation does not require oxygen, it
  is said to be anaerobic.
• The 2 main types of fermentation are
• alcoholic fermentation
• lactic acid fermentation
• Aside from the original 2 ATPs made during
  glycolysis, the only energy produced is that
  which is in the bonds of
• ethyl alcohol -- C2H6O
• lactic acid C3H5O3

30
As you can see, the role of fermentation is
simply to provide glycolysis with a steady supply
of NAD. By itself, fermentation does NOT
produce ATP. Instead, it allows glycolysis to
continue to produce ATP in the absence of oxygen.
31
Fermentation and its products are important in
several ways.
32
Fermentation and Aerobic Respiration Compared

• Both processes use glycolysis to break down
  glucose and other organic fuels into pyruvate.
• The processes have different final electron
  acceptors an organic molecule (such as pyruvate
  or acetaldehyde) in fermentation and O2 in
  cellular respiration.
• Cellular respiration produces 38 ATP per glucose
  molecule fermentation produces 2 ATP per glucose
  molecule.