UNIT 4: CELL METABOLISM · UNIT 4: CELL METABOLISM Metabolism = A process that involves using...
Transcript of UNIT 4: CELL METABOLISM · UNIT 4: CELL METABOLISM Metabolism = A process that involves using...
UNIT 4: CELL METABOLISM
Metabolism = A process that involves using energy to build or break down molecules
Photosynthesis and cellular respiration involve making and breaking energy-rich molecules
Autotrophs (self feeders)= make their own food from “inorganic”substances and energy
Ex: Plants, algae, certain bacteria
Heterotrophs (different feeders)= obtain their nutrients by feeding on other organisms
Ex: Animals and Fungi
OBTAINING NUTRIENTS: 2 STRATEGIES
Happens in: autotrophs
Goal: Converting light energy into chemical energy (glucose)
Glucose: carbohydrate monomer
C6H12O6
PHOTOSYNTHESIS
carbon dioxide + water + light →glucose + oxygen
6CO2 + 6H2O + → C6H12O6 + 6O2
PHOTOSYNTHESIS EQUATION
Reactants Products
Happens in: autotrophs AND heterotrophs (ALL organisms)Goal: converting
chemical energy (glucose) into USABLE energy (ATP) ATP = adenosine
triphosphate
CELLULAR RESPIRATION
ATP is a USABLE form of energy for the cell
Energy is released from ATP by breaking the bonds between phosphate groups
Why ATP? It ’s efficient, relatively simple, and the energy is relatively easy to access
WHY ATP?
Bond Breaks
Here!
Glucose + oxygen → Energy + Carbon Dioxide + Water
C6H12O6 + 6 O2 → ATP + 6 CO2 + 6 H20
CELLULAR RESPIRATION EQUATION
Reactants Products
CO2 + H20 + Energy (Light) → C6H12O6 + O2
C6H12O6 + O2 → Energy (ATP) + CO2 + H2O
COMPARING PHOTOSYNTHESIS AND
RESPIRATION
IMPORTANT COMPARISON!: the reactants of
one reaction are the products of the other reaction!
ATP MODELING ACTIVITY
H and OH:
BLUE
Adenine:
ORANGE
Ribose: RED
Phosphoric
Acid: YELLOW
*CUT OUT! BUT DO
NOT CUT DASHED
LINES YET!
PHOTOSYNTHESIS!
LEAVES of plants
Very large leaves (Ex: Rain Forest Leaves) are used to capture A LOT of sunlight
Pores at the bottom of leaves (stomata) take in carbon dioxide and release oxygen
WHERE ON THE PLANT DOES PHOTOSYNTHESIS TAKE PLACE?
Takes place in the chloroplasts (in leaf cells)!
2 Main Processes:
1) Light Reactions (aka light dependent reactions)
2) Calvin Cycle (aka light-independent reactions)
PHOTOSYNTHESIS SUMMARY
Thylakoids are stacked to form grana
Light Reactions take place in the thylakoid membrane
Calvin Cycle takes place in the stroma
CHLOROPLAST STRUCTURE
Purpose:
1) absorb light
2) produce oxygen
3) transfer sun energy to electrons
Requires a green pigment called chlorophyll to absorb sunlight
Where: thylakoid membrane
PART 1: LIGHT REACTIONS
Join with a molecule called NADP+ (an electron acceptor)
Sunlight splits water into hydrogen and oxygen
Hydrogen binds with NADP+, becoming NADPH, and gets sent to the Calvin Cycle
WHAT HAPPENS TO THE ELECTRONS ENERGIZED BY SUNLIGHT?
SUMMARY OF LIGHT REACTIONS
Start With:
Sunlight, water,
NADP+
End with:
Oxygen, NADPH,
ATP
Purpose: produce glucose from CO2
Uses electrons from NADPH and energy from ATP (broken back into ADP and P)
Does not require light
Where: stroma
PART 2: CALVIN CYCLE
SUMMARY OF CALVIN CYCLE
Start With:
CO2 , NADPH, and
ATP
End with:
Glucose and
NADP+
Notice that the products of the light reactions are used in the
Calvin Cycle!
How are excited electrons and ATP from light rxns used in
the Calvin Cycle? The H is needed for glucose and the
energy is required to carry out the entire process.
1. Intensity of light
2. Concentration of carbon dioxide
3. Temperature.
FACTORS AFFECTING THE RATE (SPEED) OF PHOTOSYNTHESIS
Sunlight hits clusters of pigment called Photosystems I and II
This excites electrons and joins them with protein carriers and finally NADP+
ATP is created when protons flow through an enzyme called ATP synthase
Explanation continued on next slide…
SO HOW DO WE GET ATP?
CELLULAR RESPIRATION!
THE PROCESS THROUGH
WHICH YOUR CELLS
OBTAIN USABLE ENERGY
By the end of this unit you should be able to:
Describe the purpose of cellular respiration in living
organisms
Compare glycolysis, Kreb’s cycle, and the electron transport
chain
Summarize the reactants and products of cellular respiration
Describe the structure of the mitochondria
OBJECTIVES
EQUATION
Glucose + Oxygen → Energy + Carbon Dioxide + Water
C6H12O6 + 6 O2 → ATP + 6 CO2 + 6 H2O
CELLULAR RESPIRATION SUMMARY
Location: Mitochondria (Eukaryotes), Cell Membrane (Prokaryotes)
Goal: Produce ATP from Glucose
Main Processes:
1) Glycolysis
2) Kreb’s Cycle
3) Electron Transport Chain
RECALL: WHAT IS ATP?
It is a molecule that “stores” energy in its
bonds
When used, the energy in ATP can act on other
compounds like an enzyme, and either break
their chemical bonds, or form them
ATP stands for “Adenosine Triphosphate”
STRUCTURE OF A MITOCHONDRION
1.Glycolysis occurs in cytoplasm of cell
2.Kreb’s Cycle occurs in matrix
3.ETC occurs in inner membrane
TWO TYPES OF RESPIRATION
Aerobic
With oxygen
Makes a lot of ATP
Includes all 3
steps
• Anaerobic
• Without oxygen
• Makes a little ATP
• Only glycolysis
PART 1: GLYCOLYSIS
Purpose: Glucose is broken down into two
smaller molecules (pyruvate – 3 carbons),
send electrons to ETC
Occurs in: Aerobic AND Anaerobic
Location: cytoplasm
Reactants: Glucose
Products: Pyruvate, NADH, ATP
GLYCOLYSIS
An enzyme splits
the glucose into 2
pieces, called
“Pyruvate”. The
process is called
“Glycolysis”.
The split also
produces 2 ATP
Molecules
ATP
ATP
PART 2: KREB’S CYCLE
Purpose: Pyruvate broken down into CO2, send
electrons to ETC
Occurs in: Aerobic respiration ONLY
Location: matrix
Reactants: pyruvate
Products: NADH, FADH2, ATP, and CO2
KREBS/CITRIC ACID CYCLE
The two Pyruvate
molecules enter the
mitochondria and
undergo reactions
which produce 2
more ATP
Molecules, plus
CO2 molecules as
waste
The CO2 leaves the
cell
The ATP is
available for use by
the cell for energy
ATP
ATP
CO2
PART 3: ELECTRON TRANSPORT CHAIN
Purpose: Electrons from NADH and FADH2 are passed to oxygen → Water
ATP is made using ATP Synthase
Occurs in: Aerobic respiration ONLY
Location: Inner Membrane
Reactants: Oxygen
Products: Water, ATP
ELECTRON TRANSPORT CHAIN
Inside the
Mitochondria,
oxygen (O2), the
final e- acceptor,
is used to drive
additional
reactions that
produce 32 more
ATP molecules
The process is
called Electron
Transport
Water (H2O) is
also produced, and
exits the cell
ATPATP
ATPATP
ATP
ATPATP
ATP
ATPATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATPATP
O2
H2O
ENERGY YIELD
2 ATP from Glycolysis
2 ATP from Kreb’s Cycle
32-34 ATP from Electron Transport Chain
36-38 Total ATP!!!
ANAEROBIC RESPIRATION
(FERMENTATION)
Glycolysis only (occurs where in the cell?
Cytoplasm)
Occurs in the absence of oxygen
Goal: break down glucose
▪Produce 34-36 ATP fewer than aerobic cell resp
Two Types: Lactic Acid and Alcoholic
LACTIC ACID FERMENTATION
Happens in: Animals, prokaryotes
Produces: lactic acid and ATP
Examples in Everyday Life: Muscle cells during
exercise, yogurt, pickles, etc.
LACTIC ACID FERMENTATION
ALCOHOLIC FERMENTATION
Happens in: Yeast and other microorganisms
Produces: alcohol (ethanol), CO2 and ATP
Examples in Everyday Life: Yeast causes bread to
rise!
ALCOHOLIC FERMENTATION
RESPIRATION CHART
PROCESS O2 NEEDED END PRODUCT
GLYCOLYSIS
KREBS
ELEC. TRANS.
FERMENT.