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INTRODUCTION TO BIOLOGY
UNIT TWO
Survey of the Plant Kingdom
Plant Anatomy & Physiology
Angiosperm Reproduction
Photosynthesis
Cellular Respiration
CERRITOS COLLEGE
SUMMER 2004
LECTURER – L. L. HARRIS
Biology 120
Cerritos College
INTRODUCTION TO PLANTS
I. Beginnings – A Journey Out of the Water
A. The Algae: Restricted to aquatic environments. Members of the Kingdom Protista
GREEN ALGAE (Chlorophyta)
RED ALGAE (Rhodophyta)
BROWN ALGAE (Phaeophyta)
B. Problems to Solve for a Terrestrial Life
1. How to Obtain and Transport Water
2. How to Prevent Evaporate Water Loss
3. How to Maintain a Moist Surface Area for Gas Exchanges
4. How to Support Body Against the Pull of Gravity
5. How to Carry Out Sexual Reproduction on Land
No Water for a Flagellated Sperm
Protect Zygote/Embryo from Dessication
6. How to Survive Despite Extreme Environmental Fluctuations
II. Quick Survey of the Plant Kingdom
A. Non-vascular Plants
Out of the water, but they are restricted to moist areas
1) Because they have no true vascular tissue (no xylem, no phloem)
2) Because they have a “swimming sperm” – needs moisture to swim in!
Perhaps the most common include:
MOSSES (Bryophyta)
LIVERWORTS (Hepatophyta)
B. Vascular Plants
 Pterophytes: FERNS
Successful transition onto land, but still require open water for sexual reproduction
“Amphibians of the Plant Kingdom” – Only the Sporophyte is vascularized!
For successful sexual reproduction, their swimming sperm must have water to swim in!
 Fern-Allies: HORSE-TAILS & others
 Gymnosperms: CONIFERS GINGKO CYCADS EPHEDRA
Name means “Naked Seed” – Bear their seeds along their stems
Non-swimming sperm
 Angiosperms: ANTHOPHYTA
Name means “Vesseled Seed” – Bear their seeds in a fruit’
Non-swimming sperm
Anthophytes are the Flowering Plants
Two Classes: MONOCOTS & DICOTS (See Text Table for Distinguishing Characters)
Alternation of Generations: (2N)
Sporophyte
(1N)
spores
meiosis
(1N)
Gametophyte
mitosis
(1N)
gametes
mitosis
Sperm & Egg
mitosis
(2N)
"ZYGOTE"
FERTILIZATION
Seen is a cycle of SPORIC MEIOSIS
Important Trends:
1) Sporophyte becomes the dominant generation (the “obvious” plant)
2) Reduction in the size of the Gametophyte (becomes microscopic!)
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II. Bodies of Higher Plants
A. Roots & Shoots
(Gymnosperms & Angiosperms)
(If below ground → Roots / If above ground → Shoots)
1. Root Functions
a. Absorb/Conduct water and dissolved minerals
b. Store food
c. Anchor (and may act as a structural support)
2. Shoots
Two main organ types: STEMS & LEAVES
a. Stem Functions
i. Framework for upright growth.
ii. P/S is possible in young green stems.
iii. Storage sites (Ex. potatoes = stems)
b. Leaf Functions
i. The usual sites of P/S
ii. Flowers & Cones are modified leaves
III. Plant Tissues
A. DERMAL TISSUES
1. EPIDERMIS – “skin”
Outer covering of leaves, stem, and root. Typically only one cell layer thick!
Often covered by a waxy CUTICLE – “water saving”
Modifications of Epidermis: Guard Cells
Root Hairs
Lenticles
Epidermal Hairs
2. PERIDERM – Replaces epidermis in those plants that experience Secondary Growth
B. VASCULAR TISSUES
1. XYLEM – "roots to shoots"
Conduct water and dissolved solutes from the soil
Offers structural support for the plant as well (Xylos - Greek word for WOOD)
Functional xylem tube is composed of DEAD CELLS
Living cells do not transport water. Instead special properties of Water are responsible for
assuring that water keeps moving up! COHESIVENESS & HIGH HEAT OF VAPORIZATION
2. PHLOEM – "shoots to roots"
Conduct food and other plant products in shoots & roots
Functional phloem is composed of LIVING CELLS – More on this Later
C. GROUND TISSUES – This is the bulk of a plant’s body
1. Parenchyma – majority of GTs
Functions: Photosynthesis, Storage, Secretions, Wound Healing
2. Collenchyma
Functions: Support, Texture, Strength (with Flexibility)
3. Sclerenchyma
Functions: Protection, Texture, Strength (with Rigidity)
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IV. Plant Growth
MERISTEMATIC TISSUES: Perpetually young tissues; undifferentiated tissue actively undergoing mitosis
that will give rise to new cells for added growth
A. Primary Growth
Adds LENGTH to the plant feature – Occurs at tips of roots and shoots
a. ROOT APICAL MERISTEM
Region of root tip that is most actively undergoing mitosis
b. SHOOT APICAL MERISTEMS & LATERAL AXILLARY BUDS
Shoot Apicals: At the tips of shoots
Lateral Axillary Buds: At nodes along stem; result in leaves, flowers, & lateral branches
B. Secondary Growth
Adds DIAMETER (girth) to the feature
Woody Plants – extensive 2o growth for Dicots; very little (if any) in Monocots
Non-Woody Plants (herbaceous) – little or no 2o growth
Pattern of 2o Growth:
Two Meristems: Vascular Cambium & Cork Cambium
VASCULAR CAMBIUM – makes 2o Phloem & 2o Xylem
On VC’s OUTER FACE 2o PHLOEM forms
Most is crushed against the Cork Cambium
On VC’s INNER FACE 2o XYLEM forms
SAPWOOD – conducting xylem
HEARTWOOD – non-conducting xylem
ANNUAL RINGS – EARLY WOOD (Spring Wood) & LATE WOOD (Summer Wood)
CORK CAMBIUM – gives rise to the Periderm [aka CORK]
BARK: Those tissues outside the vascular cambium
GIRDLING A TREE: Remove a strip of bark from tree’s circumference and also take a strip of VC
Purpose: Kill the tree for its permanent removal
C. Seasonal Growth Cycles
Life cycle : Seed Germination -> -> -> Seed Formation
1. ANNUALS – (example: corn)
Go through their entire life cycle in only one growing season
Experience one season of primary growth.
Very little secondary growth (if any) is noted
2. PERENNIALS – (examples: oaks, sycamores, "fruit trees")
Live for more than one growing season
Life cycle continues year after year before death
Experience continued 1o and 2 o growth
3. BIENNIALS – (examples: foxglove & asparagus)
Complete their life cycle in 2 growing seasons
1st season: Roots & Shoots
2nd season: Flowering, Fruit & Seed formation.
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Biology 120
Cerritos College
PLANT PHYSIOLOGY
I. Water Absorption
Root Hairs are the functional units of roots. Root Hairs are thin-walled epidermal ("skin") cells
Water enters the Root Hair by Osmosis
Water passes from Root Hair –> Cortex –> Endodermis
Water passes between cells and through cells
Passage to vascular tissue regulated – CASPARIAN STRIPS
Waxy band of tissue around cells – water must travel through cells
Water eventually funneled into Xylem
II. Transpiration, Water Conduction, & Cohesion Theory
A. Transpiration – loss of water due to evaporation
Occurs primarily at leaves and stems
Major Site – Stomata of leaves
B. Water conducted upward by a constant negative pressure
Tension extends downward from Leaf to Roots
C. Negative Pressure & Transpiration assure that more soil water enters Xylem
D. Summary of Cohesion Theory
As long as water molecules vacate the transpiration sites, replacement
water is sucked up through the xylem from the roots in continuous water
columns as a result of hydrogen bonding between water molecules.
III. Stomatal Regulation
A. Stoma and Guard Cells Anatomy
Stoma – hole, opening for gas exchange – flanked by Guard Cells
Guard Cells – specialized epidermal cells; have chloroplasts
B. Open State is Dependent on CO 2 & Water Levels in GCs
P/S in GCs causes CO2 levels to fall as glucose is made
Active Transport of Potassium into GCs when CO2 drops
Potassium concentration gradient moves water into GCs
High K+ means Low H2O inside GC.
Water higher outside GC than in GC, therefore water moves into GC.
Increased water in GCs –> Increased turgor –> Expose Stoma
IV. Transport of Organic Substances in Phloem
A. Translocation – Transport of Sucrose and other compounds through Phloem
From "SOURCE" to SINK" regions
Source – leaves and stems where P/S occurs (or where product is stored)
Sink – where organic compound is being translocated
B. Pressure Flow Theory (depends on pressure gradients between SOURCE & SINK region
1. Solutes actively transported out of Source cells and into Phloem "plumbing"
2. Result – water moves out of Source cells and into Phloem -> high Phloem pressure as result
3. Water & Solutes move by bulk flow from Source region toward Sink region
Source Region is HIGH PRESSURE region – Sink Region is LOW PRESSURE region
4. Solutes reach Sink – Actively transported into Sink cells
This lowers water pressure in sink cells – Water from phloem moves into Sink Cells
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Biology 120
Cerritos College
ANGIOSPERM REPRODUCTION
I. INTRODUCTION
Our discussion will be restricted to SEXUAL REPRODUCTION
All other reproduction in plants is said to be VEGETATIVE
II. THE REPRODUCTIVE SYSTEM
A. DIVISION ANTHOPHYTA
Characterized as: FLOWERING & FRUITING
Characterized as having DOUBLE FERTILIZATION:
1. Formation of ZYGOTE → EMBRYO
2. Formation of ENDOSPERM → Starchy Food for the Embryo
B. FLOWER ANATOMY
1. STEM (and PEDICLE) – for support and placement of flower
2. RECEPTACLE – Broadened region; base for ovary
3. SEPAL – for support and protection of developing flower
4. PETAL – Modified leaves.
Function: Attract Pollinators via Colors, Patterns, Nectar, …
5. STAMEN (MALE)
a. FILAMENT – Stalk that supports the anther
b. ANTHER – Male Sporangium; Gametophyte production site
6. PISTIL (FEMALE) aka CARPEL
a. STIGMA – Typically sticky; to hold & hydrate pollen grains
b. STYLE – Stalk-like; will be site of the Pollen Tubes
c. OVARY – Female sporangium; contains OVULES,
Ovule – Gametophyte production site. Opening into ovule: MICROPYLE
C. POLLINATOR
ANYTHING that carries pollen from Anther to Stigma
More specifically – many arthropods, mollusks, chordates, water, wind
Gymnosperm Pollen and many Angiosperm Grasses – wings to catch the wind
Angiosperm Pollen – without wings; majority rely on living pollinators
III. GAMETOPHYTE PRODUCTION
A. In the Ovule:
MegaSpore –> 8-nucleated gametophyte (Embryo Sac)
There is Unequal Cytokinesis: 8-nuclei divided among 7 cells
2 Important Cells: EGG (1n) & POLAR BODY (2n)
B. In the Anther:
Microspores –> 2-nucleated gametophyte “POLLEN GRAIN”
TUBE NUCLEUS – Builds the pollen tube
GENERATIVE NUCLEUS – mitosis –> 2 sperm cells
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IV. POLLINATION & FERTILIZATION EVENTS
1. Pollen delivered to stigma
2. Tube Nucleus begins to bore a Pollen Tube
3. Generative Nucleus follows behind the Tube Nucleus
4. Generative Nucleus mitosis –> 2 sperm cells
5. Tube Nucleus finds the micropyle and enters ovary
6. Sperm cells enter too!
7. One Sperm fertilizes the Egg
1n + 1n –> 2n ZYGOTE
8. Other Sperm fertilizes Polar Body 1n + 2n –> 3n ENDOSPERM
9. Ovule becomes a Seed
V. THE FRUIT
Fate of ovary is to swell and form a fruit that surrounds the seed.
Some ovaries form the CORE of some fruits – Receptacle forms the "fruit" part (APPLE, PEAR)
1o function of a fruit –> Dispersal of the seed
Some fruits taste good!
But, not all fruits taste good!
Burrs: strategy is to stick onto a passing animal
Nuts & Acorns: strategy is to roll
Some fruits never need to come off the sporophyte
Jacaranda – wind dispersal of seed
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Biology 120
Cerritos College
PHOTOSYNTHESIS
I. Introduction
A. Energy Source
THE NEED TO RESIST ENTROPY!!!
1. Chemiosynthetic Autotrophs
At geothermal vents and in soil; bacteria that never see sunlight. Instead of (or in addition to) CO 2,
they utilize inorganic compounds NH3 (ammonia), Fe (iron containing), & S (sulfur containing)
2. Photosynthetic Autotrophs – Able to trap and transform Sunlight Energy
II. Photosynthesis Defined
Trapping of solar E and its conversion to chemical ENERGY which is then used in manufacturing food
molecules from CO2 and H2O. Solar E –> Chemical E –> Food E
SUMMARY EQUATION OF P/S:
LIGHT
6 CO2 + 12 H2O
C6H12O6 + 6 O2 + 6H2O
CHLOROPHYLL
This is the fixation of CARBON (from CO2) into a form that living organisms can utilize
We (and other organisms) can also use the O2! Aerobic Cellular Respiration – studied in future lecture
And OZONE (O3) is made from O2 – Forms the “Ozone Layer” that protects cells from UV radiation
III. The Mechanics
A. P/S REQUIRES CARBON DIOXIDE
Stomata – Avenue for obtaining CO2 and releasing O2 Most are located on underside of leaves
Guard cells – cells of the leaf skin (epidermal cells) –The only epidermal cells w/ chloroplasts
Bend like a banana when full of water (turgid) – Bending "creates" stoma between them
If lose too much water they lose volume and lose their "bend" (become flaccid)
Loss of turgidity –> closing off of the stoma
B. Water is essential to P/S
Water is brought to the leaves by xylem
Water is conserved by the plant in various ways: Cutin Wax, Epidermal Hairs, Guard Cells
C. Light is need for P/S
Electromagnetic Spectrum: All Radiations
Spectrum of Visible Light
(white light)
Gamma Rays X-rays UV <– violet blue green yellow orange red –> IR MW RADIO
380nm –- 500nm – 600nm – 760nm
high E
low E
E = 1/wavelength
Long wavelengths have lower E
Short wavelengths have higher E
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D. Pigments
1. Defined – Any substance (usually a protein) that absorbs light
The color associated with a pigment though is due to the reflected wavelengths of white light
2. Excitation of Electron
Absorption of light by pigments causes electrons of the pigment to get excited.
Electron boosted to higher E level = Higher Potential E
3. Chlorophylls – Several kinds are recognized: a & b – most common
Chlorophyll a is the major photosynthetic pigment
Reflects (transmits) wavelengths of green & yellow
Absorbs wavelengths of violet, blue, and red
These wavelengths do P/S!
AKA Absorption Spectrum of Chlorophyll
Contains the Action Spectrum = Radiations Energies to do P/S!
4. Accessory Pigments
Extend the range of light available for P/S by passing the energy absorbed (e -'s) to chlorophyll a
Chlorophylls b, c, and d
Carotenoids: red, orange, & yellow (Include the Carotenes and Xanthophylls)
5. Chloroplasts contain Chlorophyll
Generalized anatomy of chloroplast: thylakoid, grana, stroma
Photosystems: located along the THYLAKOID MEMBRANES
Light-absorbing pigments are arranged in clusters called PHOTOSYSTEMS
Plants utilize: Photosystem II (lower E, P680) and Photosystem I (higher E, P700)
V. Non-cyclic Pathway of Photosynthesis 0f C3 Plants
A. P/S is a 2 stage process
Light-Dependent Rxns
(Photochemical)
B. Light-Dependent Rxns – Converts light energy to
chemical energy
Light-Independent Rxns
(Enzymatic)
(lo P.E.)
ADP + Pi
(hi P.E.)
ATP
H2O
1/2 O2
NADP+
(lo PE)
NADPH
(hi PE)
 Water splits in process called PHOTOLYSIS; releases e-'s & H+'s
 Electron transfers and H+'s make ATP and NADPH
 Generation of Oxygen Gas
 Occurs along the THYLAKOID MEMBRANE
Photosystem II:
Excited electrons are taken up and fed through an Electron Transport System.
ETS – along thylakoid membrane, special membrane proteins and enzymes
Energy released from the ETS takes ADP + P → ATP This is PHOTOPHOSPHORYLATION
 H+ are released and pool in the thylakoid compartment.
 Electrical and H concentration gradient created between compartment (high) and stroma (low).
 Used to phosphorylate the ADP to ATP out in the stroma
CHEMIOSMOTIC THEORY: Proton gradient across membrane drives the formation of ATP
 The ETS electrons are delivered to Photosystem I
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Photosystem I:
 Light E excites a P-I electron and it is picked up by another electron acceptor that passes it
to a second ETS
 E released from ETS takes NADP+ + H+ (2e-) → NADPH
 Therefore, ultimate e- & H+ acceptor is NADP+ → NADPH
 Majority of ATP that are made go to the DARK RXN
C. Light-Independent Rxns – AKA Dark Rxns
 The Calvin-Benson Cycle (FIXES CO2)
(From Light Rxn)
ATP
ADP + Pi
6CO2
C6H12O6 + H2O
NADPH
NADP+
(From Light Rxn)
 Energy released is used to fix CO2 into molecules that will form Carbohydrates (glucose)
 Occurs in the STROMA
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PHOTOSYNTHESIS
Photosynthesis – The conversion of carbon dioxide and water by light energy (sun) into a food energy
Occurs in the presence of chlorophyll. There is carbohydrate synthesis and O 2 gas is
generated; an autotrophic process
Summary equation:
light energy
6 CO2 + 12 H2O
C6H12O6 + 6 O2 + 6 H2O
chlorophyll
This process is a complex series of reactions that may be divided into 2 parts,
the Light Reactions (Light-Dependent) and the Dark Reactions (Light-Independent).
The Light-Dependent Reactions (AKA Light Rxns; AKA Hill Rxns)
Sunlight energy is used to split water molecules and, thereby, release oxygen gas. (Photolysis)
sunlight
12 H2O
6 O2 + 12 H+ + ATP
MR. SUN
visible light energy
CHLOROPHYLL
e(energized chlorophyll)
H2O

(photolysis)
|
O2

released into
the atmosphere
e- & H+
ADP + P

(photophosphorylation)

ATP

(goes to Dark Rxn)
+
NADP
(electron acceptor)

NADPH (Nicotinamide Adenine Dinucleotide Phosphate)

(goes to Dark Rxn)
Summary of Light Reactions:
1. Absorption of light energy by chlorophyll pigment
2. Photolysis of water molecule – Oxygen gas released & NADPH generated
3. Photophosphorylation – light energy stored in ATP
4. Molecules of NADPH and (most of the) ATP go to the Dark Reaction
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The Light-Independent Reactions – (AKA Dark Rxns, AKA Calvin Cycle)
This is the process that converts CO2 from the atmosphere into the sugar glucose. This is called
carbon-fixing; taking an "unusable" form of carbon and putting the carbon into a "usable" form!
6 CO2 + 24 H+ + ATP
C6H12O6 + 6 H2O
CO2
+
RuBP
Ribulose Biphosphate

(CO2 acceptor in chloroplast)


C6 sugar

(splits)


2 PGA
Phosphoglycerate
(C3 compound)
ATP

from light  energy ->
rxn

ADP
NADPH

from light  H+ ->
rxn

NADP
Phosphoglyceraldehyde
used immediately by
the cell or converted to:
PGAL
H2O -> released as a by-product
C6H12O6 Glucose
RuBP
Summary of Dark Reactions:
1. Uptake of atmospheric CO2
2. Receive and use energy of NADPH and ATP from Light Rxn
3. Make PGAL –> Synthesis of the glucose ("carbon-fixing") and the regeneration
of RuBP (now available for the next round of the Calvin Cycle)
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KINGDOM
PROTISTA
CHARACTERISTIC
KINGDOM PLANTAE
Algae
Bryophytes
&
Hepatophytes
Pterophytes
Gymnosperms
Angiosperms
no
no
no
no
yes
Phototrophic
Vascular Tissue
Seeds
Swimming Sperm
Dominant
Generation
Sori
Cones
Flowers
Major Divisions
Major Classes
Common Names
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Biology 120
Cerritos College
CELLULAR RESPIRATION
I. External Respiration vs. Internal Respiration
A. External Respiration
The inhale/exhale cycle that brings in O2 and blows off CO2
Performed by most multicellular organisms
A "whole" organism phenomenon
B. Internal Respiration = Cellular Respiration
Release of Energy from organic compounds via metabolic processes
Performed by all living cells of all organisms
A "cellular" phenomenon
II. The Two Pathways of Cellular Respiration
A. Anaerobic Respiration
Performed in the absence of O2
Occurs in cytoplasm (anaerobic condition)
Some bacteria can only take this pathway
B. Aerobic Respiration
Performed in presence of O2
Preferred path of most organisms – More Energy Efficient!
If O2 supply is low or depleted Animals will utilize the anaerobic path. (but it is limited)
III. Steps for Aerobic Respiration
For eukaryotic organisms: Aerobic Pathway can be discussed as having 5 Major Events
cytoplasmic
1. GLYCOLYSIS
mitochondrial
2.
3.
4.
5.
PREPARATORY/TRANSITION RXN
KREB'S CYCLE
ELECTRON TRANSPORT SYSTEM
ATP GENERATION via CHEMIOSMOTIC THEORY
IV. Summary Equation of Aerobic Pathway
enzymes
C6H12O6 + 6 O2
ENERGY
6 CO2 + 12 H2O + ENERGY
= 36 ATP (skeletal muscle yield)
(38 ATP [liver, kidney, heart muscle])
Know where/how the reactants are acquired – Know where the products appear along the pathway
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V. Closer Look at Glycolysis
A. Glycolysis = The Breaking of Sugar
2 ATP
C6H12O6
(glucose)
(GLUCOSE)
2 ADP + 2 Pi
\_______/
\
4 ATP
2 C3H4O3
\
(pyruvate)
2 NAD –> 2 NADH
Taken to an ETS –> ATP
Glycolysis Summary:
1. Anaerobic process – involves several enzymatic steps
2. Occurs in the cytoplasm (Compartmentalization)
3. Generation of 4 Substrate Level ATP (gross; net is 2 ATP)
2 ATPs are spent for glycolysis and 4 ATPs are made during glycolysis
4. Generation of 2 NADH – e- and H+ carrier
5. 2 molecules of PYRUVATE for each molecule of glucose
VI. Closer Look at the Mitochondrial Reactions
A. Mitochondrion General Anatomy:
1) OUTER MEMBRANE
2) INNER MEMBRANE:
a. CHRISTAE – folds that greatly increase surface area
b. ELECTRON TRANSPORT SYSTEM – NADH & FADH2
Series of embedded Cytochromes, Enzymes, & Coenzymes
c. LOLLIPOPS – Channels containing ATP Synthetase
3) OUTER COMPARTMENT – High H+ gradient established
4) INNER COMPARTMENT (aka Matrix) – Prep Rxn & Kreb's Cycle
B. Preparatory Rxn (aka Transition Rxn)
1. Pyruvate moves into the MATRIX of mitochondrion. And for each molecule of pyruvate:
NAD+
NADH
\_______/
C3H4O3 + Coenzyme A
C2H3O-CoA
(pyruvate)
(acetyl-CoA)
CO2
2. Enzymatic rxns takes PYRUVATE → ACETYL-CoA
3. DECARBOXYLATION occurs – Carbon Dioxide is released
4. REDUCTION of NAD+ to NADH
NAD+ – Nicotinamide Dinucleotide; electron acceptor
NADH carries electrons and a Hydrogen
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C. Kreb's Cycle [Hans Krebs – 1930's]
1. Occurs in the MITOCHONDRIAL MATRIX (Kreb's Cycle aka Citric Acid Cycle)
Starting Reaction: Acetyl-CoA + Oxaloacetate
(2-C)
(4-C)
Citrate (Citric Acid)
(6-C)
2. Decarboxylations occur (formation of CO2)
3. Substrate Level ATP is made (1/PYRUVATE; 2/GLUCOSE)
4. Electron Carriers are generated – NADH and FADH2
NAD – Nicotiamide Dinucleotide
FAD – Flavin Adenine Dinucleotide
D. Electron Transport System
[aka Electron Transport Chain]
1. CRISTAE MEMBRANE of the mitochondrion
2. OXIDATIONS of NADH & FADH2 (to NAD+ & FAD)
e- s are accepted – passed through the system
H+ refused by ETS – H+ are moved to outer compartment to establish a high H + gradient
3. O2 is the final electron acceptor –> water
E. Chemiosmotic Theory for Generation of ATP
1. H+s pool in the OUTER COMPARTMENT of mitochondrion
2. Sets up a concentration gradient across CHRISTAE membrane
3. PHOSPHORYLATIONS of ADP –> ATP in the MATRIX
H+ flow through lollipop where the enzyme ATP Synthase is active
This is called the CHEMIOSMOTIC THEORY of ATP generation
F. Summary: ATP Produced by Aerobic Cellular Respiration
GLYCOLYSIS
PREPARATORY
KREB'S CYCLE
Substrate Level
2 ATP
0 ATP
2 ATP
4 ATP
Respiratory ETS
2 NADH → 4 ATP
2 NADH → 6 ATP
6 NADH → 18 ATP
2 FADH2 → 4 ATP
32 ATP Therefore, 36 ATP/glucose
VII. The Anaerobic Pathways
Two Major Pathways: 1) Lactate Fermentation
2) Alcoholic Fermentation
A. SHARED START – SHARED PROBLEM
Both pathways follow GLYCOLYSIS: GLUCOSE –> 2 PYRUVATE
All organisms must deal with the toxicity of Pyruvate
B. Quick Look at Lactate Fermentation
Performed by Animals and some Bacteria
Commercial Benefits from lactic acid: __________________________________________________
Lactic Acid formation in Skeletal Muscles:
A quick, but low yield of ATP
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Leads to Muscle fatigue
C. Closer Look at Lactate Fermentation:
2 ATP (net)
GLUCOSE
2 PYRUVATE
2 LACTATE
-----------------------/
\
/
\
2 NAD+
2 NADH ---------> 2 NADH
2 NAD+
\______________________________/
THEREFORE: Net gain of ATP is only 2 molecules
NADH is used to make pyruvate less toxic (will not make more ATP)
D. Quick Look at Alcoholic Fermentation
Performed by Yeast Cells
(Kingdom Fungi)
Commercial Benefits: _______________________________________________________________
_______________________________________________________________
E. Closer Look at Alcoholic Fermentation:
2 ATP (net)
2 H2O
/
\
GLUCOSE
2 PYRUVATE
/-----------\
/-----------\
2 EtOH + 2 CO2
2 NAD+ 2 NADH ------>
2 NADH 2 NAD+
\________________________________/
THEREFORE:
Net gain of ATP is only 2 molecules
NADH used to make pyruvate less toxic (will not make more ATP)
VIII. Comparison of Aerobic and Anaerobic Pathways
AEROBIC
GLYCOLYSIS:
PREP RXN:
KREB'S & ETS:
ANAEROBIC
1. Site is cytoplasm
2. 2 ATP/glucose
3. Waste product is pyruvate
1. Site is cytoplasm
2. 2 ATP/glucose
3. Waste products are organism dependent
1. Site is the Mitochondrion
2. 2 Acetyl Co-A/Pyruvate
3. NADH/Pyruvate
3. CO2 is a “waste product”
1. Site is the Mitochondrion
2. Substrate ATP = 2/glucose
3. Chemiosmotic ATP = 32/glucose
4. “Waste products” of CO2, H2O, & heat
________________________________________________
TOTAL ATP = 36
TOTAL ATP = 2
Another way to look at this:
36 ATP potential yield in Aerobic Respiration vs. 2 ATP potential yield in Anaerobic Respiration
Therefore; 36 ATP / 2 ATP → 18 times more ATP from Aerobic Pathway than the Anaerobic Pathway
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CELLULAR RESPIRATION PATHWAYS
ANAEROBIC
AEROBIC
GLYCOLYSIS *
GLUCOSE (C6H12O6)
occurs in
cytoplasm
(PROTEINS)

(amino acids)
KREB'S CYCLE ***
|
oxaloacetate
C4
(LIPIDS)

(fatty acids & glycerol)
|
citrate
C6
+
C4
C5
moves into mitochondrion
|_________________|
if O2 present
PYRUVATE (C3)
ACETYL CoENZYME A (C2)
PREP RXN **
CO2 ATP NADH FADH2
CoA
CO2
e- donors
O2 not present
ELECTRON TRANSPORT
+
FERMENTATION
NAD
SYSTEM ****
RXNS
FAD+
H+ / eAnimals/Monerans:
|_ A series of embedded proteins
+
+ H2O
2 LACTATE (C3)
H are not accepted by the |_ accept and pass the e-s to
Yeasts:
the ETS -- pool instead in
|_ the final e- acceptor – O2.
NET ATP = 2
|_ The e-s and H+ combine
|_ with the O2 to form H2O.
|_
Fermentations are the anaerobic means
H+ H+ H + H + H + H + H + H + H + H +
+
+
+
+
+
+
+
+
+
+ O2 –> H2O
of dealing with the toxic pyruvate that forms
H H H H H H H H H
during glycolysis.
CHEMIOSMOTIC THEORY OF H+ gradient used to drive the
Total Net Energy Gain:
ATP GENERATION
formation of ATP in the matrix.
Anaerobic Path = 2 ATP/Glucose
*****
Catalyzed by ATPsynthase.
(Produced during glycolysis alone)
Aerobic Respiration is the aerobic means of dealing
with the toxic pyruvate that forms during glycolysis.
Summary of Fermentations: (balanced)
C6H12O6 –> 2 C2H5OH + 2 CO2 (Yeast)
Total Net Energy Gain:
C6H12O6 –> 2 C3H6O3 (Animal & Bacteria)
Aerobic Path = 36*ATP/Glucose in skeletal muscle
cells. Includes the 2 from glycolysis, the remaining
34 are made in the mitochondrion.
Five Steps for Aerobic Path:
Glycolysis – cytoplasmic
Summary of Aerobic Respiration: (balanced, "all" cells)
Preparatory Rxn – mitochondrial
C6H12O6 + 6 O2 -----> 6 CO2 + 6 H2O + 36 ATP
Kreb's Cycle Rxns – mitochondrial
with
Electron Transport – mitochondrial
O2
*Note: Some cells (heart muscle, kidney, & liver) can
Chemiosmotic ATP – mitochondrial
make 38 ATP/Glucose. (An extra NADH made)
ETHYL ALCOHOL (C2) + CO2
the outer compartment.
H+ H + H + H + H + H + H + H + H +
NOTE: The NADH molecules produced during glycolysis and the preparatory reaction are not shown.
18