Week 2 Chapter 4, 5, 6, 7 Flashcards
What are the ways cells interact with the environment
Cells absorb nutrients through their surfaces
Cells get rid of wastes through their surfaces
A small cell has a lot of surface area per volume
A large cell has much less surface area per volume:
PROKARYOTIC CELLS
Small cell size: (tend to be; not all) Less than 10 m(1 1millionth of a meter) No nucleus No internal organelles: Ribosomes are small: 70s Simple; structurally not complicated
organelles
- : a structure inside a cell that is bound or surrounded by its own membrane
Ribosome
– accumulations of proteins and nucleic acid
- Responsible in all cells of protein production
Why are cells smalll
There is a limit in the size of cells because of the way cells interact with the environment.
- More space more surface area easier for interaction
- Amount of surface area not going to be able to handle demand of big volume
- Matter of effeciency
Cytoplasm
– all liquid part
- Everything inside the cell is suspended in liquid cytoplasm
Eukaryotic Cells
Bigger; have nucleus
Large size ribosomes : 80s
Large size:10m – 1000m (1 mm)
(human egg is a single cell; can see naked eye)
Nucleus : surrounded by a double membrane
Eukaryotic Cells
- Animals
Nucleus: surrounded by a double membrane
- Have holes
- Material inside cell: chromatin
- Chormatin: genetic material: DNA and protein
- Nucleolus: (another structure inside nucleu)
Nucleolus
o Condensed chromatin
o Site of RNA synthesis
o DNA in long strand in pieces; linear pieces - chromosome
In RNA once piece circular
o Prokaryotic – one chromosome
o Eurkaryotic – many chormosomes
Number – indicative of characteristcis of particular organism
Human have different than other animals
The internal Organelles of Eukaryotic Cells
- Membrane-bound nucleus
- Endoplasmic reticulum
- Golgi apparatus
- Mitochondria
- Chloroplasts
- Vacuoles
- Lysosomes
- Cytoskeleton
- Flagella and Cilia
Endoplasmic reticulum
Long labrynth like membrane that fills up good portion of cytoplasm
- Two kinds
- Rougn ER:
- Smooth ER:
Rougn ER:
- studded with ribosomes
- site of protein synthesis
Smooth ER:
- no ribosomes
- site of lipid synthesis
o Connected to rough er
Golgi apparatus
- Protein processing and packaging
- (secretory proteins)
- Responsible for taking protein made in ER and packagaging them
- Any protein that cell is going to get rid of or secrete has to be package and its done in golgi apparatus
Mitochondria
- Cell powerhouse; site ofATP synthesis
- Production of energy inside a cell
- All energy takes form of ATP
Chloroplasts
- absorbs sunlight to do photosynthesis
- Leafy plants and algae only
- Photosynthesis (ATP from sunlight) and CO2 incorporation
Vacuoles
- Storage ‘compartments’: starch, enzymes
- Big;
vesicles
small storage compartments
Lysosomes
contain digestive enzymes to degrade engulfed material
Cytoskeleton
- Microtubules (tubulin)
- microfilaments (actin)
- centrioles
Microtubules (tubulin):
- organize and move the organelles
- responsible for cell shape
o Not bound by membrane
o protein
- microfilaments (actin):
movement of the cell (pseudopodia) and organelles (cyclosis)
o movement of organelles within cells
- centrioles
: organization of cell division
- organize formation of microtubules
o present during cell division
o difficult to find when cell is divided
Flagella and cilia
- ‘organs’ of locomotion:
flagella:
long, relatively few per cell
- Outside of cells
- Cells with flagella – whip back and forth – push through environment
Cilia:
- short, many thousands per cell outside
- Celia all move together – oars of ships – all pushing cell through environment
o Allow cell to spin; travel straight lines, reverse, turn around, etc
Cell membrane
o Phospholipid bilayer, imbedded with proteins
Polar charged with + and –
Tail: hydrophobic
Head: hydrophilic
Outside of cell is mostly water
Inside of cells cytoplasm is mostly water
All cell membrane are made up of phospholipid
Proteins of Cell Membranes
Some hangs around outside : peripheral protein
Span membrane; imbedded: integral protein
In order to exist in environment: they have to be matched; in part must be hydrophilic
Middle in membrane: hydrophobic
cholesterol in cell membrane
A necessary part of living things
Embedded in bilayer to stabilize more rigid the membrane
Cell wall
o Most animal cells lack a cell wall; plant have cell walls made of cellulose(polysaccharide)
o Bacterial cells have cell walls made of a polysaccharide: peptidoglycan
Cell walls: made up of carbohydrates
o True in almost all cases of cell walls
Diffusion
Diffusion across membrane is selective:
o : movement of molecules from an area of high density (high concentration) to an area of low density
Osmosis
o : movement of water across a membrane in response to solute differences outside and inside the cell
- Not only Diffusion of water through air, across a membrane; from more concentrated water to less concentrated water
- Water: solvent
Solvent
-anything that has something else dissolved in it o Solution of water and salt Water is the solvent Salt is the solute Together they make a solution
Osmosis
cell
o Water inside and outside
o Inside – cytoplasm = water + bunch of different solute (salt, protein, etc)
o Water is going to move across through membrane in response concentration of water – from more to less)
[[H2O] + [salt]
If salt goes up water goes down vice versa
WFS – water follows solute
• Water goes where solute is higher
o Equal – travel equaly inside as outside
Isotonic
Osmosis
when solute is lower
Hypotonic – swell and burst
Osmosis
- when solute is higher
Hypertonic – shrink
How molecules cross the plasma membrane
- Hydrophilic edge
- Hydrophobic inside
- Difuse through water and very very small uncharged particles
Diffusion across membrane is selective
The three transport
- (movement down the gradient or along the gradient or sometimes with the gradient)
passive transport
facilitated transport
active transport
o Gradient
– the difference in concentration
- Passive transport:
o Simple diffusion (osmosis)
o movement of solutes across membrane with a gradient (from higher concentration to lower concentration
facilitated transport :
-movement of solutes across membrane with a gradient (from higher concentration to lower concentration dependent on presence of carrier proteins
o Requires special protein present in membrane that allow those molecules (bigger) to pass through membrane however they’re still going to do it without expendure of energy of cell and with gradient/along with gradient
active transport :
movement of solutes across membrane against a gradient : requires transport protein and uses energy
-o Energy used is ATP to move across
Membrane-assisted transport
endocytosis
exocytosis
endocytosis
- get into the cell
phagocytosis and pinocytosis
Phagocytosis
- The changing the deformation of cell membrane itself to wrap around big object like cell and engulf foreign material – result is a vacuole
- A way that some cells eat
- Old rbc gets recycled – engulfed then get rid of waste
- Big things big molecules
- Whole cells
- Wbc get rid of bacteria, invaders
Pinocytosis
- Difference is size
- Small molecules but lots of them
- Result is a vesicles
- Molecules
o Exocytosis
– out of the cell
• Protein needs to export
• Cell produce material inside vesicle then fuse with membrane then outs
Reverse of endocytosis
Chromatin :
genetic material : DNA and protein
Nucleolus
: condensed chromatin
site of RNA synthesis
Cell wall
- Most animal cells lack a cell wall
- plant have cell walls made of cellulose (polysaccharide)
- Bacterial cells have cell walls made of a polysaccharide : peptidoglycan
Hypertonic solution
- Cell shrink o Shrinking animal cell that doesn’t have a cell wall – ends with a shrank cell Crenation o Plant cell have a cell wall Cell membrane separate with cell wall Plasmolysis
Hypotonic solution
- Burst
o Lysis
Why if in hospital give IV – sugar, saline solution – give isotonic solution to introduce into bloodstream if not rbc will burst
isotonic solution
- has no effect on the passage of water into or out of the cell
ENERGY and ENTROPY
1st and 2nd Law of Thermodynamics :
Energy can neither be created nor destroyed only its form can be changed.
Changing energy from one form to another is never 100% efficient some energy will be lost as unusable heat.
Inefficient energy transfer tends to increase disorder or entropy in the universe.
- Measure of loss is entropy
COUPLED REACTIONS
Exergonic reactions are coupled with endergonic reactions in order for the energy released from the exergonic reactions to be stored or used in powering endergonic reactions.
exergonic
- Reaction that gives up energy
- Give up work – ergonic
Endergonic
o – require work/energy
why does the coupling of Exergonic and endorgonic with each other in biological system important
if not then energy produced cannot be used by cell to do work
ATP
: adenosine triphosphate is the chemical that cells use to transfer energy from one reaction to another
- main compound responsible for coupling
- energy currency of the cell
o Thing make everything else happen
- Anabolic reactions transfer energy from ATP to complex molecules
ATP and coupling
- Changes form in response to energy demand of cell
o Changes to ADP (last phosphate broken off)
Not attach to molecule – still in cell
Exergonic
anabolic
o Opposite happens when cell has energy derived from food
Captured by cell by taking phosphate mol floating around cell and bind it to ADP to form ATP
Endergonic
catabolic
o Energy requiring/energy releasing
o Molecule can be added to other reaction
Formation of protein comes from breaking down ATP
Energy coming from digestion – sugar break it down
• Reaction releasing energy and coupled with ATP
dynamic relationship
All chemical reactions are dynamic relationships between all the members of the reaction.
- AB -> A + B (vice versa)
o Spontaneously little of both happen
o Tendency lies in one direction or the other
dynamic equilibrium
Equilibrium represents the natural state of reactants and products. This is a dynamic equilibrium.
- Equilibrium favors of the products if tends more towards right than left
In most biochemical reactions, the equilibrium of the reactions lies with ? and why?
the reactants OR the speed of the reaction is too slow to be of any practical use
- Enzymes are
biological catalyst
-ENZYMES lower the ACTIVATION ENERGY of these reactions so they happen more often, with
greater ease.
- removes randomness of interaction
Catalyst
o – some other molecule that speads reaction up with out itself being changed by reaction
All molecules has a certain energy content; some compounds have more than others
exorgenic
-o Product AB have different energy content vs reactant – reactant bigger than product
Difference is energy released
All molecules has a certain energy content; some compounds have more than others
endorgenic
-o Reactant smaller than product – put energy into system
NATURE of ENZYMES
Proteins
: globular proteins , 3-D structure important in forming active sites
- 3d structrure shape – conformation
o Important in formation of active sit
Nature of Enzymes
-Active sites
: form and charges important for binding
- Spot on protein that binds the reactants (substrates)
o Subs – thing that enzyme is acting on
- Has to fit with it substrates as a lock and key (specific enzyme and compound)
Nature of Enzymes
-Substrates
= reactants ; specific for active site
- Thing that enzyme is acting on
Nature of Enzymes
- Endproducts =
products
NATURE OF PROTEINS AND ENZYMES
-The secondary structure of proteins is dependent on
-Hydrogen bonding
Environmental conditions which affect H-bonding will change the structure and function of the proteins.
- Hydrogen bond – weak, affected by a lot of different environmental condition specially heat and pH
NATURE of ENZYMES
Environmental factors affecting structure:
temperature
pH
ionic strength
Enzyme control
- Enzymes can be both activated and inhibited
- Inhibition : Competitive and Non-competitive
- action: degradative, synthetic reaction
Enzymatic action
- Degradative reaction
- Synthetic reactioin
- Both cases active cite is specifically formed to fit its starting material (substrate)
- Degradative reaction
o – taking substrate and breaking it up
Synthetic reactioin
-
o Take set of substrate/product and form a new one
Inhibition
o Competitive:
- reactants which look alike compete for the active site
Some other substance the thing that enzyme (looks like) but isn’t
One competes with proper substrate with active site
See most often with poisons
• A lot of insect venoms and reptile are competitive inhibitors in our bodies
Ends up getting stuck in active site
Not reversible; permanent inhibit enzymes
Neurotoxins
Inhibition
o Non competitive
Involves an allosteric site: regulatory site
Have regulatory site; something else binds with it
• Change shape of active site
o Prevents binding of substrate
• But rid of noncompetitive inhibitor - Goes back to shape
• Reversible
Advantage to cells
Feedback inhibition
Feedback inhibition
- Theres loops all over the cell
* Way of the cell controlling whats made or used without wasting resources
METABOLISM
: ALL THE REACTIONS THAT THE CELL USES TO GET ENERGY AND TO USE IT.
2 PARTS : CATABOLISM and ANABOLISM
CATABOLISM
THE REACTIONS THAT BREAKDOWN LARGE MOLECULES (CARBOHYDRATES) TO SMALLER MOLECULES (CARBON DIOXIDE and WATER) AND RELEASE ENERGY
ANABOLISM
THE REACTIONS THAT USE ENERGY TO MAKE LARGE MOLECULES (PROTEINS) OUT OF SMALL ONES (AMINO ACIDS)
METABOLISM
CATABOLIC REACTIONS and ANABOLIC REACTIONS
OCCUR WITHIN CELLS AT THE SAME TIME
OFTEN THE BY-PRODUCTS OF CATABOLISM ARE THE STARTING POINT (REACTANTS) OF ANABOLISM
Energy conservation
ATP
energy main transport ATP breaks off a phosphate becomes ADP o release energy o exorgonic o anabolism ADP captures phospate makes ATP o Capture energy o Endorgonic o catabolism o phosphorylation
o phosphorylation
the creation of a phosphate bond two ways that can be done in cell • 1. Substrate phosphorylations • 2. Oxidative phosphorylations o cell can make more of this
Difference in Eukaryotic and Prokaryotic
- Main difference whether or not there is a nucleus
- Prokaryotic – no nucleus but with DNA
o Dna is freee; floating around, quailed up by themselves - Eurkaryotic all DNA house in nucleus
Substrate Phosphorylation
ATP made from phosphate containing substances
Oxidative Phosphoryation
-ETS makes ATP from electron cascade
Generate ATP from ADM through oxidation, loss of electron and gain of Oxygen
GETTING ENERGY FROM CHEMICALS
The energy bound in carbohydrates is released by breaking down those chemical bonds to release the energy.
Carbohydrates are oxidized to carbon dioxide and water, releasing energy in the form of ATP.
REDOX Reactions
movement of electrons from one molecule to another
Oxidation Reduction
Oxidation
loss of electrons
- anytime substance is oxidized some other chemical is reduced
o can’t happen separately
o energy is trapped so it doesn’t get lost as heat
Reduction
gain of electrons
There are three parts to cellular respiration: (aerobic respiration)
Glycolysis
Krebs cycle
ETS (electron transport system)
Glycolysis
glucose is broken down into pyruvic acid (pyruvate) releasing electrons (NADH) and ATP. - Simple sugar like glucose (monosaccharide) broken down half, into compound pyruvic acid o) Cells gets out two things 1. 2 ATP 2. 2 NADH substance getting reduce reduced electron carriers - next step is Krebs Cycle
Krebs cycle,
pyruvate is oxidized to CO2 releasing more electrons.
- 1. 2 NADH
- 2. [2 CO2] (get rid of waste product) turn all sugar into CO2
- 3. 6 NADH
- 4. 2 FADH2
- 5. 2 ATP
- 6. [CO2] reduced
- all carbon is now waste product broken down into inorganic compound
- The ATPs has been produced through substrate phosphorylation (produce a little bit of energy)
o comes from reduced electron carriers
- use sugar to get energy not to build anything
ETS
the released electrons are used to make ATP.
- Electron transport system
- way of moving electrons through the cell in such a way that flow of electrons produces enough energy so that the cell make ATP (like electricity through wire produce work)
Glycolysis
Glucose(6C) to 2 pyruvate (3C)
2 ATP
2NADH (4e-)
transition step (inside mitochondria)
2 pyruvate (3C) to AcetylCoA (2C)
1 CO2 x2
1 NADH x2
Krebs Cycle
AcetylCoA to CO2 2 CO2 x2 3 NADH x2 1 FADH2 x2 1 ATP x2
ETS ( Electron Transport System)
NADH and FADH2 are used as electron sources to power the formation of ATP in the mitochondria
- System requires a membrane
- System uses cytochromes (pigments) each goes through oxidative and reductive state
This system requires oxygen as a final electron acceptor. Results in the formation of H2O
- final dumping ground from all electron
- oxygen gets turn into water
- Movement of electrons through the chain causes H ions to be pumped out of mitochondria
- Proton-motive force causes ATP to be made by ATP synthase
C6H12O6 + O2 –> CO2 + H20
o Co2 from carb – oxidized to co2
o oxygen reduced to water
o oxidative phosphorilation
dependent upon membrane of mitochondria
32 total ATP
makes more than substrate
all sugar used left only with CO2 and H2O
o include how much energy is getting out 36 ATPs
start out with 36 ADP + 36 phosphate
transfer energy bound from uptop to energy bound to ATP
all reaction happens inside cells most atp from ETS some in kreb cycle
Energy efficiency
If glucose is completely converted into ATP :
36 ATP per glucose
Then the energy conversion is approximately 39%. In other words, 39% of the energy trapped in glucose ends up in ATP. (36 ATP) rest go to heat in environment
Balanced Equation of aerobic/cellular respiration
C6H12O6 + 6O2 –> 6 CO2 + 6H2O
CATABOLIC STAGES
- 3 stages to catabolism
- Hydrolytic stage
- Degradative stage
3 Oxidative Stage
CATABOLIC STAGES
1. Hydrolytic stage
-o (breaking up bigger molecules into smaller one)
- happens outside the cell: breakdown of large polymeric molecules
- enzymes (proteins excreted from cells work outside cell environment: exoenzymes
starch to sugar
proteins to amino acid
lipids (triglyceride) to fatty acids
CATABOLIC STAGES
2. Degradative stage
- happens in the cytoplasm
- ATP made by substrate phosphorylations
glycolysis
krebs cycle
the end process of 1st stage goes trhough process in 2
CATABOLIC STAGES
3. Oxidative
-o happens in mitochondria
- ATP made by oxidative phosphorylation
• Electron flow is producing ATP
• end result of ETS is always ATP production
• requires oxygen
CATABOLISM and ANABOLISM
ATP produced during catabolic reactions is used to make new cell material
The starting materials for these synthetic reactions are the intermediate compounds of glycolysis and the Krebs cycle.
This is the cell’s METABOLIC POOL
Examples of metabolic pool :
- Cells need to make new cell membranes in order to divide. These cell membranes need fatty acids to make phospholipids. The fatty acids are made from acetylCoA.
- Some organisms synthesize their own amino acids from various Krebs cycle intermediates like -ketoglutarate.
- If metabolic intermediates are used they need to be replaced: the pool has to stay full.
- both for respiration and build new cell material
- pool always has to stay full
- needs to be balanced; cells needs for growth, and need for energy
Anaerobic growth
- some organisms do not respire in the presence of oxygen, o2 represent a toxin to these organisms
- ATP is derived from oxidative phosphorylation without O2
- Instead of dumping electrons to O2 they dump them into Nitrate NO3, SO4 sulfate, and carbon CO3
- Other compounds are used in place of O2: nitrate and sulfate are often used instead
- sulfate reducing organisms give off foul smells associated with H2S and other reduced sulfur compounds
- NO3 –> N2 up
- SO4 –> H2S up steam mud
- CO3 –> CH4 up swamp gas (methane) stagnant water
- Single cell organisms bottom of stream, mud
ALTERNATIVES TO RESPIRATION
Aerobic respiration requires O2 to generate ATP. When organisms run out of O2 or aren’t able to get enough of it there are alternatives that cells use to keep on making energy.
What is it?
- Some cells has ability to keep running withough oxygen
o fermentation
Fermentation
- Reduction of pyruvate to alcohol or lactic acid.
- Produces little ATP but without the need of O2
- Fermentation efficiency: 2.1%
- end result is inorganic compound
- efficient is reduced not all glucose produced as ATP, most goes to waste products
Example of Fermentation
- happens with yeast (alcohol produced), muscle tissues (blood system fails to keep up enough o2 to the energy demands of those cells,
- animal cell: end product: build up of lactic acid in muscle cells
o pain stimulant – nerve pain
o pain stays until blood system restore balance
Why fermentaion is an alternative to respiration when there is no oxygen?
- Some cells just die
- Some organism can do this
- Yeast indefinite produce
Autotrophs
- Not all
- Most do, all eukaryotic do Photosynthesizes
o Algae
o Plants
o Cyanobacteria
o All produce oxygen
o Oxygenic photosentizer
Waste product
Photosynthesis
- capturing sunlight
- conversion to chemical energy
- using energy to convert inorganic carbon (low energy) into organic compounds (high energy)
Photosynthesis
2
CO2 (air) + H20 (soil/roots) = C6H12O6 (sugar) - Byproducts oxygen produced in excess - Balance by o 6CO2 + 6H2O CH12O6 + 6O2 o (reversed cellular respiration) o Endorgonic Use ATP to make it happen o Sunlight Convert to Atp o CO2 to C6H12O6 Atp power this
Where does it happen (photosynthesis) :
chloroplasts (organelle)
chloroplasts (organelle)
- Substructure of another cell/ always inside of another cell
- Consists layer of membrane: thylakoid
Thylakoid
o Inner most
Contains chlorophyll
Pigment responsible capture most sunlight
Two reactions to photosynthesis
Light and dark reactions
Reactions dependent on light striking the plant or independent of light striking them
Light-dependent and light-independent reactions
Radial -> chemical energy (light)
The light reactions are those which require the radiant energy of the sun
The dark reactions are those which do not require this energy
Light reactions
Capturing the energy of light depends on molecules which absorb light and transfer that energy to electrons : pigments
Pigments in green plants :
chlorophyll (green), carotenoids (orange)
o Pigments in most part are proteins
o Lots of chemicals are pigments
o All pigments have is the ability to absorb light and reflect light differentially
Absorb light in one set of color and emit light in different set of colors
Differential absorbance
Electromagnetic spectrum
- Form of radation energy
- Dependent upon wavelength
- Short to Longer wavelength –
o Measure from peak peak, through to through
o All red light have same wavelength
o Travel in meter
o Gamma – nano
- (Visible light)
o Small portion
o 350-750 nm
o Increase wavelength goes from violet to red
o Gets struck by different wavelength in equal amount
See it as white light
More than one – perception of color is different
o Pigments are any substance that absorb set of radiation differentially
Absorb some more than others
What happens to absorbed energy
- Used in an electron transport system
Photosystem – thylakoid
- Absorb energy ends up being transferred to electron
- Absorptioin of sunlight/radiant energy changes energy level of electrons in pigments from lower lvl to higher level
- Electron transfers energy to transfer system that makes ATP
o ADP + P = ATP
Electron transport systems
- responsible for converting electron energy into ATP
- consist of protein-like molecules (cytochromes) that act like electron shuttles
- High energy electrons are passed from one to another cytochrome until enough energy has been accumulated to produce ATP
- Flow of electrons in ETS system to make ATP
- All electron ends up as NADPH (in respiration it goes to O2)
Where does NADPH, ATP gets made
o outside of thylakoid
Stroma
**important parts of light - dependent
- Sunlight must be present
- ATP is made through oxidative processes
- Water H2O is a source of electrons
- As a result O2 is a waste product
- Cell is making
o ATP and NADPH - Take place in thylakoid
o Dependent on intact thylakoid membrane
o If ruptured nothing will happen
Light –Independent Reactions
-don’t need light to be present to do anything
CO2 -> C6H12O6 (carbon-sugar)
CO2 -> C6H12O6 (carbon-sugar)
- Need water and ATP and source of electrons coming from NADPH
- Products of light dependent reactions will be used to create sugar
- All happens in stroma of cell
- Reaction is called the Calvin-Benson cycle
Calvin-Benson cycle
o First product out of calvin benson cycle in a normal plant is a C3 compound
Normal photosynthesis in normal plants is called C3 plants
o Divided up as a set of reactions that has 3 parts
1st CO2 fixation
2nd part is Carbon reduction
Last part is regeneration
1st CO2 fixation
• Where C02 gets bound to all organic molecules
2nd part is Carbon reduction
• Where sugar is made
Last part is regeneration
• Restoring first compound
Both Light-dependent and Calvin Cycle takes place when?
Each takes energy and NADPH – use up all energy
Cycle Calvin takes place co2 is present
Light takes place as long as sunlight is present
Purpose of photosynthesis is to make?
o Photosynthesis makes food sugar
Light almost constant of energy, a lot more produced, can be used
Plants store excess sugar
Other things eat plants to get excess production
-cellular respiration get energy from sugar (mitochondria)
Stroma
– liquid suspending thylakoid
what is the enzyme responsible for CO2 fixation
Rubisco
: about 50% of all the protein in chloroplasts
6CO2 + 6 H2O C6H12O6 + 6O2
Overall reaction
6CO2 + 12H2O -> C6H12O6 + 6O2 +6H2O
Gas Exchange
- Photosynthesis is propelled by gas exchange
o By pores of leaves
o CO2 has to go to leaves and O2 has to come out
o Space filled up with water
o Xylem conducts water from roots to leaves
o if water dissipates more than ability to make – plants wilts
Transpiration
• If too high; plant wilts (gets too hot)
• When lights striking leaf gets too hot it closes
o Gas balance is not balanced
o Cell is still photosynthesizing
o Build up of O2 in intercellular space/ closed pores cant go out
• Under high transpiration
o Closed stoma
o Low CO2 and Hight O2
o The calvin cycle doesn’t work
CO2 fixation only happens if theres High CO2
Runs backwards; starts chewing up sugar and producing more CO2 – not good for cell
o High Temperature and Low Humidity
C3 plants (normal) don’t function on high transpiration and shutdown
o Tropics
o Plants evolved in different system in order to continue to photosynthesize – C4 plants
Corn, sugarcane
tropical grasses
o If water is not abundant
CAM plants Close stoma Cant run calvin cycle Plants evolved to do calvin cycle at two different times Because of cooler temp – stoma opens – night time • When 1st step of calvin cycle happens • CO2 fixation Day time • After CO2 fixed • Where greatest need of ATP and NADPH o Calvin cycle finishes Cactus Low moisture area – lots of light
- Difference in C3 C4 and CAM plants
Calvin benson cycle
o C3
Everything happens same time same place
o C4
Spatial separation of CO2 fixation vs Rest of cycle
Separate cells
o CAM
Temporal/time separation of CO 2 fixation vs rest of cycle
Pineapple
- Endnn result Sugar
Where is ATP produced in photosynthesis
chloroplast
Where is sugar made during photosynthesis
stroma of the chloroplast
