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Photosynthesis Crash Course Biology:

● Two sorts of reactions in it: light-dependent and light-independent (Calvin cycle)

● Respiration in reverse

● Needs water, carbon dioxide and sunlight

● Water: roots absorb water which gets carried around by xylem tissue

● CO2 travels in and O2 diffuses out by stomata

● Photons absorbed by pigment called chlorophyll

● Chloroplast has thylakoid which store chlorophyll, and are stacked into grand and have lumen

inside (the outside is surrounded by a fluid called the stroma)

● Light-dependent reactions: photons hit the chloroplast and an electron in the photosystem II gets

excited (“photo excitation”), which is then transported into the electron transport chain (where

energized electrons lose their energy in a series of reactions that capture the energy necessary to

keep life living)

● The missing electron in PSII splits the water molecule to take its electron and releases H+ ions

and oxygen (which diffuses out of the stomata)

● Electron goes into the cytochrome complex (and that pumped proton into the thylakoid)

● The thylakoid gets filled with positive energy from H+ ions and protons which want to escape and

so they go through the ATP synthase, which attaches a phosphate to an ADP molecule making

ATP (cellular energy)

● The electron then goes into PSII to energize the electron which makes NADPH which combines

H and NADP+ through an NADP+ reductase

● So at the end we have… ATP and NADPH and also oxygen

● Next… Calvin cycle (light-independent reactions) - takes ATP and NADPH to make glucose

● Happens in storm

● A carbon dioxide atom is fixed onto RuBP (5 carbon molecule) by an enzyme called Rubisco

which makes it unstable as its a 6-carbon chain

● It breaks into 2 molecules of a 3 Carbon molecule

● Then in the reduction phase ATP and NADPH is added, making 2 G3P molecules (3 C

compound)

● G3P is a basic molecule that can be made into many carbohydrate forms like glucose, cellulose

and starch

● Rubisco - due to being in a high O2 and low CO2 environment - started being confused and

adding O2 to RuBP creating a toxic byproduct and RuBP (bad design)

●

Bozeman Science Photosyntheiss Facts

1. Photosynthesis gives oxygen

2. Photosynthesis gives food

3. Found in bacteria, algae, protests plants, etc.

4. Site in eukaryotic cells where in happens: chloroplasts

5. Thylakoid: inside chloroplast where light reactions take place

6. Grana: stacks of thylakoid

7. Stroma: t

8. he fluid part where thylakoids are: light-independent reactions take place

9. Leaves contain many pigments like chlorophyll, carotene, etc.

10. Chlorophyll absorbs red and blue light but don’t really absorb green (they reflect it)

11. Equation: 6H2O + 6CO2 + light —> C6H12O6 + 6CO2

12. Changing the arrow makes it cellular respiration equation

13. “Photo”- light reaction (thylakoid membrane), “synthesis”- Calvin cycle (storma)

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AP Bio Notes

Photosynthesis Crash Course Biology: ● Two sorts of reactions in it: light-dependent and light-independent (Calvin cycle) ● Respiration in reverse ● Needs water, carbon dioxide and sunlight ● Water: roots absorb water which gets carried around by xylem tissue ● CO2 travels in and O2 diffuses out by stomata ● Photons absorbed by pigment called chlorophyll ● Chloroplast has thylakoid which store chlorophyll, and are stacked into grand and have lumen inside (the outside is surrounded by a fluid called the stroma) ● Light-dependent reactions: photons hit the chloroplast and an electron in the photosystem II gets excited (“photo excitation”), which is then transported into the electron transport chain (where energized electrons lose their energy in a series of reactions that capture the energy necessary to keep life living) ● The missing electron in PSII splits the water molecule to take its electron and releases H+ ions and oxygen (which diffuses out of the stomata) ● Electron goes into the cytochrome complex (and that pumped proton into the thylakoid) ● The thylakoid gets filled with positive energy from H+ ions and protons which want to escape and so they go through the ATP synthase, which attaches a phosphate to an ADP molecule making ATP (cellular energy) ● The electron then goes into PSII to energize the electron which makes NADPH which combines H and NADP+ through an NADP+ reductase ● So at the end we have… ATP and NADPH and also oxygen ● Next… Calvin cycle (light-independent reactions) - takes ATP and NADPH to make glucose ● Happens in storm ● A carbon dioxide atom is fixed onto RuBP (5 carbon molecule) by an enzyme called Rubisco which makes it unstable as its a 6-carbon chain ● It breaks into 2 molecules of a 3 Carbon molecule ● Then in the reduction phase ATP and NADPH is added, making 2 G3P molecules (3 C compound) ● G3P is a basic molecule that can be made into many carbohydrate forms like glucose, cellulose and starch ● Rubisco - due to being in a high O2 and low CO2 environment - started being confused and adding O2 to RuBP creating a toxic byproduct and RuBP (bad design) ● Bozeman Science Photosyntheiss Facts

Photosynthesis gives oxygen
Photosynthesis gives food
Found in bacteria, algae, protests plants, etc.
Site in eukaryotic cells where in happens: chloroplasts
Thylakoid: inside chloroplast where light reactions take place
Grana: stacks of thylakoid
Stroma: t
he fluid part where thylakoids are: light-independent reactions take place
Leaves contain many pigments like chlorophyll, carotene, etc.
Chlorophyll absorbs red and blue light but don’t really absorb green (they reflect it)
Equation: 6H2O + 6CO2 + light —> C6H12O6 + 6CO
Changing the arrow makes it cellular respiration equation
“Photo”- light reaction (thylakoid membrane), “synthesis”- Calvin cycle (storma)

Water and CO2 and light are reactants
Oxygen and glucose are products
Light reaction: water and light goes in - making o2 and ATP and NADPH
Light-independent reaction: takes in ATP and NADPH from light reaction and CO2 from atmosphere to make sugars
Proteins with chlorophylls in it :photosystem II and photosystem I
photorespiration: when we do not have enough CO2, O2 jumps into the Calvin cycle and using rubisco forms a chemical with no purpose and the cell has to break it down
C3 plants: G3P (3 carbon molecule) - photorespiration bad
Evolutionary solution: CAM plants: only open stomata at night and take in CO2 and make into malice acid. In daytime, close stomata (to not lose water) and take the CO2 from malice acid from photosynthesis
Another solution: C4 plants: take in CO2 and makes it into a four carbon molecule which also goes through the Calvin cycle Cellular Respiration Video Notes:
Takes place in mitochondria
Needs oxygen
Taking food and breaking it down in the process of oxygen to make ATP
Bacteria can also do respiration (aerobic) - no need mitochondria
When you run, you use respiration to make energy (ATP)
Two types of respiration - aerobic (with oxygen) and anaerobic (can be used for sprints but creates painful lactic acid)
Respiration - for heterotrophs: taking organic compounds and converting into CO2 and water (making ATP)
Autotrophs - convert co2 and water back into organic molecules. But plants also do cellular respiration
Equation: C6H12O6 + 6O2 —> 6CO2 + 6H2O + ATP
Oxygen pulls electrons close to it: huge amount of energy found in it.
Done in mitochondria, in a controlled process
Parts: folds on the inside (crustal), inner membrane, outer membrane, inter membrane space, DNA, ribosome, matrix inside inner membrane
3 steps in cellular respiration: glycolysis, Krebs cycle, electron transport chain
Glycolysis - outside mitochondria (in cytosol)
Glycolysis breaks glucose (6 C molecule) into 2 pyruvate (3C molecule). Makes net 2 ATP. Makes NADH (electron carrier)
Pyruvate diffuses into mitochondria and makes acetyl coA (2 C molecule) , releases 1 C - made into CO2 (1/3 of total Carbon dioxide output of cellular respiration)
Acetyl coA goes into Krebs cycle, breaks down further and the 2 carbons are given off as CO2, produces 2 ATP. Adding energy to NADH and FADH2 - high energy electron carrier
Electron Transport Chain - NADH and FADH2 transfer its electrons to electron transport chain - move through series of proteins and energy from it is used to pump protons into inter membrane space, the electron is added to other H+ protons and oxygen (last electron acceptor) to make water. Makes 32-34 ATP
The H+ ions accumulate in inter membrane space and want to diffuse out, can only do this by ATP synthase. Every time a proton goes through, attaches a phosphate to ADP to make ATP.
Problem: what happens if you don’t have oxygen/ mitochondria? We can still have glycolysis to make ATP but NAD+ is used up to make NADH and NAD+ is not available to be a part of glycolysis - and it shuts down glycolysis.
Solution: anaerobic respiration! Two types: lactic acid fermentation and ethanol fermentation

The process of cellular respiration has three main parts: glycolysis, Krebs cycle and the electron transport chain
If you don’t have oxygen, heterotrophs can do another process: fermentation
Thing to understand: evolution. Autotrophs don’t make food for us - they make food for themselves, so they also need to go through cellular respiration to attain ATP after they’ve done photosynthesis/ chemosynthesis
It’s a cycle: cellular respiration breaks down glucose and oxygen to make co2 and water (and ATP) and then photosynthesis uses carbon dioxide and water to make glucose and oxygen once again.
Chemosynthesis occurs where there isn’t much light… where? Deep under the ocean. There are organisms that take in hydrogen sulfide, carbon dioxide and water and within them there are certain bacterias in their gut that make simple sugars out of those. Doesn’t require light at all.
Fermentation is the process in which cells make ATP without using oxygen… which cells? Cells like yeast usually use alcoholic fermentation but cells in our body usually do lactic acid fermentation
Photosynthesis’s Equation: 6H2O + 6CO2 + light —> C6H12O6 + 6CO
Photosynthesis takes the energy within the carbons and hydrogens and creates a molecule that stores energy within its hydrocarbon bonds.
“Photo”- light reaction (thylakoid membrane), “synthesis”- Calvin cycle (Stroma)
Site in eukaryotic cells where in happens: chloroplasts
Thylakoid: inside chloroplast where light reactions take place
Grana: stacks of thylakoid
Stroma: the fluid part where thylakoids are: light-independent reactions take place
Light reaction: water and light goes in - making o2 and ATP and NADPH
Light-independent reaction: takes in ATP and NADPH from light reaction and CO2 from atmosphere to make sugars
Mitochondria has many parts: inner membrane, outer membrane, crustal, inter membrane space, matrix
Glycolysis happens outside the mitochondria
Krebs cycle happens in the inner matrix
Electron transport chain takes place along the inner membrane
Glycolysis - 6 C glucose molecule broken down into 2 3 C pyruvate and energy in terms of NADH
Krebs cycle releases NADH and FADH2 as well
These molecules are used in the ETC
The electrons travel down a “chain” just like in photosynthesis and this pumps protons (H+ ions) into the inter membrane space - which diffuse out by the ATP synthase producing ATP and also making H2O Bozeman Science - Positive and Feedback Loops
Negative feedback loop - brings you closer to your target set point when you get away from the “normal state”
Negative feedback loop is what keeps us alive
Negative feedback eg: cars going too fast - slow down, cars going too slow - go faster
Negative feedback eg 2: We have a lot of ATP! Slow down ATP production. We don’t have enough ATP, AMP is too high, we need to make ATP!
Negative feedback is opposite - if too high, helps get low, if too low, helps get high
Negative feedback brings you to homeostasis, positive feedback brings you further and further from homeostasis
Feedback loops - target setpoint trying to reach/ get away from
Negative feedback loops - Stabilize, eg: temperature regulation
Positive feedback loops - Amplification

Alterations in feedback loop leads to tragedy, eg: diabetes (problem in creating or regulating insulin)
Homeostasis - internal stable environment
Eg: maintaining body temperature, blood glucose level, osmolarity of blood through feedback loops
Ectotherms (internal temperature is the same temperature as external temperature)
Exotherm (keeps an internal constant temperature - keeps same exact rate of metabolism, eats a lot more to keep same body temp)
In humans, negative feedback loops are used to regulate body temperature, human body - 37 degrees celsius. Body needs to maintain that temperature. We use negative feedback loop.
If the human body is too hot - we sweat it out. As water molecules evaporate, that will carry some heat away
If human body too hot - blood goes to the surface of your skin, heat dissipates away, vasodilate (that's why people look red in summer)
Mammals with fur - fur will lay flat to lose temperature to lose heat by convection
If body too cold - get goosebumps , which stand hair up on end and pulls skin in
If the body is too cold - vasoconstrict. Blood vessels will close, body doesn't want blood to get too cold so we pull those in so we have less convection and body heat is gonna increase
How do we freeze to death? Vasoconstriction - body wants to keep heart and brain running so it starts sacrificing extremities like fingers and toes, so those body parts can get frostbitten
Positive feedback loop eg: fruit on tree. Target set point is to ripen the fruit to attract seed dispersers. ● Plant hormone called ethylene C2H4 given off by ripe fruit, picked up by apples next to it and cause apples other than them to ripen as well ● “One bad apple ruins the whole thing” - positive feedback!
Positive feedback loop amplifies
[not really from video] Positive human feedback, eg: childbirth. Their contractions start slowly, then the contractions get closer and closer and closer and closer - the endpoint is birth. It’s started by the baby’s head.
[not really from video] Second example: eg: menstruation - eggs grow and grow and grow and grow - until the endpoint is menstruation!
Negative feedback - opposite + target point
Positive feedback - there's always an endpoint
Type 1 diabetic - beta cells don’t work/ are destroyed. So blood glucose keeps going up and up and up and there’s no insulin to control it. Increases blood pressure, circulation problems, nausea, vomiting, loose toes/ feet as there's so much blood sugar that oxygen doesn't make it to extremities.
Type 2 diabetic - you’ve had too much glucose your whole life, lack of exercise - system gets tired and doesn’t recognize insulin as well as it did
How can we solve that problem? Insulin shots. Insulin shots throughout the day can regulate blood glucose.
90 - 95 percent of diabetes is type 2. Negative Feedback Loop: Blood Glucose Level (Essay) ● Describe the negative feedback loops of blood sugar regulation in humans using keywords Blood glucose: amount of glucose moving around your body, storing, usage in ATP
Hormone regulators are insulin and glucagon (the one that we have problems with)
Blood glucose goes up, insulin released, blood glucose goes down (negative feedback loop)
Blood glucose goes up when we eat carbohydrates/ foods with high glycemic index
Blood glucose goes down when we skip a meal

Group 7: Halogens. Have 7 valence electrons.
Why is water H2O? Oxygen has 6 valence electrons need 2 more to be stable, so shares 2 electrons with 2 hydrogens.
Why is life made of carbon? Because it has 4 valence electrons and can make strong bonds. Water - Liquid Awesome (Crash Course Biology 2)
Only substance on the planet that occurs naturally in solid, liquid and gas forms
Bond between two hydrogen atoms and one oxygen atom
Structure: H2O. Two hydrogens, each sharing an electron with oxygen in a covalent bond
V- shaped
Oxygen is greedy for electrons so slightly negative, and hence hydrogens are slightly positive (polarity of the molecule)
Because of the polarity they stick together (hydrogen bonds)
Hydrogen bonds - slight positive charge from a hydrogen atom is attracted to the slight negative from a oxygen atom (weak bond)
Result of hydrogen bonds: cohesion and hence surface tension
Cohesion: attraction between two like things. Eg: one molecule of water and another molecule of water
Water has highest cohesion of all non-metallic liquids
So if we put water in some wax paper, it beads up and holds strongly to itself. So... it likes to adhere more to itself than to the wax paper. When it is on wax paper, the water molecules like to configure to create a formation that creates the least amount of surface area - which creates surface tension
Water also does adhesion - sticking to other things. Eg: is we pour water on glass it spreads out instead of beading up because water is more adhesive to the glass than it is cohesive to itself
Adhesion: attraction between two different substances. Eg: water molecule and glass
Because of these properties water can do capillary action
Eg: if we are picking up water by a glass straw
Because of adhesion, the water molecules are attracted to the molecules in the straw. But as this molecules stick to the straw by adhesion, other nearby molecules follow by cohesion, following the first fellow water molecules. The surface tension continues to make the water molecules rise up the straw until eventually gravity pulls it back down
Since water = polar, its a good solvent (can dissolve in water).
Substances that can dissolve in water - hydrophylic and polar. And its polarity is stronger than the cohesive forces within water.
So the polar molecules interact with water and with its forces they break the cohesive little hydrogen bonds and form bonds with the water.
Hydrophobic substance - lack charged poles. Don’t dissolve because it can’t break water’s cohesive forces and are pushed out of water.
Ice is less dense than liquid water
Why? Because of hydrogen bonds. As the temperature reaches 0 degrees celsius, water takes on a crystalline structure that evenly spaces the water molecules further apart but holds them in a stronger structure (making ice which is less dense than liquid as it is spaced apart)
Importance: if ice was more dense than water, ice would sink and destroy ecosystems that life underwater even during the cold winters. Also if ice sank then sea levels would rise and we won’t have land
Water has a very high heat capacity - really good at holding onto heat
Because of that, it takes a lot of energy to heat up and cool down oceans which is a good thing because it stops sea levels rising/ falling too quickly.
Also oceans regulate temperature as it keeps it a constant because its hard to heat up water
On a smaller scale: its much easier to heat an empty pot than a pot filled with water

When sweat evaporates from your body, it cools you down. Because when you are warm, your body releases water particles which break the cohesive hydrogen bonds and evaporate, taking the heat energy as they go and leaving you cooler. Water (A Polar Molecule) - Bozeman Science
Polar? Substance with a charge (Electrons are shared unqeually) Evolutionary Significance of Cell Communication:
How cells talk to one another: cell communication
Symbiosis : two creatures live tat
Eg: symbiosis vibrio fischeri and bobtail squid
bioluminescence bc have bacteria
Bobtail squid feed the bacteria
Cell communication different roles is single cell or multi cellular
Single cell: must have communication between all bacteria by sensing environment
Multi cell: all cells in organism must communicate to be on same page
Single cell: environmental response. Eg: quorum sensing
Multi - cell: coordinate activities. Eg: epinephrine in glucose breakdown
Signal transduction pathways in single and multi is similar
Vibrio fisheri: planktonic (live by itself) - don’t glow
Vibrio fisheri: colonial (live together) - glow
How do they control that? Quorum sensing
Eg: if you have one bacteria. It gives off proteins called autoinducers.
Since its just one bacteria, the odds of it hitting another bacteria is really low.
But if you have more bacteria, so more autoinducers, eventually… autoinducers will be picked up by other bacteria.
Sets up a signal transduction pathway (series of chemical reactions that cause them to do something, eg: produce a protein)
Glowing bacteria makes protein called luciferase (are enzyme) breaks down luciferin and makes a glow.
The luciferase moves through diffusion and triggers cascade (positive feedback).
If numbers drop off, less autoinducers, less luciferase, glow stops.
Quorum sensing - shows the population density
Constraints in eukaryotes? Need to get all cells to work together.
Eg: endocrine system. Adrenal gland near kidney has a adrenal medulla which gets a message from brain called Flight or Fight response - which secretes a chemical called epinephrine.
Epinephrine sets up signal transduction pathway in all cells
Releasing epinephrine starts a cascade of events in the cell, using cyclic AMP and MRNA is transcripted, phosphatase creates and creating glucose from glycogen
Epinephrine goes through a phosphorylation cascade and uses cyclic AMP as a secondary messenger and transcripts MRNA and makes a protein/enzyme phosphatase which goes to glycogen and breaks it down into glucose
One chemical message can start signal transduction pathway
Works the same way using luciferase
We use communication to sync single celled environments with environment and coordinate

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