• Surround all cells and organelles
• Function to seperate compartments
• Control molecular traffic in and out

• Proteins are embedded in the phospholipid bilayer
• The proteins have a hydrophobic region in their middle section that keeps them embedded

• The phospholipids move freely- they can move within bilayer in all directions (laterally and flip-flop)
• The proteins float freely in the lipids

• Level of saturation of the fatty acid tails (saturated fatty acids make the membrane less fluid than unsaturated ones)
• The temperature (cold temperatures make the membrane less fluid than warm temperatures)

• Bunch of different proteins that are embedded in the fluid matrix of the lipid bilayer
• Two types: peripheral or integral

• A part of the membrane that stretches across the bilayer (goes from one side of the membrane to the other)
• It must have a hydrophobic region to keep it integrated into the bilayer

Transporters 

Enzymes

Cell surface receptors

Cell surface identity markers

Cell-to-cell adhesion proteins

Attachments to the cytoskeleton 

Because proteins have to be oriented correctly (specific side facing out and specific side facing in) to function

Sugar groups can be attached to the outside

Apolar molecules

O2, CO2, hydrocarbons

Small, uncharged polar molecules (H20)

Hypertonic

Hypotonic

Isotonic

They can directly cross through the lipids (passive transport)

 They can cross through a protein (active transport)

• Happens with or without a protein
• No energy is required
• Moves from high to low concentration gradient
• Spontaneous via diffusion
• Molecules diffuse independently of each other

• Must have a protein
• Requires energy (ATP)
• Can go against concentration gradient (low to high)

Type of passive transport

Uncontrolled movement across the membrane

Type of passive transport

Makes use of a channel or carrier transport protein

• Allows a specific molecule or ion to cross the membrane based on its size and shape
• Very specific for their transport molecule
• When right molecule binds this protein changes shape and allows the molecule through

• Example of Active Transport
• Moves protons outside of the cell against their concentration gradient
• This movement of protons creates a membrane potential, and an electrochemical (charge) gradient (positively chargen on one side and negatively charged on the other)

Uniporters

Symporters

Antiporters

A type of carrier protein used in active transport

Moves one molecule at a time

A type of carrier protein used in active transport

Moves two molecules in the same direction

A type of carrier protein used in active transport

Moves two molecules in opposite directions

• An active transport mechanism
• Uses an antiporter to move 3 Na+ out of the cell and 2 K+ into the cell
• The affinity (dictates which molecule the protein will transport at a given time) of the carrier protein for either Na+ or K+ changes so the ions can be carried across the membrane

Transport of many substances

It's accomplished by either endocytosis or exocytosis

A way to perform bulk transport

Movement of substances into the cell

Phagocytosis

Pinocytosis

Receptor-mediated endocytosis

Type of Endocytosis

The cell takes in particular matter

Type of endocytosis

The cell takes in only fluid

A way to perform bulk transport

The movement of materials out of the cell

Anabolism

Catabolism

Most of the reactions in these two types are catalyzed by enzymes

Type of Metabolism

Synthesis reactions (building something)

Type of Metabolism

Decomposition reactions (breaking something down)

• Potential energy
• Kinetic energy
• Chemical energy (energy in bonds)
• Radiation energy (light)
• Nuclear energy
• Heat (kinetic energy of molecules)

Most forms of energy can be converted to this type

It's measured in kilocalories (1 food Calorie = 1 kilocalorie = 1000 calories)

Law of enegy conservation

Any form of energy can be transformed to other forms of energy, but energy is never created or destroyed (sum of all energy is alwayss the same, it's never lost, just converted)

Disorder is more likely than order

Entropy (disorder in the universe) is always increasing

{disorder happens spontaneously, organization requires energy}

• An increase in disorder (entropy gain)
• Less "useful" (free) energy

Exergonic Reaction

Endergonic Reaction

Ribose (5-carbon sugar) + adenine + three phosphates

The energy is stored in the bonds between the phosphates

Phosphates are highly negative so they repel eachother

It takes a lot of energy to hold them together so when that bond is broken all that energy is released

• Molecules that catalyze reactions in living cells
• Most are proteins
• They lower the activation energy required for a reaction (make it easier for the reaction to occur)
• They are not changed or consumed by the reaction

• Enzymes are very specific
• They accelerate one particular reaction
• Specific substrate fits into the Enzyme's particular active site

• add energy to a reaction
• change the amount of free energy needed for a reaction to occur
• change the equillibrium
• get changed in the net reaction 

• Enzyme concentration
• Substrate concentration (lots of substrates then all the enzymes are busy)
• Environment
• Regulatory molecules

• Enzymes are normally found in environments that have its ideal conditions
• Change in pH, temperature, regulatory molecules can impact how an enzyme works (potentially destroying its 3D shape and rendering it useless)

Inhibitors

Activators

Cofactors

Competitive

Noncompetitive

Autotrophs

Heterotrophs

It's what all organisms use to extract energy from organic molecules (ex. glucose to ATP)

Occurs in all tissues at all times

1. Glycolysis
2. Pyruvate Oxidation
3. Krebs Cycle
4. Electron Transport Chain
5. Chemiosmosis

2 C3 sugars

Created in glycolysis when the C6 sugar glucose is broken in half forming these 2 C3 sugars

2 C0₂, 3 NADH, 1 ATP, 1 FADH (multiply by 2 to figure out "per glucose")

No Glucose left at the end of this cycle

• Gets its electrons from the NADH and FADH
• Electrons lose energy as they go through it
• Results in proton gradient
• Electron is given to O₂- "aerobic respiration"

• Protons passed back into inner mitochondrial membrane through the ATP synthase protein
• For each proton that comes through ADP +P is changed into ATP

38 ATP per glucose for bacteria

36 ATP per glucose for eukaryotes

• Respiration without O₂, uses organic molecules (instead of O₂) as the final electron acceptor
• Ex. ethanol, lactic acid
• Very inefficient
• Only has glycolysis step so only 2 ATP created

Ex. Humans and yeast

They can "switch over" to fermentation when O₂ is not available

Light-dependent reactions

and

Carbon fixation reactions

In the thylakoid

Capture energy from sunlight

Make ATP and reduce NADP+ to NADPH

In Stroma

Use ATP and NADPH (from light reactions) to make organic molecules from CO₂

Calvin Cycle in this

• Light is radiation from the sun (electromagnetic spectrum)
• Visible light is either reflected, transmitted or absorbed by any given surface

Able to absorb specific wavelengths of light

ex. Chlorophyll

• Main pigment in photosynthesis
• Mainly absorbs blue and red parts of spectrum
• No absorption of green and yellow (reason why most plants are green)

• They increase the range of light wavelengths that can be used in photosynthesis
• Can protect the plant form excess light (carotenoids)

• Calvin Cycle
• Purpose to build carbohydrates
• Uses energy (ATP) from light reactions
• Uses reduction potential (electrons) from NADPH from Photosystem I
• Uses a source of carbon (CO₂ from air)

1. Carbon fixation
2. Reduction
3. Regeneration of RuBP

RuBP (5C sugar) + CO₂ > 2 molecules PGA (3C sugar)

Rubisco "fixes" CO₂ from the air

Enzyme that "fixes" CO₂ from the air for the Calvin cycle

Most abundant enzyme in the world

C4 metabolism

Crassulacean acid metabolism (CAM)

This is when rubisco binds with O₂ instead of CO₂

Problem that plants with only rubisco have because rubisco can combine with CO₂ (good) or O₂ (bad)

Openings in plants' leaves

They close when plant is in hot, arid conditions because it doesn't want any more evaporation of the plants water to occur, but when it does this it closes the plant off from CO₂ entering

Enzyme that has a high affinity for CO₂ and can capture CO₂ when Rubisco can't, it then passes the CO₂ on to Rubisco for Rubisco to take it throught the Calvin cycle

Uses extra energy so has to be done in a place/way so that it uses less energy than is lost due to photorespiration