AP Bio Unit 3: Cellular Energetics

Gibbs Free Energy

Definition

Δ means ?

How is it calculated?

Gibbs Free Energy

Definition

Δ means ?

How is it calculated?

Energy to do work

delta means change

The gibbs energy is final minus initial

Endergonic Reaction

Energy Enters the System, it is put in

Low Free Energy to higher

anabolic

Non Spontatnous

the products have more stored energy

example: ATP Synthase

Positive GIbs

Exergonic Reaction

Spontanous Reaction

Catabolic

Activation Energy needed

Energy is released.

ex: ATp hydrolysis

Product has less energy stores

Negative Gibs

Enzymes

Defininition

Role

What does it do to the activation energy and gibbs free energy

-protein catalysts

-speed up chemical reactions

-reduces activation energy

-does not change Gibbs free energy

-can be reused

-they are proteins

-synthesize, modify, breakdown

2 Enzymes Models

Induced fit - it will change shape to bind to the substrate

Lock and Key - it is specific to its substrate

What are enzymes specific to

what factors affect it

• specific to its substrate, pH, tempeature, and reaction

• Higher temp → more kinetic energy and faster reactions

• too high of a temp can cause denaturing

• pH can affect it (shape change, denaturing)

• salinity (frq)

• they can change because they are proteins

First and Second Law of Thermodynamics

First- energy cannot be created or destroyed, only converted

Second - entropy always increases

Competive Inhibitor

it has the same structure to the substrate

will bind to the active site

usually not good (morphine binds to stuff)

-higher substrate will reduce the competitive inhibitor

Non Competitive Inhibitor

will bind to the allosteric site

will change the shape of the acitive site

seen in feedback inhibition “which is an example of negative feedback”

used for regulation

-increased products will inhibit more

Steps in Cellular Respiration

-glycolysis, pruvate oxiation, krebs cycle, and oxidative phisphrorylation

Redox reactions

NAD+ is reduced to NADH so it can carry electrons

The glucose is oxidized throughout

Glycolysis

-ubiquitous (know phosphofructosekinase, inhibited by citrate)

-start with glucose → 2 pruvate - Net 2 ATP (substrate level)(use 2, make 4) - 2 NAD+ reduced to NADP

-can lead to aerobic or fermentation

Pruvate Oxidation

-pruvate → acetyl CoA

-lost CO2 and electrons

-in the mitochondrial matrix

has a protein complex

Krebs Citric Cycle

• in the mitocrondial matrix

• Acytl CoA → 2 Co2, 3 NADH -? FADH2 → 1 GTP

• 2 turns per glucose so times 2

• Most NADH made

• glucose is finished off

Oxidiative phosphorylation

-mitocondrial cristae

-the NADH and FADH drop off the electrons on the electorn transport chain prpteons

-electrons drop in energy and power the proton pumps against its gardient to the intermembrane space (pH decreases)

-oxygen is the last electorn acceptor - it pulls the electrons

- Chemiosmosis: the high concentration of proton wants to go down, and it goes down through ATP synthase and then it creates most ATP

Aerobic Cellular Respiration General

Around 30 Atp is created = 686 kcal per glucose

glucose is the main organic molecule, but fats can be used and have more hydrogen to yeild more energy

Flow of Energy: Chemical → electron → proton gradient → ATP

Purpose of ATP

Used for Endergonic Reactions - moving things against its gradient, in muscles, cell communication, grwoth etc

ATP is a modified nucelotide

7.3 kcal = 1 ATP

Anaerobic Respiration

Fermentation

-in some organisms, Anaeruobic Respiration can be carried out with another electronegative compound insetad of O2

Fermentation is to reuse NAD+ so glucose can be broken down in the glycolysis, this is ususally inefficient and can only get 2 ATP from each glucose

• Ethanol - produces CO2 and Alchol (yeast and bacteria)

• Lactic Acid - lactate is produced (acidic) done by muscles and fungi

Photosynthesis

Uses carbon dioxide and water and light energy to make sugar and O2

This is an endergonic reaction because energy is. Put in and entropy is reduced

Light Reaction

H2O + light → into energy ATP AND NADPH

• occurs in thlakoid membrane

• Electron Transport Chain, Photosystems,

• THe light is absorbed by the Chlorophyl + protein (photosystems) - this poweres electrons derived from water -

• ATP is made in the Electron trasnport chain to make ATP for the Calvin Cycle (into membrane space) - chemiosmosis

• NADP+ is reduced to NADPH and carries powered hydrogens to the calvin cycle to put into glucose

• Water is split to use e- and H+

Linear Electorn Flow

vs Clyclic

• syntheisize ATP and NADPH 1:1

• Cyclic - there is not enough NADP+ and more ATP is made by putting back the elctrons

  • needed because 9:6 ratio needed in the calvin cycle

Calvin Cycle

-occurs in the stroma

-3 CO2 - 9ATP, 6 NADPH (6 waters?)

- Carbon is Fixed by the Rubisco

-G3P is made and it is the precursor for “biomass”

-3 atp and. 2NADPH per turn

Chemical energy into a carb

after the G3P is harvested - RuBP is restored with other steps

C3 vs C4 vs CAM

Why?

adaptation for drier environments to reduce water loss through transpiration

To prevent Photorespiration (caused by closing of stomata and not getting new CO2) → waste of energy, etc

C3 - is most common and will make a 3 carbon structure

C4 - 4 carbon structure is made 0 serpeates the cells

CAM - open stomata at night, and fixed it into organic acids and then releases the carbon dioxide during the day to do the light reactions

Metabolic pathway

Linked enzyme chemical reactions

Precursor→ infermidiatsz → products

Autotrophs

Photo vs chemo

Photo use photons

Chemosynthesis

Energy coupling

Exertonic reaction drives endergonic reactions

ex: ATP hydrolysis can be couples with an enderthermic reaction to build smth or make a bond

Chlorophyll

Role and stuff

• Pigment that absorbs light

• Reflects green

• Absorbs blue and red

Absorption spectrum

Shoes the amount of lightn

wave lengths

positive feedback

-the product or the stimulus will promote more of that

-a process that occurs in a feedback loop that increases the effects of a small disturbance

negative feedback

what is an example

-connects with homeostasis

-will maintain homostesis in response

-regulation

-sugar regulation with glucagon and insulin\

• -like insulin and glucagon towards sugar stimulus

  • high blood glucose levels → insulin → lower glucose and put it into the muscles →

  • low blood glucose → glucagon → break glycogen → increase blood sugar

  • antigonisitc hoRMONES

activation energy

to start the reaction by arranging the reactants appropriately and breaking their existing bonds

phosphorylation

adding a phosphate group to a protein or smth

this makes it active, changes it shape

amplification

one molecule will activate multiple

each enzyme will act on many copies of protein

The substrate concentration effect on enzymes

Low → less chances of substrate interacting with enzyme

medium- more but not all the enzymes are being used

high → all the enzymes are being used “saturated”

ribozymes

RNA that can function as enzymes in splicieosomes

Homeotstasis

the tendecny of a living system to maintian its internal condirtions at a constant and optimal level

how do living organisms follow the second law of thermodynamics

-they have to input energy in order to keep order

-when energy is lost as heat, the entropy is increased