Photosynthesis

Photosynthesis is a process that harnesses energy from the sun to convert it into energy-containing substances that can be used for fuel. One of the most essential substances that cells use to store and release energy is called adenosine triphosphate, or ATP. It consists of adenine, ribose (5-carbon sugar), and 3 phosphate groups.

Adenosine diphosphate is a compound similar to ATP, but it has 2 phosphate groups instead of 3. When a cell has available energy, it can store small amounts of it by adding phosphate groups to ADP to produce ATP. This energy can then be released by breaking the chemical bonds in the 2nd & 3rd phosphate groups. So basically, ATP is like a rechargeable battery.

In summary, ATP is like a fully charged battery, while ADP is partially charged, and can be charged when phosphate groups are added.

ATP is used for carrying out active transport, such as with sodium-potassium pumps, where membrane proteins pump sodium ions out of the cell, and potassium ions into it. ATP is also the motor for contracting muscles such as the wavelike movement of cilia and flagella, as well as the light of a firefly.

“In the process of photosynthesis, plants convert the energy of sunlight into chemical energy stored in the bonds of carbohydrates.”

Chlorophyll and Chloroplasts

Photosynthetic organisms capture energy from sunlight with pigments-- principally with chlorophyll,

which reflects green light, but absorbs light from other regions in the visible spectrum.

Accessory pigments reflect colors in other areas of the spectrum such as orange and red (helping chlorophyll maximize the amount of light energy absorbed from the sun), which is why these colors appear in fall.

Thylakoids are saclike chlorophyll-containing membranes, and in a stack, are referred to as grana. The fluid within the chloroplast is known as the stroma.

Electrons produced by chlorophyll require a special "carrier" called an electron carrier, a compound that accepts electrons and transfers them (and their energy) to another molecule.

NADP+ (nicotinamide adenine dinucleotide phosphate) is one of these compounds, which holds two electrons and a hydrogen ion in order to convert it into NADPH. With this, energy from sunlight can be trapped in chemical form, and the high-energy electrons can then be used to build sugars.

Photosynthesis uses the energy of sunlight to convert water and carbon dioxide (low-energy reactants) into high-energy sugars and oxygen (products) ……………..

Photosynthesis involves two sets of reactions:

Light-dependent reactions

require the direct involvement of light and light-absorbing pigments

Light-independent reactions

use ATP and NADPH molecules produced in the light-dependent reactions to produce high-energy sugars from carbon dioxide

Light-dependent reactions use energy from sunlight to convert ADP and NADP+ into the energy and electron carriers ATP and NADPH. These reactions also produce oxygen as a by-product. Thylakoids contain clusters of chlorophyll, known as photosystems, which are surrounded by accessory pigments. These photosystems absorb sunlight and generate high-energy electrons that are passed to electron carriers within the membrane. Photosystem II (despite its name, this process occurs before photosystem I since it was discovered after), is where light-dependent reactions begin. Light is absorbed, raising electrons to a higher energy level, which are then passed to the electron transport chain. As these electrons continue to pass, the thylakoid membrane is able to provide new electrons (to replace the ones lost) from water molecules.

Light-independent reactions (Calvin cycle) then use the ATP and NADPH molecules to produce high-energy sugars from CO2.

-Energy for this process is supplied by compounds from light-dependent reactions. Six molecules of CO2 are used to produce a single 6-carbon sugar molecule.

Chemiosmosis is when H+ ions (from split water) that have been pumped into the thylakoid space have been accumulating so that there is an uneven concentration.

Carbon-Fixation is when CO2 is added to organic compounds. First, CO2 enters the stroma, and rubisco (enzyme) combines the CO2 with a 5-C sugar (Ribulose biphosphate, RuBP), this then creates a 6-carbon compound. This cycle occurs 6 times.

Cross Section of a Leaf

Stoma: openings are holes in the bottom of the leaf, guarded by guard cells. They control whether or not the holes stay open or if they’re going to shut (water pressure allows this to happen).

On a dry day, these holes fill with water and close to prevent additional water lost

On a moist, humid day, these openings will stay open so the water in the air can enter, and oxygen can leave

Xylem tissue distributes water/minerals from the roots to various areas of the plant, and the phloem carries food from the leaves to the roots: water goes down, and food goes up.

Cellular Respiration

When transferring electrons and when molecules are receiving electrons, its called a redox reaction

An electron transport chain is a controlled passing of electron

Series of molecules that excited electrons pass along to release energy

Releasing energy pumps proton into thylakoid space

Photolysis

splitting of water during photosynthesis

H2O>O+2H++2e-

electrons go to photosystems, protons stay in thylakoid space, oxygen is released as a waste product

photosystem I is the rest station to boost the energy level so it can go down the next step of electron transport chain

Photostbtgesus Ciebxyme

Ferrodoxin transfers electrons to the NADP+ in the stroma

Carrier ion

Picks up H+ and excited electrons from ETC to become NADPH

Identify how organisms get energy

How does cellular respiration work?

Process of energy conversion that releases energy from food in the presence of oxygen

The chemical summary of cellular respiration is Oxygen + Glucose > Carbon Dioxide +Water + Energy

6O2+C6H12O6 > 6CO2+ 6H2O + Energy

Enzyme controlled reactions that allow the slow release of glucose so that you dont burst into flames when you eat

Glycolysis

enters a chemical pathway known as glycolysis. A small amount of energy is released

Krebs Cycle

A little more energy is converted form the carbon sugars, releasing the energy in the form of ATP, Co2 is the waste

Occurs inside of the mitochondria, specifically the matrix

Electron Transport

Inner membrane, where the proteins in the electron transport chain is found

using oxygen, water is produced

majority of the ATP made

Photosynthesis and cellular respiration can be though of as “opposite processes” (mrs Alvarez disagrees when it is worded this way), the products of one become the reactants of the other

Integral part of the carbon cycle

Oxygen + glucose > carbon dioxide + water + energy

Respiration requires a cell to exchange gases, we need oxygen within the cell, and carbon dioxide is produced as a waste.

Respiration: breathing on macro scale

Cellular respiration we have two different processes, based on whether or not they require oxygen to occur

Aerobic

Where it all happens (mitochondria)

Matrix- mitochondria’s cytoplasm

1. Glycolysis happens in the cytoplasm, anarobic

Formation of acetylyclA cytoplasm to matrix

Citric Acid Cycle (Krebs) occurs in the mitochondria matrix

ETC (inner membrane_

chemiosmosis

Using a protein gradient that we built up to pass it down

Store energy atp- adenosine triphosphate

collect hydrogen: Nadh- nicotamide adenine dinuceuotide

FADH2

Redox Reactions

Oxidation-reduction reactions transfer electrons from 1 substance or another glucose is oxidized during cellular respiration losing electrons to oxygen

Oxygen is reduced during cellular respiration accepting electrons and hydrogen from glucose

(glucose: oxidized, oxygen: reduced)

Anaerobic- Glycolysis

Step 1: Glycolysis

Series of 10 enzymes catalyzed reactions

Single glucose split into 2 pyretic acid molecules

One 6-C sugar > two 3c sugars

2 categories of reactions -use app, yield app and NADH

Anaerobic, occurs in the cytoplasm

An energy-releasing process uses 2 App reduces 2 Arp and 2 NADH

one reaction removes 4 electrons and passes them to NADH (each NADH accepts a pair of electrons

Very fast and doesn’t require O2

Reactants: glycose 2 atp

Products: 2 pyretic acid, 2 NADH, 4 ATP

Next step: 90% of energy in glucose still unused

so the acetyl CoA bridge helps us break it down further

2 pyretic acid molecules enter bridge

-cytoplasm > Matrix

Degraded by removal of C

Creates acetic acid

Combines with Coenzyme

Forms complex Acetyl CoA

starts with 2 pyruvates

ended with acetyl

2 co2

2 NADH

Step 3 Krebs cycle

Series of eight enzyme controlled steps

formation of oxaloacetate and citric acid

Final stage in the oxidation of carbohydrates, 2 acetyl coA enter cycle, one at a time

coenzyme a released

acetyl combines with oxaloacetate, making citric acid

Reactants: Acetly Coa

Products:

Where did all the H+ (NADH and FADH molecules) go?

step 4: electron transport chain

-series of molecules that excited electrons pass along, to release energy as ATP

ETC: moving from carrier to carrier > release energy

H+ ions are pumped for matrix into the intermembrane compartment: electrochemical gradient

ETC and chemiosymosis sumamry

start= 10 NADH, 2 FADH

end= 30 ATP, 4 ATP

Mitochondria and Inner membrane-

Fermentation: In the absence of oxygen, fermentation releases energy from food molecules by producing ATP, this happens until cellular respiration can happen again

Alcoholic fermentation (yeast)

Yeasts and a few other microorganisms use alcoholic fermentation, which produces ethyl alcohol and carbon dioxide

Lactic acid fermentation

Most organisms carry out fermentation using a chemical reaction that converts pyretic acid to lactic acid

Quick energy- for short, quick bursts of energy, the body uses ATP already in muscles as well as ATP made by lattice acid fermentation

long-term energy

For exercise longer than about 90 seconds, cellular respiration is the only way to continue generating a supply of ATP