Photosynthesis What happens during the process of photosynthesis? Why is ATP useful to cells? What...

Cellular ReactionsMs. Luaces, Honors Biology

PhotosynthesisWhat happens during the process of

photosynthesis?

Why is ATP useful to cells?

What role do pigments & electron carriers play in photosynthesis?

What are the reactants and products of photosynthesis?

What factors affect photosynthesis?

8.1 Energy & LifeEnergy is the ability to do work

Have to be able to obtain and use energy in many forms (light, heat, electricity, or chemical compounds)

One of the most important compounds that cells use to store and release energy is called adenosine triphosphate (ATP)

8.1 Chemical Energy & ATP

ATP is made up of: 1. Adenine 2. A 5-carbon sugar called ribose 3. 3 phosphate groups

Sometimes seen as ADP (has 2 phosphates instead of 3, and can store small amounts of energy)


ATP can easily release energy (by breaking chemical bonds) or store energy (by adding chemical bonds) between its phosphate groups to supply a basic energy source for all cells ADP will store energy when you add a phosphate ATP will release energy when you take away a

phosphate


How do we use the energy provided by ATP? Carry out active transport by pumping Na+ ions

out of cells and pumping in K+ ions Contract muscles Build proteins & respond to signals Breathe


ATP is NOT a good long-term storage molecule. Sugar molecules, like glucose, store 90 times the energy ATP does Heterotrophs (?) & Autotrophs (?) therefore

are always looking to take in/make sugar or carbs to power their cells

8.2 Photosynthesis: An Overview

Energy from the sun travels to Earth in the form of light. Plants gather it in light-absorbing molecules called pigments Plants principal pigment is chlorophyll

Chlorophyll a & b are present, and capture blue-violet and red regions of the color spectrum


Photosynthesis takes place inside organelles called chloroplasts, which contain many thylakoids arranged in stacks Chlorophyll are found inside the thylakoid

membranes The fluid portion of the chloroplast is known as

the stroma


When chlorophyll absorbs light, a large fraction of that light energy is transferred directly to electrons in the chlorophyll molecule An electron-carrier accepts

the electrons and transfers them, along with the energy, to another molecule

Photosynthesis electron-carrier is known as NADP+


Photosynthesis uses the energy of sunlight to convert water and carbon dioxide (reactants) into high-energy sugars and oxygen (products) 6CO2 + 6H2O C6H12O6 + 6O2 (light)


Photosynthesis involves 2 kinds of reactions: Light-dependent reaction

Requires light and water (for electrons & hydrogen ions)

Occurs in the thylakoidsOxygen is released as a byproduct

Light-independent reactionDoesn’t require lightRequires carbon dioxide, ATP & NADPHOccurs in the stromaCreates sugars and carbs

Let’s Get Funky!Create a song / rap / act / drawing showing the

process of Photosynthesis. Your creative imagination should include: Light Leaf Chloroplast Thylakoid Chlorophyll Excited Electron NADP+ Sugar

*** If you are doing an act, you MUST have a narrator!!

9.1 Cellular Respiration: Overview

Organisms get the energy they need from food How much energy

depends on the kind of food

Energy is measured in calories: the amount of energy needed to raise the temperature of 1 gram of water by 1 degree CelsiusFats: 9 calories per

gramCarbs & Proteins: 4

calories per gram

9.1 Chemical Energy & Food

Food must be broken down gradually to control the release of energy and create compounds such as ATP to directly power the cell If we broke down food all at once, most of the

energy would burn away in the form of heat


Cellular respiration is the process that releases energy from food in the presence of oxygen 6O2 + C6H12O6 6CO2 + 6H2O + Energy Notice anything??


Cellular respiration has 3 main stages: 1. Glycolysis: creates very little energy 2. Krebs cycle: creates a little more energy 3. Electron transport chain (ETC): creates the

majority of the energy ; directly involves the world’s most powerful electron acceptor - Oxygen


Aerobic

Requires oxygen

Ex: Electron Transport Chain

Anaerobic

Doesn’t require oxygen

Ex: Fermentation

** Glycolysis & Krebs don’t DIRECTLY use oxygen, but are involved with products/reactants of oxygen

9.1Where Do These Processes Occur?

Cytoplasm

Glycolysis

Mitochondria

Krebs Cycle

Electron Transport Chain (ETC)


Cellular respiration is balanced by photosynthesis: the equations are reverse of each other One processes gives the reactants of the other

9.2 GlycolysisThe first set of reactions in cellular respiration

is Glycolysis (sugar-breaking). During glycolysis: 1 molecule of glucose (6 carbon molecule) 2

molecules of pyruvic acid (3 carbon molecule) Uses NAD+ as an electron acceptor to become

NADH Remember, Glycolysis doesn’t require oxygen!

9.2 GlycolysisWhat does glycolysis produce?

2 ATP molecules NADH 2 pyruvic acid molecules

9.2 Krebs CycleDuring Krebs, pyruvic acid is broken down into

carbon dioxide in a series of energy-extracting reactions Also known as the citric acid cycle Pyruvic acid is converted into acetyl-coA and

then into citric acid One molecule of glucose = 2 turns of the cycle Uses NAD+ & FAD as electron acceptors NADH

and FADH2

9.2 Krebs CycleWhat are the products of Krebs cycle?

2 ATP molecules NADH & FADH2 Carbon dioxide

9.2 ETCThe electron transport chain uses high-energy

electrons from glycolysis & Krebs cycle to convert ADP & ATP NADH & FADH2 release their electrons, and as

they pass down the line, they generate energy to spin something known as ATP synthase

With each rotation, the enzyme grabs an ADP molecule and attaches a phosphate group, producing ATP

Oxygen is directly involved here

9.2 ETCWhat are the products of ETC?

36 ATP (on average) Water

Let’s VisualizeCreate a table that lists the 3 steps of cellular

respiration and include:Where does it take place?

Directly requires oxygen?

What are the reactants?

What are the products?

Glycolysis

Krebs Cycle

ETC

9.2 Cellular RespirationAll together, cellular respiration produces about

36 ATP, water, and carbon dioxide. The rest of the energy is lost in the form of heat

9.3 Fermentation In the absence of

oxygen, fermentation releases energy from food molecules by producing ATP

Cells convert NADH to NAD+ by passing high-energy electrons back to pyruvic acid in the cytoplasm

2 types: Alcoholic and Lactic Acid Fermentation

9.3 FermentationAlcoholic

Used by yeasts & microorganisms

Causes bread dough to rise

Pyruvic acid + NADH Alcohol + CO2 + NAD+

Lactic Acid

Used by bacteria & humans (when?)

Creates cheese, yogurt, buttermilk

Pyruvic acid + NADH Lactic acid + NAD+

9.3 Fermentation3 main sources of ATP:

ATP already in the muscles: few seconds of intense activity

ATP made by lactic acid fermentation: short quick bursts of energy

ATP made by cellular respiration: exercise longer than 90 seconds

Let’s Practice!Study Workbook A – Pg. 97-99

Work with a buddy, answers only, one sheet of paper

Photosynthesis What happens during the process of photosynthesis? Why is ATP useful to cells? What...

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