Photosynthesis Using light to make food.

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8-1 Energy and life

• Energy – the ability to do work

• In living things it is needed to move and also to build new proteins and amino acids.

• Where does energy that living things need come from?

Autotroph

• "self-feeding“– any organism that makes its own food

• without eating• decomposing • absorbing other organisms or organic

molecules.

Auto – selfTroph – to feed

Photosynthetic autotrophs• "feed" themselves with light energy

– include plants– photosynthetic protists (algae) – photosynthetic bacteria

Cyanobacteria Algae & bacteria

Heterotrophs

• Get their food from eating autotrophs or from eating other heterotrophs

Hetero - other

Chemical Energy and ATP

• Energy comes in many forms (heat, light, electricity)

• It can be stored in molecules such as carbohydrates and lipids

• The chemical fuel for cells though is ATP

• Adenosine Triphosphate

Tri- three

This is how it works

• Energy from food is used to convert ADP to ATP. As a result of adding a phosphate a small amount of energy is stored.

Di - two

Using biochemical energy

• This energy can be used to do all kinds of cell work

• Active transport– Pumps– Motor Proteins – Synthesis of proteins and nucleic acids

8-2 Photosynthesis Overview

• During Photosynthesis light energy is used to convert water and carbon dioxide into sugar(glucose) and oxygen

Photo – Syn – to put together

Chlorophyll• green pigment that

absorbs light energy

• located in the membranes of chloroplasts– thylakoids in

stacks, called grana

– In stroma •carbon dioxide

is built into sugars.

The absorption spectrum

• White light is composed of the colors of the rainbow

• ROYGBIV

8-3 The reactions of Photosynthesis

Step 1• The light energy strikes the leaf

– passes into the leaf – hits a chloroplast inside an individual cell.

Step 2• light energy enters the chloroplasts

– captured by the chlorophyll inside a grana.

Step 3 Inside the grana -part of the energy is

used to split water into hydrogen and oxygen

Step 4

• Releasing of excess (waste) – As oxygen into the air.

Stomata of cactus plant

Step 5

• hydrogen – taken to the stroma along with the grana’s

remaining light energy.

Step 6• Carbon dioxide enters the leaf

– passes into the chloroplast.

Step 7

• Stroma the remaining light energy – used to combine hydrogen and carbon dioxide

• making Carbohydrates.

Step 8

• The energy rich carbohydrates are carried to the plant’s cells.

Step 9

• Energy rich carbohydrates– used by the plants cells to drive all its life

processes– Holds energy in chemical bonds

Summary of Photosynthesis

Photosynthesis and Respiration