Photosynthesis Chapter 8

THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTH

Food Chain

THE FOOD WEB

Almost all plants are photosynthetic autotrophs, as are some bacteria and protists Autotrophs generate their own food or organic matter through photosynthesis Sunlight energy is transformed to energy stored in the form of chemical bonds (a) Mosses, ferns, and flowering plants (b) Kelp (c) Euglena (d) Cyanobacteria THE BASICS OF PHOTOSYNTHESIS

Heterotrophs Organisms that are not able to make their own food and have to eat other organs to obtain energy. Ex. Toad, fish

Autotrophs or heterotrophs? Humans Blue-green algae Paramecium Euglena Yeast Pine tree Moss Mushroom crocodile

Light Energy Harvested by Plants & Other Photosynthetic Autotrophs 6 CO H 2 O + light energy → C 6 H 12 O O 2

Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water AN OVERVIEW OF PHOTOSYNTHESIS Carbon dioxide WaterGlucoseOxygen gas PHOTOSYNTHESIS

What is photosynthesis in general terms? The conversion of CO 2 and water into glucose. The glucose is used as an energy source for plants. The “carbon skeletons” of glucose can also be modified and made into other molecules by the plant.

What is the formula for photosynthesis? 6 carbon dioxide + 6 water  glucose + 6 oxygen gas Usually you see the words over and under the arrow indicate necessary components that are not changed or used up by the reaction.

Different wavelengths of visible light are seen by the human eye as different colors. WHY ARE PLANTS GREEN? Gamma rays X-raysUVInfrared Micro- waves Radio waves Visible light Wavelength (nm)

WHY ARE PLANTS GREEN? It's not that easy bein' green Having to spend each day the color of the leaves When I think it could be nicer being red or yellow or gold Or something much more colorful like that… Kermit the Frog

Electromagnetic Spectrum and Visible Light Gamma rays X-raysUV Infrared & Microwaves Radio waves Visible light Wavelength (nm)

Sunlight minus absorbed wavelengths or colors equals the apparent color of an object. The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others. Reflected light

Why are plants green? Reflected light Transmitted light

Where in a cell is photosynthesis performed? chloroplasts in eukaryotes cytoplasm of prokaryotes

WHY ARE PLANTS GREEN? Plant Cells have Green Chloroplast s photosynthetic pigments (i.e., chlorophylls, carotenoids).

Chloroplasts absorb light energy and convert it to chemical energy Light Reflected light Absorbed light Transmitted light Chloroplast THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED

In most plants, photosynthesis occurs primarily in the leaves, in the chloroplasts A chloroplast contains: stroma, a fluid grana, stacks of thylakoids The thylakoids contain chlorophyll Chlorophyll is the green pigment that captures light for photosynthesis Photosynthesis occurs in chloroplasts

The location and structure of chloroplasts LEAF CROSS SECTION MESOPHYLL CELL LEAF Chloroplast Mesophyll CHLOROPLAST Intermembrane space Outer membrane Inner membrane Thylakoid compartment Thylakoid Stroma Granum StromaGrana

When is photosynthesis performed? Whenever the organism is exposed to light.

How many stages are there in photosynthesis? What are their names? Two Stages: Light Dependent Reactions Light Independent Reactions AKA the Light and Dark Reactions

The Calvin cycle makes sugar from carbon dioxide ATP generated by the light reactions provides the energy for sugar synthesis The NADPH produced by the light reactions provides the electrons for the reduction of carbon dioxide to glucose Light Chloroplast Light reactions Calvin cycle NADP  ADP + P The light reactions convert solar energy to chemical energy Produce ATP & NADPH AN OVERVIEW OF PHOTOSYNTHESIS

The O 2 liberated by photosynthesis is made from the oxygen in water (H + and e - ) Plants produce O 2 gas by splitting H 2 O

Light Dependent Reactions Take in water and produce Oxygen and lots of electrons in the form of NADPH and energy in ATP Occurs in the Thylakoid membrane of the chloroplast

Light Independent Reactions AKA Dark reactions or Calvin cycle Takes in Carbon Dioxide and ATP and electrons in the Form of NADPH Makes Glucose Occurs in the stroma the fluid like portion of the chloroplast.

Review: Photosynthesis uses light energy to make food molecules Light Chloroplast Photosystem II Electron transport chains Photosystem I CALVIN CYCLE Stroma Electrons LIGHT REACTIONSCALVIN CYCLE Cellular respiration Cellulose Starch Other organic compounds A summary of the chemical processes of photosynthesis

How do the reactants of photosynthesis get to the chloroplast? CO 2 diffuses into leaf and chloroplast from air. H 2 O is carried to the leaf by the xylem. H 2 O enters plants through the roots. Water enters chloroplast by osmosis. Light is absorbed by the photosystems found in the chloroplasts in any GREEN part of a plant.

How do the products of photosynthesis leave the chloroplast or leaf and where do they go? Glucose is moved out of the cell by facilitated diffusion and is dissolved in the liquid carried in the phloem. The sugar solution is carried to the non-photosynthesizing parts of plants. O 2 exits the leaves by diffusion through open stomata. Some is used by the plant for cellular respiration. Water in the form of water vapor can diffuse out of leaf through open stomata. (evaporation through stomata = transpiration)

includes of occur in occurs in uses to produce uses Concept Map

Photosynthesis includes of occur in occurs in uses to produce uses Light dependent reactions Thylakoid membranes StromaNADPH ATP Light Energy ATPNADPHO2O2 Chloroplasts Glucose Light independent reactions Concept Map