Photosynthesis

Glencoe Ch. 8

Kansas Science Standards

The sun is the primary source of energy for life through the process of photosynthesis.-plants and other photosynthetic organisms use energy from the sun to make glucose.- photosynthesis is a series of chemical reactions that takes place in a chloroplast.

Energy for Life; all living things need energy!

Without energy, things tend to get messy.

ex: your room, death

Entropy: natural tendency toward disorder.

Two Laws of thermodynamics:

1. Energy cannot be created nor destroyed, just changed from one form to another, i.e. chemical (food) energy converted to mechanical (movement energy)2. Some energy is always lost (usually as thermal energy) during the change or “Entropy increases” i.e. trophic levels in the food chain.

Autotrophs:

get energy from the sun (or chemicals) to make own food.

Heterotrophs:

obtain energy from food it eats.

Remember??

Metabolism

All of the chemical rxns in a cell

Metabolic pathway = series of chem. rxn in which the product of one rxn is the substrate for the next. 2 types:

Catabolic – (catabolism) break down molecules to release energy

Anabolic – (anabolism) use energy to build larger molecules from smaller ones

Anabolic steroids?

hormones that build up molecules of protein to make muscles

Balance between catabolic and anabolic pathways affected by circadian rhythms, activity periods demand energy from glucose

Introduction to Plants

Energy is stored in the bonds between atoms and molecules (food) = chemical energy

http://www.bing.com/images/search?q=chemical+food+energy&view=detail&id=D0B8159D8F5E6616C858C30DF7FB7FBB50583354&first=1&FORM=IDFRIR&qpvt

=

Plants change light energy into chemical energy which is stored in the bonds of glucose molecules that make up organisms. (anabolic pathway)

sun

6CO2 + 6H2O -------- 6O2 + C6H12O6

Carbon water oxygen glucose

Dioxide

http://www.youtube.com/watch?v=C1_uez5WX1o

Photosynthesis

Products of photosynthesis:

Makes glucose to store energy.

Also stores energy short term in the molecule ATP.

ATP: adenosine triphosphate

Small molecule that stores small amounts of energy for a cell.

Like pennies of energy compared to the $20 bill of glucose.

Energy in ATP can be used anywhere in the organism.

ATP

Energy is stored in the bond of the last phosphate group.

Like a rechargeable battery.

Absolutely necessary for life processes!

http://www.bing.com/images/search?q=atp&view=detail&id=760CFE3A35731F10F0227628A9A367A8793A4189&first=1&FORM=IDFRIR&qpvt=

Plants take in carbon dioxide

Pore on bottom of leaf called stoma (stomata pl.).

Let CO2 into leaf.

Let water vapor out.http://www.youtube.com/watch?v=0PEYAOKTqEU&feature=related

Stomate: open and closed

Plants get water through roots!!!

Water is absorbed from soil through the roots.

Photosynthesis

Photosynthesis happens in the chloroplast of a plant cell.

Chloroplast parts:

Thylakoids - membrane bound disks

Granum - stack of thylakoids.

Stroma - juicy inside.

Double membrane around outside.

Own, separate DNA

Micrograph of chloroplast

Chloroplasts gather sun energyPigments: molecules that absorb certain wavelengths of light energy.

Chlorophyll: several pigments that absorb mostly violet-blue and red wavelengths and reflect green.(chlorophyll a and chlorophyll b most common)

Carotenoids (ex: β-carotene) absorb blue/green, reflect yellow, orange, red

http://www.bing.com/images/search?q=chlorophyll&view=detail&id=740A7FAFFFE7B29220ACCA4E3FCCAA798E3489D2&first=31&FORM=IDFRIR&qpvt=

Pigments:

A pigment is a molecule that absorbs light in the visible portion of the electromagnetic spectrum. The leaves of most plants are rich in pigments. These pigments absorb light and convert it into chemical energy to fuel the production of sugars. The primary photosynthetic pigment is chlorophyll a. Other pigments such as chlorophyll b and carotenoids are referred to as accessory pigments. These absorb light and funnel the energy to chlorophyll a. Different pigments absorb different types (wavelengths) of light. Some pigments might absorb blue light better than other wavelengths of light, for example. Others may absorb all of the colors well, or none.

CO2 + H2O -----> O2 + C6H12O6

Glucose = C6H12O6

The carbon in glucose comes from carbon dioxide (CO2)

The hydrogen in glucose comes from water (H2O)

The oxygen in glucose comes from CO2.

The sun energy is stored in the bonds that hold the glucose molecule together.

Factors affecting Photosynthesis

Water

Temperature

Intensity of light

Concentration of CO2

Power to the Plankton

Overview of Photosynthesis

Two Parts:

Light-dependent reactions

Light-independent reactions

Chloroplast

Light-dependent reactions

Occurs within thylakoid membrane of chloroplast.

Chlorophyll energized by sunlight. (needs light)

Sun energy moves to ATP and NADPH. (energy carriers)

Oxygen produced.

NADPH

Another energy carrying molecule like ATP.

Like a rechargeable battery:

NADP + H ---> NADPH(Low energy) (High

energy)

http://www.fw.vt.edu/dendro/forestbiology/photosynthesis.swf

Light Reactions animation

Light-independent reactions

Happens in the stroma of chloroplast.

Uses energy from light-dependent reactions (ATP and NADPH) to make glucose from CO2.

Does not need light to work.

Photosynthesis animation overview PH

Calvin cycle

The Calvin Cycle

Calvin Cycle Animation

Photosynthesis Animated Overview

Alternate pathways

C4 – plants in hot dry areas keep their stomata closed on hot days, fix carbon as a 4-carbon compound. (corn, sugar cane)

CAM – crassulacean acid metabolismplants living where water is scarce

keep stomata closed in day, store CO2 as an acid that they can use in daytime for Calvin cycle.(cacti, orchids, pineapple)

YouTube Resources:

Photosynthesis song detailed overview

Bozeman Photosynthesis