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Photosynthesis. Energy & Life. Photosynthesis is the process of capturing and transforming the energy of sunlight into chemical energy. (What type of organisms can make their own food?) a. Autotrophs – organisms that can make their own food

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energy life

Energy & Life

Photosynthesis is the process of capturing and transforming the energy of sunlight into chemical energy. (What type of organisms can make their own food?)

a. Autotrophs – organisms that can

make their own food

b. Heterotrophs – organisms that

obtain energy from the food they

consume

energy life1

Chemical Energy and ATP

a. ATP – energy molecule used by cells (Fig. 8-2)

b. Energy is stored in the bonds between phosphate

c. When these bonds are broken energy is released

Energy & Life

energy life3

Using Biochemical Energy

a. Active Transport

http://www.dnatube.com/video/359/Active-Transport

b. Motor proteins move organelles

throughout the cell

http://www.youtube.com/watch?v=tL99pwdvmhU

c. Synthesize various molecules

Energy & Life

photosynthesis an overview

Understand the significance of Helmont’s, Priestley’s, and Ingenhousz’s experiments.

6CO2 + 6H2 O 

C6H12O6 + O2

Photosynthesis: An Overview

photosynthesis an overview1

Light and Pigments (Fig. 8-5)

    • A. Wavelength – distance between crests; shorter wavelengths have higher energy than longer wavelengths

Photosynthesis: An Overview

photosynthesis an overview2

Light and Pigments (Fig. 8-5)

    • B. Photon – a particle of light
    • C. In photosynthetic organisms, absorbed energy is used to make chemical energy (glucose)
    • D. Photosynthetic pigment – molecule that absorbs light (color you see is the color being reflected)
    • 1. chlorophyll a - primary pigment; converts light energy to chemical
    • energy

Photosynthesis: An Overview

photosynthesis an overview3

Light and Pigments (Fig. 8-5)

    • D. Photosynthetic pigment (con’t)
    • 1. chlorophyll a - (con’t)
    • a. reflects green light
    • b. absorbs red & blue light
    • c. normally hides other
    • pigments
    • 2. Chlorophyll b – accessory
    • pigment; absorbs light and
    • transfers the energy to
    • chlorophyll a

Photosynthesis: An Overview

photosynthesis an overview4

Light and Pigments (Fig. 8-5)

    • D. Photosynthetic pigment (con’t)
    • 3. carotenes & xanthophylls –
    • accessory pigment; colors
    • can be seen in autumn when
    • chlorophylls start to break
    • down
    • E. Absorption spectrum – the different
    • colors (wavelengths) of light
    • absorbed by each pigment

Photosynthesis: An Overview

reactions of photosynthesis1

Inside a chloroplast

  • A. Thylakoids – flattened sacs of photosynthetic membranes; pigments and proteins are organized into photosystems in order for light energy to be captured & stored as chemical energy
  • B. grana – stacks of thylakoids
  • C. stroma – region between grana

Reactions of Photosynthesis

reactions of photosynthesis2

II. Electron Carriers – molecules that can accept a pair of high-energy electrons and protons and transfer them to another molecule (NADP+)

Reactions of Photosynthesis

reactions of photosynthesis3

There are two sets of reactions that take place within the chloroplasts: The light dependent reactions & the Calvin Cycle (also know as the light independent or the dark cycle)

Reactions of Photosynthesis

reactions of photosynthesis4

Light Dependent Reactions

  • A. Takes place only in the presence of light
  • B. Occurs on membranes of thylakoids
  • C. Produces high energy compounds that are used in the dark reaction: ATP and NADPH
  • D. Photosystem II
  • 1. pigments absorb light energy and electrons are boosted to a higher energy level

Reactions of Photosynthesis

reactions of photosynthesis5

Light Dependent Reactions

  • D. Photosystem II (con’t)
  • 2. lost electrons are replaced by the splitting of H2O into 2 e-,2 p+, and O2
  • a. electrons are picked up by NADP
  • b. protons (H+) are pumped into inner thylakoid space

Reactions of Photosynthesis

reactions of photosynthesis6

Light Dependent Reactions

  • E. Photosystem I
  • 1. pigments use energy from light to re- energize the elctrons from photosystem II
  • 2. produces NADPH which also powers the Calvin Cycle

Reactions of Photosynthesis

reactions of photosynthesis7

Light Dependent Reactions

  • http://www.youtube.com/watch?v=Oi2_n2wbB9o

Reactions of Photosynthesis

reactions of photosynthesis8

The Calvin Cycle – (light independent, dark reaction) – uses ATP and NADPH from the light dependent reactions to produce high energy sugars (Fig. 8-11)

    • A. Takes place with or without the presence of light as long as ATP and NADPH are available
    • B. Occurs in the stroma of chloroplast
    • C. 6CO2 molecules enter the cycle from the atmosphere and combine with 6 five carbon molecules

Reactions of Photosynthesis

reactions of photosynthesis9

The Calvin Cycle (con’t)

    • D. The resulting 12 three carbon molecules use the energy from ATP and NADPH to produce 12 high energy three carbon molecules
    • E. 2 of these molecules are used to synthesize sugar and other compounds
    • F. The remaining 10 molecules are used to produce more of the “starting” 6 carbon molecule of the cycle

Reactions of Photosynthesis

reactions of photosynthesis10

FactorsAffectingPhotosynthesis

  • A. Light intensity – as intensityincreases the rate of photosynthesisincreases (up to a point)
  • B. Temperature – photosynthesisoccursrapidlyatspecifictemp.; extreme temps. are damaging to enzymes
  • C. H2O – decrease in water slows rate of photosynthesis
  • D. Minerals – must bepresent in certain amounts

Reactions of Photosynthesis

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