chapter 8 8... · chapter 8 cellular energy . energy ! ... cellular respiration ! ... lactic acid !...
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Chapter 8
Cellular energy
Energy
! The ability to do work
Quick Review:
! Autotroph – makes its own food from the energy from the sun
! Heterotroph – must consume food to get energy
Different types of autotrophs:
! Photoautotrophs – convert light into energy
! Chemoautotrophs- use inorganic substances for energy (hydrogen sulfide)
Metabolism
! All of the chemical reactions in a cell
Catabolic pathways
! Release energy by breaking down larger molecules into smaller molecules
Anabolic metabolic pathways
! Builds larger molecules ! Ex: photosynthesis
ATP
! Adenosine triphosphate ! Molecule that provides chemical energy ! When ATP is broken down (removal of
a phosphate group), energy is released
Chloroplasts
! Contain chlorophyll – allow plants to undergo photosynthesis
! They capture light energy from the sun to produce energy for plants
! Leaves have large surfaces that act as light collectors for plants
Parts of the chloroplast
! Thylakoids - Flattened saclike membranes that are arranged in stacks
! Grana – stacks of thylakoids ! Stroma – fluid-filled space outside the
grana
Diagram of chloroplast
Photosynthesis
! The anabolic pathway in which light energy from the Sun is converted to chemical energy to use by the cell
During photosynthesis:
! According to the second law of thermodynamics, heat is released in this process
Leaves of Trees
! Yellow, red, and orange pigments also exist in leaves of trees
! Chlorophyll (green) is most abundant, that’s why leaves are green
! In autumn, chlorophyll breaks down, making the rest of the pigments visible
Photosynthesis energy
! Energy for photosynthesis is used to make glucose
! Glucose is made outside of the chloroplasts
Photosynthesis
! Made of 2 reactions 1. Light reactions – require light to take
place 2. Calvin cycle – does not require light
! Generally does not occur at night because it depends on the products of light reactions
Cellular respiration
! Living organisms obtain energy by breaking down organic molecules during cellular respiration
Aerobic
! Requires oxygen
anaerobic
! Does not require oxygen
Fermentation
! Occurs without oxygen ! 2 types 1. Lactic acid
! Causes muscles to feel sore
2. Alcoholic ! Occurs in some yeast and bacteria
How are photosynthesis and cellular respiration related?
! The products of photosynthesis are used in cellular respiration
! The product of photosynthesis is glucose
! Glucose is then the substrate used in photosynthesis
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