Energy & Photosynthesis

Energy for life processes Energy is the ability to cause matter to move or to change The ability to do work Work for a cell includes Growth & repair Active transport Reproduction Synthesis of molecules Lots of other stuff!!!

Type of cellular energy Potential energy Stored energy Example: chemical energy in the chemical bonds of molecules such as ATP & glucose Kinetic energy Energy of motion Examples: electrical energy in the flow of electrons, muscle contraction, active transports

Biochemical pathways A series of reactions in which the product of one reaction is the reactant of the next Examples: Photosynthesis: only autotrophs are capable of this Cellular respiration: Both autotrophs & heterotrophs perform this to release energy to do cellular work

Biochemical pathways

Thermodynamics The study of energy transformations 1st law of thermodynamics Energy cannot be created or destroyed, only converted from one form to another Examples: stored chemical energy in glucose  stored chemical energy in ATP  mechanical energy to move your body  heat energy to maintain your body temperature

ATP – the energy molecule ATP = adenosine triphosphate Monomers: Adenosine, Ribose, 3 phosphate groups

ATP/ADP Cycle

ATP Phosphorylation: addition of a phosphate group and ENERGY The energy is stored in the bonds BETWEEN the phosphate groups (approximately 10 million ATPs are made per second!!) In order to release the energy – the bond must be broken! Bond between the 2nd & 3rd phosphate (see structure diagram)

Light energy & the Electromagnetic Spectrum

Wave description Electromagnetic radiation – form of energy that exhibits wavelike behavior as it travels through space Longer wavelength = lower energy (& vice versa) Has the ability to “energize” molecules and move electrons to carry the energy

EM Spectrum-background Shows all forms of electromagnetic radiation Visible light is the portion we will talk about (although plants absorb other parts of the spectrum). This is the part that we can see. ROY G BIV is the order of colors from low to high energy (so long to short wavelength (750 nm to 380 nm)

EM Spectrum

Light When light strikes an object, it is: See next slide for examples Absorbed – then we can NOT see it Transmitted – goes through the object so we can see it on the other side of the object (like stained glass). The object must be transparent or translucent (like wax paper) for it to do this Reflected – then we CAN see it because it bounces back to our eyes. See next slide for examples Combinations of the 7 basic colors being A/T/R provide all the shades of color that we see.

Color Examples When all colors are absorbed – BLACK When all colors are reflected – WHITE If only one color is reflected – OBJECT APPEARS THAT COLOR IT IS THE PIGMENT MOLECULES THAT ARE PRESENT THAT REFLECT & ABSORB LIGHT ENERGIES AND THUS PROVIDE AN OBJECT WITH ITS COLOR

Chloroplasts

Pigments Molecules that absorb energy of specific wavelengths. REMEMBER: whatever they absorb, we DON’T see – but they use it for energy! Chlorophyll is the main pigment for photosynthesis

Chlorophyll There are several versions of chlorophyll (a & b are the main types) Chlorophyll a is in all photosynthetic organisms – absorbs RBV light energies Chlorophyll b is in land plants FYI: Chlorophyll c and d are the algae and bacteria These 2 pigments reflect GREEN so that is the color we see!

Be able to interpret the diagram What colors are absorbed? What colors are reflected? Percentages? Color of leaf? b

Accessory Pigments Absorb some of the wavelengths that chlorophyll does not Carotenes & xanthophylls REFLECT oranges & yellows We see these colors in the fall when chlorophyll declines Anthocyanins REFLECT reds & purples Tannin (waste product) gives brown color to dying leaves

Chloroplast Type of plastid Site of photosynthesis Has 3 major parts

Parts of a chloroplast Thylakoid membranes: Grana (granum) flattened sacs of photosynthetic membrane Embedded with chlorophyll & other pigments Grana (granum) Stack of thylakoid membranes Connected to each other Organizes pigments into 2 types of photosystems Stroma: gel like material surrounding grana

5 parts to label