Bs 161 exam 3- summary notes

1.
Describe the structure of the chloroplast.
● Double Bilayer Membrane
● Circular DNA
● Reproduces by Binary Fission
● Internal Membrane System *NOT IN MITOCHONDRIA*

Describe the internal membrane (i.e., organelle) structure within a chloroplast (i.e., thylakoid
membrane, thylakoids and grana).
A. Outer Membrane: (Similar to Cell Membrane)
B. Inner Membrane: (Similar to Cyanobacteria)
a) Granum: (pl. Grana) a single stack of thylakoid;
I) Thylakoid: disk-shaped sub-organelles; formed in the inner membrane
* Internal Membrane System independent from the inner membrane*
i) Thylakoid Membrane
- Photosystems (Photosystem I, II): collect photons from the sun
1) Contains chlorophyll, accessory pigments, and associated proteins
Chlorophyll: pigment that absorbs UV light;


Mitochondria (Inner Membrane Space) Chloroplast (Inner Membrane Space)

● Build up proton motive force ● No processes occur in this space


**Plants intake CO2 to increase biomass, Humans exhale CO2 to decrease biomass**
Describe the general structure of a leaf and explain where it “inhales” CO2
and “exhales” O2.
● Cuticle: clear,waxy substance on surface of leaf; prevents water loss;
● Epidermis: (similar to the skin of a human)
● Mesophyll: contains cells with chloroplast; meat of a leaf;
● Vascular Bundle: transporting water and sugar;
● Stroma: (pl. Stomata) where CO2 is inhaled and O2 is exhaled; mouth of the cell; found
underneath a leaf to prevent water loss. (Similar to Mitochondrial Matrix in Mitochondria)
Write out the general reaction for photosynthesis
● CO2 + H2O + light → C6H12O6 + O2 + H2O

Compare/contrast it to the general reaction for cellular respiration.


Photosynthesis Cellular Respiration

● CO2 + H2O + light → C6H12O6 + ● C6H12O6 + 6O2 → 6CO2 + 6H2O
O2 + H2O + 32 ATP
● Reactants: Glucose, Oxygen

, ● Reactants: Carbon Dioxide, Water, ● Product: Carbon Dioxide, Water,
Light Energy Energy (ATP)
● Product: Glucose, Oxygen, Water

2.
Outline/overview the 3 stages of photosynthesis separated into the light-dependent and light-
independent reactions.
● Light Dependent
1. Light Capture (occurs in Thylakoid Membrane via Photosystems)
2. Formation of ATP + NADPH (occurs in Stroma)
● Light Independent
3. Carbon Fixation (occurs in Stroma)

3.
Describe the visible spectrum of light and identify the wavelength(s)/color(s) that are
absorbed/reflected by plants.
● Visible Light Spectrum - R.O.Y.G.B.I.V
● Violet-Blue Light: 400 nm to Red light: 700 nm;
● Shorter Wavelength = More Energetic;
● Absorbed: R,O,Y,B,I,V; Reflected: G.

Explain the photoelectric effect.
● Electrons are removed from a molecule by photons hitting the molecule

List the different types of pigments found in chloroplasts and identify which
wavelength(s)/color(s) of light each absorb/reflect.
● Carotenoids: Accessory pigment;
- Absorbs: blue and green light
- Reflects: red, orange, and yellow light
● Chlorophyll (Chlorophyll a and Chlorophyll b)
- Absorbs: violet-blue and red light
- Reflects: green light
- Only Chlorophyll a converts light energy to chemical energy
Explain why leaves that were once green in the spring, appear orange/red/yellow in the fall.
● The plant no longer produces chlorophyll. The carotenoids are reflecting the
orange/red/yellow spectrum of the visible spectrum.
Explain the function of the hydrocarbon tail (hydrophobic) on a photosystem
● Tethers the chlorophyll in the Thylakoid Membrane
4.
Describe the general structure (i.e., the light-harvesting complex and the reaction center)
1) Photosystems (Thylakoid Membrane)
a) Antenna Complex: Captures photons and channels energy to the reaction center;
- Contains chlorophyll b and carotenoids;
I) Resonance Energy Transfer: Chlorophyll b from Antenna Complex