AP Biology 3B

all living things (not just animals) experience or undergo

cellular respiration: produces ATP

photosynthesis

when plants convert solar energy to chemical energy (food)

• occurs in plants, algae, protists, and prokaryotes

chemical equation for photosynthesis

6CO₂ + 6H₂O > C₆H₁₂O₆ + 6O₂

site of photosynthesis

chloroplast (membrane bound organelle)

mesophyll

chloroplasts mainly found in these cells of leaf

stomata

pores in leaf (CO₂ enters / O₂ exits)

chlorophyll

green pigment in the thylakoid membrane of chloroplasts

• essential for photosynthesis

• converts sun light to electron energy

stroma

fluid filled space in the inner membrane

thylakoid

a membrane/sac

lumen

fluid filled space in the thylakoid

redox reaction (OIL RIG)

a process in which water is oxidized and carbon dioxide is reduced

• oxidation = loss of electrons (or losing H)

• reduction = gain of electrons (or gaining H)

OIL RIG meaning

Oxidation is Loss
Reduction is Gain

stages of photosynthesis

• Light dependent reaction (photo)

• Calvin Cycle (synthesis)

Describe the light dependent reaction (photo) stage

• energy conversion reactions

• convert solar energy to chemical energy

• produce ATP & NADPH

• two photosystems in the thylakoid membrane

describe the calvin cycle (synthesis) stage

• sugar building reaction

• uses chemical energy (ATP & NADPH) to reduce CO₂ & synthesizes C₆H₁₂O₆

• in the stroma

describe the two photosystems in the thylakoid membrane

• a light-catching unit: large complex of proteins and pigments that capture the sunlight

• collections of chlorophyll (a) molecules

• transfers high energy electrons for ATP and NADPH

Name and function of Photosystem II

• P₆₈₀

• absorbs light energy at 680nm

name and function of photosystem I

• P₇₀₀

• absorbs light energy at 700nm

first step of a light dependent reaction

• Light excites chlorophyll electrons (in photosystems) and become energized

second step of a light dependent reaction

• Excited electrons pass through electron transport chain (ETC), making ATP via chemiosmosis

function of the proton pump in a light reaction

• pumps hydrogen from the stroma to the lumen (low to high concentration gradient)

• creates a high concentration of hydrogen for the ATP Synthase to make ATP

low pH means what type of environment

• acidic environment

• aka. pH2

• high hydrogen concentration

high pH means what type of environment

• normal environment

• aka. pH9

• low hydrogen concentration

function of ATP synthase

• phosphorylates ADP to ATP to make ATP energy

• uses hydrogen to make ATP

  • Phosphorylation: adding a phosphate to diphosphate to make it triphosphate

What is the energy source of active transport in a light dependent reaction?

from the electrons traveling down the electron transport chain (ETC)

Step 3 (last step) of a light dependent reaction

electrons reduce NADP+ (to form NADPH) and are replaced by photolysis of water

• NADP+ is reduced to NADPH

• NADP+ is the final electron acceptor

why would the process of the light dependent reaction stop

electrons are lost to the electron transport chain and therefore will no longer create ATP / energy

purpose of photolysis of water

water serves as an electron donor for the electron transport chain (photosystems) to compensate for the lost electrons (due to the ETC)

describe photolysis of water

• water is in the lumen and therefore is split (by the sun) in the lumen to make 2H+ electrons 

• eventually creates O₂ that will leave to the atmosphere via the stomata

in a light dependent reaction, when the H+ electrons are traveling to the stroma from the thylakoid space, what type of transport is it

passive transport because it moves from high to low concentration, and therefore does NOT use energy

photophosphorylation is

the process of using photosystems to make ATP & ADPH via ETC and Chemiosmosis

calvin cycle occurs in the

stroma

calvin cycle requires what products

ATP & NADPH

1st phase of calvin cycle

• Carbon Fixation

  • CO₂ from the air is imbedded in the cycle and combined with RuBP to make 3-Carbon compound called PGA

  • catalyzed by enzyme rubisco

  • aka. carbon fixation

2nd phase of calvin cycle

• Reduction

  • ATP and NADPH are used to convert PGA into G3P

  • PGA gains electrons (reduction)

    • ATP converted to ADP

  • ADP & NADP⁺ return to light dependent reaction to start process again 

3rd phase of calvin cycle

• Regeneration of RuBP

  • Some G3P make glucose, and others will be recycled to regenerate RuBP

  • Allows for more CO₂ to be fixed in the cycle

  • requires ATP

describe G3P

• product of the Calvin Cycle

• 3 carbon sugar

factors that affect photosynthesis

• temperature

• light intensity

  • more light = more reaction rate

• concentration of CO₂

  • more CO₂ = more reaction rate

(experiment vocab) tissue culture

technique to grow cells in the laboratory

(experiment vocab) cell line

a type of cell grown in the lab for experiment 

• HeLa Cell

(experiment vocab) In Vitro

an experiment in a test tube

(experiment vocab) In Vivo

an experiment in a test tube

(experiment vocab) Nutrient medium

a liquid nutrient used to feed the cells in the lab

(experiment vocab) radioactive isotope

an isotope of an element is used to “tag” the molecules studied.

(experiment vocab) Assay

an experiment

• COVID-19 PCR test