Chapter 8 Improved

Antenna pigment:

pigment molecule that directly absorbs light and transfers the energy absorbed to other pigment molecules

Calvin cycle:

light independent reactions of photosynthesis that convert carbon dioxide from the atmosphere into carbohydrates using the energy and reducing power of ATP and NADPH

Carbon fixation:

process of converting inorganic CO2 gas into organic compounds

Carotenoid:

photosynthetic pigment, yellow, orange, red, that functions to dispose of excess energy

Chemoautotroph:

organism that can build organic molecules using energy derived from inorganic chemicals instead of sunlight

Chlorophyll a:

form of chlorophyll that absorbs violet, blue, and red light and consequently has a bluish-green color, the only pigmentation molecule that performs the photochemistry by getting excited and losing an electron to the electron transport chain

Chlorophyll b:

accessory pigment that absorbs blue, red, orange light and consequently has a yellowish-green tint

Chloroplast:

organelle in which photosynthesis takes place

Cytochrome complex:

group of reversible oxidizable and reducible proteins that forms part of the electron transport chain between photosystem II and photosystem I

Electromagnetic spectrum:

range of all possible frequencies of radiation

Electronic transport chain:

group of proteins between PSII and PSI that pass energized electrons and use the energy released by the electrons to move hydrogen ions against their concentration gradient into the thylakoid lumen

Granum:

stack of thylakoids located inside a chloroplast

Heterotroph:

organism that consumes organic substances or other organisms for food

Light harvesting complex:

passes energy from sunlight to the reaction center in each photosystem, it consists of multiple antenna pigments that contain a mixture of 300 to 400 chlorophyll a and b molecules as well as other pigments like carotenoids

Light dependent reaction:

first stage of photosynthesis where certain wavelengths of the visible light are absorbed to form two energy carrying molecules

What molecules does a light dependent reaction form?

ATP and NADPH

Light independent reactions:

second stage of photosynthesis, through which carbon dioxide is used to build carbohydrate molecules using energy from ATP and NADPH

Mesophyll:

middle layer of chlorophyll rich cells in a leaf

P680:

reaction center of photosystem II

P700:

reaction center of photosystem I

Photoact:

ejection of an electronic from a reaction center using the energy of an absorbed photon

Photoautotroph

organism capable of producing its own organic compounds from sunlight

Photon:

distinct quantity or packet of light energy

Photosystem:

group of proteins, chlorophyll, and other pigments that are used in the light dependent reactions of photosynthesis to absorb light energy and convert it into chemical energy

Photosystem I:

integral pigment and protein complex in thylakoid membranes that uses light energy to transport electrons from plasticyanin to NADP+

In the photosystem I what happens to NADP+?

it becomes reduced go NADPH in the process

Photosystem II:

integral protein and pigment complex in thylakoid membranes that transports electrons from water to the electron transport chain

What is a product from photosystem II?

oxygen

Pigment:

molecule that is capable of absorbing certain wavelengths of light and reflecting others which is the reason for color

Primary electron acceptor:

pigment or other organic molecule in the reaction center that accepts an energized electron from the reaction center

Reaction center:

complex of chlorophyll molecules and other organic molecules that is assembler around a special pair of chlorophyll molecules and a primary electron acceptor, capable of undergoing oxidation and reduction

Reduction:

gain of electrons by an atom or molecule

Spectotrophotometer:

instrument that can measure transmitted light and compute the absorption

Stoma:

opening that regulates gas exchange and water evaporation between leaves and the environment, typically situated on the underside of leaves

Stroma:

fluid filled space surrounding the grana inside a chloroplast where the light independent reactions of photosynthesis take place

Thylakoid:

disc shaped, membrane bound structure inside a chloroplast where the light dependent reactions of photosynthesis take place

Thylakoid lumen:

aqueous space bound by a thylakoid membrane where protons accumulated during light driven electron transport

Wavelength:

distance between consecutive points of equal position, inversely proportional to the energy of the radiation

Carbohydrates:

chemical compounds

What happens after the energy of sunlight is captured?

it is used to organize electrons whose energy is then stored in the covalent bonds of sugar molecules

Cyanobacteria:

plants, algae, and a group of bacteria

What would cyanobacteria be classified as in reference to photosynthesis?

photoautotrophs

What would animals, fungi, or most bacteria be classified as in reference to photosynthesis?

heterotrophs

What does photosynthesis require for its process?

specific wavelengths of visible sunlight, carbon dioxide, and water all as substrates

After photosynthesis is completed what does the cycle release?

oxygen as a waste product

What does photosynthesis produce?

glyceraldehyde-3-phosphate and simple carbohydrate molecules that can be converted into glucose, sucrose or any other sugar molecule

Each stoma is _____________

flanked by guard cells that regulate the opening and closing of the stomata by swelling or shrinking in response to osmotic changes

Chloroplast-containing cells exist mostly where?

in the mesophyll

Chloroplasts have what?

a double membrane envelope

Chlorophyll:

a pigment responsible for the initial interaction between light and plant material, and numerous proteins that make up the electron transport chain

Whats the location of chlorophyll?

embedded in the thylakoid membrane

Sunlight is absorbed by __________ and converted into ____________

chlorophyll, stored chemical energy

The chemical energy harvested during the light dependent reaction drives _________

the assembly of sugar molecules from carbon dioxide

Light is not used as a reactant in which reaction?

light independent reactions

Energy carriers:

certain molecules in the light dependent reactions that temporarily store energy

Referring to photosynthesis, light energy is converted into what?

chemical energy

What is the most powerful wavelength?

shorter ones, longer ones are less powerful

The difference between wavelengths relates to ____________

the amount of energy carried by them

The longer the wavelength the ____________

less energy it carries

Organic pigments have a ________________ that they can absorb

narrow range of energy levels

Energy levels lower than those represented by red light are _______________

insufficient to raise an orbital electron to an excited, quantum state

Energy levels higher than those in blue light will do what to molecules???

physically tear them apart in a process called bleaching

What is the range that human retinal pigments can see?

700 nm and 400 nm of light

Certain objects like a prism or a drop of water are seen because _______________

they disperse white light to reveal the colors to the human eye

What are the wavelengths of violet and blue?

short

Red and similar colors have what length wavelength?

longer wavelengths

What is the red of a tomato called?

lycopene

What is the yellow of corn seeds called?

zeaxanthin

What is the orange of an orange peel called?

B-carotene

When a leaf is exposed to the full sun the light dependent reactions are required to ______________

process an enormous amount of energy but if that energy is not handled properly it can do significant damage

Where do many carotenoids reside? What do they do?

in the thylakoid membrane, absorbs excess energy and safely dissipates that energy as heat

What light dies a B-carotene absorb?

blue and green

What light does chlorophyll absorb?

blue and red

The color green is always __________

reflected or transmitted

What does carotenoid absorb?

the short wavelength blue region

What do carotenoid reflect?

longer yellow, red, and orange wavelengths

Chlorophyll a and b are made up of what?

a long hydrocarbon chain attached to a large, complex ring made up of nitrogen and carbon

Not all photosynthetic organisms have full access to what?

sunlight

The overall function of light dependent reactions is to do what?

comvert solar energy into chemical energy in the form of NADPH and ATP

What happens to energy captured by biological molecules but is not yet stored in a useful form?

the energy us transferred from chlorophyll to chlorophyll until eventually it is delivered to the reaction center

The buildup of hydrogen ions inside the thylakoid lumen creates a what?

concentration gradient

How is ATP created?

passive diffusion of hydrogen ions from hydrogen ions from high concentration to low concentration

Where does high concentration originate?

in the thylakoid lumen

Where does low concentration originate?

in the stroma

Why does the cell have the fuel needed to build carbohydrate molecules for long term storage?

after the energy from the sun is converted into chemical energy and temporarily stored in ATP and NADPH molecules

What is the lifespan of products of light dependent reactions?

millionths of seconds

What is the lifespan of products of light independent reactions?

almost indefinitely

Where does carbon come from?

carbon dioxide

What components are needed to initiate the light independent reactions?

CO2, ribulose-1, 5-bisphosphate carboxylase/oxygenase, three molecules of ribulose bisphosphate

What is RuBP made of?

five atoms of carbon flanked by two phosphates

RuBisCO catalyzes a reaction between ______________

CO2 and RuBP

What happens for each CO2 molecule that reacts with one RuBP?

two molecules of another compound 3-phospho glyceric acid form

What is 3-phosphoglyceric acid made of?

three carbons and one phosphate

Each turn of the calvin cycle involves what?

one RuBP, one carbon dioxide and forms two molecules of 3-PGA

Why is carbon fixation named that?

because CO2 is “fixed” from an inorganic form into organic molecules

ATP and NADPH are used to convert the six molecules of 3-PGA into _____________

six molecules of a chemical called glyceraldehyde 3-phosphate, G3P

A reduction reaction in the calvin cycle always involves what?

the gain of electrons by 3-PGA

Reduction:

the gain of an electron by an atom or molecule

For ATP, energy is released with ________________

the loss of the terminal phosphate atom, converting it into ADP; for NADPH, both energy and a hydrogen atom are lost, converting it into NADP+, these molecules return to the nearby light-dependent reactions to be reused and re-energized

In the regeneration step in the calvin cycle what happens? 

only one of the G3P molecules leaves the Calvin cycle and is sent to the cytoplasm to contribute to the formation of other compounds needed by the plant