Vocab - Cellular Respiration and Photosynthesis

cellular respiration

the oxidation of glucose (and other molecules), and the capture of energy in a form that is useful to the cell and the cell’s source of ATP energy

net reaction of cellular respiration

C6H12O6 + 6O2 –> 6CO2 + 6H2O + energy (ATP)

glycolysis

occurs in the cytosol, does not require oxygen, also occurs in bacterial cells, and it dates from the earliest days of life

cytosol

where glycolysis occurs

NADH

passes their electrons to the electron transport chain in the inner mitochondrial membrane

citric acid cycle

describe later

oxidative phosphorylation

the result of this is most of the ATP yield from cellular respiration

reduced electron carriers

NADH and FADH2

electron transport

reduced NADH and FADH2 (from the oxidation of food molecules) pass their electrons to the electron transport chain in the inner mitochondrial membrane

inner mitochondrial membrane electron carriers

the electrons lose energy as they move from electron carrier to electron carrier in the membrane

H+ pumping across the inner membrane

energy is used to pump H+ ions, against their
electrochemical gradient into intermembrane space

intermembrane space

the space between the inner and outer membrane of the mitochondrion

proton gradient

ATP synthase

The potential energy stored in the form of the H+ gradient is used by this to make ATP

O2 evolution

electron transport blockers

poisons can block transport as well as suffocation

uncouplers

allow electron transport to continue but dissipate the H+ gradient

fermentation

happens when there is no oxygen available

lactate

during fermentation pyruvate from glycolysis is converted to lactate or ethanol instead of acetyl-CoA

function of fermentation

it allows the NADH that is formed in glycolysis to dump its electrons somewhere and cycle back to glycolysis as NAD+, thus keeping glycolysis and its ATP production going

other food molecules

molecules other than glucose (other sugars, amino acids, fragments of fatty acids) can be fed into the pathway at various points, so they can supply metabolic energy too

intermediates

drawn off from the pathway to serve as precursors in biosynthetic reactions

biosynthetic reactions

used to construct the organic molecules of the cell

light reactions

energy from light is used to create temporary chemical energy in the form of ATP and high-energy electrons carried by NADPH

Calvin cycle

temporary chemical energy from the light reactions is used to create stable, storable chemical energy – carbohydrate

CO2 fixation

the incorporation of carbon from CO2 into organic compounds entering the Calvin Cycle

photosynthetic pigments

chlorophylls and carotenoids

chlorophyll a

participates directly in the light reactions and absorbs mainly blue-violet and red light

chlorophyll b

absorbs mainly blue and orange light and broadens the range of light a plant can use

carotenoids

various shades and yellow and orange and gives pigment to foods like carrots

absorption spectrum

color light they absorb during photosynthesis

photosystem

an assembly of several light harvesting complexes that gather sunlight and pass the energy to a reaction center complex

pigments of photosynthesis

pigments in the light-harvesting complex absorb light and transfer the energy to the reaction center chlorophyll a

reaction center chlorophyll a

chlorophyll a molecules are oxidized after absorbing the energy from the light-harvesting complex

chlorophyll oxidation

primary electron acceptor

an excited electron is captured by the acceptor

photophosphorylation

The production of ATP by chemiosmosis during the light reactions of photosynthesis

Calvin cycle

CO2 reduction (CO2 fixation)

the Calvin cycle makes carbohydrate by fixing (reducing) CO2

14^C tracer

in the 1940s, Melvin Calvin discovered using radioactive carbon (14C) as a tracer

rubisco

the first enzyme of the Calvin cycle

RuBP

the first reaction of the Calvin cycle

3-phosphoglycerate

RuBP (5C) + CO2 (1C) –> 2x3-phosphoglycerate (2x3C)

1-glyceraldehyde-3-phosphate

net gain of the Calvin cycle

3 turns (that is, 3 carbons fed in) –> 1 glyceraldehyde-3-phosphate