Cell Bio Processes Flashcards
What are the limiting factors of photosynthesis?
Temperature- rate of photosynthesis, enzymes in process directly affected by temp
Light Intensity- if no sunlight in available, then photolysis of water cant occur without required light energy
Carbon Dioxide- concentration of CO2 is important because the Calvin Cycle is dependent on CO2
What is cellular respiration?
Process that converts chem energy in glucose bonds into chem energy that holds phosphate groups to atp
organic substances broken down to simpler products while releasing E
released E incorporated into ATP used for metabolic processes
Step-by-step degradation of sugar radiated by enzyme @ each step
Done by all cells; not oxygen dependant
What is glycolysis?
Sugar breaking reactions
precedes both aerobic and anaerobic respiration
breaks down 6 carbon glucose into two molecules of 3 carbon pyruvate
What happens in glycolysis?
6 carbon glucose is broken down into two molecules of 3 carbon pyruvate.
Glycolysis requires 2 ATP,
Produces: 2 substrate-level phosphorylations (4 ATP)
1 reduction of NAD and NADH (2 NADH)
-Net: 2 ATP and 2 NADH –> 2 pyruvate
glucose –> 2 pyruvate –> 2 pyruvic acid
Compare and contrast anaerobic and aerobic respiration.
Anaerobic Respiration: -no oxygen =fermentation -alcoholic or lactic acid fermentation Aerobic Respiration: -oxygen dependant =oxidative phosphorylation -carried out by most plants and animals
- both start with glycolysis
- net ATP is much higher in aerobic respiration (around 18 times more efficient)
What is ATP? Why is ATP important?
chemical battery for all cells
production requires membranes to generate current
used to transport substnaces in active transport
supplies E for contraction, chromosomes, and flagella
on-off switch for reactions and messages
most of ATP made via ETC
main reason cells need constant oxygen supply
What happens in photosynthesis? What is photosynthesis?
process that forms simple sugars from CO2 and H2O with light and chlorophyll
in chloroplast
-light E is absorbed, converted to ATP and NADPH, then synthesized into sugar phosphates to makes sucrose, cellulose, starch, and other end products
-main pathway E and carbon enter food webs
-reduction process where H reduced by coenzyme in contrast to cellular respiration where glucose is oxidized
CO2 + H2O –> glucose + oxygen
What is oxidative phosphorylation?
a cellular respiration process
net ATP varies; ~36 ATP
in organisms with eukaryotic cells that have mitochondria
can happen without oxygen
What is the krebs cycle?
aka tricarboxylic acid cycle
in mitochondrial matrix
pyruvate is further broken down by other enzyme mediated reactions into CO2
NADH and FADH2 are products
What is the electron transport system? What happens in the ETS/ETC?
aka electron transport oxidative phosphorylation
occurs on 3 sites in the inner mitochondrial matrix
uses NADH and FADH2 from krebs cycle
e- and H+ are liberated; NAD+ and FAD+ are formed
electrons move between acceptor molecules imbedded in inner mitochondrial membrane
as electrons moves across the membrane, energy in the electrons move H ions into outer compartments, freeing H+ from NADH and FADH2
-increases concentration between outer and inner mitochondrial membranes
H+ from inner compartment combine with e- and O (final e- acceptor) to make H20)
H+ diffuse into inner through membrane by passing ATP synthase protein channel (chemiosmosis)
–> causes ADP and P to make ATP
each NADH generates ~3 ADP; each FADH2 generates ~2 ATP
What is lactic acid fermentation?
an anaerobic cellular respiration process
done by certain types of bacteria and overworked muscles
lactic acid found in yeast, sauerkraut, and muscles
forms 2 ATP (no NADH) and 2 lactic acid
caused by intense muscle activity (little O2 available)
What is alcoholic fermentation?
an anaerobic cellular respiration process
produces ethanol and 2 ATP (no NADH)
happens in certain types of bacteria and yeast
examples:
- CO2 in bread making
- Alcohol in wine making and brewing
- Lactic acid in milk fermentation
What is the calvin cycle? What happens in the calvin cycle?
dark reaction
uses energy in the form of ATP and NADPH to form carbs
used by plants and algae to turn CO2 into sugar, usable E for autotrophs
most cells use the C3 pathway where CO2 reacts with RuBP; products split to form 3C compounds giving the pathway its C3
results in photorespiration; sugar breaks down
not useful in hot.dry days when plants close stomates to conserve water
–>some plants do C4 or CAM instead, which binds CO2 with a more efficient enzyme allowing it to trap CO2 without opening stomates as often
–this leads to the plants using CO2 for the Calvin (-Benson) cycle
What are C3 plants?
a major metabolic path where CO2 is fixed during photosynthesis
around 95% of plants
aka carbon fixation stage
occurs in the stroma of chloroplasts
uses E from light reactions to fix CO2 into organic molecules
fixation of CO2 stores and uses chem E in the form of organic compounds
uses CO2, ATP, NADPH; makes ADP, NADP+, and 3 PGAL\
uses enzymes (mainly Rubisco)
-8 steps
What is photosystem II? What happens in photosystem II?
first protein complex in light-dependent reactions of oxygenic photosynthesis
located in the thylakoid membrane of plants, algae, and cyanobacteria
1: light captured by the pigment in chloroplast and water is split into H, e-, and O (photolysis)
2: light hits e-, they jump to higher E level
3: E is transferred by fluorescence (photons of longer wavelengths) between pigment molecules in an antennae complex until captured @ reaction centre
4: energetic e- funneled to ETS in thylakoid membrane
5: e- move between acceptors in thylakoid membrane (first with photosystem II, then moving through photosystem I)
6: energetic e- and H ions used H to make ATP by noncyclic photophosphorylation as chemiosmosis
7: as H ions pass through the channel protein ATP synthase, and forms NADPH from NADP+
8: E from light is now present in chem bonds associated with ATP and NADPH
