6. respiration Flashcards
what do we need energy for?
- making new cells by cell division
- making substances e.g. proteins
- making our muscle cells work (contract)
- sending electrical impulses along neurons
what is stored in glucose?
chemical energy which is used to generate ATP during the breakdown of glucose
what do animal cells need to survive?
we need oxygen and food so that we can release energy
CO2 is a waste product that we breathe out
what is the word equation for aerobic respiration?
oxygen+glucose->energy+CO2+water
what is respiration?
a series of enzyme controlled reactions so that chemical energy in the glucose is gradually released to produce the energy transfer molecule ATP
what is ATP
(adenosine triphosphate) is an energy transfer molecule which transfers energy from energy-releasing reactions in a cell to the energy-consuming reactions in the cell
example of a energy releasing reaction
respiration
example of an energy-consuming reaction
protein synthesis in the cell
what is fermentation (anaerobic respiration)?
the breakdown of glucose without oxygen
during this glucose is only partly broken down - it occurs in the cytoplasm
describe fermentation in animal cells (stage 3)
when oxygen runs out, pyruvate is converted into lactate which then causes muscle fatigue - it would only produce 2ATP (occurs in cytoplasm)
describe fermentation in plant/fungal cells (stage 3)
when no oxygen is available, pyruvate is broken down into ethanol (alcohol) and carbon dioxide - 2ATP produced
CO2 diffuses out of the cell and is lost, without it the ethanol cannot be converted back into pyruvate - if fermentation goes on too long the build up of ethanol will kill the yeast/plant cells (occurs in cytoplasm)
what is the word equation for fermentation in plant cells
glucose->ethanol+carbon dioxide+energy
what is the word equation for fermentation in animal cells
glucose->lactate+energy
describe first stage in the breakdown of glucose
glucose is broken down into 2 pyruvate molecules and releases enough energy to yield 2ATP molecules - further breakdown depends on the presence/absence of oxygen
describe the second stage in the breakdown of glucose
if oxygen is present, pyruvate will diffuse into the mitochondrion and so that it can be completely broken down into water and CO2 - enough energy is released to yield 36ATP (18 x 2)
