Respiration Flashcards
the
needs for cellular respiration
to transport substances across membranes
active transport
metabolic pathways
structure of mitochondria
outer mitochondrial membrane - separates contents of mitochondria from the rest of the cell
inner mitochondrial membrane - contains electron transport chains and ATP synthase
cristae - increase sa for oxidative phosphorylation
inter membrane space - proteins pumped into this space by electron transport chain
matrix - enzymes for the Krebs cycle and link reaction
what are the stages of aerobic respiration
- glycolysis
2/ link reaction - krebs cycle
- oxidative phosphorylation
reaction for aerobic respiration
glucose + oxygen —–> carbon dioxide + water
what is the process of glycolysis
glucose is converted into pyruvate in the cytoplasm
explain the process of glycolysis
- 2 ADP and 2 Phosphates combine and form 2 ATP and glucose which combine forming hexose bisphosphate (phosphorylation)
- Hexose bisphosphate splits into 2 triose phosphate (2 TP)
- to each TP molecule a phosephate group is added forming 2 triose bisphosphate (phosphorylation)
- 2 triose bisphosphate is oxidised which forms 2 pyruvate molecules
when the triose bisphosphate is oxidised a hydrogen ion is removed which the NAD coenzyme accepts, it becomes reduced NAD
ADP is phosphorylated into ATP
where does the link reaction occur and what is it
it is when pyruvate becomes acetyl coenzyme A and occurs in the mitochondria (mitochondrial matrix)
explain the link reaction
- pyruvate enters the mitochondrial matrix, oxidative decarboxylation takes place and it loses carbon dioxide and hydrogen and forms acetate
- hydrogen is accepted by NAD and it becomes reduced NAD
- 2 CARBON ACETYL groups combine with coenzyme A producing acetyl coenzyme A
- ACETYL COA delivers acetyl group to the Krebs cycle
what is the krebs cycle and what occurs
mitochondrial matrix
acetyl coA into oxaloacetate
explain the krebs cycle
- acetyl coA is delivered from the link reaction which delivers the acetyl group and combines with oxaloacetate forming citrate
- citrate undergoes decarboxylation and dehydrogenate producing co2 and reduced NAD
- citrate is converted into a 5 carbon molecule which undegoes further decarboxylation and dehydrogenation which regenerates oxaloacetate
what does FAD do
it accepts hydrogens in the krebs cycle
differences for nad and fad
NAD takes part in all stages FAD is only in krebs cycle
NAD accepts 1 hydrogen FAD accepts 2
reduced NAD is oxidised at the start of the electron transport chain which releases protons and electrons whilst reduced fad is further oxidised further along the chain
reduced NAD results in synthesis of 3 ATP but reduced fad results in 2 atp
where are coenzyme derived from
vitamins
what is oxidative phosphorylation
where atp is made
takes place in the cristae of the mitochondria
process of oxidative phosphorylation
- NAD and FAD are attached to cristae. These accept electrons in glycolysi, link and krebs cycle to become NADH/FADH
- H atom from NADH/FADH splits into e- and H+. e- enters ETC, H+ stays in the matrix
- e- pass down carriers in ETC in a series of oxidation, reduction reactions
- As e- pass down carriers they lose energy, this is used to transport H+ ions across membranes into intermembrane space via active transport.
- This creates a conc gradient and H+ passes through ATP synthase (protein channel) by facilitated diffusion which makes ADP+Pi > ATP
- e- rejoins with H+ to make H atoms, H atoms combine with CO2 to make water.
O2 is therefore known as the terminal electron acceptor
What causes a change of shape in the protein ATP synthase
The flow of H+ (protons] causes a change of shape in the protein ATP synthase and leads to ATP synthesis.
what is chemiosmosis
it is when Hydrogen ions flow down a concentration gradient from intermembrane spaces to the matrix through atp synthase which provides energy to join ADP to Pi forming ATP
WHAT IS SUBSTRTAE Phosphorylation
it is the production of ATP involving the transfer of a phosphate group from a short lived highly reactive intermediate e.g. creatine phosphate
how much atp is produced from aerobic respiration
38 ATP molecules per glucose respired
anaerobic respiration
occurs in the absence of oxygen
obligate anaerobes
cannot survive in the presence of oxygen
facultative anaerobes
synthesize atp by aerobic respiration if oxygen is present but can switch to anaerobic in the absence of oxygen
obligate aerobes
can only synthesize atp in the presence of oxygen
lactate fermentation
reduced NAD transfers hydrogen to pyruvate to form lactate ( pyruvate is reduced top lactate by enzyme lactate dehydrogenase)
this regenerates more oxidized NAD for glycolysis
alcoholic fermentation
pyruvate is converted into ethanal catalysed by pyruvate decarboxylase. ethanal accepts a hydrogen from reduced nad becoming ethanol. regenerated NAD continues to act as a coenzyme soo glycolysis can occur
what is respiratory quotient
co2 produced divided by o2 consumed
carbohydrates, proteins and lipids
