Cellular respiration Flashcards
What is the end product of cellular respiration?
The production of ATP
What is the function of ATP?
Provides energy for many of the bodies processes such as macromolecule synthesis, cell division, motility (mobility of gametes), transport, signalling etc.
How is the energy from ATP extracted?
By undergoing hydrolysis
Where does ATP come from?
The food we eat
What food sources can ATP come from?
Glucose (main one), amino acids, fatty acids, glycerol
What happens to ATP when you’re active?
It is used to fuel body activities
What happens to small simple molecules (e.g. glucose, amino acids, glycerol, fatty acids) when you’re active?
They are broken down into ATP
What happens to large complex molecules (e.g. glycogen, proteins, triglycerides) when you’re active?
They are broken down into smaller molecules
What happens to ATP when you’re inactive (e.g. sleeping)?
It gets stored in complex molecules as an energy store
How can the energy from food be wasted?
In the forms of heat and nitrogenous waste and faeces
What happens to the energy extracted form cellular respiration?
It is absorbed into the blood stream
Explain the process of extracting food into energy using glucose as an example
Glucose is energy extracted from food, it is then absorbed into the blood stream. Glucose is then absorbed by a cell with the help o insulin where it is either used for cellular respiration (ATP production) or stored for later times (glycogen production)
What regulates the release of energy from glycogen?
Glucagon
What are the three major biochemical pathways for energy extraction?
Glycolysis, Krebs cycle and electron transport and chemiosmosis
What process enables blood sugar levels to be controlled?
Homeostasis
What is the normal blood glucose levels?
70-110mg/dL
What happens when blood sugars fall below normal levels?
Alpha cells in the pancreas secrete glucagon. This increases breakdown of glycogen into glucose (glycogen stored in liver and skeletal muscle), fatty acids (in adipose tissue) and increased synthesis and release of glucose (in liver)
What happens when bond sugars are above the normal level?
Beta cells secrete insulin. Increases rate of: glucose transport into target cells, rate of glucose utilisation and ATP generation, conversion of glucose into glycogen, amino acid absorption and protein synthesis, triglyceride synthesis in adipose tissue
What is glycolysis?
The anaerobic process that occur in the metabolism to produce ATP
What is the net energy gain from glycolysis per glucose molecule?
1 glucose = 2 ATP
How many reactions are involved in glycolysis? How does this number vary between other organisms?
10, it doesn’t vary very much (indicates that it is perhaps the first metabolic processes to have evolved)
Where does glycolysis occur? What does this mean for the metabolic rate?
In the cytoplasm
It is very easily accessed so it can occur quickly
How does glycolysis produce its energy? What is the energy expenditure and output/waste products?
Harvests energy by oxidising glucose into pyruvate
Produces 2 ATP (by substrate level phosphorylation [adding a phosphate group]) and 2 NADH
Waste produce is pyruvic acid
How does glycolysis link up and start the krebs cycle?
The pyruvic acid is converted into acetyl coenzyme A
How can you produce acetyl coenzyme A (CoA)?
Either oxidised from pyruvic acid (main way of making acetyl CoA) or complex carbohydrates metabolised (through different mechanism and bypasses glycolysis)
What are the products of the krebs cycle with acetyl CoA?
1 ATP (energy), 2 CO2 (waste), 1 FADH2 (electron carrier), 3 NADH (electron carrier)
Where does the krebs cycle occur? What is this reaction present in that glycolysis wasn’t? What kind of process does this make it?
In the matrix of the mitochondria, it is done in the presence of O2 so it is aerobic
What happens to the NADH and FADH2 after the Krebs cycle?
Used in the electron transport chain and chemiosmosis
What happens during the electron transport chain?
At each step, electrons lose potential energy, this energy is used to pump protons across membrane forming strong electrochemical gradient, as protons go back across membrane ATP synthase uses proton gradient energy to phosphorylase ADP forming ATP
How much ATP does the electron transport chain produce? Is this number always the same? why?
26-28
No because electrons can get ‘lost’ as they ‘leak’ from the membrane resulting in varying amount of protons being pumped across membrane
What is the final electron acceptor? What does it form?
O2, forms H2O
Is O2 good four organisms? Why? What is done about it?
No, it creates lots of free free oxygen radicals which damage DNA, cells, fats etc. However anti-oxidants help to clear up these free radicals reducing damage
What happens when the mitochondria begins to fail?
More electron begin to leak out so the cytochrome proteins in the electron chain are released into the cytoplasm of the cell which initiates apoptosis preventing further cell damage and other neighbouring tissue damage
Where does the electron transport chain occur?
The double membranes of the cristae
Explain the electron transport chain process
NADH an dFADH2 are oxidised to produce 1 or 2 electrons
Electrons are passed down multiple protein complex
Each time an electron passes a protein and H+ is pumped into the inter-membrane space of the cristae
The last protein complex completes redox reaction reducing O2 to H2O and removing electron
Explain the process of chemiosmosis
H+ flows down concentration gradient (e.g. form high conc in inter-membrane space into mitochondrial matrix) though ATP synthase
ATP synthase then makes ATP form ADP + P
How many ATP does the electron transfer chain (ETC) and chemiosmosis produce? What does it depend on?
26 or 28
Proper oxidation of the NADH and FADH2, amount of leaking during electron transfer
What does the ETC create and what does hits give rise to?
ETC creates an energy rich electrochemical gradient geeing rise to a proton-motive force
What is the function of ATP synthase?
To combien inorganic phosphorous onto an ADP molecule to make ATP
How does ATP synthase combine P with ADP to form ATP?
There is a turbine structure within the synthase and the protons when going with the concentration gradient turn the turbine. This generates energy which is used to combine the P onto the ADP
Why does the ETC chemiosmosis produce much more ATP than glycolysis or the krebs cycle?
Glycolysis and krebs cycle are substrate level phosphorylation. However ETC is power by a molecular machine driven by oxidative phosphorylation increasing efficiency
Why is only 26 or 28 ATP produced in the ETC and chemiosmosis?
Phosphorylation and redox reactions are not directly couple so have a ratio, not just a straight number
Glycolytic NADH electrons must be shuttled into the mitochondria and transferred to another NAD+ or FAD –> this produces less ATP therefore varying ATP production
Energy in H+ may be used for other mitochondrial processes
Explain the aerobic cellular respiration processes and the energy production at each stage per glucose molecule
Glycolysis turn glucose into 2 pyruvate molecules (2 ATP) and produce 2NADH.
The NADH are shuttled into mitochondria and the 2 electron on this are transferred to NAD+ or FAD in the mitochondria
Pyruvate is oxidised into 2 Acetyl COA and 2 more NADH
2 Acetyl COA is then used in krebs cycle/citric acid cycle (2 ATP) and produce 6 NADH and 2 FADH2
All the NADH and FADH2 is then used in the ETC and chemiosmosis for oxidative phosphorylation (26/28 ATP)
Other than glucose, what other nutrients can be used in aerobic respiration?
Triglycerides and proteins
How are triglycerides used in aerobic respiration?
Fatty acids can be used to generate acetyl COA and glycerol can be fed into the glycolysis process
How are proteins used in aerobic respiration?
Proteins broken down into amino acids which can be used to produce pyruvate
How can the rate of cellular respiration be controlled with glucose?
By stimulation or inhibiting the 3rd protein in the glycolysis of glucose, phosphofructokinase
How is phosphofructokinase stimulated?
AMP
How is phosphofructokinase inhibited?
ATP
What happens to the glucose when phosphofructokinase is inhibited
It encourages it to be stored as glycerol
What happens when insulin no longer works?
It is hard for glucose to get inside the cells therefore there is limited cellular respiration from glucose and no glycogen being stored
Where is insulin produced?
By the beta cells of Islets of Langerhans in the pancreas
What is the function of insulin?
promotes glucose uptake into cells either for ATP production or storage in the liver
Where is glucagon produced?
By the alpha cells of the Islets of Langerhans in the pancreas
What is the function of glucagon?
Stimulate the breakdown of glycogen to increase blood sugar levels
How is blood sugar maintained?
Through a balance of insulin and glucagon
What is diabetes mellitus? What does it cause?
A disease where the bodies ability to respond or produce insulin is impaired
This causes abnormal metabolism of carbohydrates and elevated levels of glucose in the body
What are the two types of diabetes?
Type 1 and type 2
What is type 1 diabetes/insulin dependent diabetes? What percent of diabetes does this affect? What group of people does it mainly impact?
Where the body doesn’t produce insulin as the beta cells are destroyed due to autoimmune, genetic or environmental factors
5-10%
Mainly younger people (grow out of it in adulthood)
What is type 2 diabetes/non-insulin dependent diabetes? What percentage of diabetics does this affect?
What group does it mainly affect?
Where the pancreas produces insulin but the insulin receptors on cells are non-funcitonal (e.g. insulin resistant)
90-95%
Main affects people 40+
What are the side effects of diabetes?
Excessive thirst, frequent urination, extreme hunger, unexplained weight loss, tiredness, changes in vision, numbness, slow healing wounds, high frequency of infection (know 3)
