Chapter 8- Cellular metabolism (1) Flashcards
What is a metabolic pathway?
A series of chemical reactions occurring within a cell.
What part of the pathway is modified by a sequence of chemical reactions?
The initial chemical (metabolite)
The reactions in a metabolic pathway are catalysed by?
Enzymes
What is the main aim of metabolic pathways?
To generate ATP
If ATP production falls by 5- 10%, then what will happen to the cell?
The cell is likely to die
ATP depletion may trigger what?
Apoptosis- where a cell realises that it hasn’t got enough energy and selectively kills itself.
By selectively killing itself, the surrounding cells are now not competing with that cell so the probability of those cells surviving is higher.
What are the two metabolic pathways?
1- Catabolic pathways
2- Anabolic pathways
What do catabolic pathways do?
Break down food into smaller molecules with the release of energy.
This results in ATP production and transfer of energy
Breaks down macromolecules
What do anabolic pathways do?
Anabolic pathways are biosynthetic and use the energy released by catabolism to synthesize molecules that the cell requires
What is biosynthetic?
The production of complex molecules within living organisms or cells.
How do cells release energy in relation to food molecules?
Cells release energy by the oxidation of food molecules.
How is the energy released by the oxidation of food molecules stored?
It is stored in the chemical bonds of a set of carrier molecules.
What do carrier molecules include?
1- ATP- adenosine triphosphate
2- NADH- nicotinamide adenine dinucleotide
ATP is a nucleotide that contains 3 main structures:
1- Nitrogenous base (adenine)
2- Ribose sugar
3- 3 phosphate groups bound to the ribose
How is ATP broken down into ADP?
Through the process of hydrolysis- addition of a water molecule
ADP is formed when one phosphate is removed from ATP.
Electron carriers are involved in what type of reactions?
Redox reactions- carrying electrons from one reaction to another.
What is the process of glycolysis?
Converts a 6 carbon glucose molecule into two 3 carbon molecules of pyruvate.
Where does glycolysis occur?
In the cytoplasm
What is the net gain of glycolysis?
2 molecules of ATP and 2 molecules of NADH for each molecule of glucose
How is ATP formed?
By ADP and phosphate coming together.
There is fast ATP production during glycolysis, but has a low what?
Low yield
When there is no oxygen available, pyruvate turns into what?
Lactate. This reaction is catalysed by lactate dehydrogenase
When does the conversion from pyruvate to lactate occur?
When the intake of oxygen cannot match the amount of energy we are using up.
When there is oxygen available, what is pyruvate converted to?
Acetylecoenzyme A and carbon dioxide is formed.
This is called a transition reaction and occurs in the mitochondria.
What is a key intermediate to transfer 2 carbon atoms into the Krebs cycle?
AcetylCOA
