Basic Concepts of Metabolism. Flashcards
In which cells does metabolism take place?
In almost every cell.
Why do cells take part in metabolism?
It is the way that cells gain energy to build organelles and perform various functions.
What are the 2 steps that need to occur in metabolism?
The extraction of energy from food.
Using nutritional energy to build various organelles and for other bodily tasks such as movement.
What are the steps that occur in metabolism called?
Catabolism.
Anabolism.
What is catabolism?
Catabolism produces energy by taking the nutrients from carbs, lipids and proteins and breaking them down into their smallest components.
What is anabolism?
Anabolism uses the energy produced by catabolism to make proteins and other organic structures.
In what form is the energy produced by catabolism?
ATP.
Is catabolism an oxidative or reductive process?
Oxidative.
What are the high energy molecules that are obtained by catabolism?
ATP.
NADH.
NADPH.
FADH2.
How can you tell that ATP, NADH, NADPH and FADH2 are high energy molecules?
Because they all have a lot of hydrogens.
How many stages are there in catabolism?
3.
What is the 1st stage of catabolism?
The digestion of nutrients which are broken down into their pre-cursor molecules.
What nutrients are broken down via catabolism?
Proteins.
Fats.
Carbohydrates.
What are the pre-cursor molecules for proteins?
Amino acids.
What are the pre-cursor molecules for carbohydrates?
Carbohydrates are polysaccharides so their pre-cursor molecules are monosaccharides.
What are the pre-cursor molecules for fats?
Glycerol and fatty acids.
Why are nutrients from the diet broken into their component parts?
Because only the component parts are absorbed through the small intestine into the bloodstream.
Is stage 1 of catabolism extracellular or intracellular?
Extracellular as it occurs in the digestive system.
What happens when the component parts of nutrients are absorbed?
The component parts are absorbed by the intestinal mucosal cells into the bloodstream where they are transported to various cells.
Is the 2nd stage of catabolism extracellular or intracellular?
Intracellular.
What occurs during the 2nd stage of catabolism.
Each individual component is broken down to form a common intermediate.
What is the common intermediate formed in the 2nd stage of catabolism?
Acetyl-CoA which is a 2 carbon molecule.
Does catabolism occur in a specific organelle within the cell?
No.
Each class of organic molecule is broken down via a different pathway and in a different organelle.
Is acetyl CoA formed by the components of fats, carbs and proteins?
Yes.
Acetyl-CoA is formed by multiple dietary components which have different pathways.
What organelle is responsible for the formation of acetyl CoA?
Acetyl CoA is always formed in the mitochondria. It is always the final step of the pathway for each component.
Where does stage 3 of catabolism occur?
In the mitochondria.
What is the 3rd step of catabolism?
The further oxidation of acetyl-CoA to a usable form of energy (ATP) and a waste product (CO2).
What is always the final stage of step 2 of catabolism?
The formation of AcoA in the mitochondria.
Do the first 2 steps of catabolism create any high energy products?
Yes.
They create many high energy products such as NADH, NADPH and FADH2 which are also converted to ATP.
What is anabolism?
The process by which the body uses precursors and turns them into cellular macromolecules.
How does the body obtain the precursors that are used in anabolic processes to create cellular macromolecules.
From the diet.
They can be synthesised by the body.
They can be recycled by the body.
Name some cellular macromolecules that are formed by anabolism?
Proteins.
Nucleic acids.
Polysaccharides.
Does anabolism require energy?
Yes.
Does catabolism require energy?
No.
How does anabolism get the energy required to build macromolecules?
From the high energy molecules that are produced via catabolism.
What are the products from catabolism reduced to after anabolism?
ADP.
NAD+.
NADP+.
FAD.
Does metabolism occur in 1 organ or in many organs?
In many organs.
Why must metabolism be regulated?
Because, it occurs in many organs and they need to synchronise work load.
How is metabolism in different organs controlled?
There is a communication system that organs use to tell other organs how hard to work.
What are the 2 types of signal that cells can use to communicate with each other during metabolism?
Intracellular signal.
Intercellular signal.
What is an intercellular signal?
Signals between different cells.
Give an example of an intercellular signal?
When glucose levels rise in the body, the pancreas secretes insulin into the bloodstream.
Insulin is sent to the liver cells and will be received by a specific receptor on the cell membrane.
The receptor will then cause an intracellular response within the individual liver cells.
What is a primary messenger?
It is an intercellular signal that will attach to a receptor on the cell membrane.
This will cause the release of an intracellular messenger.
What is a secondary messenger?
When a primary messenger binds to the membrane receptor, the receptor will release an intracellular messenger or 2nd messenger to go to the nucleus.
Can any primary messenger bind to any cell membrane receptor?
No.
Each type of stimulus that is released by a cell will have a unique receptor to which it binds on the target cell.
What is an intracellular signal usually a response to?
An intercellular signal.
What will an intracellular signal do?
It will travel into the interior of the cell and will tell the various organelles what to do.
What is signal transduction?
The process of converting an intercellular signal into a intracellular signal.
What are the 3 types of intercellular signal?
Synaptic signalling.
Endocrine signalling.
Direct contact signalling.
What is synaptic signalling?
When a synaptic cell will produce neurotransmitters aimed at a specific target cell.
The neurotransmitter will find a specific receptor on the target cell which elicits the production of a second messenger and a change inside the cell.
What kind of cells are common synaptic cells?
Nerve cells.
What kind of molecules are used for endocrine signals?
Hormones.
How does endocrine signalling work?
A hormone is released by a cell and will travel through the bloodstream to a specific receptor on a target cell.
What is direct contact signalling?
Where 2 adjacent cells can communicate via contact between gap junctions or cell surface receptors.
What do cells need to signal via direct contact?
Both cells must have compatible receptors or junctions on their cell membranes.
What are the 4 types of intercellular signal receptors?
Gated ion channels.
Receptor enzyme (catalytic receptor).
G protein coupled receptors (GCPRS).
What is an intracellular receptor that can receive intercellular signals?
Steroid receptors.
Where is a steroid receptor located?
In the nucleus.
How will a steroid enter the nucleus?
It will cross the cytoplasmic membrane.
Once in the cytoplasm it will bind to a specific receptor and form a complex.
The complex will then cross the nuclear membrane and enter the nucleus.
What happens to the steroid receptor complex once they enter the nucleus?
Once in the nucleus, it will bind to an enhancer region of DNA.
This activates a specific gene in the promoter region.
The activated gene will produce mRNA that will lead to a gene product such as a protein.
Do all the messengers that travel to steroid receptors bind to receptors in the cytoplasm?
No
Some will cross directly into the nucleus and bind to a receptor there.
Some may bind directly to DNA.
What molecule tends to be the primary messenger that are received by steroid receptors?
Hormones.
Why must hormones be lipophilic?
Because they must cross the cytoplasmic membrane.
How do gated ion channels work?
They are channels within the cell membrane that will open or close in response to an intercellular signal.
