Question

1. The endomembrane system is a collection of cell structures that work together. Each of the following are part of the endomembrane system: cell membrane, nucleus, ribosomes, endoplasmic reticulum, and golgi bodies.  

   • Explain how each of these cell structures are related to each other in function. In other words, briefly describe the central dogma of Biology. (Hint: your answer should be all about proteins!!)

2. Briefly describe the overall process of cellular respiration. Please DO NOT discuss specific stages of the process (ie glycolysis, pyruvate oxidation, Krebs cycle and ETC).

   • Where in the cell does cellular respiration take place?  

   • What are the reactants? What are the products?  

   • What is the purpose of the reaction?

Answer 1

1.As we know the endomembrane system consist of many cell structures like endoplasmic reticulum, plasma membrane, nucleus, ribosomes and golgi apparatus, lysosome, vesicles. All of these structures are connected to perform the functions. As the central dogma stands for the 2 processes, 1st :- transcription(DNA --> RNA) and 2nd :-translation(RNA --> protein).It all starts from the nucleus where DNA being transcripted to mRNA in the presence of RNA polymerase which contains the information of DNA then the mRNA leaves the nucleus and moves to the ribosome in the cytoplasm where protein is synthesised by reading and using the information which the mRNA contains.At some places the ribosome is directly attached to the endoplasmic reticulum called as rough ER. Now the endoplasmic reticulum receives the protein from where the proteins are collected in the cisternae or lumen of ER and when enough amount of protein is collected these are folded and are exported to the golgi apparatus with the help of vesicles. Now the proteins can be directly sent to the lysosome or can go to the golgi apparatus for packaging then are finally released in the cytoplasm.

2. Cellular respiration is simply the process where O2 is utilised by the cells for the catabolic reaction(breakdown of nutrient molecules) to derive energy in the form of ATP molecules required for proper functioning and to regulate the metabolism of our body. A resultant release of co2(by product) occurs besides the energy released.

3. Mitochondria is the main site for cellular respiration although the enzymatic reactions required for cellular respiration starts in the cytoplasm. The main 3 steps of cellular respiration are:- glycolysis, kreb's cycle and electron transport. The glycolysis occurs in the cytoplasm of cell while the other 2 steps, kreb's cycle and electron transport occurs in the mitochondia. (kreb's cycle in the matrix and electron transfer on the inner membrane of mitochondria).

4. C6 H12 O6 + 6O2----->6CO2 + 6H2O +Energy released(ATP).

5. The main purpose of cellular respiration is to fulfill the requirement of energy to the cells so that they can regulate the essential functions to maintain their metabolism. Every process inside our body needs energy. So as to compensate this requirement of energy our body needs to produce energy.