Question

7) Give characteristic dimensions for each of these organisms: Escherichia coli; Yeast (Saccharomyces cerevisiae); Liver cell (hepatocyte); Plant cel. (10 points) (8) Describe the different levels of metabolic regulation. (5 points) (9) Describe the main aspects of the central dogma for genetic information transfer. (5 points)

Answer 1

Hi Answer;

Q.7. Give characteristic dimensions of each of these organisms: Escherichia coli, Yeast (Saccharomyces cerevisiae) ; Liver cells (hepatocytes) and Plant cells

1. Escherichia coli

It is arod shaped bacterium having gram negative nature and its width is about 0.5 μm and 0.2 μm in width and length respectively. The E.coli cells have a thin cell wall having only 1-2 layers of peptidoglycans.

2. Yeast (Saccharomyces cerevisiae)

It is believed that the first time yeast was isolated from skin of grapes. It is one of the extensively studied model in eukaryotic organisms. it is a globular-shaped, yellow-green yeast belonging to the Fungi kingdom. It has two forms of cells to grow haploid and diploid. Both cells grow and divide by mitosis but haploid cells are more sensitive than diploid.

3. Liver cells (hepatocytes)

Liver cells (hepatocytes) are the dominant cells of liver about 80% of the liver is made by these cells. Liver cells are approximately 100 mm in diameter and having width of 5µm. These cells are inovolved in protein synthesis and protein storage. They also involved in carbohydrate transformation and synthesis of cholesterol, bile salts and phospholipids.

4. Plant cell

The plant cell size varies between 10 to 30 micrometer. The plant cell have stretching power and a normal 30 micrometer plant cell can stretch up to 100 micrometer. A plant cell is different from other type of eukaryotic cells it have rigid cell wall, a central vacuole, plasmodesmata and plastids. The different kind of plant cells are available which are as follows: parenchyma cells, sclerenchyma cells, collenchyma cells, xylem cells, and phloem cells.

Q.8 Describe the different levels of metabolic regulation

Metabolism mean the digestion or break down of complex material to simpler one and release of energy. This energy is utilized by the organism for performing their vital body functions. In metabolism process mostly regulated by the enzymes which are the expression product of some specific genes. Most of the metabolism are regulated by two major pathways.

1. Changing the activity of pre existing enzymes
2. Changing the amount of enzyme

These two aspects can be discussed one by one:

1. Changing the activity of pre existing enzymes

The activity of the pre existing enzymes can be change by following methods:

1. By changing the substrate avilabilty: as we know that enzyme bind to the substrate nd form enzyme substrate complex before forming the product. If we change (increase or decrease) the substrate concentration the activity of enzyme cn be controlled.
2. Product inhibition: it also plays important role if we avoid product inhibition then the metabolism reaction can be run longer.
3. Allosteric regulation: if we maintain allosteric inhibition then reaction can be run longer.
4. pH of reaction: As the pH of the reaction is major factor for the enzyme reaction. If we change the pH it stops the reaction hence by changing pH of reaction we can regulate the metabolic reaction.

1. Changing the amount of enzyme

By increasing or decreasing the enzyme amount in the cells we can regulate the metabolism. It can be done by following methods.

1. Alternation in the enzyme transcription level: If the gen transcription is changed then the production of particular enzyme can be controlled. The controlled transcription can regulate the enzyme production efficiently and hence also control the metabolic reaction
2. Degradation of messenger RNA for the enzyme:The level of mRNA directly implies the production of that protein in cells. With help of small inhibitor RNA the mRNA can be degrade which further control the production of enzyme.
3. Post translational changes: after protein formation it goes for the post translational modification if during this phase the proteins are cleaved by the proteases then it will effect the amount of enzyme and we can control the metabolism reaction.

4. Q.9. Describe the main aspects of centrl dogma for genetic information transfer?

   The central dogma is the process or a group of events by which the instructions in DNA are converted into functional products. The central dogma explains the flow of genetic information’s from DNA to RNA and t proteins.

   According to this theory the DNA contain all information which are converted into functional proteins and these information’s are translated with the help of RNA, where RAN act as carrier and carry the information to ribosome. And in Ribosome these information’s are converted into products