UNIT 2: Prokaryotic and Eukaryotic Cell Biolo 1. Describe the structure of the c
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UNIT 2: Prokaryotic and Eukaryotic Cell Biolo 1. Describe the structure of the cell membrane and describe its components 2. Mycoplasma was placed in an isotonic, hypertonic and hypotonic environment. Rank in order, the best to the worst environment for this cell type. Explain the reason for the rankings. 3. Rank in the order from best to worst, which of the following environments would Explain the following terms with the use of diagrams: 4. Outline the differences and similarities between diffusion, facilitated diffusion, active transport and group translocation.Explanation / Answer
Cell membrane or plasma membrane separates inside of a cell from outer world. Cell membrane is present in every living organism on this earth. Cell membrane is concerned with a vast varieties of functions such as protection,trnsport of substances,cell adhesion, ion conductivity, cell signalling etc.
Components
According to Fluid Mosiac Model proposed by Singher and Nicolson, cell membrane is a fluid like structure composed of lipids, proteins and carbohydrates. Amoung the three lipids are abundant, consisting of almost 60% of cell membrane. Proteins consist of almost 35-38 % of total volume. Carbohydrates are least and are present in conjugated form with proteins(Glycoproteins) or with lipids(Glycolipids). Carbohydrates are found on outer surface of cell membrane.
Lipids
Three types of amphipathic lipids are found i.e Phospholipids, Glycolipids and Sterols. Lipids maintain the permeability of membrane by switching to fluid or crystalline state.
Proteins
There are many types of proteins present,some are integral or transmembrane proteins, some are peripheral proteins while as others are linked with lipids and are called as Lipid Linked Proteins.Main function of proteins is transport.
Carbohydrates
Carbohydrates are present in the form of glycolipids or glycoproteins. They are important in cell-cell recognition and cell-cell adhesion.
2-
Since Mycoplasma lack cell wall, therefore they would undergo normal phenomenon like other cells.
Isotonic solution- in isotonic solution the cell would be in equilibrium with outer environment. Hence it would be best environment to live.
Hypertonic solution- As outside solute concentration is more, but mycoplasma have sterols and polyphenols in their plasma membrane which give them protection from shrinking. Moreover it synthesizes compatible osmolytes like proline, glyceine betaine which makes the cellular concentration isotonic to outer environment and prevent water loss.
Hypotonic solution- The outer environment has less solute than inside if cell, so water will enter cell and cause plasmolysis. This will be wrost for cell.
Similarities:-
all of above are concerned with transport of substances
Differences
diffusion is simply movement of substances from higher gradient to lower.
facilitated diffusion is special type of diffusion which occurs with help of transport proteins.
Active transport recquires energy in form of ATP for transport of substances against their concentration gradient.
Group transport transports many substances at a time with consumption of ATP.
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