Similarities between Prokaryotic and Eukaryotic cells
DNA
They both have DNA as their genetic material. Membrane They are both membrane bound.Ribosomes
They both have ribosome.Metabolism
They have similar basic metabolism.Diverse
They are both amazingly diverse in forms.Difference between Prokaryotic and Eukaryotic cells
Nucleus
The significant difference between prokaryotic and eukaryotic cell is that eukaryotic cell has a prominent nucleus and many membrane-bound organelles, which are not present in prokaryotic cell .DNA
The DNA of a prokaryotic cell floats in cytoplasm near the centre (this region is called nucleoid); the DNA of eukaryotic cell is held within the nucleus.Intracellular division
There is much higher level of intracellular division of labour in eukaryotic cells than in prokaryotic.
Size
Eukaryotic cells are, on average, Genome composition and length The DNA of eukaryotes is much more complex and extensive than the DNA of prokaryotes.Cell wall
Prokaryotes have a cell wall composed of peptidoglycan that is a single large polymer of amino acids and sugar. The cell walls of eukaryotic cells is made of cellulose (in plants) or chitin (in fungi)Size
Cells vary greatly in size. The smallest cells are bacteria called mycoplasmas, with diameter between 0.1 pm to 1.0 pm. The bulkiest cells are bird eggs, and the longest cells are some muscle cells and nerve cells. Most cells lie between these extremes. Relative Sizes of cells Cell size and shape are related to cell function. Bird eggs are bulky because they contain a large amount of nutrient for the developing young.Long muscle cells are efficient in pulling different body parts together. Lengthy nerve cells can transmit nerve signals between distant parts of animal’s body. On the other hand small cell size also has many benefits. For example human red blood cells are only 8 pm in diameter and therefore can move through our tiniest blood vessels.
Relation between cell size and surface area
Most cells are small in size. Large cells have less surface area in relation to their volume while small cells of the same shape have more surface area. This relationship between cell size and surface area to volume ratio works to limit cell size. As the size of a ceil increases, cell volume increases more rapidly than its surface area. The need of nutrients and rate of waste production are directly proportional to cell volume.The cell takes up nutrients and excretes wastes through its surface cell membrane. So a large volume cell demands large surface area. But a large cell has a much smaller surface area relative to its volume than smaller cells have. Hence we conclude that the membranes of small cells can serve their small volumes more easily than the membrane of large cell.
Effect of cell size on surface area
Cell membranes act as barriers to most, but not all, molecules.That is why cell membranes are called differentially or semi-permeable membranes separating the inner cellular environment from the outer environment. While exchanging matter with cells' environment, cell membranes maintain equilibrium inside the cell as well as outside. This control of the passage of molecules into and out of cells is made possible through the phenomena of diffusion, facilitated diffusion, osmosis, filtration, active transport, endocytosis and exocytosis.
Relationship between Cell function and structure
The bodies of animals and plants are made of different cell types. Each type performs specific function and all coordinated functions become the life processes of the organism. We can imagine the specialities of different cell types and the contribution of individual cells to the healthy functioning of the body.For example in human body; Nerve cells conduct nerve impulse and thus contribute in coordination in body. Muscle cells undergo contraction and share their role in movements in body. Red blood cells carry oxygen and white blood cells kill foreign agents and so contribute in the roles of blood in transportation and defence.
Some skin cells act as physical barriers against foreign materials and some as receptors for temperature, touch, pain etc. The cells of bone deposit calcium in their extracellular spaces to make the bone tough and thus contribute to the supporting role of bones. cell works as an open system i.e. it takes in substances needed for its metabolic activities through its cell membrane.
Then it performs the metabolic processes assigned it. Products and by-products are formed in metabolism. Cell either utilizes the Products or transports them to other cells. The by-products are either stored or are excreted out of the cell.
Post a Comment