Describe the Biochemical Composition Structure and Replication of Dna Essay
Background
DNA is an abbreviation for deoxyribonucleic acid, but it is usually known by its initials alone. DNA is found in practically all living organisms, and it is now known to carry genetic information from one cell to the next, and from one generation to the next. The units of inheritance, called genes, are actually sections of the DNA molecule.
Nuclei of the cells of higher organisms contain thread-like bodies called chromosomes, which consist of DNA, wrapped around proteins.
So understanding how the DNA molecule behaves inside cells helps explain how genetics works at the simplest level.
In the nucleus of every normal cell of the human body there is over 1 metre of DNA, divided between 46 chromosomes.
DNA is a fascinating substance, because it can split into 2 halves, each of which can be built up to re-form the missing sections. It is, therefore, a molecule which is able to reproduce itself - essentially a characteristic of living organisms. For this reason, DNA is sometimes called the basis of life. It can also pass instructions out to the cytoplasm, in order to control the way the cell operates.
In the cell there are also other forms of a similar substance, RNA , ribonucleic acid, which are used to turn the genetic information into proteins that the cell needs. These proteins are mostly enzymes, used to control chemical activities in the cell, collectively known as its metabolism.
The structure of DNA
DNA is an example of a macromolecule, i.e. a large molecule with a special shape, which is built up from many smaller parts called sub-units .
If you could magnify part of a nucleus, you would see the DNA molecule looking like a twisted rope ladder - a double helix.
The two strands forming the sides of the ladder give it a strong yet flexible structure, which does not vary along its length.
Stretched between these are the "rungs" of the ladder, the parts of the DNA molecule which vary, and so the differences carry genetic
DNA is an abbreviation for deoxyribonucleic acid, but it is usually known by its initials alone. DNA is found in practically all living organisms, and it is now known to carry genetic information from one cell to the next, and from one generation to the next. The units of inheritance, called genes, are actually sections of the DNA molecule.
Nuclei of the cells of higher organisms contain thread-like bodies called chromosomes, which consist of DNA, wrapped around proteins.
So understanding how the DNA molecule behaves inside cells helps explain how genetics works at the simplest level.
In the nucleus of every normal cell of the human body there is over 1 metre of DNA, divided between 46 chromosomes.
DNA is a fascinating substance, because it can split into 2 halves, each of which can be built up to re-form the missing sections. It is, therefore, a molecule which is able to reproduce itself - essentially a characteristic of living organisms. For this reason, DNA is sometimes called the basis of life. It can also pass instructions out to the cytoplasm, in order to control the way the cell operates.
In the cell there are also other forms of a similar substance, RNA , ribonucleic acid, which are used to turn the genetic information into proteins that the cell needs. These proteins are mostly enzymes, used to control chemical activities in the cell, collectively known as its metabolism.
The structure of DNA
DNA is an example of a macromolecule, i.e. a large molecule with a special shape, which is built up from many smaller parts called sub-units .
If you could magnify part of a nucleus, you would see the DNA molecule looking like a twisted rope ladder - a double helix.
The two strands forming the sides of the ladder give it a strong yet flexible structure, which does not vary along its length.
Stretched between these are the "rungs" of the ladder, the parts of the DNA molecule which vary, and so the differences carry genetic