This paper encompasses detailed class notes on Nucleic Acid, The difference between DNA and RNA, functions of the nucleus, types of nucleic acids, chemical structure of RNA and DNA, types of RNA and DNA, Replication of RNA and DNA, DNA sequences in chromosomes, DNA molecule, High order DNA structu...
The nucleus regulates all life processes in a cell and plays a vital role in hereditary
information. This information is encoded on the genes that originate on the chromosomes.
Each chromosome comprises of DNA (deoxyribose nucleic acid). RNA (Ribose nucleic acid)
is located within the nucleus and also the cell cytoplasm. Genetic information makes each
organism distinctive.
2. Functions of the nucleus
Controls cell metabolism
Responsible for cell division
Controls protein synthesis
Controls the production of RNA
Responsible for the transfer of hereditary characteristics.
3. Nucleic acids
Nucleic acids play a role in the regulation and transmission of hereditary characteristics and
the structure of proteins that are produced in the course of protein synthesis. Each individual
organism comprises of proteins that are distinctive to merely that organism. This is why
organs are not merely removed from one organism to another. If the proteins are not
analogous, then the body will reject the organ. This is why organ transplants show the
greatest success between siblings (brothers and sisters). The closest a parent can be to their
offspring is 50% because each offspring is a combination of 50% male parent and 50%
female parent.
There are two types of nucleic acids;
DNA - deoxyribose nucleic acid and
RNA - ribose nucleic acid.
DNA is found in the threadlike chromosomes and RNA is found mainly in the nucleolus and
the cytoplasm. DNA strands contain active sections called genes.
4. Structure
Each nucleic acid consists of a number of basic building blocks called nucleotides. Each
nucleotide consists of three parts:
, 1 phosphate ion
1 pentose sugar
1 nitrogenous base
Nitrogenous bases are divided into two complementary groups:
Purines:
Pyrimidines:
DNA forms a double strand where purines will only bond with pyrimidines. DNA contains
Thymine and RNA contains Uracil instead of thymine. The other nitrogenous bases are found
in both DNA and RNA. A back bone of phosphates and pentose sugars join to the
nitrogenous bases, resulting in a long chain. The nitrogenous bases are attached to each of the
pentose sugars.
5. The DNA molecule
The DNA molecule is a double helix (twisted) strand. The four nitrogenous bases can be
arranged in any order with a purine attached to a pyrimidine. The combination of nitrogenous
bases is the code system for the messages from the DNA. A weak hydrogen bond holds the
complementary nitrogenous bases together. This occurs as follows:
Adenine always only joins to Thymine
Guanine always only joins to Cytosine
Special DNA sequences exist in each chromosome
replication origins – multiple locations where the replication machinery first binds to
start replication
centromere – center “pinch point” of a chromosome that allows one copy of each to
be pulled apart into two daughter cells during division
telomere – specialized sequences at the chromosomes end that facilitate replication
there
Higher-order DNA structure
How do cells efficiently store very long chains of DNA?
DNA wraps around protein “spools” to form nucleosomes
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