Types of Nucleic Acids and Protein Synthesis

Nucleic Acids

DNA molecules contain information that instructs a cell how to synthesize the correct enzymes.

Genetic information

• Inherited traits result from DNA information that is pas.sed from parents to child.
• A gene is a portion of a DNA molecule that contains the genetic information for making one kind of protein.

DNA molecules

• The nucleotides of a DNA strand are arranged in a particular sequence.
• The nucleotides are paired with those of the second strand in a complementary fashion.

The genetic code

• The sequence of nucleotides in a DNA molecule represents the sequence of amino.
• Acids in a protein molecule.
• Genetic information is transferred from the nucleus to the cytoplasm by RNA molecules.

RNA molecules

• RNA molecules are usually single stranded, contain ribose instead of de-oxyribose. and contain uracil nucleotides In place of thymine nucleotides.
• Messenger RNA molecules which are synthesized in the nucleus contain a nucleotide sequence that is complementary to that of an exposed strand of DNA.
• Messenger RNA molecules move into the cyioplasm, become associated with ribosomes and act as patterns for the synthesis of protein molecules.

Protein synthesis

• Molecules of transfer RNA serve to position amino acids along a strand of messenger RNA.
• A ribosome binds to a messenger RNA molecule and allows a transfer RNA molecule to recognize its correct position on the messenger RNA.
• The ribosome contains enzymes needed for the synthesis of the developing protein and holds the protein until it is completed
• Its the protein develops, it folds into a unique shape.
• ATP provides the energy needed for these events.

Duplication of DNA

• Each daughter cell needs a copy of the parent cell's genetic information.
• DNA molecules are duplicated during inter-phase of the cell's life cycle.
• Each new DNA molecule contains one old strand and one new strand.

Changes in Genetic Information

The amount of information within a DNA molecule is very large Occasionally a change or mutation occurs in the genetic information.

Nature of mutations

• Mutations involve a variety of kinds of changes within DNA molecules.
• A protein synthesized from damaged DNA information is likely to be nonfunctional.
• Repair enzymes can correct some forms of DNA damage.

Effects of mutations

• The mutations that cause a decrease in cell efficiency are of most concern.
  The mutation that occurs in a cell of a developing embryo may affect a great number of cells in the developing body.