Genetic Code and the Introduction of RNA

• DNA contains a blueprint for the synthesis of proteins.

• RNA is needed to convert information found in the DNA to a sequence of amino acids.

• The three types of RNA are: messenger RNA (mRNA), Transfer RNA (tRNA) and Ribosomal RNA (rRNA).

• Messenger RNA carries messages from DNA in the nucleus to the ribosomes in the cytoplasm.

• Transfer RNA transfers amino acids to the ribosomes.

• Ribosomal RNA makes up part of the ribosomes.

The Central Dogma of Molecular Biology

• Genetic information is transferred from DNA to RNA to proteins in a process called protein synthesis.

Protein Synthesis and the Importance of Protein

• Protein Synthesis occurs in two steps.

• Transcription is the first step. In this step, the RNA molecule produced is based on a DNA template.

• Translation is the second and last step. In this step, mRNA is read by a ribosome and is converted to an amino acid sequence.

• Proteins are important for the structure and function of cells.

• 50% of a cell’s dry weight is composed of proteins

• Proteins functions in animals include metabolism (enzymes), support (i.e., collagen and keratin), transport (membrane proteins), defense (antibodies), regulation (some hormones), and motion (muscle tissue).

Genetic Code and Analyzing the Code

• Groups of three nucleotides form codons.

• Each codon codes for a particular amino acid.

• Some codons signal the process of protein synthesis to start or stop.

• The genetic code is redundant, unambiguous, non-overlapping, nearly universal, and conservative.

• The genetic code is redundant because all but two amino acids are encoded by more than one codon.

• The genetic code is unambiguous because one codon never codes more than one amino acid.

• The genetic code is non-overlapping because codons are read one at a time.

• The genetic code is nearly universal because all codons specify the same amino acids in all organisms (with a few minor exceptions.)

• The genetic code is conservative because if several codons specify the same amino acid, the first two bases are usually identical.

Mutations

• A mutation is any permanent change in an organism’s DNA and the two types are point mutation and chromosome-level mutations.

• The types of point mutations are silent mutations, missense mutations, nonsense mutations, and frameshift mutations.

• In silent mutations, there is no change in the amino acid.

• In missense mutations, there is a change in the amino acid in the protein.

• In nonsense mutations, it changes the amino acid into a stop codon.

• In frameshift mutations, the reading frame is shifted which alters the meaning of all subsequent codons and there is an addition of or deletion of one or more nucleotides.

• The types of chromosomal mutations are deletion, duplication, inversion, and translocation.

• Deletion occurs when something goes wrong in meiosis which causes a chromosome to get removed.

• Duplication occurs when sister chromatids do split apart which causes genes to be copied onto the chromosome.

• Inversion occurs when a chromosome breaks and in the process of inversion, the chromosome that breaks gets flipped and then attaches itself back to the other half of the chromosome from which it broke off from.

• Translocation occurs when a chromosome links itself to a different chromosome that also broken.

• (The website that I obtained the information from about the four types of chromosomal mutations is located in the link attached. https://www.thoughtco.com/types-of-chromosome-mutations-1224525 )