· Genetic messages（codes for amino acids）： sequences of nitrogenous bases

· A key feature in the unity of life: genetic material in all living organisms is DNA.(deoxyribonucleic acid )

· DNA- mainly found in the nucleus where it forms chromosomes. It is also found in chloroplasts and mitochondria of eukaryotic cells.

· RNA- main component of ribosomes which play an important role in protein synthesis. Some could also be found in the nucleus and cytoplasm.

Viruses--Certain viruses (such as SARS-CoV-2) contain · · · · RNA as their genetic material instead of DNA. These viruses cause a variety of different diseases, such as COVID-19, Ebola, mumps and influenza.Viruses are not considered to be living organisms, since they are unable to replicate by themselves. They are dependent on other living cells for replication and survival. Viruses also lack a cellular structure, which is another reason they are not considered to be living

· A phosphate group --acidic and negatively charged

· A base (1 ring or 2 rings )--contains nitrogen ( N )

Adenine（A）

Thymine（T）

Cytosine（C）

Guanine（G）

bases in RNA：

Adenine（A）

Uracil（U）

Cytosine（C）

Guanine（G）

· transfer RNA(tRNA)--Anticodon--responsible for transporting amino acids to ribosomes during protein synthesis

· ribosomal （rRNA）-- forms part of ribosomes