DNA and RNA

• DNA is made up of four nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G).
• Ribonucleic acid (RNA) is similar to DNA, but with some key differences:
• There are 64 possible combinations of three nucleotides (codons), but only 20 different amino acids used by cells.
• During translation, mRNA is read as triplets called codons that code for specific amino acids.
• RNA has a similar double helix structure but contains uracil bases instead of thymine.
• The sequence of bases on the template strand determines which amino acids are added to the growing polypeptide chain.
• The strands are held together by base pairing between nucleotides containing bases adenine, guanine, cytosine and thymine.
• DNA replication is the process by which DNA makes a copy of itself during cell division.
• The DNA double helix is stabilized by hydrogen bonds between complementary base pairs.
• The sugar component of RNA is ribose instead of deoxyribose.
• Translation occurs when mRNA binds to ribosomes, which read the sequence of bases on the mRNA strand and use it as instructions to build proteins using tRNAs.
• Some codons do not specify an amino acid, instead they signal the end of protein synthesis or start/stop signals.
• Genes are segments of DNA that contain instructions for making proteins or regulating their production.
• Protein synthesis involves two main processes: transcription and translation.
• Translation occurs at ribosomes, where tRNAs bring amino acids to the ribosome based on their anticodon complementarity to the corresponding codon on the mRNA.
• Each base can form two hydrogen bonds with its complementary partner.
• Adenine always pairs with thymine, while guanine always pairs with cytosine.
• Transcription produces an mRNA copy of the gene's information from the DNA template.