Molecular Biology: DNA, RNA, and Protein Synthesis

• The central dogma of molecular biology follows the process: DNA → RNA → Protein
• Organisms require nitrogen to synthesize nucleotides and amino acids.
• A polymer consists of repeating monomers that form larger molecules.
• Proteins consist of amino acids.
• Hemoglobin's function involves carrying oxygen in blood.
• Enzymes catalyze and accelerate chemical reactions.
• Antibodies play a crucial role in fighting infections.
• Proteins are enzymes that function to speed up chemical reactions.
• Nucleic acids are composed of nucleotides, while proteins consist of amino acids.
• A nucleic acid is a polymer, and its monomer is a nucleotide.
• Ribosomes are produced in the nucleolus.
• Pyrimidines include cytosine and thymine, while purines include adenine and guanine.
• The progression from gene to protein involves gene → DNA → chromosome → protein.
• Protein synthesis involves transcription and translation
• Transcription synthesizes mRNA.
• Translation synthesizes proteins using mRNA.
• The purpose of transcription is to produce mRNA from DNA in the nucleus.
• The function of translation is to produce proteins from mRNA at the ribosome.
• mRNA carries genetic code transcribed from DNA.
• A codon consists of a three-nucleotide sequence that codes for an amino acid.
• tRNA carries amino acids to the ribosome during translation.
• The anticodon on tRNA matches the mRNA codon.
• mRNA carries the genetic code from DNA to the ribosome.
• tRNA transports amino acids to the ribosome for protein assembly.
• rRNA forms the structure of the ribosome, which is essential for translation.
• mRNA undergoes splicing, where introns are removed and exons are joined together.
• The mG cap protects mRNA from degradation.
• The poly-A tail prevents mRNA degradation.
• Introns are removed during mRNA splicing.
• Exons are expressed and contribute to the final mRNA sequence.
• A point mutation involves a single nucleotide change in the DNA sequence
• A frameshift mutation results from insertions or deletions in the DNA sequence.
• Mutations are harmful when they disrupt protein function.
• Mutations are helpful when they create beneficial traits.
• Silent mutations do not change the amino acid sequence of the resulting protein.
• Mutation affects gene expression by changing protein structure.
• Mutation does NOT affect expression if it occurs in non-coding DNA or is silent.
• The endoplasmic reticulum (ER) modifies and transports proteins within the cell.
• The Golgi apparatus packages and sorts proteins for their final destinations.
• The process from DNA to protein involves DNA → mRNA → ribosome → protein.

Lytic and Lysogenic Cycles

• The lytic cycle results in immediate destruction of the host cell.
• The lysogenic cycle involves viral DNA integrating into the host genome.
• Viruses utilize host ribosomes to produce viral proteins.
• Viruses are used to deliver genetic material for gene therapy

Nucleic Acids & Proteins

• A nucleotide consists of a phosphate group, sugar, and base.
• RNA monomers contain ribose and uracil, while DNA monomers contain deoxyribose and thymine.
• Proteins are made of amino acids linked by peptide bonds.
• Protein function determined by the sequence of amino acids and the protein’s shape.
• DNA codes for RNA through transcription, and RNA directs protein synthesis through translation.

Protein Synthesis Stages

• RNA synthesis encompasses initiation, elongation, and termination.
• RNA is synthesized through transcription.
• RNA processing involves splicing, capping, and adding a poly-A tail and functions to protect and mature RNA.
• Protein synthesis includes initiation, elongation, and termination.
• Proteins are synthesized through translation.
• At the A site, tRNA enters the ribosome.
• At the P site, peptide bonds form between amino acids.
• At the E site, tRNA exits the ribosome after donating its amino acid.

RNA Types

• mRNA carries the genetic code from DNA to ribosomes.
• rRNA forms the structure of ribosomes.
• tRNA is charged with amino acids in the cytoplasm.
• tRNA contains an anticodon sequence complementary to mRNA codons.
• The sequence of mRNA determines the sequence of amino acids in a protein.
• rRNA creates A, P, and E sites on the ribosome for translation.
• Stop codons (UAA, UAG, UGA) do not have corresponding tRNA anticodons.
• After protein synthesis, mRNA is broken down.

Mutations

• Silent mutations have no effect on the amino acid sequence of a protein.
• A point mutation involves a change in a single base in the DNA sequence.
• Missense and frameshift mutations alter the amino acid sequence.
• A nonsense mutation results in a premature stop codon, truncating the protein
• Insertion mutations add a base to the DNA sequence. Whereas deletion mutations remove a base.
• Mutations affect protein synthesis by altering amino acid sequences.

DNA, mRNA and tRNA

• DNA complement of ATC is TAG.
• mRNA complement of AUC is UAG → tRNA
• UCG codes for the amino acid Serine (Ser).
• mRNA complement of DNA sequence GAT is CUA.
• Complement of DNA sequence TAC is AUG → tRNA
• Lysine codons are AAA and AAG.
• DNA complement of mRNA GAU is CTA.
• mRNA complement of tRNA CAU is GUA.

Explore the central dogma of molecular biology: DNA → RNA → Protein. Understand the roles of nitrogen in synthesizing nucleotides and amino acids. Learn about polymers, proteins, nucleic acids, and the processes of transcription and translation in protein synthesis.