Molecular Genetics and Protein Synthesis

Set of instructions for making proteins, universal across species. Uses codons (sequences of 3 nitrogenous bases) that specify specific amino acids.

DNA segments that carry instructions for building proteins (genes) or RNA molecules.

DNA segments that do NOT directly code for proteins or RNA.

A sequence of three nitrogen bases that specifies a particular amino acid.

A non-coding DNA segment that tells RNA Polymerase where to begin transcribing a gene.

A protein-coding segment of a gene.

A non-protein-coding segment of a gene.

Carries the DNA gene's message to be translated into a protein.

Part of the ribosome; aids protein synthesis.

Brings amino acids to the ribosome for protein assembly.

Segment of DNA with protein-building instructions.

DNA message copied to mRNA

mRNA carries the genetic code from DNA to ribosomes, guiding the sequence of amino acids in protein synthesis.

The two subunits of a ribosome separate after protein synthesis is complete, releasing the mRNA and the newly formed polypeptide.

After release, the polypeptide chain folds and twists spontaneously into a 3D shape, sometimes aided by chaperone proteins.

Enzymes can modify proteins after synthesis, adding sugars or other molecules, impacting their function.

Multiple ribosomes can attach to one mRNA molecule, simultaneously synthesizing multiple polypeptide chains.

A change in the DNA sequence that can be inherited, potentially leading to altered proteins and genetic disorders.

A specific change in a gene's nucleotide sequence, causing incorrect protein production or no protein at all.

A change involving a single nucleotide base in a gene, affecting protein function by changing amino acid sequences.

Replacing one nucleotide base with another in a gene triplet, potentially changing the amino acid it codes for.

An insertion or deletion of a nucleotide base in a gene, shifting the reading frame and causing a non-functional protein.

After transcription, mRNA undergoes modifications before leaving the nucleus. A guanine cap is added to the 5' end for ribosome recognition, and a poly-A tail is added to the 3' end to prevent degradation. Introns (non-coding regions) are removed, and exons (coding regions) are spliced together.

The 5' end of mRNA binds to the small ribosomal subunit. The start codon (AUG) is located after the guanine cap. An initiator tRNA with the anticodon UAC and the amino acid methionine binds to the start codon. The large ribosomal subunit then attaches.

The ribosome moves along the mRNA, exposing codons. Each codon is recognized by a tRNA with the appropriate anticodon, carrying a specific amino acid. A ribozyme forms a peptide bond between the amino acids. The first tRNA detaches, and the process repeats.

The mRNA molecule moves one codon after a peptide bond is formed. The first tRNA separates, returns to the cytosol, and picks up a new amino acid. Elongation and translocation occur concurrently.

When a stop codon (UAA, UAG, or UGA) is encountered, a release factor binds. This releases the polypeptide chain from the ribosome, and the ribosome dissociates.

Mistakes during DNA copying (S phase) can lead to changes in the DNA sequence.

Chemicals that can alter DNA by adding, deleting, or changing nucleotides.

High-energy sources (X-rays, gamma rays, UVB) can damage DNA, causing it to be shifted, scrambled, or deleted.

Ribosomal RNA (rRNA) is a type of RNA that plays a crucial role in protein synthesis. It is a structural component of ribosomes - the cellular machinery responsible for protein synthesis. rRNA also has enzymatic activity, meaning it can catalyze chemical reactions needed for protein assembly.

Transfer RNA (tRNA) delivers specific amino acids to the ribosome during protein synthesis. It acts as an interpreter, reading the mRNA codons and bringing the correct amino acid to be added to the growing protein chain.

Protein synthesis is vital for all living organisms because proteins are the workhorses of cells. They perform a wide range of functions, including structural support, enzymatic activity, transport, and communication. Without proteins, life as we know it would not exist.

The length of a gene is determined by the number of codons it contains, which code for a single protein. Genes can range from 150 to 30,000 codons long.

Transcription is the process of copying genetic information from DNA into RNA. The process occurs in the nucleus of cells and involves the creation of a messenger RNA (mRNA) molecule that carries the genetic code from the DNA to the ribosomes for protein synthesis.

RNA polymerase is an enzyme that plays a crucial role in transcription. It reads the DNA sequence and uses it as a template to build a complementary mRNA molecule.

RNA polymerase has a specific binding site that recognizes a particular sequence of nucleotides in the promoter region. This sequence, often TATATATATA in eukaryotes, signals RNA polymerase to bind and initiate transcription.