Cell Biology: Understanding the Basics of Genetic Transcription and Translation

The Cell

• Basic unit of all living tissue.

The Nucleus

• Structure found in most human cells.
• Contains the genome.

Human Genome

• Split between 23 pairs of chromosomes.
• Each chromosome contains a long strand of DNA.
• DNA is tightly packaged around proteins called histones.

Genes and DNA

• Sections within DNA are called genes.
• Genes contain instructions for making proteins.

Transcription Process

1. Gene Activation
   • Occurs when a gene is "switched on."
   • Enzyme RNA polymerase attaches to the start of the gene.
2. RNA Synthesis
   • RNA polymerase moves along DNA, creating messenger RNA (mRNA).
   • Free bases in the nucleus are used to form mRNA.
   • DNA code dictates the order of bases in mRNA.

mRNA Processing

• mRNA must be processed before being used for protein production.
• Involves removing and adding RNA sections.
• Processed mRNA exits the nucleus into the cytoplasm.

Protein Synthesis

1. Ribosome Binding
   • Ribosomes are protein factories in the cytoplasm.
   • Bind to the mRNA.
2. Amino Acid Chain Formation
   • Ribosome reads mRNA code to produce an amino acid chain.
   • There are 20 different types of amino acids.
   • Transfer RNA (tRNA) molecules carry amino acids to the ribosome.
3. Translation
   • mRNA is read three bases at a time (triplet).
   • Each triplet corresponds to a specific amino acid, delivered by tRNA.
   • Amino acids are added to a growing chain.
4. Protein Folding
   • Once the chain is complete, it folds into a 3D shape.
   • The folded chain becomes a functional protein.