Bio C2. synthesis

Protein synthesis

how cells use information in DNA to make proteins.

DNA → RNA → Protein

DNA → RNA → protein → cellular function

Step 1: Transcription

Location: Nucleus

During transcription:

1. A section of DNA containing a gene is used as a template.

2. The DNA strands separate in that region.

3. An RNA molecule is produced.

4. The resulting messenger RNA (mRNA) carries the genetic instructions.

5. The mRNA leaves the nucleus through a nuclear pore.

Simple idea:DNA → mRNA

Step 2: Translation

Location: RibosomeThe mRNA travels to a ribosome.During translation:

1. The ribosome reads the mRNA.

2. Transfer RNA (tRNA) brings amino acids.

3. The amino acids are joined together in the correct order.

4. A polypeptide/protein is produced.

Simple idea:mRNA → protein

Explain how protein synthesis controls the physiology of the cell.

Proteins perform many of the cell’s important functions.The DNA contains instructions for making proteins, so gene expression affects what a cell can do.

Enzymes

Speed up chemical reactions.

Receptors

Receive signals from other cells or hormones.

Transport proteins

Move substances across the cell membrane.

Structural proteins

Provide support and maintain cell shape.

Contractile proteins

Allow muscle cells to contract.

Channels

Allow specific ions or molecules to cross membranes.

Hormones/signaling molecules

Some proteins participate in communication between cells.