How Genes Turn On and Off and Control Cells

Cancer Biology and RNA Interference

The second page focuses on cancer development mechanisms and therapeutic approaches. It explains how promoter regions regulate transcription and how methylation patterns affect cancer cell behavior.

Definition: RNA interference (siRNA) is a biological process where RNA molecules inhibit gene expression by destroying specific mRNA molecules.

Example: Cancer cells often show abnormal methylation patterns in promoter regions, leading to uncontrolled cell division.

Highlight: Tumors are classified as benign or malignant based on their growth patterns and ability to spread.

Vocabulary: Proto-oncogenes are normal genes that can become cancer-causing oncogenes when mutated.

Quote: "Tumor Suppressor genes slow down cell division, repair DNA mistakes, and promote apoptosis."

Control of Gene Expression and Epigenetic Mechanisms

The first page details the fundamental processes of genetic control and cellular differentiation. Transcription factors bind to DNA to regulate mRNA production, with specific mechanisms controlling gene activation and deactivation.

Definition: Epigenetics refers to heritable changes in gene expression that don't involve changes to the DNA sequence itself.

Example: Oestrogen, being lipid-soluble, can enter the nucleus and bind to DNA, altering gene expression patterns.

Vocabulary: Microarrays are tools used to analyze which genes are active or inactive in cells.

Highlight: Stem cells are classified based on their differentiation potential, from totipotent (can form any cell type) to unipotent (limited to one cell type).