DNA Methylation and Cancer Detection

The video explains DNA methylation, a key epigenetic modification affecting gene expression. It introduces DNA methyltransferases (DNMTs) responsible for adding methyl groups to DNA, particularly during embryonic development, and maintaining methylation patterns in differentiated cells. The video also covers CpG sites, where methylation commonly occurs, and the role of TET enzymes in DNA demethylation. It highlights how methylation patterns are altered in cancer, leading to gene silencing and tumor progression, and discusses the potential for using these patterns in cancer detection.

What is the primary reason different cells express different genes despite having the same DNA sequence?

• Gene expression is identical in all cells.

• Cells randomly express genes.

• Epigenetic modifications like DNA methylation.

• Different cells have different DNA sequences.

What is the role of promoter DNA methylation?

• It repairs damaged DNA.

• It activates gene expression.

• It silences genes and maintains cell types.

• It duplicates DNA sequences.

Which enzyme is responsible for maintaining DNA methylation patterns after cell differentiation?

• DNMT3a

• DNMT3b

• DNMT1

• TET

What is the function of DNMT3a and DNMT3b in early development?

• They are responsible for de novo methylation.

• They convert cytosine to uracil.

• They remove methyl groups from DNA.

• They repair DNA damage.

What molecule provides the methyl group for DNA methylation?

• FAD

• NADH

• ATP

• SAM

What is the initial product formed when a methyl group is added to cytosine?

• Thymine

• 5-methylcytosine

• 5-hydroxymethylcytosine

• Uracil

What role do TET enzymes play in DNA methylation?

• They duplicate DNA strands.

• They convert 5-methylcytosine to 5-hydroxymethylcytosine.

• They add methyl groups to DNA.

• They repair DNA breaks.

In cancer cells, what is typically observed in promoter CpG islands?

• Hypermethylation

• Complete demethylation

• Hypomethylation

• No change in methylation

What is the consequence of widespread hypomethylation in cancer cells?

• Increased gene silencing

• Enhanced DNA repair

• Activation of tumor suppressor genes

• Genomic instability

How can changes in DNA methylation patterns be used in cancer detection?

• By identifying changes in DNA sequence

• By detecting alterations in methylation patterns

• By measuring DNA replication rates

• By observing cell division rates