GENETICS , BLOCK 11

What is regenerative medicine?

Repair or replace damaged cells or tissues to restore normal function.

What are the two defining properties of stem cells?

Self-renewal and differentiation.

What is self-renewal?

Ability to divide and produce identical stem cells.

What is differentiation?

Ability to become specialised cell types.

What is totipotent?

Can form all cell types including placenta.

What is pluripotent?

Can form all body cell types.

What is multipotent?

Can form a limited range of related cell types.

What is oligopotent?

Can form a few cell types.

What is unipotent?

Can form only one cell type.

Why are pluripotent stem cells useful in therapy?

They can grow indefinitely and form any cell type.

Why are adult stem cells less useful?

They are rare, hard to isolate, and have limited growth.

What are induced pluripotent stem cells (iPSCs)?

Differentiated cells reprogrammed into a pluripotent state.

Which factors generate iPSCs?

Oct4, Sox2, Klf4, c-Myc.

Why can cells be reprogrammed?

They retain the full genome; only gene expression changes.

What is the key advantage of iPSCs?

Patient-specific → reduced immune rejection.

What is somatic cell nuclear transfer (SCNT)?

Transfer of a somatic cell nucleus into an enucleated egg.

What does SCNT produce?

An embryo capable of generating pluripotent stem cells.

How does SCNT reprogram cells?

The egg cytoplasm resets the nucleus.

What is the difference between iPSC and SCNT?

iPSC uses transcription factors; SCNT uses an egg.

What are the two main roles of stem cells in therapy?

Replace damaged cells and provide signalling support.

What are the steps of stem cell therapy?

Take cells → reprogram → edit → differentiate → transplant.

What is autologous therapy?

Using the patient's own cells.

What is allogeneic therapy?

Using donor cells.

Why is the eye a good target for stem cell therapy?

Immune privileged, accessible, and requires few cells.

What is gene therapy?

Introducing genetic material to treat disease.

What are the three gene therapy strategies?

Replacement, silencing, editing.

What is gene replacement therapy?

Adding a functional copy of a gene.

What is gene silencing therapy?

Turning off harmful gene expression.

What is gene editing therapy?

Correcting mutations in DNA.

What is in vivo gene therapy?

Delivering genes directly into the patient.

What is ex vivo gene therapy?

Modifying cells outside the body and reintroducing them.

What are the two types of gene delivery vectors?

Viral and non-viral.

What are advantages of viral vectors?

High efficiency and strong gene expression.

What are risks of viral vectors?

Immune response, toxicity, genotoxicity.

What is a key feature of AAV vectors?

Do not usually integrate into the genome.

What is a key feature of lentiviral vectors?

Integrate into genome for long-term expression.

What is an example of a non-viral system?

Lipid nanoparticles.

What is RNA interference (RNAi)?

Gene silencing by degrading mRNA.

What happens to double-stranded RNA?

Cut into siRNA by Dicer.

What is the role of RISC?

Uses siRNA to bind and degrade mRNA.

What is the result of RNAi?

No protein is produced.

At what level does RNAi act?

Post-transcriptional.

What is CRISPR-Cas9?

A gene editing tool that cuts DNA at specific sequences.

What determines the target site in CRISPR?

Guide RNA (gRNA).

What enzyme cuts DNA in CRISPR?

Cas9.

What are the two repair mechanisms in CRISPR?

NHEJ and HDR.

What does NHEJ cause?

Error-prone repair → gene knockout.

What does HDR allow?

Precise DNA repair.

What disease uses gene replacement of Factor VIII?

Haemophilia A.

Why are blood diseases good targets for gene therapy?

Cells are easily accessible.

What do stem cells do?

Self-renew + differentiate.

What are iPSCs?

Reprogrammed differentiated cells.

What does RNAi target?

mRNA.

What does CRISPR target?

DNA.

What are the strategies of gene therapy?

Replace, silence, edit.