Bio 101- Gene Therapy and DNA Replication

Gene therapy

A treatment that fixes or replaces faulty genes to cure or reduce the effects of disease.

What is the main goal of gene therapy?

To replace or fix a faulty gene

Steps in gene therapy

1) Insert healthy gene into a carrier (usually a virus) 2) Deliver to target cells 3) Cells replicate the healthy gene 4) Treated cells replace diseased ones.

What are viruses used for in gene therapy?

As vehicles to carry healthy genes into cells

Stem cells

Cells that can turn into any other type of cell in the body.

Where are adult stem cells mainly found?

Bone marrow

Why are stem cells useful for gene therapy?

They can change into needed cell types

Gene therapy issues

Hard to deliver genes to the right cells, control gene activity, and avoid off-target effects.

What is an “off-target effect” in gene therapy?

The gene goes into the wrong cells

Which is NOT a major problem in gene therapy?

Stopping transcription completely

How many single-gene diseases exist?

About 10,000

Genetic testing

Examines DNA to identify changes or mutations that can lead to disease.

How is genetic testing related to gene therapy?

It identifies which genes may need to be treated or replaced

Cell division

The process of one cell splitting to form new cells for growth, repair, and reproduction.

Cell division is needed for:

All of the above

Which tissue grows the fastest in mammals?

Antlers

DNA replication

The process of making a copy of DNA before cell division.

Why must DNA replicate before a cell divides?

To ensure each new cell gets a full set of DNA

Where does DNA replication occur?

Nucleus

DNA helicase

Unzips the DNA double helix for replication.

Topoisomerase

Prevents DNA from twisting or tangling during replication.

DNA polymerase

Enzyme that adds nucleotides to form new DNA strands and checks for errors.

Which enzyme is responsible for adding new nucleotides during DNA replication?

DNA polymerase

Semi-conservative replication

Each new DNA molecule has one old strand and one new strand.

What does “semi-conservative” mean?

One parent strand stays with a new strand

During transcription, ___ , which is a ,____  makes mRNA.

RNA polymerase; enzyme

DNA replication mistakes

Happen about once every 10,000 base pairs but are corrected by DNA polymerase.

What happens if DNA replication errors aren’t corrected?

Mutations can occur

Mammalian cells average how many mistakes after correction?

1 in a billion

Cancer

Disease caused by uncontrolled cell division from mutations or external factors.

What are common causes of cancer?

All of the above

The most preventable cause of cancer in the U.S. is:

Smoking

Why are cells that divide often (like skin cells) more likely to develop cancer than nerve cells?

They copy DNA more frequently, increasing mutation chances

Alzheimer’s and cell division

In Alzheimer’s patients, neurons are pushed to divide, causing cell death months before other symptoms appear.

Why can promoting neuron division lead to damage in Alzheimer’s patients?

Neurons normally can’t divide and die under pressure to do so