topic 8

Which type of mutation results in an early stop codon

Nonsense mutation

Which type of mutation results n no change of the amino acid base sequence

Silent mutation

Which type of mutation involves the substitution of one nucleotide for another

Point mutation

What is the function of the Okazaki fragments in DNA replication

To synthesise the lagging strand of DNA discontinuously

Wha ‘tis the role of DNA ligase

To join the Okazaki fragments on the lagging strand

What are some uses of embryonic stem cells

• Parkinsense disease - replace lost dopamine - producing neurones

• Type 1 diabetes - generate insulin-producing beta cells

• Macular degeneration - replace damaged retinal cells

• Spinal chord injury - rebuild nerve connections

Advantages of uses embryonic stem cells

They are versatile as they v=beocme any tissue type

They offer long term potential curative treatments

Ethical concerns of embryonic stem cells

• involves the destruction of embryos

• Immune injection risk - cells aren’t genetically matched

• Can form tumours if the cell division isn’t controlled

Uses of mulitpotent (adult stem cells)

• leukemia - bone marrow transplants are used to restore blood cells after chemotherapy

• Burns/ skin grafts - skin stem cells are used for regenerating damaged tissue

• Cartilage / bone repair

Advantages of uses multipotnet adult stem cells

• no embryo destruction as they’re harvested from consenting adults, so there are fewer ethical issues

• Lower risk of immune injection if from the same patient

What are the disadvantages of adult stem cells (multipotent)

• many people donate one marrow, it they need to be a close math in blood type and at homer body antigens

• There is a chance that the cells used are rejected by the patients immune system

• Limited differential potential

• They are harder to isolate and. Grow in large quantities

• They may have accumulated mutations over time

What are the uses for induced pluripotent stem cells (IPS)

• they are programmed for adult somatic cells (e.g skin cells) using transcription factors

• As all somatic cells contain the same genetic material scientists can use specific transcription factors to target genes that control pluripotency

• Scientists ‘switch on’ these genes that are usually silenced in differentiated cells, which allows them to revert pluripotent cells

What are teh uses of IPS cells

• Parkinson’s, diabetes, spinal cord injuries ect.

• Disease modelling: create patient - specific cells for studying diseases like Alzheimer’s

• Drug testing - reducing the need for animal models

What are the advantages of ips cells

• no embryo destruction, therefore fewer ethical issues

• IPS cells can be made form the patients own cells so there is no risk of immune rejection

• They’re tailored to the individual

Disadvantages of iPS cells

• low efficiency and high cost: converting adult somatic cells (e.gskin cells) inot iPS cells is very inefficient and only a small fraction of treated cells become pluripotent

• There are high costs involved due to specialised transcription factors and careful cell culture conditions

• Potential issues wiht cells becoming cancerous