Gene Expression Flashcards
Define ‘mutation’
Any change to the base sequence of DNA
What are the 6 types of genetic mutation?
Addition, deletion, inversion, translocation, duplication, substitution
What are the 3 main types of genetic mutation (effect on phenotypes)?
Silent, termination/nonsense, frameshift
What is an ‘addition’ mutation?
One or more bases are added to the DNA sequence.
What is a ‘substitution’ mutation?
One or more bases are swapped with another.
What is an ‘inversion’ mutation?
A sequence of bases is reversed.
What is a ‘deletion’ mutation?
One or more bases are removed from the DNA sequence.
What is a ‘duplication’ mutation?
One or more bases are repeated.
What is a ‘translocation’ mutation?
A sequence of bases is removed from one location in the genome and inserted into another location, on the same chromosome or a different chromosome.
What is meant by a ‘silent’ mutation?
Has no effect on AAs coded for/protein produced/phenotype.
What is meant by a ‘Termination/Nonsense’ mutation?
A stop codon is coded for and protein made shorter.
What is meant by a ‘Frameshift’ mutation?
Changes the number of amino acids coded by the DNA sequence.
4x Mutagenic Agents?
UV radiation; ionising radiation; chemicals; viruses.
Chemicals can act as ____ ____, which cause mutations how?
Can act as base analogs: they substitute for a base in DNA replication.
How do alkylating agents cause mutation with guanine?
Chemicals can delete or alter bases, e.g. alkylating agents that add an alkyl group to guanine, so its new structure pairs with thymine.
How does UV radiation cause mutation with thymine?
Causes adjacent thymine bases to pair up together.
What is a zygote?
A cell as soon as sperm fuses with egg
What is a blastocyst? How many cells?
A hollow ball of cells in very early embryonic development with cells differentiated into either placenta cells or embryo cells. Around 128 cells.
What is the structure and function of the umbilical cord?
Vessel that connect embryo to placenta, in order to provide oxygen, nutrients and remove waste material from the embryo
What is a stem cell?
An undifferentiated cell lineage with the ability to divide indefinitely (and form more stem cells).
What is differentiation (of cells)?
To become a specialised cell lineage (type)
What is a totipotent stem cell?
A stem cell lineage that can become any type of differentiated cell
- What is a pluripotent stem cell?
- A stem cell that can differentiate into most cell types, e.g. a stem cell lineage in the blastocyst phase of development (embryonic cell or placenta cell).
What is a multipotent stem cell? Example?
A stem cell lineage that can become a few types of differentiated cell. E.g. bone marrow stem cells can differentiate into red blood cells (erythrocytes), lymphocytes and platelets
What is a unipotent stem cell?
A tem cell lineage that can become one type of differentiated cell
Benefits of stem cells in regenerative medicine? (x4)
Scientists can gain access to adult human cells without taking tissue from patient; and use these to grow new tissues; which will not be attacked by the patient’s immune system, (as they display the same antigens as the patient themselves); patient will also not be required to take long courses of immunosuppressants, which can be harmful.
What impacts the growth and development of plant tissues? What impacts their effect?
Plant growth factors affect the differentiation of plant stem cells. These are chemicals involved in the growth and development of plant tissues - they have wide effects on plant growth and these effects depend on concentration of the growth factors.
Where are pluripotent stem cells usually taken from? When?
The inner cell mass of the blastocyst. These are taken from excess embryos from IVF
When are pluripotent stem cells available naturally?
Usually, these pluripotent stem cells are only present in very early development post-fertilisation: once the blastocyst stage of development has commenced (approx. 4 days post-fertilisation), where the inner cell mass totipotent stem cells differ as they cannot differentiate to form a placenta.
What are iPS cells?
Induced pluripotent stem cells
How do you get iPS cells?
- Adult cells are made to express a series of specific transcription factors, which are usually associated with embryonic pluripotent stem cells.
- These factors cause adult body cells to express genes associated with pluripotency.
- Via infection of the adult cells with a modified virus, which passes on its genes to the adult cell’s DNA, allowing the adult cell to produce the required transcription factors and undifferentiate!
OR, via the transfer of and then growth of adult stem cells in an altered growth medium containing certain transcription factors.
Two main advantages of iPS cells?
- Avoid the need of embryos! Can derive pluripotent SCs from adult tissues.
- Could make iPS cells from a patient’s own cells - genetically identical and avoid tissue rejection by the immune system.