A2 Booklet 2- Gene Expression and DNA Technology Flashcards
How do gene mutations occur?
They occur spontaneously, during DNA replication and an increased mutation rate due to mutagenic agents such as UV light, X-rays, benzene.
What are the different types of gene mutation?
Substitution, deletion, addition, duplication, inversion and translocation.
Describe each type of gene mutation
Substitution- one or more bases are replaced by another base. Can still produce a functioning protein due to degenerate code.
Deletion- causes a frame shift from point of deletion (unless a codon is deleted) which results in wrong protein/dysfunctional protein.
Addition- also a frame shift from point of addition. Protein non-functional/wrong one.
Duplication- one or more bases are repeated. Frame shift from point of duplication. Protein formed is the wrong one or non-functional.
Inversion- a sequence of bases is inverted.
Translocation- a sequence of bases moved from one location in DNA molecule to another part of genome.
How can mutations lead to tumours?
Rate of cell division is controlled by two main sets of genes:
• Proto-oncogenes, which stimulate cell division.
• Tumour suppressor genre which slow cell division.
If a mutation occurs in the code for proto-oncogenes, they can begin to stimulate cells to divide too quickly (they are then oncogenes).
If a mutation occurs in a tumour suppressor gene, it becomes inactive and the rate of cell division increases without restraint.
What are the different types of stem cells?
Totipotent, pluripotent, multipotent and unipotent.
Totipotent stem cells are found in early mammalian embryos for a limited time (32 Cells). Can differentiate into any type of cell.
Only part of their DNA is translated, resulting in specialisation.
Pluripotent stem cells are found in embryos and can differentiate into any type of cell EXCEPT placenta or umbilical cord cells.
Multipotent stem cells are found in mature mammals. Cells can differentiate into very limited types of specialised cells (in bone marrow, multipotent cells can produce any type of blood cell).
Unipotent stem cells are found in nature mammals and can only differentiate into one cell (cardiomyocetes can only differentiate into heart muscle cells).
What is differentiation and cell specialisation?
What is the role of a transcription factor?
Differentiation is when a cell becomes specialised.
Happens when some genes are “switched” on/off by protein transcription factors.
Transcription factors attach to promoter region close to target gene(s) which stimulates transcription of targeted gene(s) by activating RNA polymerase.
How can induced pluripotent stem cells (iPS cells) be produced and what are they used for?
Produced from unipotent stem cells using specific protein transcription factors, which are used to express or inhibit genes so that these cells can develop similar characteristics to embryonic stem cells.
Can develop into wide range of tissues.
Used to treat human disorders due to specialisation and unlimited division.
How is transcription regulated?
Transcription factors, moving from the cytoplasm to the nucleus, inhibit or stimulate transcription of certain genes.
A transcriptional factor is a protein that binds to specific promoter religion close to target gene(s).
How does oestrogen regulate gene expression?
Hormones can enter target cell and “switch on” a gene.
Oestrogen is lipid soluble as it is derived from cholesterol and is a steroid hormone.
How is translation regulated?
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What is epigenetics?
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How does methylation and acetylation effect gene expression?
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What are the differences between malignant and benign tumours?
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Explain abnormal methylation of cancer-related genes
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What is recombinant DNA technology? What are the main methods?
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