Gene Expression Flashcards
What is a mutation
An alteration to the DNA base sequence that happens during DNA replication
What are addition and deletion mutations?
Where one or more base is inserted or deleted from the DNA sequence
What is a substitution mutation?
Where one base in the DNA sequence is replaced by another
What is a duplication mutation?
Where one or more bases duplicate and repeat
What is an inversion mutation?
Where a group of bases become separated from the DNA sequence, then rejoin in the reverse order
What is a translocation mutation?
Where a group of bases get separated from the DNA sequence, and are then inserted into the DNA of a different chromosome
Is a mutation resulting in a change to the amino acid sequence always harmful?
No, it may be neutral if the change in the protein has no effect. Could also be beneficial which helps natural selection
What is a mutagenic agent? Give an example
Factors that increase the rate of gene mutation e.g alcohol and benzene
What is a stem cell?
Undifferentiated cells, that can divide and turn into other specific cell types
Totipotent cell definition
Can develop into any cell type including the placenta and embryo
Pluripotent definition
Can develop into any cell type excluding the placenta and embryo
Multipotent definition
Can only develop into a few different types of cell
What happens to totipotent cells during embryonic development?
Certain parts of the DNA are translated so only some genes are switched on to differentiate the cell into a specific type
Give one feature of pluripotent cells and the use of this feature
They can divide in unlimited numbers so can be used to repair or replace damaged tissue
What is a unipotent cell? Give an example
A cell that can only develop into one type of cell, example is cardiomyocytes
Which types of stem cell are found in embryos?
Totipotent and pluripotent
Give some uses of stem cells
Bone marrow transplants, treating blood disorders, research
What is a transcription factor?
A protein that controls the transcription of genes so that only certain parts of the DNA are expressed
How do transcription factors work?
Bind to promoter region which makes it easier or more difficult for RNA polymerase to bind to the gene, this increases or decreases the rate of transcription
What does epigenetics mean
A heritable change in gene function without change to the base sequence of DNA
How does increased methylation of DNA affect gene transcription?
Adds a CH3 group to cytosine bases which prevents transcription factors from binding therefore gene transcription is suppressed
How does decreased acetylation of histones affect gene transcription?
Decreasing acetylation increases positive charge of histones so binding becomes too tight and prevents transcription factors from accessing the DNA. Therefore gene transcription is suppressed
How might epigenetic changes affect humans?
Could cause disease like cancer
Characteristics of benign tumours
Slow growth, cells retain function and normal shape, easy to treat, don’t spread easily
Characteristics of malignant tumours
Rapid uncontrolled growth, cells don’t retain function and often die, spreads easily and quickly, difficult to treat
Describe the role of tumour-suppressor genes
Code for proteins that control cell division, stop cell division when the DNA is damaged
Explain how tumour-suppressor genes can be involved in developing cancer
A mutation in a gene could code for a non functional protein. Increased methylation or decreased acetylation could prevent transcription. Cells will divide uncontrollably resulting in a tumour
Describe the role of proto-oncogenes
Control cell division, code proteins that stimulate cell division
Explain how proto-oncogenes can be involved in developing cancer
Mutation in a gene could turn it into a permanently activated oncogene. Decreased methylation or increased acetylation can cause excess transcription which results in uncontrolled cell division and the formation of a tumour
Explain how abnormal methylation of genes can cause cancer
Hyper-methylation of tumour-suppressor genes or oncogenes can impair their function and cause the cell to divide uncontrollably
Explain how oestrogen can be involved in developing breast cancer
Oestrogen is an activated of RNA polymerase, so in high oestrogen concentration areas, cell division can become uncontrolled
What is a genome?
The complete set of genetic information contained in the cells of an organism
What is genome sequencing?
Identifying the DNA base sequence of an individual, so we can determine the amino acid sequence of the polypeptides coded for by DNA
What is the proteome?
The complete set of proteins in a cell
Applications of genome sequencing:
Genetic matching, personalised medicine, synthetic biology
How have sequencing methods changed over time?
Used to be a manual process but is now more automated
