Gene Expression Flashcards
acetylation
The addition of acetyl groups to histones. Acetylation activates the gene by
making it more accessible to transcription factors.
addition
A form of gene mutation in which one or more nucleotide bases are inserted into a DNA sequence. This may result in a frameshift to the right.
benign
Describes a tumour that is non-cancerous. Such tumours grow slowly, are enclosed in a capsule and remain at the site of origin. They can usually be removed by surgery.
cancer
a non-communicable disease resulting from tumour cells that metastasise
cellular proteome
the proteins expressed in a given type of cell
complementary DNA (cDNA)
A single strand of DNA complementary to the mRNA template strand.
complete proteome
all of the proteins coded for by the genome
deletion
A form of gene mutation in which one or more nucleotide bases are removed from
a DNA sequence. This may result in a frameshift to the left.
differentiation
a process in which cells become specialised for function
DNA hybridisation
The process by which a single-stranded segment of DNA is combined with a complementary fragment of DNA or RNA.
DNA ligase
An enzyme that joins the sugar-phosphate backbone of two DNA segments.
DNA polymerase
An enzyme that synthesises a double-stranded molecule of DNA from a
single template strand using complementary nucleotides.
DNA probe
A short, single-stranded segment of DNA that can be fluorescently or radioactively labelled. DNA probes are used to locate specific alleles of genes.
DNA sequencing
Determining the entire DNA nucleotide base sequence of an organism.
duplication
A form of gene mutation in which one or more nucleotide bases are repeated.
This may result in a frameshift to the right.
epigenetics
The study of changes in gene expression that are not due to alterations in the nucleotide base sequence of DNA.
frameshift mutation
A form of gene mutation in which the addition or deletion of nucleotide bases alters all subsequent triplet codes in a DNA sequence. This often leads to the production of a non-functional protein.
gel electrophoresis
A technique that separates fragments of DNA by size using electric current.
gene machine
A method of artificially manufacturing genes by feeding the desired sequence of bases into a computer.
gene mutation
A change to at least one nucleotide base in DNA or the arrangement of bases. Gene mutations occur spontaneously and may result in changes to genotype.
gene therapy
A technique in which a functional gene, cloned from a healthy individual, is inserted into cells that lack the gene.
genetically modified organism (GMO)
an organism that has had its genome altered
genetic counselling
A service that provides information and advice to people affected by
or at risk of genetic diseases. This helps individuals and families to make informed decisions.
genetic fingerprinting
A technique used to genetically identify an organism. It has applications in forensics, paternity testing, diagnostics and the breeding of plants and animals.
genetic screening
testing individuals for certain faulty alleles
genome
the complete genetic material of an organism
hypermethylation
Increased methylation of DNA. This results in the inactivation of tumour suppressor genes and the resulting formation of tumours.
hypomethylation
Reduced methylation of DNA. This results in the activation of oncogenes genes and the resulting formation of tumours.
induced pluripotent stem (iPS) cells
Unipotent cells that have been reprogrammed (using transcriptional factors) to become pluripotent stem cells. iPS cells are capable of self-renewal.
inversion
A form of gene mutation in which a group of nucleotide bases ‘break off’ from the DNA sequence and reattach in the same position but in the reverse order.
in vitro
Describes a procedure that takes place outside of a living organism in a controlled environment e.g. DNA is amplified using PCR in a thermocycler.
in vivo
Describes a procedure that takes place inside of a living organism e.g. fragments of DNA can be transferred to a host cell (using a vector) where they are amplified.
malignant
Describes a tumour that is cancerous. Such tumours grow rapidly, are not enclosed in a capsule and can spread to other regions of the body. Treatment involves radiotherapy, chemotherapy or surgery.
marker genes
An additional gene inserted into a plasmid that is used to aid in the identification of host cells that have taken up the desired gene. Marker genes are easily recognisable e.g. fluoresce or provide antibiotic resistance.
metastasis
The process by which cells break off from a primary tumour and spread to other areas of the body, forming secondary tumours.
methylation
The transfer of methyl groups to cytosine bases of DNA. Methylation inhibits transcription by making the DNA less accessible to transcriptional factors or preventing transcriptional factors from binding. This deactivates the gene.
multipotent cells
Stem cells found in mature mammals that can only differentiate into a limited number of cell types (specific to a tissue).
mutagenic agent
an agent that increases the rate of gene mutations above normal level
mutation
a random change in DNA which may result in genetic variants
mutation rate
The frequency of mutations per biological unit (e.g. per cell division).
non-coding DNA
DNA that does not code for a protein but instead controls gene expression.
oestrogen
A steroid hormone involved in the initiation of transcription. It joins to a receptor site on a transcriptional factor, activating the DNA binding site and stimulating transcription.
oncogenes
Mutations of proto-oncogenes that are activated continuously.
personalised medicine
A form of medical care that enables doctors to provide healthcare
customised to an individual’s genotype.
pluripotent cells
Stem cells found in embryos that have the ability to differentiate into almost all types of cell.
polymerase chain reaction (PCR)
An in vitro technique used to rapidly amplify fragments of DNA.
primers
Short nucleotide sequences, complementary to one end of each of the DNA fragments.
promoter
region of DNA where RNA polymerase binds during transcription
proto-oncogenes
Genes that stimulate cell division upon the attachment of growth factors to specific receptor proteins on the cell membrane.
recognition sequence
specific bas sequences of DNA that restriction enzymes cut
recombinant DNA
a combination of DNA from two different organisms
recombinant DNA technology
The process by which segments of DNA are transferred from one organism to another.
restriction endonucleases
Enzymes that cut DNA molecules at recognition sequences creating sticky ends.
reverse transcriptase
An enzyme that synthesises DNA from RNA.
risk factor
A variable associated with a greater chance of developing a disease or
infection.
RNA interference (RNAi)
A method of controlling gene expression by breaking down target mRNA molecules, preventing translation.
silent mutation
A type of substitution mutation that produces the same amino acid due to the degeneracy of the genetic code.
stem cells
Cells that are unspecialised and retain the ability to differentiate into a range of cell types.
sticky ends
The staggered cut formed by restriction endonucleases in double-stranded DNA.
substitution
A form of gene mutation in which one nucleotide base is exchanged for another.
terminator
Region of DNA where RNA polymerase is released, ending transcription.
thermocycler
A machine controlled by a computer that varies temperatures at
predetermined time intervals.
totipotent cells
Stem cells found in early mammalian embryos which have the ability to differentiate into any type of body cell.
transformation
The reinsertion of plasmids back into bacterial cells to form transgenic bacteria. This involves mixing the plasmids and bacterial cells in a medium containing calcium ions.
tumour
An abnormal mass of cells formed by uncontrolled cell division.
tumour suppressor genes
Genes that slow cell division, repair DNA and cause the breakdown of cells with damaged DNA by apoptosis.
transcriptional factors
Specific molecules which pass from the cytoplasm of a cell into the nucleus, where they bind to complementary base sequences of DNA and initiate transcription.
transgenic organism
an organism that contains recombinant DNA
translocation of bases
A form of gene mutation in which a group of nucleotide bases ‘break off’ from the DNA sequence on one chromosome and are added to the DNA sequence on a different chromosome.
unipotent cells
stem cells found in mature mammals that arise from multipotent cells and can only differentiate into a single cell type.
variable number tandem repeats (VNTRs)
Repeated sequences of non-coding nucleotide bases. It is unlikely that two unrelated individuals will have the same VNTRs.
vector
A carrier used to transfer a gene from one organism to another e.g. plasmid.
whole-genome shotgun (WGS) sequencing
a method of sequencing an organism’s entire genome. This involves cutting the DNA into small segments and aligning overlapping sections using computer algorithms
