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Biology- Genetics (II)

Key Concepts:

Terms in this set (93)

Conservative mutation
A substitution where an amino acid is swapped for one of similar chemical properties.
Non-conservative mutation
A substitution where an amino acid is swapped for one with different chemical properties.
Mutation
A sudden change in the structure or quantity of DNA in a cell
Gene mutation
A mutation where one or more bases in a DNA sequence are affected.
Chromosome mutation
A mutation where there are changes in the number or structure of whole chromosomes
Substitution
A gene mutation where one base is swapped for another.
Deletion
A gene and frameshift mutation where a base is removed from a DNA sequence
Addition
A gene and frameshift mutation where a base is inserted into a DNA sequence.
Frameshift mutation
A mutation that changes how the triplet codes are read so that nearly every amino acid thereafter is incorrect.
Duplication
A gene and frameshift mutation where a series of bases are repeated.
Nonsense mutation
A substitution mutation that causes a codon to be replaced by a stop codon so the polypeptide is too short.
Missense mutation
A substitution mutation where a codon is changed so that a different amino acid is produced.
Silent mutation
A substitution mutation that has no effect on the polypeptide due to the degeneracy of the genetic code.
Inversion
Gene mutation where a group of bases separate and rejoin the same place in the DNA sequence back-to-front.
Translocation
Gene mutation where a group of bases on one chromosome separate and join a non-homologous chromosome.
Non-disjunction mutation
A chromosome mutation where individual chromosomes fail to separate during meiosis, so the individual has an extra or missing chromosome.
Polyploidy
A chromosome mutation where all homologous chromosomes fail to separate during meiosis, so the organism has an extra set(s) of chromosomes.
Differentiation
Process by which cells become specialised
Stem cells
Undifferentiated cells capable of dividing into more cells of the same type.
Totipotent
Stem cells that can differentiate into any cell type
Pluripotent
Stem cells that can differentiate into nearly all cell types.
Multipotent
Stem cells that can differentiate into a few cell types
Unipotent
Stem cells that can differentiate into only one cell type
iPS cells
Unipotent stem cells that have been changed back into pluripotent stem cells through the use of transcriptional factors
Pre-initiation complex
Complex formed when transcriptional factors and other co-factors bind to the promoter region.
Spliceosome
A molecular machine that removes the introns from pre-mRNA.
ER-alpha
A receptor found attached to transcriptional factors that is complementary to the shape of oestrogen.
Transcriptional factors
Proteins that bind to the promoter region to initiate transcription.
Promoter region
A specific sequence of DNA found upstream of a target gene that initiates its transcription.
Terminator region
A region of DNA that stops transcription when RNA polymerase reaches it.
Epigenetics
The study of the influence of environmental factors on heritable changes in the way DNA is coiled around histones.
Tags
The chemicals found on DNA and histones that form the epigenome.
Epigenome
The second layer to the genome made up of the tags found on DNA and histones.
Methylation
The addition of CH3 groups to a molecule. In an epigenetic context, this molecule is cytosine.
Deacetylation
The removal of COCH3 groups from a molecule
Acetylation
The addition of COCH3 groups to a molecule
Epigenetic silencing
When a gene is switched off due to increased methylation and deacetylation.
Methyl transferase
The enzyme that catalyses the methylation of cytosine
RNA interference
A way of preventing gene expression even when it has already been transcribed.
siRNAs
Short, double-stranded RNA segments totally complementary to target mRNAs that guide RISC to the mRNA to be cleaved.
MicroRNAs
Short, double-stranded RNAs where only the seed is complementary to the target mRNA.
DICER
An endonuclease protein that cleaves precursors to form siRNAs and microRNAs.
Argonaut
Protein that attaches to siRNAs or microRNAs and catalyses the cleavage of the target mRNA.
Guide strand
Strand of siRNA that binds to argonaut and the target mRNA.
RISC
The complex that cleaves target mRNA so it can't be translated and the gene cannot be expressed.
Seed
Part of a microRNA complementary to the target mRNA.
Cancer
A group of diseases caused by a large mass of uncontrollably dividing cells with the potential to metastasise.
Tumour
A large mass of uncontrollably dividing cells
Benign
A slow-growing tumour that doesn't metastasise
Malignant
A rapidly growing, often life-threatening, tumour with the potential to metastasise
Adhesion molecules
Substances produced by benign tumour cells that stick them together so the tumour remains localised
Metastasis
The process in which a malignant tumour spreads around the body to form secondary tumours
Proto-oncogene
A healthy gene that stimulates mitosis
Growth factors
Signalling proteins that trigger a cell to divide by mitosis
Oncogene
A mutated version of a proto-oncogene that causes accelerated cell growth and division and can lead to cancer
Apoptosis
Programmed cell death
Necrosis
Tissue death due to disease, injury or poor blood supply
Tumour suppressor gene
Gene that inhibits mitosis, repairs DNA damage and triggers apoptosis in damaged cells
SNPs
Single base variations associated with disease
Microsatellites
Short runs of repetitive base sequences used as genetic markers
Shotgun sequencing
Approach when a genome is split into sections, sequenced individually and then overlaid to piece them back together.
Gel electrophoresis
A technique used to separate DNA fragments based on size
BAC
A plasmid used for storing DNA fragments until needed
Sanger sequencing
A technique involving ddNTPs to produce different length strands of DNA that can then be pieced together to get the original base sequence
ddNTPs
Nucleotides with fluorescent bases that terminate DNA replication if incorporated into the new strand.
Annealing
Bonding to form double-stranded DNA
Taq polymerase
DNA polymerase sourced from thermophilic bacteria. Used in Sanger sequencing and PCR.
Genetic engineering
Obtaining a specific gene from one organism and placing it into another organism.
Transgenic
Describes an organism that has had a gene introduced into it from another organism
Recombinant DNA
Combined DNA from different sources
Vector
Medium which carries DNA from one cell to another
cDNA
DNA made from mRNA using reverse transcriptase
Restriction endonucleases
Enzymes which cut DNA at a recognition sequence to leave blunt or sticky ends
Blunt ends
Straight edges left behind on two DNA strands after it has been cut by a restriction endonuclease
Sticky ends
Overhang of exposed, unpaired bases left behind on a DNA strand after it has been cut with a restriction endonuclease
Recognition sequence
The base sequence that determines where a restriction endonuclease cuts
Palindromic
Describes a recognition sequence with a base sequence that reads the same forwards and backwards
Gene machine
Machine that can synthesise a gene using oligonucleotides
Oligonucleotides
Small, overlapping single strands of nucleotides used to assemble a gene in the gene machine
In vivo
Within a living organism
Transformation
Process in which bacterial cells take up a plasmid containing cDNA
Heat shock
Technique used to allow a plasmid to cross the cell surface membrane of a bacterium
Replica plating
Technique used to identify bacterial colonies that have been transformed
Marker gene
A gene that is easily identifiable so can be used to test whether a bacterium has taken up a plasmid with cDNA
In vitro
"In glass" I.e. Outside a living organism
PCR
An in vitro method of amplifying a DNA sample
Augmentation
In gene therapy, this is adding genes to faulty DNA
Supplementation
In gene therapy, this is using a healthy dominant allele to mask the effects of a faulty recessive allele
DNA probes
Short, single-stranded sections of DNA used to test for the presence of a particular allele in a sample of DNA.
Genetic screening
Using DNA probes to test for the presence of an allele in a patient's DNA.
VNTRs
Introns, the pattern of which is unique to almost every individual
Southern blotting
A technique used to transfer DNA from gel electrophoresis to a nylon membrane
Genetic fingerprinting
An analytical technique used to identify individuals based on their VNTR pattern.
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