Module Six - Genetic Change Flashcards
Mutation Biotechnology Genetic Technologies
what is a mutagen?
an agent that causes a genetic mutation
what is the effect of a mutagen?
produces mutations in DNA, which can result in loss of function of a particular gene
what is a mutation?
- a change in the genetic material of a cell
- sequence of nucleotides in DNA is changed
what are mutagenic agents?
agents that damage DNA and can lead to permanent changes in the DNA
what is the process of inducing a mutation called?
mutagenesis
what is the result of mutagenesis?
induced mutations
what does carcinogenic refer to?
cancer-causing
what are the three main types of mutagens?
- chemical
- natural
- physical
what are chemical mutagens?
chemicals that cause mutations when exposed at high frequencies or for prolonged periods of time
what is the consequence of chemical mutagens in DNA?
causes a change in DNA that alters the function of proteins, making the cells impaired
what are two examples of chemical mutagens?
- ingested chemicals: alcohol
2. environmental irritants and poisons: asbestos
what are naturally occurring mutagens?
- mutations that spontaneously show up due to DNA replication error
- agents that are present at normal levels within natural environments
what are the two types of naturally occurring mutagens?
- biological mutagens
2. non-biological mutagens
what is an example of a non-biological naturally occurring mutagen?
mercury
what is are examples of biological naturally occurring mutagen?
viruses, bacteria, fungi
what are examples of physical mutagens?
heat, ionising radiation
what is radiation?
any transfer of energy through space from a source
what is an example of radiation?
electromagnetic radiation from the sun
why is ionising radiation so dangerous?
has enough energy to break chemical bonds in molecules, like DNA
what are the two main types of radiation that may cause mutation?
electromagnetic radiation, ultraviolet radiation
what are the types of mutation?
point, frameshift, chromosomal
what is a point mutation?
a change of a single nucleotide, thus resulting in a different amino acid
what is an example disease caused by a point mutation?
sickle cell anaemia
can a point mutation result in a frameshift mutation?
yes
how can a point mutation result in a frameshift mutation?
the insertion or deletion of a single nucleotide can shift the entire DNA sequence, therefore coding for a whole sequence of incorrect amino acids
what are the five criteria used in order to distinguish a certain type of mutation?
- origin
- amount of genetic material changed
- effect of the mutation on DNA
- effect of the mutation on phenotype
- heritability of mutations
how can a mutation’s origin help distinguish the type of mutation?
- spontaneous mutations : arise randomly due to errors during DNA replication
- induced mutations : arise as a result of an environmental agent
how can the amount of genetic material changed due to a mutation help distinguish the type of mutation?
- point mutations : changes to a single base pair on a single gene
- frameshift mutations : may affect a single gene or as a sequence of genes
how can the effect of the mutation on DNA help distinguish the type of mutation?
- substitution
- insertion
- deletion
how can the effect of the mutation on phenotype help distinguish the type of mutation?
- silent mutation : no change in phenotype
- could be harmful, neutral or beneficial
how can the heritability of the mutation help distinguish the type of mutation?
- somatic cell : non-reproductive cell
- germ-line cell : reproductive cell
what are the different types of changes to proteins due to point mutations?
- nonsense mutations
- missense mutations
- silent mutations
- neutral mutations
what are nonsense mutations?
- the accidental change in an amino acid to a stop codon
- cuts the protein short
what are missense mutations?
- point mutations that result in an amino acid change
- makes the protein less functional
what are silent mutations?
- changes that do not cause a change in type amino acid
- different codes that could translate into the same amino acid
what are neutral mutations?
- changes that result in an amino acid of the same type as the original
what are chromosomal mutations?
- large scale changes
- affects the overall structure of a chromosome or the entire number of chromosomes
what are the four types of chromosomal mutations?
- deletion
- insertion
- inversion
- translocation
what is a chromosomal deletion?
occurs when a section of DNA is removed and not replaced
what is the effect of chromosomal deletion?
results in a reduction in the number of genes in a chromosome
what is a chromosomal insertion?
occurs when a portion of DNA is duplicated and inserted
what is the effect of chromosomal insertion?
results in an increase of the number of genes on the chromosome
what is a chromosomal inversion?
occurs when a section of DNA is removed, flipped 180°, then reinserted (reversed base order)
what is the effect of chromosomal inversion?
can cause diseases such as haemophilia
what is chromosomal translocation?
occurs when a section of DNA is moved from one chromosome to another non-homologous chromosome
what is the effect of chromosomal translocation?
leads to gene fusions, where two normally separate genes are joined
what is aneuploidy?
occurs when one or more extra copies of a chromosome are made, or an entire missing chromosome
what is an example of aneuploidy?
down syndrome
- extra copy of chromosome 21
what are somatic mutations?
- occur in non-reproductive cells cells
- often due to an error before mitosis
- can both affect and not affect phenotype
- is not passed down
what are germline mutations?
- occurs in the sexual reproductive cells
- affects the gametes, which can be passed down
how do mutations in coding DNA segments affect an individual?
- affects the type or sequence in amino acids in a protein
- directly affects the protein, therefore the phenotype as well
how do new alleles arise from mutagens?
mutagens –> mutation –> physical change in DNA –> new allele
what is the DNA that has neither a protein-coding nor a regulatory function called?
junk DNA
what differentiates coding DNA from non-coding DNA?
non-coding DNA has so no protein end-product
how is non-coding DNA important?
- regulatory sequences that promote ‘switch on’ and ‘switch off’ genes
- code for things like rRNA
how do mutations that affect non-coding DNA affect the individual?
mutations in non-coding genes are linked to developmental and congenital abnormalities
how do mutations that affect non-coding DNA in germline cells affect the individual?
- can lead to a miscarriage
- congenital abnormalities
what are the factors that contribute to genetic variation?
fertilisation, meiosis and mutation