mutations and mutegens Flashcards
substitution and impact
where a base is replaced and has a relatively small effect of the polypeptide chain. unless it is a start or stop condon
inversion and impact
where the sequences of a small number of bases is inverted and has a relatively small impact on the chain. unless a start or stop codon.
deletion and impact
where a base is deleted which causes a frameshift and has a large impact on the chain.
insertion and impact
where a base is added which causes a frame shift and has a large impact on the chain.
what are mutations
Mutations are changes to the DNA sequences in genes and chromosomes. They can only be passed on to the next generation if they occur in sex cells. Some mutations are harmful, some are helpful and some are neutral in their effects.
what are mutagens
Often mutations occur following the exposure of a cell’s DNA to environmental factors called mutagens. Mutagens are factors that cause changes in DNA. They can include: radiation and some chemical substances.
gene mutation scale
Gene Mutations (also called Point mutations) involve small scale changes to the DNA base sequences within genes.
chromosome mutation scale
are larger scale mutations involving whole extra trisomy or missing chromosomes monosomy.
when do mutations occur
the process of DNA replication occurs (when the chromosomes are being duplicated). resulting in gene mutations. OR a cell is undergoing meiosis and non-disjunction of chromosome pairs (homologous pairs or chromatids don’t separate properly) which results in missing or extra chromosomes in sex cells, resulting in chromosome mutations.
how are chromosome mutation detected
Ultimately, karyotyping is often performed to produce a karyogram to see if the individual suffers from aneuploidy (an incorrect chromosome number) or whether sections of chromosomes have been translocated to other chromosomes.
what are chromosome mutations
Chromosome mutations involve the addition or deletion of entire chromosomes or the deletion, addition or mixing of segments of chromosomes. These mutations can affect the phenotypes of affected individuals in a multitude of negative ways, often leading to states of impaired health referred to as syndromes.
what are gene mutations
Gene mutations are caused by small changes in the DNA (or mRNA base sequence) that are caused by mutagens (forms of radiation / chemicals that can alter nucleic acids). Some gene mutations are also described as Point mutations because they affect one nucleotide only.
effects of gene mutations
They often result in a change in the amino acid sequence of a polypeptide chain which then may alter the shape and hence function of the final protein. Sometimes they result in no protein being made at all. Some mutations are harmful, some are beneficial and some are neutral (eg. silent mutations that don’t alter any amino acids).
why do genes mutations have sig affects of proteins
Protein function is directly linked to protein structure (and in particular to the shape of the protein molecule). Mutations (changes in the DNA base sequence) can result in a different amino acid being coded for, leading to a faulty protein or no protein being made.
what are proteins
Proteins are organic (large carbon containing) molecules that are made of long chains (called polypeptide chains) of amino acids. These amino acids are the sub-units that are sequenced together in various ways to make proteins (there are 20 or so different types of amino acids).
