Mutations Flashcards
Create a table contrasting gene and somatic mutation.
Gene mutation
- germ line (hereditary)
- recall: germ cell = sex cell
- occurs to germ cell destined to become egg or sperm or zygote at sing-cell stage
- Impacts every cell
- Can be passed to offspring
- e.g. Sickle Cell Anaemia
Somatic
- recall: somatic cell = body cell
- occurs in body cells/tissue
- “acquired mutation” happens during lifetime
- Ranges from localised regional impact to potential systemic effect
- tissues that derive from mutated cell will be impacted
- won’t be passed on to offspring
- e.g. lung cancer from smoking
Describe point mutation.
- “substitution”
- nucleotide replaced with different nucleotide
- only affects codon for single amino acid
Describe frameshift mutation.
- “deletion”
- removal of a nucleotide
- alters every codon after mutation
- “insertion”
- adds nucleotides
- alters every codon after mutation
What are three types of point mutations?
- Silent
- nucleotide replaced but codon still produces same amino acid - Missense
- codon results in different amino acid, may or may not alter protein’s function - Nonsense
- codon now ‘stop command’
- leads to loss protein functionality
What are chromosome mutations?
- large-scale
- may affect one chromosome or non-homologous pairs
- results in entire genes or sets of genes being altered
- often occur during crossing over meiosis (prophase 1)
Describe deletion.
(single chromosome)
- loss one of more gene(s) from parent chromosomes
Describe insertion.
(multiple chromosomes)
- one or more gene(s) removed from one chromosome and inserted into another non-homologous chromosome
- occur by error during prophase 1 (meiosis) when chromosomes swapping genes to increase diversity
Describe duplication.
(single chromosome)
- addition of one or more genes
- any repetition of a region of DNA that contains one or more genes
Describe inversion.
(single chromosome)
- complete reversal of one or more gene(s)
- order genes backwards from parent
- gene is swapped “end to end”
Describe translocation.
(multiple non-homologous chromosome)
- chromosome swap one or more gene(s) within same or different chromosome
List large scale mutation effects.
- duplication of multiple genes causes genes to be overexpressed while deletions result in missing or incomplete genes
- lead to cells that are not viable (cell often dies)
What is a fusion protein?
- gives cells a growth advantage, leading to tumors
Define aneuploidy.
Improper no. chromosomes in cell
Define autosomal aneuploidy.
abnormal no. autosomal chromosomes in cell e.g. 45 or 47
Define sexual aneuploidy.
abnormal no. sex chromosomes (monosomy = 1, trisomy = 3)
Define non-disjunction.
pair of chromosomes that fail to separate
Considering non-disjunction, how doe sexual aneuploidy and autosomal aneuploidy occur?
Sexual aneuploidy results from non-disjunction in meiosis I and II. Autosomal aneuploidy results from non-disjunction (chromatids) mitosis
What is a karyotype?
- display of total complement of a species’ chromosomes
- indicates no. and visual appearance of the chromosomes in cell nuclei
- taken during mitotic metaphase with chemical interruption of anaphase
- cell ruptured and photographs taken
- photos examined based on centromere position, length of chromatid arms and then matched with pairs
- anomalies then detected
What causes mutations?
Mutagens -> physical or chemical agent that changes genetic material of an organism
List examples of physical, chemical, heavy metal and biological causes of mutations.
Physical
- X-rays
- radioactive decay
- solar radiation
Chemical
- asbestos
- benzopyrene
- boric acid
Heavy metal
- lead paint
- nickel-cadmium batteries
Biological
- viruses
