Mutation
change in base sequence of an organisms DNA
Mutagen
environmental factors that causes mutations
Cellular error
cell makes mistake during cell division causing mutations
electromagnetic radiation
a mutagen which causes mutations through transfering high energy to atoms they hit. This causes them to lose electrons, and breaks the chemical bonds in DNA. death or mutation
electromagnetic radiation sources
UV-light --> sun x-rays --> medical imaging machines (PET scanners) gamma rays --> radioactive elements, (uranium-236)
Chemicals
can be accidentally incoperated into DNA instead of bases, can insert itself into DNA, can make gaps in the DNA
Chemicals- microbes
mycotoxins = poisonous chemicals produced by fungi aflatoxin b1- insterts itself into DNA
Chemicals- plants
cycasin = mutagenic chemical found in cycad plant reacts to enzyme in tummy --> breaks down to chemical that badly reacts to DNA
Chemicals- animals
dimethylnitrosamine = produced in stomach when nitrate consumed nitrate --> ham, sauasage, smoked salmon
Point mutations
change in one nucleotide
Insertion
extra nucleotide added
deletion (point)
nucleotide not added/deleted
substitution
wrong nucleotide added
frames-shift point mutation
when a single base is deleted/inserted, every codon after is messed up. can change the amino acid chain produced
Mi-sense (substitution)
codon codes for different amino acid
Non-sense (substitution)
codon becomes stop codon (pre-maturely stops polypeptide growth)
silent
wrong nucleotide subbed in, same amino acid produced
sickle cell anemia
genetic disorder that causes abnormal hemoglobin, resulting in some red blood cells assuming an abnormal sickle shape
sickle cell anemia cause
normal code = GAG mutated code = GTG changes amino acid from glutamic acid to valine mis-sense point mutation/coding DNA mutation
chromosonal mutation
changes in the numbers or structure of chromosomes occurs during errors in cell division (mainly meiosis)
deletion (chromosomal)
section breaks off and is lost
inversion
section breaks off, flips around and reattatches
transloacation
sections breaks off, sticks to different chromosome
duplication
a section copied more than once accidentally
non-disjunction
Chromosomes do not segregate equally into daughter cells, results in too many/few chromosomes
ALL (chromosomal effect)
if breakage occurs in centre of gene, gene will be destroyed
deletion, inversion, transloaction (chromosomal effect)
genes are moved to a new place
duplication (chromosomal effect)
changes in amount of protein produced
non-disjunction (chromosomal effect)
diseases
Down Syndrome (Trisomy 21)
A genetic disorder caused by the presence of all or part of a third copy of chromosome 21.
Down Syndrome cause
chromosomal mutation, non-dysjunction during gamete formation can be caused by germline mutation
germ cell
cell that can divide via meiosis to form sex cells
germ-line mutation
change in DNA of a germ cell a mutation occurring in gametes; passed on to offspring, parents not affected
stomatic cell
body cell
somatic mutation
change in DNA of somatic cell only affects the daughter cells of the mutated somatic cell offspring are unaffected as somatic cells cant form gametes
lung cancer
results from uncontrolled somatic cell growth in the lungs offspring would not get lung cancer non-coding DNA example
coding DNA
DNA which codes for a protein, a gene
non-coding DNA
DNA that does not code for a protein
Makes functional RNA
non-coding dna which codes for RNA (tRNA, rRNA) if mutation occurs protein synthesis may be affected
Regulatory sequences
determine when and how much protein a gene makes if mutation occurs gene transcription levels may change
Repetitive sequences
Regions of DNA which are the same sequence repeated over again introduced by viruses or are pseudogenes (inactive gene copies) Have no affect if mutated
Gene Pools
Total collection of alleles for all genes in a population
number of genes, frequencey and number of alleles
Gene pool characteristics
Retain the genetic info of the pop
used to compare pops
dynamic
Factors affecting gene pools
gene flow
genetic drift
mutations
selection pressures
Gene Flow
movement of alleles between populations, can change allele frequency
Genetic Drift
Random events occuring within the population, can lead to changes in allele frequency
Mutation (affecting gene pools)
change in organisms DNA, acts as a source of new alleles
Selection Pressures
External factors which affect an organisms ability to survive
Positive Selection Pressures
Increase allele frequency
Negative Selection Pressures
Decrease allele frequency
operators
regions of DNA where repressors can bind to stop protein synthesis from occurring.
non-coding regulatory sequences.
promoters
help RNA polymerase to bind to the coding DNA.
non-coding regulatory sequences.