Mutations- Inquiry question 1

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.