Studied by 3 people
gene
a unit of inheritance
a section of dna
gene locus
fixed position of gene on a chromosome
allele
different forms of the same gene
can have multiple alleles - eg. blood
diff alleles hv slight variation in base sequence
snps
single nucleotide polypmorphisms
alleles that differ by only 1 base
lead to variations in aa sequence
creates diversity
helps in dna fingerprinting
genome
the entire genetic info of an organism
eg. in humans, dna in nucleus (chromosomes) & mitochondrial dna
eg. in plants. chromosomes, chloroplast dna, mitochondrial dna
eg. prokaryotes, circular dna, plasmids
human genome project
aimed to discover complete set of human genes
benefits
screening: dev of gene probes to detect sufferers & carriers of genetic diseases
medical: discovery of new proteins, used to dev new treatments
discovered that most of the gene is not transcribed — mostly junk dna
mutations
completely random
new alleles formed
mutagens
increase likelihood of mutations
ionizing radiation, gamma rays
non ionizing radiation, uv rays
chemicals, asbestos, tar
eg. sickle cell anemia (process)
dna: gag → gtg on non transcribed strand. creation of alleles Hbs → transcribed
mrna: gag → gug on 6th codon position → translated
polypeptide: 6th amino acid glutamic acid → valine on beta chain.
consequences
hemoglobin mols stick together in blood
form bundles → rigid → distort rbcs into sickle shape → block capillaries → restrict blood flow → damage tissues
only return to org shape in high o2 conditions in lung
changes occur again & again (repeat)
reduces lifespan of rbcs to 4 days
can cause anemia — rbcs cannot be replaced fast enough
