Transcript Genetics
Genetics
Vicky “Bio-lover” Atzl
Farah “Bird-hater” Momen
Meiosis
a. Meiosis 1 separates homologous pairs
(known as reduction division)
crossing over occurs in Prophase 1 resulting in
genetic variation (not in mitosis)
b. Meiosis 2 separates homologous pairs into
sister chromatids: produces 4 haploid
gametes (meiosis 2 resembles mitosis)
Alleles
a. dominant vs. recessive
b. homozygous vs. heterozygous
Dominant allele is expressed over recessive
Homozygous has two of the same allele (AA or
aa); heterozygous has two different alleles (Aa)
and therefore has dominant phenotype
c. phenotype vs. genotype
Phenotype is the physical appearance of an
expressed allele; genotype is the genetic makeup
of an organism
Non-Mendelian inheritance
a. incomplete dominance (pink flower color)
When a heterozygote’s two alleles blend
b. co-dominance (blood type)
When a heterozygote’s two alleles are expressed equally.
c. sex linked (mainly X-linked: color blindness, hemophilia)
epistasis (coat color) presence of certain alleles on one
locus mask the expression of alleles on another locus and
express their own phenotype instead.
pleiotropy (dwarfism, giantism) one allele affects various
phenotypes in an organism.
polygenic (skin color) multiple alleles are required for the
expression of a characteristic
Chi-square analysis
a. used to determine if observed results are
significantly different from expected results
b. know how to use formula when given & how to
interpret results
• degrees freedom (1 less than number of classes of
results)
• if x^2 less than p=.05, then difference can be due
to random chance and hypothesis accepted
DNA & RNA
a. DNA: ACTG nitrogen based nucleotides in
double helix formation
• A pairs with T, C pairs with G
b. RNA: ACUG nitrogen based nucleotides in
single helix formation
Central Dogma
DNA is transcribed into RNA; that is further
translated into proteins that code for traits.
Transcription: RNA polymerase copies
template strand and makes mRNA
Translation: ribosomes in cytoplasm
match tRNA codons to mRNA codons; amino
acids carried to P site of ribosome and forms
polypeptide chain. Chain ends at one of stop
codons.
Gene regulation
Operons
Inducible: lac operon
I DIDN’T FINISH!
Mendelian inheritance
a. monohybrid crosses
• Aa x Aa = 3:1 ratio
• Law of Segregation