Download 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