Exam 3 Flashcards
Mendelian genetics
study of variation through patterns and prediction of inheritance
the probability of what things will look like
Mendel’s contributions
a. genes are material elements (chromosomes)
b. genes come in pairs (homologous chromosomes)
c. elements can retain character through generations (at times expressed or not)
d. gene pairs separate when forming gametes (meiosis)
monohybrid characteristics
a. 3:1
b. F1 heterozygous (word by itself implies dominant)
dihybrid characteristics
a. 9:3:3:1
b. two traits = four gametes
c. each allele will have one of each trait
d. label each box of Punnett square for both traits
shortcut (or check) to dihybrid Punnett square
make monohybrid square for each trait and multiply answers together
incomplete dominance
when traits of F1 hybrids falls between the phenotypes of the two parents (when red and white flowers produce pink)
with dominance lacking, an intermediary trait manifests
codominance
neither of the heterozygous alleles is dominant over the other and both affect the phenotype
antigen
protein on outside of cell (A and/or B)
example of an X-linked disease
red-green colorblindness
higher percentage are male, because females have two X chromosomes and thus a greater chance at getting a normal allele)
example of autosomal recessive disorder
albinism
requires two recessive genes to manifest
nondisjunction
when members of a chromosome pair fail to separate during anaphase I, resulting in some cells with either one or three chromosomes)
nondisjunction in meiosis I
pairs of homologous chromosomes fail to separate
nondisjunction in meiosis II
sister chromatids fail to separate
aneuploidy
abnormal number of chromosomes
trisomy 21
Down syndrome
three number 21 chromosomes
Klinefelter syndrome
male with an extra X (XXY)
Turner’s syndrome
female with only one X (XO)
chromosome deletion
portions missing from chromosome
chromosome inversion
portions cut out and reinserted upside down
translocation
all or part of a chromosome fused to a different chromosome
chromosome duplication
portion of chromosome duplicated
pleiotropy
one gene influences several hereditary characters
polygenic inheritance
variations in characteristics that occur along a continuum, like skin or eye color, or height, which are controlled by several genes
pedigrees
tool for mapping family relationships
biotechnology
the manipulation of organisms or their components to make useful products
transgenic organisms
organisms artificially altered with genes from other species
where HGH (human growth hormone) reproduces
genetically modified bacteria
GMO (genetically modified organisms)
taking genes from another organism and putting them into another organism to take advantage of a particular trait
plasmid
a small ring of self-replicating DNA separate from the chromosome(s), found in prokaryotes and yeasts
restriction enzymes
the “cutting enzyme,” naturally occurring enzymes in bacteria that can cut DNA fragments at specific sequences
DNA ligase
the “pasting enzyme,” one that attaches or rejoins DNA fragments with complementary ends
recombinant DNA
DNA combined from two different sources
recombinant DNA process
• gather plasmids from bacteria and genes of interest from DNA
• restriction enzymes recognize and bind to specific sequences
o breaks apart sugar-phosphate backbone, opening up the DNA helix
o two plasmids start at opposite ends of strands (5 – 3 direction) in search of recognition sequences
o enzyme cuts out DNA at recognition sequences
o leaves overhangs, or sticky ends
• DNA ligase pastes everything together
• now can reproduce the recombinant DNA
polymerase chain reaction (PCR)
multiple copies of DNA from a small sample