Doug Peterson
Content Outline
Heredity and Evolutionary Change
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Types of mutations and their consequences.
o Point mutations- occur when a single nucleotide in the DNA of a gene is
incorrect.
 Substitution- the replacement of one nucleotide with an incorrect
nucleotide. Can result in silent, missenese, or nonsense mutations.
 Silent mutation- the new codon still codes for the same amino acid.
 Missense mutation-occurs when the new codon codes for a new
amino acid. This could result in production of a protein that is
unable to fold properly, thus cannot carry out its normal function
(ex: sickle-cell disease).
 Nonsense mutation- occurs when the new codon codes for a stop
codon. Causes the protein to be much shorter.
 Deletion- a nucleotide is omitted from the nucleotide sequence. Results in
a frameshift mutation.
 Frameshift mutation- result of deletion or insertion causes all
subsequent nucleotides to be displaced one position. All codons
will be changed.
 Insertion- a nucleotide is added to the nucleotide sequence. Results in a
frameshift mutation.
Role of non-nuclear inheritance in phenotypic expression.
o Extranuclear genes- genes that are not located in the nucleus.
o Mitochondria, chloroplasts, and plant plastids contain small circular DNA
molecules that carry genes coding for proteins and RNA.
 These organelles reproduce themselves and transmit their genes to
daughter organelles.
 Products of mitochondrial genes make up protein complexes of electron
transport chain and ATP synthase.
 Defects in them results in the amount of ATP.
 This primarily affects the nervous system and muscles.
 Mitochondrial diseases from a person’s mother may contribute to
diabetes, heart disease, and Alzheimer’s.
Techniques used in the isolation, manipulation, and expression of genetic material.
o Recombinant DNA- contains DNA segments or genes from different sources.
From one chromosome to another or one organism to another.
o Restriction enzymes- cut DNA at specific sequences.
o Restriction fragments can be separated by gel electrophoresis. DNA fragments of
different lengths are separated as the diffuse through a gelatinous material under
the influence of an electric field. Shorter fragments move faster and further than
larger fragments.
o Restriction fragment length polymorphisms (RFLPs) - restriction fragments
between individuals that differ in length because of slight differences in DNA
sequences (polymorphisms).
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o DNA fingerprinting- an individual’s unique collection of DNA restriction
fragments, detected by gel electrophoresis and nucleic acid probes.
o Short tandem repeats (STRs) - short sequences of nucleotides that repeat multiple
times.
o Complementary DNA (cDNA) - DNA obtained from mRNA using the enzyme
reverse transcriptase.
o Polymerase chain reaction (PCR) - copying fragments of DNA millions of time
using synthetic primers that initiate replication at specific nucleotide sequences.
Relating the applications of genetic engineering to medicine and agriculture.
o DNA tech is being used in the diagnosis of genetic and other diseases. Offers
potential for better treatments or cures of certain disorders.
o Large-scale production of human hormones and other proteins. Safer vaccines.
o Can be used to modify the metabolism of microorganisms so that they can be used
to extract minerals from the environment or degrade various types of potentially
toxic waste.
o Transgenic animals and plants- scientists introduce a gene from one animal or
plant into the genome of another. Done to improve agricultural productivity and
food quality.
Concepts of a gene pool.
o Population- a localized group of individuals that are capable of interbreeding and
producing fertile offspring.
o The total aggregate of genes in a population at any one time is the population’s
gene pool.
 Consists of all alleles at all gene loci in all individuals of the population.
Knowledge of the concept of Hardy-Weinberg equilibrium.
o When the allele frequencies in a population remain constant from generation to
generation. In Hardy-Weinberg equilibrium, there is no evolution.
 All traits are selectively neutral (no natural selection).
 Mutations do not occur.
 The population must be isolated from other populations (no gene flow).
 The population is large (no genetic drift).
 Mating is random.
Applying Hardy-Weinberg equation to solve problems involving genotypic and
phenotypic frequencies in populations.
o Genetic equilibrium is determined by the values:
 Allele frequencies for each allele (p, q)
 Frequency of homozygotes (p2, q2)
 Frequency of heterozygotes (pq + qp = 2pq)
o The following two equations hold:
 p+q=1
 p2 + 2pq + q2 = 1
Identifying factors that contribute to changing allele frequencies in a population.
o Natural selection- the increase or decrease in allele frequencies due to the impact
of the environment.
o Mutations- introduce new alleles that may provide a selective advantage.
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o Gene flow- the introduction or removal of alleles from the population when
individuals leave or enter.
o Genetic drift- random increase or decrease of alleles, simply through chance.
 Founder effect- when allele frequencies in a group of migrating
individuals are not the same as that of their original population.
 Bottleneck effect- when the population undergoes a dramatic decrease in
size.
o Nonrandom mating- occurs when individuals choose mates based upon their
particular traits.
 Sexual selection- when females choose males based upon their appearance
or behavior or ability to beat other males in contests.
 Inbreeding- occurs when individuals mate with relatives.
Analyzing how new traits become established in populations.
o Mutations- provide raw material for new variation.
o Sexual reproduction- creates individuals with new combinations of alleles
(genetic recombination).
 Crossing over- exchange of DNA between nonsister chromatids of
homologous chromosomes.
 Independent assortment of homologues- creates random combinations of
maternal and paternal chromosomes.
 Random joining of gametes- contributes to the diversity of gene
combinations in the zygote.
o Diploidy- presence of two copies of each chromosome in a cell. Recessive alleles
can be “stored” for future generations until recessive homozygous condition is
met.
o Outbreeding- mating with unrelated partners.
o Balanced polymorphism- maintenance of different phenotypes in a population.
Less advantageous alleles are maintained through heterozygous individuals.
Recognizing populations as the units of evolution.
o Population- a localized group of individuals that is capable of interbreeding and
producing fertile offspring.
o Populations of the same species may be isolated from one another, thus
exchanging genetic material only rarely.
o Individuals near the population center are more likely to breed with members of
their own population than other populations, and thus, on average are more
closely related to one another than members of other populations.
 This can lead to speciation and later evolution.
References
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Campbell, N. A., & Reece, J. B. (2005). Biology. (7th ed.). Benjamin-Cummings Pub Co.
Pack, P. E. (2008). Cliffsap biology. Cliffs Notes.