What can we expect of each
other and the key to success?
Genetics
Biology 332
Mary Ellard-Ivey
Outline
Class business and Review of DNA
Theory Practice
policies function
ִcentral dogma
History of Heredity
What is genetics?
Genetic variation Learning Doing
ִcontinuous vs.
Review of nature of
discontinuous genetics genetics
variation
genes DNA structure
Processing
Molecular basis of
allelic variation
Business Interesting data
Students who process information During
lectures or soon after lectures are more
successful on exams
http://www.nsci.plu.edu/~mivey/33208/
Cannot process by trying to write down
everything said or projected
I will help you with small processing tasks
1
Hippocrates
(460-377 BC)
Pangenesis
ִminute particles (“gemmules”) from every
part of the body entered seminal
substance of parents.
ִCombined to give a new individual with
traits of both
ִPan = All parts involved
Heredity
Thomas Hardy William Harvey (1578-1657)
I am the family face;
Epigenesis
Flesh perishes, I live on,
Projecting trait and trace
Through time to times anon,
Speculated on origin of birds eggs.
And leaping from place to place
Over oblivion.
The years-heired feature that can
A fusion of formless/substance of both
In curve and voice and eye parents.
Despise the human span
Of durance--that is I;
The eternal thing in man, Zygote amorphous - differentiation
That heeds no call to die.
Views of heredity before
Heredity before Mendel Mendal
Pangenesis Epigenesis Preformation
ovistic spermistic
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Leeuwenhook, 1632-94 What is genetics?
Samentierchen
(minute animals)
Preformed embyos
whose nutritional
needs catered for
by egg
Spermistic
Malpighi (1628-94) What is genetics
Ovistic view Study of genes
How they are transmitted
Genomes cell to cell and generation
Studying development of avian embyos
to generation
Biochemical basis
Preformed embryo in egg How they are organized How they can be manipulated
How they replicate
Gregor Mendel. Experiments in
Plant Hybridization (1865) Genetics
Classical Genetics Molecular Genetics Evolutionary Genetics
Paper discussed
Mendels principles Structure of DNA Quantitative genetics
discrete elements Meiosis and Mitosis Chemistry of DNA Hardy-Weinberg equilibrium
(characters) we now Sex determination Transcription Evolution
Sex linkage Translation Speciation
call genes Chromosomal mapping Recombinant DNA
Cytogenetics technology
(chromosomal changes) Control of gene expression
DNA mutation and repair
Extrachromosomal inheritance
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Heredity
Thomas Hardy Nucleic acids
I am the family face;
Flesh perishes, I live on,
A polymer of nucleotides linked by
Projecting trait and trace condensation reactions
Through time to times anon,
And leaping from place to place Nucleotide = building block of a nucleic
Over oblivion. acid
The years-heired feature that can ִPentose sugar
In curve and voice and eye
ִPhosphate
Despise the human span
Of durance--that is I; ִNitrogenous base
The eternal thing in man,
That heeds no call to die.
“The eternal thing in man that
heeds no call to die” DNA Structure
DNA replication is
the basis of the
perpetuation of life
through time
Genes as determinants of
inherent properties of species DNA Structure (Figure 1-4)
What makes a species what it is?
ִgenes
What causes variation within a species?
ִalleles
4
Assembly of nucleotides
Phosphate
Phosphodiester bonds
ִester = bond between alcohol (OH of
sugar) and acid (phosphoric acid)
ִphosphodiester in DNA
Nitrogenous bases
purines
pyrimidines
Structure of DNA (review) Base pairing in DNA
Purines
ִ2 rings
Pyrimidines
ִ 1 ring
Adenine and Thymine: 2 hydrogen bonds
Guanine and cytosine: 3 H bonds
5
DNA structure-the double
helix RNA
Polymer made by covalent
bonds called phosphodiester RNA
linkages
ִdoes not form a double helix
Backbone sugar phosphate
ִis single stranded
Sequence of bases unique
for each gene
Sequence of bases dictates
protein structure
Double stranded
A T and G C
Strands are antiparallel
Helical
RNA structure DNA replication
Ribose
RNA Structure (fig 5.27) Outline
Class business and Review of DNA
policies function
Phosphate ִcentral dogma
History of Heredity
Genetic variation
Nitrogenous base What is genetics ִcontinuous vs.
discontinuous
ִpurines
variation
ִpyrimidines Review of nature of
genes DNA Molecular basis of
structure allelic variation
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Generation of form Transcription process
DNA RNA Protein
transcription translation
replication
enzymes signalling
structural
Translation process
Structure of eukaryotic gene Process of translation
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Types of variation
Discontinuous
variation
ִcharacter in two or
more distinct forms
called phenotypes
ִe.g albinism in
humans
Gene codes for ability to make melanin
Genetic variation =A
Genes and alleles
Gene codes for inability to make
melanin = a
Many different alleles in a population
genotype phenotype
Two alleles per diploid individual A/A pigmented
A/a pigmented
a/a non-pigmented
Alleles always in same position “locus”
on chromosome
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Discontinuous variation Variation
Several gene affect
skin color Discontinuous
Difference between
pigmented vs non-
pigmented caused by
one gene
Continuous
Discontinuous variation
Two types of discontinuous variation
Polymorphism Mutation
two or more common wild-type and rare
forms mutants
Continuous variation
Important in plant
and animal breeding
ִweight
ִmilk production
ִseed weight
Bell shaped distribution
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Molecular Basis of Allelic
variation Haplosufficient
Melanin Biosynthesis If roughly the normal function obtained
with one copy versus two
tyrosinase
tyrosine melanin
(not a pigment) (pigment)
Molecular Basis of Allelic
variation
Alteration in amino acids may
ִnot affect structure/function of enzyme =
silent mutation
ִIntermediate effect
ִdestroy structure/function of enzyme =
null allele
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