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BASIC GENETICS, COMMON TO
ALL LIVING THINGS
CHROMOSOME
GENOME
GENE
DNA
NUCLEOTIDES
MUTATION
NATURAL SELECTION
DNA PART I:
STRUCTURE, REPLICATION
GENOME: SUM TOTAL OF ALL HERITABLE DNA IN CELL
GENOME SIZE:
E. coli genome: 4 million base pairs, 1mm in length
Human: closer to 4 billion base pairs.
Chromosome
A single molecule of DNA
The single molecule of DNA is always double stranded
In bacteria - the chromosome is circular! And there is only 1
What is the difference between chromosome and genome?
GENE
Segment of DNA that encodes 1 protein
Usually several hundred base pairs in length
E. coli genome, with some
important genes named
(not all!)
DNA
Name of the chemical that makes up the chromosomes in all living things
All DNA shares some important chemical characteristics
Made up of 4 kinds of nucleotides (ACTG), double
stranded
All DNA differs slightly in the way that it’s put together that makes each living
thing unique
One of 4 bases in
DNA:
Adenosine
Guanine
Cytosine
Thymine
Structure of a nucleotide, the building block of DNA chains
DNA BASE PAIRING: A with T, C with G
REPLICATION
DNA
DNA
Requires:
Nucleotides (raw material)
DNA polymerase (enzyme)
DNA template
GENOTYPE vs. PHENOTYPE
Potential vs. actual or 'expressed' properties
The genotype of an individual refers to the information encoded by all
the genes, which are all present in duplicate
The phenotype refers to how the genes are expressed as physical
traits in the individual or bacterial cell.
DNA PART II:
TRANSCRIPTION,
TRANSLATION,
MUTATION,
Control of gene expression
DNA
DNA
replication
DNA
RNA
PROTEIN
transcription translation
1 PROTEIN
1 GENE
The Central Dogma
RECIPE
DNA
RNA
PROTEIN
Transcription:
Produces an mRNA molecule that
matches the sequence of the gene
DNA
Requires:
DNA template
Nucleotides (raw material)
RNA polymerase (enzyme)
RNA
mRNA molecule
gene
Translation:
Convert the mRNA information into
a protein molecule
RNA
PROTEIN
Requires:
mRNA, Ribosomes,
tRNA molecules carrying amino acids
tRNA molecules carrying each
amino acid
Ribosome
Protein
mRNA
TRANSCRIPTION and
TRANSLATION ANIMATIONS
Transcription:
http://www.fed.cuhk.edu.hk/~johnson/teaching/genetics/animations/transcription.htm
McGraw Hill
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html
Very nice animated exercise
http://gslc.genetics.utah.edu/units/basics/transcribe/
Very simple and nice cartoon of transcription and translation
http://www.lewport.wnyric.org/jwanamaker/animations/Protein%20Synthesis%20-%20long.html
Another nice simple animation of both
hhttp://www.wisc-online.com/objects/index_tj.asp?objid=AP1302
Others + games at: http://science.nhmccd.edu/biol/ap1int.htm
INTRONS, EXONS, NON-CODING DNA
Noncoding DNA, sequence between genes
Introns
Exons
Eukaryotes only
MUTATION
RECIPE
DNA
RNA
PROTEIN
BACTERIAL GENETICS, CONTINUED
MUTATION
Change in genetic material (base sequence of the DNA)
TYPES OF MUTATION
Base substitution
A T
A
G
G
C
T
C C
A
T
C
A C
A
G
A
C
T
C C
A
T
C
(May or may not be Missense)
Nonsense
Frameshift
A T
C
G
G
C
T
A T
A
G
T
C C
C C
A
T
A
C
T
C
HOW DOES MUTATION OCCUR??
Mistakes in replication - chemical mutagens - radiation
Compounds that cause mutation are called mutagens
Mutations that occur without seeming cause are ‘spontaneous’
Cells have safeguards and repair mechanisms
MUTATIONS CAN BE BENEFICIAL!
THE ONE BIG FLY HAD ONE RED EYE
THE ONE BIG FLY HAD ONE RED EYE
THE ONE BIG FLY HAD ONE RED EYE
THQ ONE BIG FLY HAD ONE RED EYE
Point mutation, missense
THE ONE BIG FLY HAD ONE RED EYE
THE ONE BIG FLY HAD ONE RED EYE
THE ONE BIG FLY HAD ONE RED EYE
THE ONE QBI GFL YHA DON ERE DEY E
Frameshift,
insertion
THE ONE BIG FLY HAD ONE RED EYE
THE ONE BIG FLY HAD ONE RED EYE
THE ONE BIG FLY HAD ONE RED EYE
THE ONE BIG
Nonsense
MUTATION???
Mutation = alteration in DNA base pair sequence
Mutation sometimes occurs naturally - mistakes during DNA replication
Mutation may also occur because of environmental exposure to chemicals, UV
light, radiation, etc.
Consequences of mutation??
There may be none
Protein may be altered
Protein may be non-functional or not made at all