Dr.%20Kathleen%20Hill

1
Dr. Kathleen Hill Assistant Professor Department
of Biology The University of Western
Ontario khill22_at_uwo.ca Office Hours Monday 1 to
5pm Room 333 Western Science Centre Research
Website http//www.uwo.ca/biology/Faculty/hill/in
dex.htm
2
GenomesDNAGenes to Proteins

• Kathleen Hill

January 18 Lecture/Workshop January 25th Lab Tour
WSC 333
3
The human genome is a multi-volume instruction
manual

• The GENOME is a multi-volume instruction manual
• Each CHROMOSOME is a volume of text
• Genes are a chapter of text in the volume
• The text is written in a chemical language that
  has a four letter alphabet A,C,G,T NUCLEOTIDES

4
Our instruction manual can be read in our DNA
DNA sequence
Genome
Chromosome
Gene
Text
Volume
Chapter
Manual
5
Human Genome
46 chromosomes 22 pairs of autosomes 1 pair of
sex chromosomes
Male Karyotype
6
Human nuclear DNA is highly packaged in
chromosomes
7
DNA has a double helix structure
8
Nitrogenous Bases The DNA language alphabet
9
Key Concepts
Two key properties of nucleic acids
ACGT TGCA
Complementary
3
5
Antiparallel
ACGT TGCA
5
3
10
Antiparallel
Antiparallel
Complementary
11
Chromosome Landscape
Chromosome
millions of nucleotides
Gene
106 to 108 nucleotides
DNA sequence
Single nucleotides
12
Landscape of a chromosome
Genes occupy little landscape on a chromosome
13
Viruses are nonliving and have the greatest
diversity in genome types
ssDNA dsDNA ssRNA dsRNA single molecules multiple
molecules
14
Bacterial Genomes Single molecules, circular
dsDNA Smaller circular plasmid genomes -
extragenomic
15
Bacterial Genomes Single molecules, circular
dsDNA Smaller circular plasmid genomes -
extragenomic
Genetic information can be exchanged between
bacteria via plasmids and between the plasmid and
the bacterial chromosome
16
Bacterial Genomes Single molecules, circular
dsDNA Smaller circular plasmid genomes -
extragenomic
Viruses can infect bacteria and add genetic
information to the bacterial host chromosome
17
Bacterial Genomes Single molecules, circular
dsDNA Smaller circular plasmid genomes -
extragenomic
Genome is not enclosed in a separate compartment
in the prokaryotic cell Genomic DNA is not
protein packaged
18
Eukaryotic Cell Genome is contained in separate
cell compartment
19
Eukaryotic Genomes
Membrane compartmentalized
Protein packaged
20
Animal Cell
Genome
Genome
21

• Mitochondrial DNA
• Double stranded
• Circular
• Located in the mitochondrion

22
Genomes of closely related organisms show more
similar organization
23
Genome Size
24
Genome Size and Number of Genes
Human Genome 3.4 billion nucleotides
25
Differences in Gene structure
Continuous
Discontinuous
26
Exons produce message introns do not
Continuous
Discontinuous
27
Eukaryotic Genes are interrupted by noncoding
intronic sequence
Genes of mammals have more intronic sequence than
flies, yeast and bacteria
28
GENES
29
Gene
Certain Information in the DNA sequence is
processed to result in proteins that can carryout
an essential cell function
30
One strand of the DNA sequence (the template) is
written into a intermediate message Messenger
RNA
31
One strand of the DNA sequence (the template) is
written into a intermediate message Messenger
RNA (mRNA)
32

• mRNA
• Single stranded
• Complex secondary structure
• Complementary sequence shows hydrogen bonding

33
(No Transcript)
34
A distinguishing feature of mRNA is the polyA
tail
35
The message is then translated into a new
language Amino acids are a 20 letter alphabet of
the protein language
36
One code used to translate from nucleic acid to
protein sequence
Each codon will be translated to an amino acid
37

• amino acid carrier

tRNA is the translator

• Carries the anticodon
• The anticodon is complementary to the codon

38
Site of translation on the t-RNA
39
Amino acids are linked together in a protein chain
40
Overview of the key players in translation
41
In eukaryotes
In prokaryotes the process occurs simultaneously
on same mRNA strand
In nucleus
In cytoplasm