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Today: How
do genes
work?
Discussions
begin/began
this week.
Homework
#1 posted
Fig 5.26
Information
flow in cells
Protein
Fig 5.21
Proteins are the
“doers” of the cell.
They act as:
•Enzymes
•Structural Support
•Transporters
•Signals
Proteins are a
string of amino
acids
The relationship between DNA and genes
a gene - DNA used to produce RNA or protein
promoter
coding region
terminator
non-gene
DNA
Only a small percent
of DNA codes for
proteins
Fig 21.7
DNA Composition:
In humans:
•Each cell contains ~6 billion nucleotides of
DNA.
•This DNA is ~2 meters long and 2 nm wide.
•~98% does not directly code for amino acids
•In a single human cell only about 3-5% of
genes are expressed at a time.
Fig 6.2
Length of
human DNA
in each cell
The length of DNA
in each of your cells
is longer than you are
tall.
Width of DNA
Power of ten:
http://www.youtube.com/watch?v=A2cmlhfdxuY
DNA Composition:
In humans:
•Each cell contains ~6 billion base pairs of
DNA.
•This DNA is ~2 meters long and 2 nm wide.
•~1.5% directly codes for amino acids
•~25% is genes
•In a single human cell only about 5-10% of
genes are expressed at a time.
The relationship between DNA and genes
a gene - DNA used to produce RNA or protein
promoter
coding region
terminator
non-gene
DNA
4 nucleotides
in DNA
?
fig 16.5
20 amino acids in proteins
fig 5.17
How can 4 nucleotides code for 20 amino acids?
IF
Ratio
(nucleotide:amino acid) Possible combinations
1:1
41 4
How can 4 nucleotides code for 20 amino acids?
IF
Ratio
(nucleotide:amino acid) Possible combinations
1:1
41 4
2:1
42 16
How can 4 nucleotides code for 20 amino acids?
IF
Ratio
(nucleotide:amino acid) Possible combinations
1:1
41 4
2:1
42 16
3:1
43 64
How can 4 nucleotides code for 20 amino acids?
IF
Ratio
(nucleotide:amino acid) Possible combinations
1:1
41 4
2:1
42 16
3:1
43 64
•There are more possible combinations than
amino acids.
fig 17.4
Combinations of
3 nucleotides
code for each 1
amino acid in a
protein.
Differences between
DNA and RNA
Fig 5.27
fig 17.4
Combinations of
3 nucleotides
code for each 1
amino acid in a
protein.
fig 17.5
the Genetic Code
Changes in DNA can change the protein
Fig 17.22
Changes in
DNA can
change the
protein...
sickle-cell
anemia
The fat cat ate the rat.
change one letter
The zat cat ate the rat.
The fat cat ate the rat.
change one letter
The zat cat ate the rat.
delete one letter
The atc ata tet her at.
fig 17.4
Combinations of
3 nucleotides
code for each 1
amino acid in a
protein.
fig 5.26
The information
in genes is what
to make and
when to make it.
Protein
Genes have three basic parts
a gene
promoter
coding region
terminator
non-gene
DNA
fig 5.26
Genes contain
the information
to make RNA
and/or proteins.
The information
in genes is what
to make and
when to make it.
Protein
When to make a protein is critical for proper
development.
fig 21.7
Genes are replicators
(selfish gene)
fig 19.4
Viruses infect
living cells, take
over, and produce
more virus.
Bodies are vessels for the transmission of genes
fig 21.8
Transposons
Genes are replicators (selfish gene)
Transposons: mobile DNA
fig 21.9
fig 21.8
Barbara McClintock, discoverer of transposons
Genes are replicators (selfish gene)
Transposons: mobile DNA
fig 21.9
Retrotransposons: mobile and self-replicating
DNA
fig 21.9
fig 21.7
Genes are replicators
(selfish gene)
Next: How
do your
genes make
you, you?
Discussions
begin/began
this week.
Homework
#1 posted