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8/11/2019 4-1 Introduction to DNA
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List the various techniques used in DNA p
Describe the nature of DNA
Learning Objectives
Explain how DNA technology is usedin paternity and maternity testing
1
3
Summarize how DNA technologyhas facilitated police work
2
4
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DNA technology
Sex crimes Victim and perpetrator
Only perpetrator left alRape-murder
DNA technology Identify the perpetreven without witne
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Cell
DNA
Human body containsabout 60 trillion cells
60 000 000 000 000
Except red blood cells
Each cell has a nucleus
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In the nucleus
Genetic material
Weighs about 7 picograms
Chromosomes,
genes, DNA The Human Geno
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DNA
Cannotbe found directly at the crime scen
Blood, semen, saliva, skin cells,hair (sometimes) and body parts
Canfind biological materials that contain D
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Chromosome
different orga
In the nucleus
Humans
23 pairs of chromosomes
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Humans
23 pairs of chromosomes
22 pairs autosomal
2 sex determining chromosomes
Genetic inform
XY Male
XX Female
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Chromosomes
Different sizes & shapes
Chromoso
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Chromosomes
Staining withfluorescent dyes
Distinctive patterns of
bright & dark bands
ChromosoDifferent chromosomescontain different genes
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Pairs of chromosomes
Homologous
Same size
Contain same genetic structure
One from mother; one from father
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Genes
DNA material made up of codingand non-codingregions
Codingregions Genes
90 to 95% of DNon-codingregions
Junk DNA
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Genes
Number of genes in the genomevaries from species to species
Complex organisms More genes
Several 100s to 1000sBacteria
30 000Humans
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What are genes made of?
What is DNA made of?
Made of base pairs
A single gene
1000 to 10 000 base pairs
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What is DNA made of?
Sugar
Ribose
2-deoxyribose
Ribose
2-deoxyribose
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2-deoxyribose A phosphate
of 2-deoxyrib
- H2O
What is DNA made of?
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Phosphate ester Nucleotide
Base
What is DNA made of?
Bases Attached to 2-deoxyribose
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Bases
4 bases
Heterocyclic
Nitrogen containing
Aromatic
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Bases
N
NNH
N
NH2
NH
NNH
N
O
NH2
N
NH
NH2
O
NH
NH
O
O
H3C
Adenine Guan
Cytosine Thym
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N
NN
N
NH2
O
O
O
NH
N
N
O
NH2N
O
O
O
N
NH2
ON
O
O
O
NH
O
O
H3C
N
OO
PO
O
P
P
O
O
O
O
O
PO
O
O
What is DNA?
4 nucleotides inpolymer chain
The phosphate
links the sugars
A
G
C
T
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What is a double helix?
DNA
Stable under normal conditions
Twochains wound together
Held in place by hydrogen bon
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Hydrogen bonds
H
O
H
H
OH
Makes water a liquid
Bases in DNA hydrogen bond together
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Complementary base pairing
A and T
C and G
A
G
N
NN
N
N
OHH
H
N
NN
N
O
N
H
N
H
H
H
What is a double helix?
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Paris japoni
Human DNA
3 billion base pairs
150 billion base pairs
Paris japonica
What is a double helix?
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Sequence of base pairs
Write the code with A, T, C and G
The genetic code
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-C-C-T-G-A-G-G-A-G-
Code for one amino a3 nucleotides
The genetic code
Part of code for a prote
Proline Glutamate
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Part of the gene for hemoglobin
The genetic code
Different amino ac
-proline-glutamate-glutamate-
One wrong letter
Different protein
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-proline-valine-glutamate-
The genetic code
-proline-glutamate-glutamate-
-C-C-T-G-A-G-G-A-G-
-C-C-T-G-T-G-G-A-G-
Disease Sickle cell anemia