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DNA and Genes
Modified Chapters 10, 11, & 12
DNA verse RNA….Review

DNA and RNA are nucleic acids
◦ DNA – genetic information
◦ RNA – used to build proteins
Built by nucleotides
 Can be single stranded or double
stranded
 Bases
 Bonds

DNA verse Gene??

DNA
◦ Nucleic acid
◦ Comprised of
chromosomes
◦ Every person
genetically unique

Gene
◦ Segment of DNA
◦ Carries instructions
for products to be
made
◦ Every person has
same genes, but each
varies
DNA Replication
Complete set of genetic
instructions must pass
from one generation to
the next
 Begins at specific sites
on a double helix
 Proceeds in both
directions

Overview:
1. Strands separate
a. New nucleotides
b. Result: 2 DNA copies, each:
1 new & 1 old chain
2. DNA polymerase
3. Leading strand
4. Lagging strand
5. Primer
Flow of Genetic Information from
DNA to RNA to Protein

Information contained in DNA is stored in
blocks called genes
◦ genes code for proteins
◦ proteins determine what a cell will be like

DNA stores information in nucleus
◦ instructions are copied from the DNA into messages
comprised of RNA
◦ these messages are sent out into the cell
 direct the assembly of proteins
Flow of Genetic Information from DNA to
RNA to Protein

The path of information is often referred to as the
central dogma
DNA  RNA  protein

Gene expression :
◦ Transcription
 messenger RNA (mRNA) made from a gene within the DNA
◦ Translation
 Using the mRNA to direct the production of a protein
Transcription:
First step
◦ Occurs in nucleus
◦ Genetic information
transferred from DNA to
RNA
◦ Important players:



◦
◦
RNA polymerase
Ribosomal RNA (rRNA)
Introns removed
Exons spliced together
Translation
Second step
 Occurs in cytoplasm
 Conversion from the
nucleic acid language to
the protein language
 Important players:

◦ Messenger RNA (mRNA)
 mRNA is “read” in threenucleotide units called
codons
◦ Transfer RNA (tRNA)
The genetic code (RNA codons)
There are 64 different codons in the genetic code!!!!
Genes gone bad…

Mutation
◦ Any change in the
nucleotide sequence of
DNA
◦ Can result in changes in
the amino acids in proteins
◦ Often harmful, but are they
always??

Mutations may result
from
◦ Errors in DNA replication
◦ Physical or chemical agents
called mutagens
How are Genes Regulated??

In cellular differentiation:
◦ Certain genes turned on
and off
◦ Cells become specialized in
structure and function

In gene expression:
◦ A gene is turned on and
transcribed into RNA
◦ Information flows from
genes to proteins, genotype
to phenotype
DNA TECHNOLOGY
How do we use DNA to our
advantage???
Cloning
 Recombinant DNA
 GMO

Cloning Plants and Animals

Nuclear transplantation
◦ Involves replacing nuclei of egg cells with nuclei from
differentiated cells
◦ Has been used to clone a variety of animals

Scottish researchers cloned the first mammal
in 1997
◦ Dolly!!
◦ Reproductive cloning
Recombinant DNA Technology
Set of techniques for combining genes
from different sources into a single DNA
molecule
 genetically modified (GM) organism

◦ organism that carries recombinant DNA

Recombinant DNA technology is applied in
the field of biotechnology
◦ Biotechnology uses various organisms to
perform practical tasks
Genetically Modified (GM) Foods

Replacing traditional
plant-breeding programs

Corn has been
genetically modified to
resist insect infestation
Recombinant DNA Techniques
Bacteria….
 To work with genes
in the laboratory,
biologists often use
bacterial plasmids

◦ Small, circular DNA
molecules
Recombinant DNA Techniques

Plasmids
◦ Can easily incorporate
foreign DNA
◦ Readily taken up by bacterial
cells
◦ Act as vectors
 DNA carriers that move
genes from one cell to
another

Can help biologists
produce large quantities
of a desired protein
Cutting and Pasting DNA with Restriction Enzymes

To combine the
plasmid and gene:
◦ piece of DNA must be
spliced into a plasmid
 Accomplished using
restriction enzymes
 cut DNA at specific nucleotide
sequences
 cuts produce pieces of DNA
called restriction fragments
 May have “sticky ends” that
are important for joining
DNA from different sources
Transformation of Insulin Gene

human insulin gene isolated and cut from its
location on the human chromosome
◦ using a restriction enzyme

plasmid is cut using the same restriction
enzyme

desired DNA (insulin gene) and plasmid DNA
can be joined using DNA ligase

plasmid now contains the genetic instructions
on how to produce the protein insulin

Bacteria can be artificially induced to take up
the recombinant DNA plasmids and be
transformed
◦ successfully transformed bacteria will
contain the desired insulin gene

transformed bacteria containing the insulin gene
can be isolated and grown

As transformed bacteria grow they will produce
the insulin proteins coded for the recombinant
DNA
◦ Insulin harvested and used to treat diabetes
DNA Fingerprinting and Forensic Science

DNA technology has
rapidly revolutionized the
field of forensics
◦ scientific analysis of
evidence from crime scenes

Uses:
◦
◦
◦
◦
Paternity
Victim identification
Crimes
Evolutionary research
 Study ancient pieces of
DNA
 Cheddar Man!!!!
Tracking the Anthrax Killer

In October 2001, Florida man died from
inhalation anthrax
◦ By the end of the year, four other people had
also died from anthrax

Investigators analyzed the genome of the
anthrax spores used in each attack
◦ Able to establish that the spores from all of
the cases were identical
 Suggested a single perpetrator of the crime
 Able to match the anthrax with one laboratory
subtype
 The Ames strain
“Conviction…”

Betty Anne Waters
◦ Ayer, MA

1982 – brother arrested for murder

Waters went to CCRI
◦ GED
◦ Associates
◦ Went to Roger Williams to get Bachelors and
Law degree

Became brothers lawyer
◦ Witnesses lied****
◦ DNA evidence in 1990’s
◦ Innocence Project

Released in 2001 after serving 18 years in prison
◦ $3.4 million dollar settlement
http://www.imdb.com/video/imdb/vi4273341977/