Molecular Genetics p' 4346 and 401407 and Chapter 19

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Molecular Genetics - p. 43-46 and 401-407 and
Chapter 19
The process by which an organism is capable of
giving rise to a new organism similar to
themselves is known as __________________________.
Closely tied to reproduction is
_______________________ - the transmission of
biological traits from a parent to offspring.
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Chromosomes
The genetic information to make a new human being
is found on the chromosomes in the nucleus of
each cell. Each cell has __________chromosomes.
These are arranged in _______ pairs of
_______________________________ with one
homologous chromosome from the male parent and
the other homologous chromosome from the female
parent.
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Chromosomes
Each chromosome is composed of chemical called
____________________________ that records the
genetic information.
4
Structure of DNA
DNA consists of a ______________________
connected by ___________ ______________________ 
Backbone of the helix consists of _______________
______ _____________________ 
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Structure of DNA
Lying between these 2 stands and joining the
sugar groups are pairs of nitrogenous
bases  There are 4 bases ___________________ __
_________________ ___________________ ____________
_______
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Structure of DNA
Hydrogen bonds permit the binding of adenine to
thymine i.e. A - T or T
A due to ___________________
cytosine to guanine C - G or
G C due to
___________________ The combination of a sugar,
phosphate, and one base is called a
______________________.
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Structure of DNA

• Although all DNA molecules have the same general
  pattern of structure, the arrangement of bases
  (A, T, C, G) along each strand is unique to each
  individual 
• thus, my DNA is different than your DNA
• ________________________is now used to determine
  individuals involved in crimes

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Structure of DNA
The ___________________________ spells out the
genetic instructions to determine each trait that
makes up our body. Although the genetic
instructions are written in a language involving
only 4 symbols (____________________), there is
limitless variation in the genetic instructions,
as there are about 1 billion base pairs in our 46
chromosomes.  
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Structure of DNA
A sequence of 3 bases - called the
____________________ forms the genetic
code. What is coded? ______________________ -
the building blocks of proteins that make up
____________________. For example CTG will
code for one amino acid, CGT will code for
another, AAA for another, etc.
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How is the Genetic Code Used?
______________________ - duplication of DNA.
This is necessary in ________ ___________________
_____ DNA bases "unzip" to expose the bases.
Each separate strand serves as a
_______________________
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How is the Genetic Code Used?
Replication cont New strands are formed from
free nucleotides (nutrients from our diet)
Nucleotides line up by ________________________
next to each template. Base pairing and bonding
of the nucleotides to form new strands of DNA is
under the direction of an enzyme called
________________________
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How is the Genetic Code Used?
Replication cont The DNA molecules separate to
form two new complementary DNA molecules. One DNA
molecule will end up in each of the two cells
produced by _______________________
13
Replication diagram from textbook p. 403
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How does the cell use the genetic information?
The cell uses the genetic information to make new
proteins that form new structures of the body.
DNA does not directly participate in the
formation of a new protein thus, the genetic
code must be copied on to a molecule that does.
This molecule is called ______________________
and the copying is called ________________________
____. After the genetic information is copied,
mRNA brings the genetic code to a
__________________________ that forms a new
protein in a process called ______________________
_.  
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Transcription

• Start with a DNA strand
• DNA unzips to expose the nitrogenous bases.
• RNA nucleotides are free in the nucleus and they
  come together to form a single-strand of mRNA
  that is complementary to one DNA strand (the
  ___________________")

Coding strand
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Transcription
The bases of RNA are complementary to DNA except
that thymine is now replaced by ______________
i.e. A - U Formation of mRNA is
under the direction of the enzyme
_____________________
Coding strand
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Transcription
(3) The single-stranded mRNA consists of many
nucleotides, but each group of 3 form a
___________________ that codes for a specific
amino acid. The sequence of codons determines
the sequence of amino acids in a protein. The
mRNA moves out of the nucleus into the cytoplasm
to a __________________ - the organelle involved
in protein synthesis.
3 codons
18
Transcription - Summary diagram on p. 404

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Translation
Translation is the final step in using the
genetic code to make ____________________and
occurs in the ___________________ The ribosome
consists of two globular regions that open up
the mRNA strand attaches to the smaller region of
the ribosome. Translation begins by the movement
of a ribosome down the mRNA strand.
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Translation
The assembly of proteins requires the use of
another kind of RNA called _____________
_________________________ This is folded into a
complicated "cloverleaf" shape. At one end of
the molecule is a ____________________
_______________________ which are collected by
tRNA from free amino acids in the cytoplasm. 

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Translation
At the other end of tRNA is the anticodon loop
containing a sequence of three bases called the
_____________________ The bases of the anticodon
are exposed to line up with complementary base
pairs of a __________________ on mRNA.  

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Translation
1. First step in translation is
_______________________ One tRNA with an
anticodon that is complementary to the start
codon enters a ribosome This tRNA molecule brings
a specific ___________________ into the ribosome
to start the formation of a protein.
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Translation
2. Within each ribosome there is enough space
for the alignment of ________ tRNA
molecules. Once the tRNA anticodon is paired with
the mRNA codon, the amino acid from tRNA is
released and joined by a peptide bond to the
adjacent amino acid to form a protein chain. This
occurs many times to join hundreds of amino acids
to form the protein called _____________________
______  
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Translation
3. Termination When the complete protein is
formed, a _____________________ appears This
causes separation of the protein from the
ribosome. The mRNA, tRNA, and the ribosome are
available to be used again. New protein helps
form the tissues and organs of the new organism
and new traits are expressed.
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Chromosomes
The genetic information to make a new human being
is found on the 23 pairs of ______________________
_______________ in the nucleus of each cell. Of
the 46 total chromosomes, _______chromosomes came
from your father (_______________________) and
__________came from your mother
(__________________________).  
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Chromosomes
At fertilization, they joined to form the 23
homologous pairs of your chromosomes. As they
joined, they combined to form the
_________________ that made you a unique
individual. Thus, some of your traits came from
your father and some from your mother.
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Chromosomes

• Of the 23 homologous pairs of human chromosomes
• 22 pairs are the _______________________
• 1 pair are the _____________________________
• display of human chromosomes is called a
  __________________
•  

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Genes
Each chromosome contains a linear arrangement of
___________ which are also paired on homologous
chromosomes one gene came from your father and
one gene came from your mother. A gene is a
region of ______________ that is the fundamental
unit of __________________
2 genes that control a single trait
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Genes
Each gene consists of a series of genetic codes
that determine the appearance of a trait.  There
are many genes on each chromosome. All of
our genes form our _____________________.
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Genes
The transmission of a single trait to an
offspring is controlled by 2 genes at the same
position on homologous chromosomes . These 2
genes are referred to as __________________ -a
pair of which controls a trait.
2 alleles that control a single trait
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Genes
An allele may be a ____________________ its
trait will appear or be expressed in the
offspring - OR - an allele may be a
____________________ its trait is hidden if it
is paired with a dominant gene, and the trait
will appear only if both genes in the pair are
recessive.
2 alleles that control a single trait
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For instance, a pair of genes controls eye
color The allele for brown eyes is dominant
(designated as B) and the allele for blue eyes is
recessive (designated as b). What are the
possible gene combinations in the offspring?
______________________________
2 alleles that control eye color
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Gene combinations - BB, Bb, and bb - form the
______________________ - symbols to identify the
trait BB is homozygous dominant. Bb is
heterozygous. bb is homozygous recessive - the
only way a recessive trait can appear.
2 alleles that control eye color
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What is the eye color of BB? Bb? bb? Eye
color forms the phenotype. Phenotype of BB and
Bb is ____________________ Phenotype of bb is
__________________
2 alleles that control eye color
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Inheritance of a Single Trait
Inheritance of a single trait is called a
______________________ Our example of a single
trait is earlobe attachment Remember a trait is
controlled by 2 genes E is dominant allele for
free earlobes e is recessive allele for attached
earlobes A man who is heterozygous for free
earlobes marries a woman who is also heterozygous
for free earlobes. What is the chance they will
have a child with attached earlobes?
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Inheritance of a Single Trait
First step is to determine the genotypes of the
parents. ? is Ee ? is
Ee After spermatogenesis, the sperm could be E
or e. After oogenesis, the oocyte could be E or
e. Next step is to set up a _____________________
_______
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Inheritance of a Single Trait

So what is the chance these parents will produce
a child with attached earlobes? free earlobes?

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Inheritance of Gender
Sex chromosomes of a male are ________and a
female is ________ During spermatogenesis, there
is a 50 chance that the sperm will carry an X
and 50 chance the sperm will carry a Y. During
oogenesis, there is a 50 chance that the oocyte
will carry one X and 50 it will carry the other
X. If these parents mate, what are the chances of
having a male baby or a female baby?
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Inheritance of Gender
To work a genetics problem, we set up a
_______________________ The possible sperm are
shown on one side and the possible oocytes are
shown on the top. The interior of the square
shows the possible results of fertilization.
So what are the chances of having a male baby? A
female baby?
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Inheritance of 2 Traits _____________________
2 traits are dimpled cheeks and tongue
rolling D is dominant allele for the presence
of dimpled cheeks d is the recessive allele for
no dimpled cheeks T is dominant allele for the
ability to roll the tongue t is recessive allele
for the inability to roll tongue These 2 traits
are on different homologous chromosomes. 2
parents who are both heterozygous for both traits
mate. What will be the ratios of phenotypes in
their potential offspring?

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Inheritance of 2 Traits Dihybrid Cross
? is DdTt and ? is also DdTt. What are the
potential sperm produced by the male? These
traits are inherited independently of one another
so the genes will separate during spermatogenesis
into 4 types ________ ________ ________
_________ Similarly, there will be 4 possible
oocytes that can be formed during
oogenesis ________ ________ ________
_________

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Inheritance of 2 Traits Dihybrid Cross
We now set up a Punnett square putting the male
gametes on one side and female gametes on the
top. We now need to have ______ interior
squares to represent the possible gene
combinations during a mating.

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Inheritance of 2 Traits Dihybrid Cross

What are the chances an offspring will have
dimples and can roll tongue? What are the
chances of a child with dimples but cannot roll
tongue? What are the chances of a child with no
dimples and cannot roll tongue?
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Genetics Problems
A good understanding of the inheritance of traits
can be accomplished by understanding the genetics
problems on pages 203-208 of your laboratory
manual that was done in lab last week. If you
do not understand how to do these problems, see
me or your lab TA so that we can go over them
with you. Answers to these problems will be
emailed to you. Compare with your answers and be
sure that you understand how the problems were
done. There will be 10 to 12 genetics problems
on the final exam.
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What can go wrong?

• ___________________________ failure of
  homologous chromosomes to separate during
  meiosis. Resulting gametes end up with abnormal
  number of chromosomes.
• occurs in sex chromosomes
• occurs in autosomes

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Nondisjunction of Sex Chromosomes
Nondisjunction results in oocytes or sperm with
abnormal number of sex chromosomes.
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Nondisjunction in Oogenesis
If the abnormal oocytes are fertilized by normal
sperm, offspring have abnormal chromosome
numbers Turners syndrome ________and metafemale
________ syndrome individuals are female but
sterile and often mentally impaired
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Nondisjunction in Oogenesis
Klinefelters syndrome ________ individual is
male but has underdeveloped testes, enlarged
breasts, and learning disabilities. YO -
___________
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Nondisjunction in Spermatogenesis
If nondisjunction occurs in spermatogenesis,
sperm produced could be XX, YY, or O if improper
separation occurs in Meiosis I or XY or O if
improper separation occurs in Meiosis II. If
these sperm fertilize a normal X ovum XXX
________________________ XYY -
________________________(tall male most are
normal but some show mental deficiency) XO
____________________________ XXY
___________________________
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Nondisjunction of Autosomes
Most common autosomal nondisjunction occurs in
chromosome 21 resulting in 3 copies instead of
2 called ______________________ Results in
________________________ short stature, flat
faces, poor reflexes, and mental impairment Life
span _____________________________
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Nondisjunction of Autosomes
Down syndrome appears most commonly what type of
mothers? ___________________________________
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Abnormal Genes
Each time a cell divides its DNA is copied Each
time a protein is made, DNA is copied by
mRNA. Normally, the copies that are made are
exact duplicates of the original. However, in a
very few instances, a mistake may be made,
resulting in an abnormal gene. A
___________________________is a change in a gene
that produces altered proteins.
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Abnormal Genes
A good example of a mutation resulting in an
abnormal protein is __________________________. He
moglobin is composed of 267 amino acids joined
together. In the sequence of genetic codes, GAA
is the code for the proper amino acid in a
sequence. In sickle-cell anemia, the code has
mutated to GTA, resulting in a different amino
acid being added to the molecule. Result?
_______________________
normal Hb sickle cell Hb
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Defective Genes

• Several human disorders are the result of the
  inheritance of defective genes from the parents.
  
• Autosomal dominant disorders
• ____________________________ brain disorder in
  which an abnormal protein is produced that
  damages brain cells and causes a loss of motor
  control
• H huntingtons
  
  h - normal
• Symptoms do not appear until ages 35-45.
• Why would this be a problem in a family?

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The gene for Huntingtons disease has now been
found, and scientists are now trying to figure
out how it causes brain cell destruction. We now
can test a person to determine if this gene is
present. Recent CBS News profile of Jake Dowell,
UW hockey player from Eau Claire whose father has
Huntingtons. He has decided not to be tested.
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Defective Autosomal Dominant Genes

• _______________________ high levels of
  cholesterol in blood can cause atherosclerosis in
  coronary arteries
• - many have early heart attacks
• ___________________________ (NF) tumors
  appear in skin and muscles
• ___________________________

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Defective Autosomal Recessive Genes

• _____________________________ transmitted by a
  defective recessive gene on chromosome 7
• C normal
• c cystic fibrosis
• - trait is transmitted by normal parents who are
  heterozygous Cc x Cc (see genetics
  problems)

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Defective Autosomal Recessive Genes

• Phenylketonuria (PKU) defective recessive gene
  on chromosome 12.
• P normal
• p ? PKU
• - affected individuals are unable to breakdown
  the amino acid phenylalanine
• - can damage _________________________
• - warning about presence of phenylalanine
  printed on ___________________________
• 3. Albinism (see genetics problem on pedigrees)

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Defective Sex-Linked Recessive Genes
Sex-linked recessive disorders are present on the
_______ chromosome. In a female, the trait is not
shown (it is recessive) due to the presence of a
normal X chromosome XN Xn XN normal X
chromosome Xn X chromosome carrying the
recessive trait Although these females do not
show the trait, they are carriers. In a male, the
trait appears due to presence of a single X
chromosome Xn Y How would a female show the
trait?
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Defective Sex-Linked Recessive Genes
To solve problems, again use the small Punnett
square. For instance, colorblindness is a
sex-linked trait. If a colorblind man marries a
woman with no history of colorblindness in her
family, what are the chances they will have a
colorblind child?
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Defective Sex-Linked Recessive Genes

• Sex-linked recessive disorders
• ____________________________________
• ____________________________________
• 3. ___________ (severe combined immunodeficiency
  disease)
• - disease of babies caused by defective gene
  that forms _____________________________
  _
• - babies have no immunity and die at an
  early age from minor infections
• 4. __________________________________________

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Defective Sex-Linked Recessive Genes
Hemophilia is another sex-linked trait. What is
role of hemophilia in history? Present in the
_______________________________ Started with
Queen Victoria as a carrier.
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Defective Sex-Linked Recessive Genes
What is this family tree for the transmission of
a genetic trait called? _______________________
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Human Genome Project
The Human Genome Project involves the complete
mapping and understanding of all the genes of
human beings. Project was started in 1989 and was
finished in 2003. Human genome consists of some
___________________ genes. This is a much
smaller number than originally thought (your text
has 100,000 genes). How will understanding the
human genome help us?
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Human Genome Project

• How will understanding the human genome help us?
• improved diagnosis of disease (genes for
  ____________diseases have been identified)
• earlier detection of genetic predispositions to
  disease
• gene therapy to treat diseases
• match organ donors with recipients

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DNA Technology
For the first time in history, scientists are
constructing DNA to achieve new genotypes and
phenotypes. Recombinant DNA technology involves
the removal of DNA from one species and
transferring it to another to form new genetic
combinations. Process involves removal of the DNA
of a gene from one cell and inserting it into a
__________________________ the most common one
used is Escherichia coli or E. coli. Due to rapid
multiplication of the bacteria, many new copies
of the gene are produced. How is the process
done?
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DNA Technology
1. DNA of a gene is removed from 2 cells a. a
gene for a specific trait removed from a human
cell. b. a ___________________ a loop of DNA
from E. coli, is removed. 2. DNAs from both are
cut with restriction enzymes at specific
sites. 3. DNAs are mixed and base pairing
occurs.
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DNA Technology

• Enzyme DNA ligase connects the human DNA with
  plasmid DNA in the bacteria.
• Plasmids with new DNA are taken up by new
  bacteria.
• Bacteria with new human gene multiply and can be
  inserted into human. Bacteria produce new
  proteins that are available in the human.

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Applications of DNA Technology

• Agriculture
• a. Bovine growth hormone (BGH) is produced from
  genetically engineered bacteria injected into
  cows.
• Results in cows? ________________________________
  _
• _______________________________________________
• Plants have been injected with bacterial genes
  that make them more resistant to diseases or grow
  faster.

70
Applications of DNA Technology

• 2. Environment
• Genetically altered oil-eating bacteria have
  been used to clean up oil spills.
• Endangered species can be cloned to help increase
  their numbers.

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Applications of DNA Technology

• 3. Medicine
• a. DNA technology can diagnose 1400 human
  genetic disorders.
• Genetic testing can be done on a person to
  determine if any of ones genes contain abnormal
  traits.
• It may be possible to develop your own
  _________________________________ to show you
  potential health problems that may occur.

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Applications of DNA Technology
3. Medicine cont. c. __________________________
can be used to correct for an abnormal gene.
Normal gene is placed into a virus that is
inserted into a human cell. Viral DNA with
normal gene is copied into human DNA as cells
divide by mitosis.
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Applications of DNA Technology
3. Medicine cont. d. ________________________
are developed using DNA technology. e.
________________________ can be produced in large
quantities from bacteria. Insulin from
genetically engineered bacteria is replacing
insulin from cows and pigs used to treat diabetes
mellitus. Several other hormones can be
produced.
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Applications of DNA Technology
4. Criminal Investigation - _____________________
___________ DNA can be isolated from blood and
cells found at a crime scene. DNA is placed
into a gel plate that is exposed to an electrical
current technique is called ____________________
_________. The current fragments the DNA and
pulls it apart.
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4. Criminal Investigation - DNA fingerprinting
Fragments of DNA appear as separate dark areas
in the gel.
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DNA fingerprinting cont. Here is a DNA
fingerprint from blood of 7 individuals and
blood from a crime scene. Which one is a match?
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DNA Technology Ethics and Safety
DNA technology holds tremendous promise for
agriculture and medicine, but several questions
are raised. Could a superbacterium be produced
that causes widespread disease? Could it be used
as a form of bioterrorism? Could genetically
altered plants cause environmental damage by
outcompeting with our native plants?
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DNA Technology Ethics and Safety
Who would have access to your genetic report
card? Could it be used to deny you health
insurance? Should we clone a human? Scientists
have successfully cloned sheep (Dolly was first),
cows, pigs, and mice. Cloning is causing a lot of
controversy today. Recent findings in cloned
mice indicate that clones have many
______________________________. This may not
make it possible to effectively clone a human.
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DNA Technology Ethics and Safety
The real issue is to use DNA technology to bring
about beneficial changes without harming
ourselves or our environment. Several scientific
and government agencies are now working to
establish regulations and policies before
problems occur. With advances coming every day,
it is time that all of us think about the
benefits and risks of living in a
biotechnological society.