Download Changes in DNA can produce Variation

5.2

Differences or variation in DNA are what
makes us different from each other!
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Each human cell contains 46 chromosomes
 Each cell has 3 billion base pairs of DNA (wow!)

Our DNA is 99.99% similar

Of the 6 billion base pairs of DNA, only 5%
are in the genes that code for RNA and
proteins.
.

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Errors can occur when DNA is copied
UV light, X-rays, chemicals, etc. affect
DNA
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Substitution – Exchanges one base for
another.
 CTGGAG---- CTGGGG
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Insertion – Extra base pairs are inserted.
 CTGGAG---- CTGGTGGAG
 Deletion-
Section is lost, or deleted.
 CTGGAG -----CTAG
 Frameshift- Message is no longer read
correctly.
 THE FAT CAT SAT --- HEF ATC ATS AT
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Cells have different ways to repair
mistakes
Certain enzymes can proofread DNA
such as correcting mismatched base
pairs
1.
The mutation causes no effect.
1. Amino acids have more than 1 code
2. Enough protein may be produced already
2.
The effect of a mutation is minor.
1. Could affect skin/eye/hair pigmentation
3.
The effect of a mutation is great.
1. Genetic disorder/disease

Sometimes passed from parents to offspring
 Sickle Cell Anemia
 Cystic Fibrosis (CF)
 Hemophilia
 Tay- Sachs Disease
 Huntington’s Disease (HD)
 Hypercholesterolemia
 Cancer
 Alzheimer's
 Emphysema
 Diabetes
 Cancer

Their behavior can prevent it:
 Not smoking can prevent emphysema and many
types of cancer

Most genetic disorders cannot be cured,
although progress is being made.

Families who have a history of genetic
disorders are recommended to undergo
counseling before having a child. They can
find out how it could affect their offspring.

Some genetic disorders can be treated if
diagnosed early enough, such as PKU
(lacking a certain enzyme).
 If known, that child can be put on a certain diet
and medicine routine.

Mutation occurs on gene
that codes for hemoglobin

Hemoglobin – a protein that
carries oxygen in red blood
cells

Mutation causes 1 amino
acid to be replaced with
another

Need 2 recessive
genes to be affected
(ss)

Can be a carrier (Ss)
5.3
Random changes in
DNA can introduce
new traits in an
organism
 Humans can breed
animals to get the
certain traits they
want.

 Ex: a cow that gives
more quantities of
milk
Bloodhound – strong sense of smell
The process of
selecting and
breeding
parent
organisms to
pass on
particular traits
to the
offspring.
Selective
Breeding

A sequence of DNA from an organism is
first isolated, then inserted into the DNA
of another organism.

The DNA inserted usually codes for a
particular trait of interest

GMO – Genetically modified
organism

Can make plants
more insect
resistant.

Create crops suitable
for areas with poor
soil conditions
PROS
CONS
Food can be resistant to
certain bacteria and
pests.
 Reduces chemical
pesticides
 Increases food
production
 Add nutrients



Possibly harmful to the
human body but still
unknown
Could risk wild
population like salmon

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Can be used to produce new and better
drugs for treating disease
Determine the side effects of a drug on an
individual
Can be used to screen for and treat genetic
disorders
May soon allow
scientists to correct
certain recessive
genetic disorders by
replacing defective
genes with copies of
a healthy one.
 First step of gene
therapy is to isolate
a copy of the gene.

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Scientists are trying
to input that gene
into the cell by
attaching it to a cold
virus. Attempts in
humans have not
been successful.

However, the outlook
is promising.

Crime scenes – skin,
hair, blood

DNA profile – a DNA
fingerprint

Everyone different
except identical
twins!
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https://www.youtube.com/watch?v=PwdDa6
QCDWw
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All the genetic material in an organism.

The human genome project wanted to
sequence all of the human genome
(that’s a lot)
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We can then compare DNA across species
 We have similar genes to fruit flies and mice
A technique that
uses technology to
make copies.
 Can be applied to a
segment of DNA or a
whole organism

Dolly 
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Place gene that
codes for producing
insulin

That bacteria then
replicates in large
numbers
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Treats people with
diabetes