Heredity

1
Heredity Cloning

• By Trevor Sless

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Introduction

• Genetics is the study of heredity and variation
• Heredity is passing genetic information from one
  generation to the next
• Units of heredity are called genes
• Genes reside in Deoxyribonucleic acid (DNA)
• DNA is organized into chromosomes
• Chromosomes are located in the cell nucleus

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Gregor Mendel

• Gregor Mendel was a Czech monk who grew peas and
  noticed that some characteristics were dominant
  and some were recessive
• He discovered that one plant with round peas and
  one with wrinkled peas produced an offspring with
  round peas
• He published his research in 1866
• Today this is called Mendelian genetics
• Its the start of modern genetics

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Chromosomes

• Chromosomes are coiled up strands of DNA
• Humans have 46 chromosomes
• 22 pairs plus XX or XY
• Half of your chromosomes come from your father,
  and the other half come from your mother
• Different organisms have different numbers of
  chromosomes

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Inherited Traits

• You inherit traits from your parents
• You get one copy of a gene from each of your
  parents
• One gene may be dominant or recessive
• In other cases both genes may be expressed
  (co-dominance)
• A phenotype is a characteristic
• A genotype is the combination of genes that leads
  to the phenotype
• e.g. Aa for dominant/recessive or AB for
  co-dominant

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Some examples of heredity

• Do you have attached earlobes?
• Can you roll your tongue into a tube?
• Do you have brown eyes?
• Do you have curly hair?

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Dominant Recessive Genes

• Genes come in pairs one from each parent so
  you have two copies of every gene
• Often there is a dominant and recessive version
  of a particular type of gene
• If both genes are dominant you get the dominant
  trait or phenotype (e.g. AA) homozygous
• If you get one copy of each (e.g. Aa) you exhibit
  the dominant trait heterozygous
• If both genes are recessive you get the recessive
  trait (e.g. aa) - homozygous

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Dominant/Recessive Heredity Chart Sample 1
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Dominant/Recessive Heredity Chart Sample 2
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Rh Factor Family Tree
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Colour Blindness Family Tree
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Co-dominant Genes

• Weve discussed dominant and recessive genes
• In some cases neither gene is dominant or
  recessive i.e. co-dominance
• Coat colour of Shorthorn cattle is an example
• If you cross a purebred white bovine (WW) with a
  purebred red bovine (RR) the offspring (RW) will
  be neither red nor white, but roan, which is a
  mixture of the two

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DNA

• DeoxyriboNucleic Acid
• Double helix shape
• Four bases
• Each group of three bases codes for one amino
  acid
• Amino acids are the building blocks for proteins

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Experiment Extracting DNA

• Step 1 Mix together mashed up kiwi, tap water
  and laundry detergent in a measuring cup
• Step 2 Put the measuring cup in a bowl of hot
  water for 12 minutes
• Step 3 Put the measuring cup in a bowl of cold
  water for 5 minutes
• Step 4 Filter the mixture through filter paper
  and collect the liquid in a cup
• Step 5 Add rubbing alcohol to the collected
  liquid

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Genetic Mutations

• Genetic mutations are caused when DNA copies
  itself incorrectly
• Not all gene mutations are bad without gene
  mutations there wouldnt be evolution and
  without evolution we wouldnt exist at all!
• Humans now sometimes change an organisms DNA on
  purpose!

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Genetically Modified Organisms

• People usually modify organisms to help that
  organism survive better or to make it better for
  farming
• Sometimes people modify things just for
  experiments
• There is a big debate going on about whether or
  not humans should be allowed to do this

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What is Cloning?

• Cloning is making an exact genetic copy of an
  organism
• The organism does not need to be living to be
  cloned you may have heard of wooly mammoths and
  other extinct animals being cloned
• In nature, many types of organisms clone
  themselves

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How Cloning Works

• Step 1 an egg cell is taken from a donor and its
  DNA is removed
• Step 2 another cell is taken from the organism
  to be cloned, still with DNA
• Step 3 the two cells are fused with an electric
  shock
• Step 4 the fused cell is placed in the womb of a
  female
• Step 5 the cell starts to grow and when it is
  born it is exactly the same as the second donor

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Cloning Examples

• Probably the best known example of cloning is
  Dolly the sheep
• After Dolly, many other animals were cloned,
  mostly rats and mice
• Recently, scientists in Britain were given
  permission to clone human stem cells, but there
  is still a huge debate going on

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Cloning Pros

• Probably the biggest pro in cloning is that
  animals that have been extinct could
  theoretically be brought back to life, although
  this has never been done
• Another pro is that we could possibly clone
  organs, instead of organisms, and use them for
  transplants

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Cloning Cons

• Probably the biggest con is that clones tend to
  have a shorter lifespan and a better chance of
  getting diseases
• People might use human clones as an organ bank
• It could also start a new form of segregation,
  where all non-clones would think theyre better
  than clones
• If a clone is born, who would take care of it?

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Summary

• Chromosomes
• Genotypes and Phenotypes
• Dominant/Recessive and Co-dominant genes
• DNA
• Genetically modified Organisms
• Cloning

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Bibliography-books

• Brookes, Martin. Whats the Big Idea? Genetics,
  London Hodder Childrens Books, 1998
• Claybourne, Anna. Introduction to Genes and DNA,
  London Usborne, 2003
• Elrod, Susan and Stansfield, William. Genetics
  Fourth Edition, New York McGraw-Hill, 2002
• Hooper, Tony. Breakthrough Genetics, Winchester
  Zoë Books, 1992
• Jones, Steve and Van Loon, Borin. Introducing
  Genetics, New York Totem Books, 1994
• Norman, Penny. DNA Wizard, El Sobrante, CA
  Science Wiz, 2004

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Bibliography-websites

• About Genes, Murdoch Childrens Research
  Institute, 2 April 2005. http//www.genecrc.org/si
  te/lc/lc1g.htm
• Alexis tsarevich, Alexis Romanovs Maternal
  Family Tree, 26 March 2005. http//blood.kuzbass.c
  om/alexis.php
• BBC Radio 4 A Twist to Life, BBC, 2 April
  2005. http//www.bbc.co.uk/radio4/science/atwistto
  life.shtml
• Build a DNA Molecule, Genetic Science Learning
  Centre, 3 March 2005. http//gslc.genetics.utah.ed
  u/units/basics/builddna/
• Cloning Conundrum, Cloning Nuts and Bolts, 2
  April 2005. http//whyfiles.org/148clone_clash/2.h
  tml

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Bibliography-websites

• Cloning Fact Sheet, Human Genome Project
  Information, 3 March 2005. http//www.ornl.gov/sci
  /techresources/Human_Genome/elsi/cloning.shtml
• How is DNA Organized into Chromosomes, National
  Fragile-X Foundation, 2 April 2005.
  http//www.fragilex.org/html/dna.htm
• Mutations, A Mutated Gene, 2 April 2005.
  http//www.brooklyn.cuny.edu/bc/ahp/BioInfo/MUT/Mu
  t.Mutation.html
• NOVA Online, NOVA, 26 March 2005.
  http//www.pbs.org/wgbh/nova/baby/cloning.html
• NOVA Orchid Hunter, NOVA, 26 March 2005.
  http//www.pbs.org/wgbh/nova/orchid/images/amat_me
  ndel.jpg

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Bibliography-websites

• Office of University Communications, University
  of Pennsylvania, 2 April 2005. http//www.upenn.ed
  u/pennnews/article.php?id704
• Photo auction, XIX International Congress of
  Genetics, 26 March 2005. http//www.geneticsmedia.
  org/images/spl_watsoncrick_small.jpg
• State Human Cloning Laws, National Conference
  of State Legislators, 3 March 2005.
  http//www.ncsl.org/programs/health/genetics/rt-sh
  cl.htm
• T. rex fossil has 'soft tissues', BBC NEWS
  Science/, 31 March 2005. http//news.bbc.co.uk/2/h
  i/science/nature/4379577.stm
• Tokyo Medical University Genetics Cell
  Chromosome DNA, Tokyo Medical University, 2
  April 2005. http//www.tokyo-med.ac.jp/genet/cdi-e
  .htm