Genes and Gene Technology
     What do Genes Look Like?
Pieces of the Puzzle
    Genes

      determine the traits of an organism
    

     are passed on from one generation ...
What a Gene Has to Be Able to Do

    Supply instructions for cell processes and

    building cell structures

    Be co...
The Subunits of DNA
    DNA is made of only four subunits which

    are called nucleotides

    Each nucleotide consists...
The Four Bases
  Thymine

 Adenine
 Guanine
 Cytosine


    They each have a slightly different shape.



    The bas...
Chargraff’s Rules

    In the 1950’s, Erwin Chargraff found that

    the amount of adenine in DNA always
    equals the ...
A Picture of DNA
    Rosalind Franklin was able to create

    images of DNA molecules using a process
    known as X-ray...
Eureka!
    James Watson and Francis Crick were

    also investigating the structure of DNA.

    Based on Franklin’s im...
Making Copies of DNA
    One side of DNA is complementary to the

    other.

    DNA splits down the middle where the tw...
More About Traits
    Incomplete dominance

      Sometimes one trait is not completely
    
      dominant over another...
More About Traits
    Genes Influence Traits

      Sometimes one gene influences more than
    
      one trait
     S...
More About Traits
    Importance of Environment



    Many things in your environment influence

    how you grow and d...
Think/Pair/Share
    List and describe the parts of a nucleotide.





    Which bases pair together in a DNA

    molec...
Section 2


HOW DNA WORKS
Unraveling DNA
    DNA is often wound around proteins,

    coiled into strands, and then bundled up
    even more. In a ...
Genes and Proteins
  Proteins act as chemical triggers for many

of the processes within cells. Proteins help
determine t...
Protein Synthesis: Transcription
    The first step in making a protein is to

    copy one side of the segment of DNA
  ...
Transcription
Protein Synthesis: Translation
    The mRna is then fed through a ribosome.

    The ribosome reads three bases of the
  ...
Protein Synthesis: Translation
    The amino acids are dropped off at the

    ribosome.

    As more mRNA is fed through...
Protein Synthesis: Translation
    The ribosome starts reading the mRNA at

    the START codon. AUG is almost always
   ...
Translation
Changes in Genes
    Changes in the number, type, or

    order of nucleotide bases on a
    piece of DNA are known as
  ...
Types of Mutations



 Deletion

 Insertion

Substitution
Mutations
    There are three possible consequences to

    changes in DNA: an improved trait, no
    change, or a harmfu...
Mutants Among Us?
    Mistakes during DNA replication are

    estimated to occur in 1 of every 10,000
    base pairs.

 ...
Example of Substitution
    A mutation, such as a substitution, can be

    harmful because it may cause a gene to
    pr...
Uses of Genetic Knowledge
    Scientists can manipulate individual genes

    within organisms. This kind of
    manipula...
Think/Pair/Share
    What is the function of the ribosome in

    protein synthesis?

    What are the three types of mut...
Genes And Gene Technology
Genes And Gene Technology
Genes And Gene Technology
Genes And Gene Technology
Genes And Gene Technology
Genes And Gene Technology
Genes And Gene Technology
Genes And Gene Technology
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Genes And Gene Technology

  1. 1. Genes and Gene Technology What do Genes Look Like?
  2. 2. Pieces of the Puzzle Genes  determine the traits of an organism   are passed on from one generation to another  located on chromosomes Chromosomes are made of  protein   DNA= deoxyribonucleic acid
  3. 3. What a Gene Has to Be Able to Do Supply instructions for cell processes and  building cell structures Be copied each time a cell divides 
  4. 4. The Subunits of DNA DNA is made of only four subunits which  are called nucleotides Each nucleotide consists of  a sugar   a phosphate  a base Nucleotides are identical except for the  base
  5. 5. The Four Bases Thymine   Adenine  Guanine  Cytosine They each have a slightly different shape.  The base is usually referred to by the first  letters in their names: A, T, G, C.
  6. 6. Chargraff’s Rules In the 1950’s, Erwin Chargraff found that  the amount of adenine in DNA always equals the amount of thymine. Also the amount of guanine always equals  the amount of cytosine. These findings are known as Chargraff’s  rules.
  7. 7. A Picture of DNA Rosalind Franklin was able to create  images of DNA molecules using a process known as X-ray diffraction. The images that Franklin created  suggested that DNA has a spiral shape.
  8. 8. Eureka! James Watson and Francis Crick were  also investigating the structure of DNA. Based on Franklin’s image, they  concluded that DNA resembles a twisted ladder shape known as a double helix. They used their DNA model to predict how  DNA is copied.
  9. 9. Making Copies of DNA One side of DNA is complementary to the  other. DNA splits down the middle where the two  bases meet. The bases can be used as a pattern for a  new complimentary side.
  10. 10. More About Traits Incomplete dominance  Sometimes one trait is not completely  dominant over another  These traits don’t blend together but each allele has its own degree of influence
  11. 11. More About Traits Genes Influence Traits  Sometimes one gene influences more than  one trait  Some traits are the result of several genes acting together
  12. 12. More About Traits Importance of Environment  Many things in your environment influence  how you grow and develop Healthy diet   Exercise You may have the genes to grow tall but  you won’t reach your full potential height without the proper nutrients
  13. 13. Think/Pair/Share List and describe the parts of a nucleotide.  Which bases pair together in a DNA  molecule? If a sample of DNA were found to contain  20 percent cytosine, what % of guanine would be in this sample? Why?
  14. 14. Section 2 HOW DNA WORKS
  15. 15. Unraveling DNA DNA is often wound around proteins,  coiled into strands, and then bundled up even more. In a cell that has a nucleus, the strands of DNA and proteins are bundled into chromosomes. A gene consists of a string of nucleotides  that give the cell information about how to make a specific trait.
  16. 16. Genes and Proteins Proteins act as chemical triggers for many  of the processes within cells. Proteins help determine traits. Another type of molecule that helps make  proteins is called RNA, or ribonucleic acid. RNA is so similar to DNA that RNA can serve as a temporary copy of a DNA sequence.
  17. 17. Protein Synthesis: Transcription The first step in making a protein is to  copy one side of the segment of DNA containing a gene. This copy is called messenger RNA (mRNA). This copy is identical to the original section  except instead of copying thymine, the copy has uracil. After being made, the mRNA moves from  the cell’s nucleus into the cytoplasm.
  18. 18. Transcription
  19. 19. Protein Synthesis: Translation The mRna is then fed through a ribosome.  The ribosome reads three bases of the mRNA at a time. These groups of three bases code for a  specific amino acid. The groups are called codons. Transfer RNA (tRNA) delivers amino acids  from the cytoplasm to the ribosome
  20. 20. Protein Synthesis: Translation The amino acids are dropped off at the  ribosome. As more mRNA is fed through the  ribosome, tRNA brings more amino acids to drop off. As they are dropped off they join together.
  21. 21. Protein Synthesis: Translation The ribosome starts reading the mRNA at  the START codon. AUG is almost always the START codon, especially for eukaryotes. Once the ribosome reads the STOP  codon, the amino acids that are joined together form the protein that the mRNA was coded to make.
  22. 22. Translation
  23. 23. Changes in Genes Changes in the number, type, or  order of nucleotide bases on a piece of DNA are known as mutations. Insertion: Base is added that  wasn’t in original sequence Substitution: Base that was in  original sequence is replaced by another Deletion: Base from original  sequence is removed
  24. 24. Types of Mutations Deletion Insertion Substitution
  25. 25. Mutations There are three possible consequences to  changes in DNA: an improved trait, no change, or a harmful trait. Mutations happen regularly because of  random errors when DNA is copied. Any physical or chemical agent that can cause a mutation in DNA is called a mutagen. Examples: X-rays, UV radiation, asbestos,  chemicals in cigarette smoke
  26. 26. Mutants Among Us? Mistakes during DNA replication are  estimated to occur in 1 of every 10,000 base pairs. We have built-in DNA checking  mechanisms that catch most of these mutations and correct them. The final error rate is as low as 1 in 1 billion.
  27. 27. Example of Substitution A mutation, such as a substitution, can be  harmful because it may cause a gene to produce the wrong protein. A simple change in an amino acid can  cause a disease such as sickle cell anemia. Sickle cells are not as good at carrying oxygen and also are more likely to cause dangerous blood clots.
  28. 28. Uses of Genetic Knowledge Scientists can manipulate individual genes  within organisms. This kind of manipulation is called genetic engineering. Your DNA is unique, so it can be used like  a fingerprint to identify you. DNA fingerprinting identifies the unique patterns in an individual’s DNA. Its two main uses are identifying evidence in criminal cases and determining whether people are
  29. 29. Think/Pair/Share What is the function of the ribosome in  protein synthesis? What are the three types of mutations? What  is a mutagen? Explain the relationship between genes and  proteins. What is a codon? 

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