1 / 38

Chapter 7

Chapter 7. Genes and Technology. Section 1: What Do Genes Look Like. The Pieces to the Puzzle. The gene must be able to carry out two processes 1) it must be able to supply complex instructions for cell processes and building cell structures

aimon
Download Presentation

Chapter 7

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 7 Genes and Technology

  2. Section 1: What Do Genes Look Like

  3. The Pieces to the Puzzle • The gene must be able to carry out two processes • 1) it must be able to supply complex instructions for cell processes and building cell structures • 2) It must be able to be copied each time a cell divides • This ensures that hereditary information is passed on • Before the 1940’s most scientists believe that proteins contained DNA • When and how did this perspective change?

  4. Nucleotides-The Subunits of DNA • Nucleotides – the subunits of DNA (4 of them) • Consists of a sugar, phosphate, and a base • Nucleotides are identical except for the type of base present • The four bases are: • 1. adenine (A) • 2. thymine (T) • 3. guanine (G) • 4. cytosine (C)

  5. Chargaff’s Rule • In the 1950’s a biochemist named Erwin Chargaff was studying samples of DNA • He discovered that the amount of adenine and thymine were always the same and that cytosine and guanine were always the same • This led to Chargaff’s Rules: • A = T • G = C

  6. A Picture of DNA • More clues came from chemist Rosalind Franklin • She was able to take images of DNA molecules • The process was known as X ray diffraction • The image that Franklin created suggested that DNA had a spiral shape

  7. Eureka! • Along with many other scientists, James Watson and Francis Crick were also studying The mystery of DNA’s structure • They had been try to make a model of DNA, but nothing worked • After seeing Franklin’s images, Watson and Crick put it all together! • DNA is shaped like a twisted ladder (a double helix)

  8. DNA Structure (see drawing on board) • DNA is shaped like a spiral staircase (double helix) • The two sides of the ladder are made of alternating sugar and phosphate molecules • The rungs of the ladder are composed of a pair of nucleotide bases • Please take the time now to draw the DNA molecule on the board • What does DNA stand for? • Deoxyribonucleic Acid • http://www.dnatube.com/video/365/DNA-Replication

  9. Making Copies of DNA • Because A always bonds with T and C with G, the bases on one side of the molecule become a template or pattern, for the other side • One side is then complementary to the other • What would be the complementary side to the following DNA segment be - ACCG? • TGGC • Before DNA can replicate it must split down the middle

  10. More News About Traits • Incomplete Dominance – when one trait is not completely dominant over the other • i.e. red flower and a white flower have pink offspring • One Gene Can Influence Many Traits • i.e. For a white tiger one gene influences both it’s fur and eye color • Many genes can influence a single trait • i.e. In humans skin, hair, and eye color are influenced by several genes

  11. QUIZ TIME! Take out a ½ a piece of paper.

  12. Chapter 7 –Quiz 1 1) List Chargaff’s Rules 2) _________ are the smallest subunits for DNA 3) _________ took an image of DNA, that allowed Watson and Crick to discover DNA’s shape 4)what is the complementary side to this DNA strand AGGTTCCATGCC 5) ____________ is when one gene or trait is not completely dominate over the other Bonus) ____________ is any change in the order of the bases in DNA

  13. Chapter 7 – Quiz 1 Answers 1) A=T and C=G 2) Nucleotide 3) Rosalind Franklin 4) AGGTTCCATGCC = TCCAAGGTACGG 5) Incomplete Dominance Bonus) Mutation

  14. Section 2: How DNA Works http://video.google.com/videoplay?docid=-4167644462303807708&ei=hUxXS5X9AqTwqAOq5dHIAQ&q=DNA+transcription+%26+translation&hl=en&view=3#

  15. Genes and Proteins • The bases in DNA read like a book • The bases A,T,G, and C form the alphabet for the genetic code • Groups of three bases in a row (codon) codes for a specific amino acid • i.e CCA codes for the amino acid proline, while AGC codes for serine • Remember amino acids are the building blocks of protein! • So proteins are just long chains of amino acids

  16. Why Proteins? • Proteins are found throughout the cell and act as chemical messengers • These proteins “express” the directions found in your genes • i.e your height, eye color, etc. • Human cells contain about 100,000 genes • The human body contains 50,000 different proteins • Proteins are the reason for the multitude of different shapes, sizes, colors, and textures found in living things

  17. The Making of a Protein • The first step in making a protein is to copy the section of the DNA containing a gene • Remember that the DNA has to unwind and unzip • A copy of this section is made with the help of copier enzymes (RNA polymerase) • The gene is copied into mRNA • m = messenger • Remember RNA has U (uracil) instead of T (thymine) • This “message” leaves the nucleus, enters the cytoplasm, and is fed through a ribosome • Ribosomes - are the “factory” where proteins are made out of amino acids

  18. The mRNA fed through the ribosome 3 bases at a time • Codons - are sections of 3 bases in a row, that “code” for a specific amino acid • There are 20 different amino acids • As codons are read by the ribosome, a tRNA molecule brings the correct amino acid to the ribosome • t = transfer • The amino acids continue to be “hooked” together until the ribosome reads a stop codon (UGA, UAG, or UAA) • The protein is now finished and will be transported by the Golgi or Rough ER and be sent to the right place to do it’s job

  19. Change in Genes • Mutations - mistakes or changes to the order of bases in DNA • Deletion - when a base is left out • Insertion - when an extra base is added • Substitution - when an incorrect base replaces a correct base • This is the most common type of error (I will ask this on the exam) • Fortunately repair enzymes are continuously on patrol checking for errors • Occasionally repairs are not made and the mistake becomes a permanent part of the genetic message (DNA)

  20. Differences Between RNA & DNA

  21. An Example of Substitution • ACT CCT GAA GAA AAA • UGA GGA CUU CUU UUUThr - Pro - Glu - Glu - Lys • Substitution • ACT CCT GTA GAA AAA • UGA GGA CAU CUU UUU • Thr - Pro - Val - Glu -Lys • An example of a simple change like this can lead to dramatic changes in an organism • Sickle Cell anemia is caused this way

  22. Mistakes Happen and How Does DNA Get Damaged? • There are 3 possible consequences to changes in DNA • 1) an improvement to an organism • 2) no change at all • 3) harmful or deadly change • If a change happens to a sex cell, the change can be passed on to the offspring • Mutagens - physical or chemical agents that cause mutations

  23. Genetic Counseling • Most genetic conditions are recessive disorders (ss) • That means both parents pass the gene on to their offspring • Carrier - A person who carries the recessive gene, but does not have the condition (Ss) • Pedigree - is a tool used by genetic counselors for tracing a trait through generations of a family • On a pedigree circles represent females, squares represent males • Empty circles or squares = not affected/non carrier • Half circles or squares = not affected/carrier • Full circles or squares = affected/carrier

  24. Chapter 7 Quiz 2 • 1)_____________ the “factory” (organelle) where amino acids are assembled into proteins • 2) ____________ are any mistakes in DNA • 3) ____________ a physical or chemical agent that can cause damage (mutation) to DNA • 4) ____________ is copied from DNA and carries the genetic message (of a gene) to the protein factory • 5) ____________ is a tool used by a genetic counselor to help trace a trait through generations • Bonus) ___________ is when you place a gene from another organism into the DNA of a different organism

  25. Section 3 - Applied Genetics • Humans have been aware of the benefits of selective breeding for thousands of years • Selective Breeding - is when humans choose idealistic traits in other organisms, and breed those organisms together • Genetic Engineering when scientists transfer the genes from one organism to another organism • Genetic engineering is already being used to some extent • Examples include; Dolly, disease resistant plants, repairing damaged genes

  26. Living Factories • The bases, in DNA, are the same in every living organism • This “sameness” allows the genes from one organism to be placed in another organism using genetic engineering • Recombinant DNA - the type of DNA that results from placing a gene from one organism into the DNA of another (bacteria) • Recombinant DNA can be used to produce insulin in large amounts • How is this done???????? (see page 166)

  27. Chapter 7 Quiz 3 • This field of science allows scientists to transfer genes from one organism to another organism ____________ • The resulting DNA from placing a gene of one organism into another is called? • __________ is when you compare DNA fragments, from different samples, to each other • ______________ is the project where scientists “decoded” every gene and chromosome in human DNA • Bonus: Take the following DNA strand and turn it into RNA, TAC CCG GGA TAT CAG

  28. DNA Fingerprints • DNA Fingerprinting - when you compare DNA fragments from different individuals, with a known DNA sample • In the laboratory DNA can be separated based on its size

More Related