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DNA Chapter 10.

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Presentation on theme: "DNA Chapter 10."— Presentation transcript:

1 DNA Chapter 10

2 10.1 Discovery of DNA Griffith’s Experiments (1928)
Griffith’s experiments showed that hereditary material can pass from one bacterial cell to another. The transfer of genetic material to one cell from another cell or from one organism to another organism is called transformation.

3 Page 194

4 Avery’s Experiments (1940’s)
Avery’s work showed that DNA was the heredity material that transfers information between bacterial cells.

5 Hershery-Chase Experiment
Hershey and Chase confirmed that DNA, and not protein, is the hereditary material. Page 195

6 Structure of DNA 10.2

7 DNA – The Blueprint of Life
Established by James Watson and Francis Crick (1950’s) DNA contains the instructions for making proteins within the cell. Shape of a double helix Made up of repeating sub-units called nucleotides

8 DNA codes for genes Gene - A segment of DNA that codes for a protein, which in turn codes for a trait (skin tone, eye color…etc.), a gene is a stretch of DNA.

9 Deoxyribonucleic acid - DNA
Monomer: nucleotides Each nucleotides has: Deoxyribose sugar Phosphate group (1 of 4) nitrogen containing base

10 The 4 Bases in DNA are: Thymine (T) Cytosine (C) Guanine (G)
Adenine (A)

11 Nitrogen Rings Purines have double rings of carbon-nitrogen (G, A)
Pyrimidines have single carbon-nitrogen rings (C, T)


13 Complementary Base Pairing
Base Pairing Rules 1. C and G 2. T and A

14 How do the nitrogenous bases stick together?
Hydrogen bonds! 3 H bonds hold G & C together 2 H bonds hold T & A together

15 DNA Replication 10.3 Occurs when chromosomes duplicate before mitosis & meiosis Makes an exact copy of the DNA H bonds between bases break and enzymes “unzip” the molecule

16 Steps of DNA Replication (pg. 201)
Enzymes called helicases separate the DNA strand breaking the H bonds at the replication fork Enzymes called DNA polymerase add complementary nucleotides DNA polymerase falls off when done replicating and the result is an identical strand of DNA


18 Semi-conservative replication- Each old strand of nucleotides serves as a template for each new strand.

19 Another View of Replication
Use of the ladder configuration better illustrates how complementary nucleotides available in the cell pair with those of each old strand before they are joined together to form a daughter strand.

20 Mutation A change in the nucleotide sequence of a DNA molecule.
DNA proofreading and repair prevent many replication errors. Unrepaired mutations that affect genes that control cell division can cause diseases such as cancer.

21 Protein Synthesis 10.4 The Central Dogma: the flow of genetic information from DNA to RNA to Protein

22 Protein Synthesis 2 Parts
Transcription – makes a RNA molecule complementary to a portion of DNA. Translation – occurs when the sequences of bases of mRNA directs the sequence of amino acids in a polypeptide.

23 RNA Ribonucleic Acid 2nd type of nucleic acid Monomer = nucleotide
Ribose sugar 1 of 4 N bases Phosphate group

24 N-bases: A, G, C, & U Uracil replaces Thymine
Base pairing rules: A-U, G-C Purpose: to transfer genetic material from DNA (inside the nucleus) to the site of protein synthesis (in the cytoplasm)

25 How does RNA differ from DNA?
Different sugars (deoxyribose vs. ribose) Different N-bases (thymine vs. uracil) Different shapes (double helix vs. single strand)

26 Types of RNA: Messenger RNA (mRNA): Transfer RNA (tRNA):
Carries genetic info from the nucleus to the cytoplasm Transfer RNA (tRNA): Carries specific amino acids to the ribosome to build the protein Ribosomal RNA (rRNA): Major component of the ribosome organelle Site of protein synthesis Most abundant type of RNA

27 3 Types of RNA

28 Notebook Quiz 1. Outline the flow of genetic material in cells.
List the 3 parts of a nucleotide. What role does helicase and DNA polymerase play in DNA replication? a. Write the complementary strand of DNA to the DNA template below… b. Write the complementary strand of RNA to the DNA template below… G A T T A C A T C C G A C T A C 5. What is the purpose of RNA? 6. List 2 differences between DNA and RNA (be specific).

29 How is RNA made? Transcription
The process by which RNA is copied from DNA in the nucleus

30 Steps of Transcription:
RNA polymerase binds to the promoter section of DNA DNA unwinds and separates RNA polymerase adds nucleotides complimentary to the DNA template strand Process ends once RNA polymerase reaches the termination signal on the DNA

31 Definitions: RNA polymerase: enzyme use to make an RNA polymer from DNA Promoter: Starting point on DNA DNA template: Strand of DNA that RNA is complementary to (create from) Termination signal: Ending point on DNA





36 Products of Transcription:
mRNA, tRNA, & rRNA All products move out of the nucleus and go into the cytoplasm to be used in protein synthesis DNA  RNA mRNA tRNA rRNA

37 Proteins carry out the genetic instruction in DNA
Protein Synthesis: The making of proteins at the ribosome The amount and kind of proteins produced in a cell determine its structure & function Proteins carry out the genetic instruction in DNA

38 Protein Review: Monomer = amino acids 20 different types
Linked together by peptide bonds Sequence of amino acids determines the proteins structure and function

39 The Genetic Code: The correlation between nucleotide sequence (DNA or RNA) and amino acid sequence (protein) Codons: combination of 3 mRNA nucleotides that code for a specific amino acid


41 Types of codons: 64 codons code for 20 amino acids
Thus more than one codon codes for an AA Start codon: (AUG) starts the process of translation Stop codons: (UAA, UAG, UGA) ends the process of translation


43 Circular Genetic Code

44 Translation: The process of assembling polypeptides (proteins) from nucleotide sequence in mRNA “Translating” from one language (nucleotides) into another language (amino acids)

45 Steps of Translation Initiation: mRNA binds to the ribosome and the tRNA carrying methionine binds to the start codon Elongation: as mRNA codons move through the ribosome, tRNA’s add specific amino acids to the growing polypeptide chain Termination and Disassebly: the process continues until a stop codon is reached and the newly made protein is released







52 So what is the Central Dogma?
The flow from DNA to RNA to Protein

53 Notebook Quiz What type of RNA is pictured here? What is its function?
List the 4 bases in RNA? What is the function of mRNA? Define translation. Where are proteins assembled in the cell? Describe the flow of genetic material in the cell. In other words, how do cells make proteins?

54 #1) T A C C G G A T G C C A G A T C A A A T C

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