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Ch. 5: DNA and Modern Genetics!! “The Molecule of Life”

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Presentation on theme: "Ch. 5: DNA and Modern Genetics!! “The Molecule of Life”"— Presentation transcript:

1 Ch. 5: DNA and Modern Genetics!! “The Molecule of Life”

2 Do Now!!  What is DNA?  Why is it important?  List three places in the body where you can find DNA.  What is DNA?  Why is it important?  List three places in the body where you can find DNA.

3 Objectives  To explain the structure of DNA  To identify the different types of bases how they pair up  To list the scientists involved in discovering DNA  To explain the structure of DNA  To identify the different types of bases how they pair up  To list the scientists involved in discovering DNA

4 So what is DNA?  A molecule that stores information  What do the letters stand for?  D EOXYRIBO N UCLEIC A CID  Where is it found?  In the nucleus (or nuclear region in prokaryotes)  What is it used for?  Blueprints of your genes/traits  To make proteins!  A molecule that stores information  What do the letters stand for?  D EOXYRIBO N UCLEIC A CID  Where is it found?  In the nucleus (or nuclear region in prokaryotes)  What is it used for?  Blueprints of your genes/traits  To make proteins!

5 What is DNA Made of?  Repeating units of nucleotides  Nucleotides are made of 3 components :  5 carbon sugar (Deoxyribose)  Phosphate Group  Nitrogenous base  Repeating units of nucleotides  Nucleotides are made of 3 components :  5 carbon sugar (Deoxyribose)  Phosphate Group  Nitrogenous base

6 Nitrogenous Bases  Purines  Have 2 rings (double ring structure) a.Adenine (A) b.Guanine (G)  Pyrimidines  Have 1 ring (single ring structure) a.Thymine (T) b.Cytosine (C) c. Uracil (U) instead of Thymine in RNA

7 Nitrogenous Bases

8 Chargaff’s Rule  Erwin Chargaff  Discovered that A pairs with T and C pairs with G.  Chargaff’s rule:  A=T, C=G  Amounts vary between species  Erwin Chargaff  Discovered that A pairs with T and C pairs with G.  Chargaff’s rule:  A=T, C=G  Amounts vary between species

9 What is the complimentary sequence?? ATGCTAATTCGCATCG

10 Do Now!  What makes up a nucleotide?  What is the difference between a purine and a pyrimidine? Identify the purines and pyrimidines we talked about!  Please write the complementary sequence: TGACCAGTTTAGCTAGGGC  What makes up a nucleotide?  What is the difference between a purine and a pyrimidine? Identify the purines and pyrimidines we talked about!  Please write the complementary sequence: TGACCAGTTTAGCTAGGGC

11 Objectives  To identify the scientists who contributed to the discovery of DNA  To define the structure of DNA  To complete a DNA structure worksheet  To identify the scientists who contributed to the discovery of DNA  To define the structure of DNA  To complete a DNA structure worksheet

12 Rosalind Franklin  Used X-ray diffraction to determine shape of DNA  X-ray diffraction:  X-rays aimed at molecule, bounce off electrons  Determines the molecule’s shape  Used X-ray diffraction to determine shape of DNA  X-ray diffraction:  X-rays aimed at molecule, bounce off electrons  Determines the molecule’s shape

13 Rosalind Franklin  Took now famous photo 51  Data indicated that DNA was a double helix shape  Helped Watson and Crick solve the structure of DNA  Took now famous photo 51  Data indicated that DNA was a double helix shape  Helped Watson and Crick solve the structure of DNA

14 Watson and Crick  Built a model of the double helix DNA molecule:  two outside strands consist of alternating sugar and phosphate molecules  thymine and adenine bases pair to each other by two hydrogen bonds  cytosine and guanine bases pair to each other by three hydrogen bonds *Go back to your DNA sequence!

15 DNA Structure  DNA looks like a twisted ladder!  Rails: alternating deoxyribose sugars and phosphates  Rungs (steps): base pairs (C-G, A-T) bonded by hydrogen bonds  DNA looks like a twisted ladder!  Rails: alternating deoxyribose sugars and phosphates  Rungs (steps): base pairs (C-G, A-T) bonded by hydrogen bonds

16 Do Now! Label the parts of the DNA! A B C D

17 Objectives  To review DNA structure  To define DNA replication  To identify the steps of DNA replication  To review DNA structure  To define DNA replication  To identify the steps of DNA replication

18 DNA Replication  Allows cells to get an exact copy of DNA.  Replication:  Parent strands separate, serve as templates  Daughter DNA produced (have one DNA strand from parent and one new strand)  Allows cells to get an exact copy of DNA.  Replication:  Parent strands separate, serve as templates  Daughter DNA produced (have one DNA strand from parent and one new strand)

19 Steps to Replication  1- The two DNA strands unwind and separate:  Helicase- enzyme that separates the DNA molecule  1- The two DNA strands unwind and separate:  Helicase- enzyme that separates the DNA molecule

20 Steps to Replication o 2- Nucleotides match up base by base with the nucleotides on each TEMPLATE DNA strand:  All of the C’s pair with the G’s and all of the A’s pair with the T’s.  DNA Polymerase: enzyme that creates new DNA by assembling nucleotides

21 Steps to Replication  3- Each new daughter DNA molecule has one strand of new DNA and one from the original parent strand.

22 Replication Animation!  iew0/chapter3/animation__dna_replication__quiz_1_.html iew0/chapter3/animation__dna_replication__quiz_1_.html  iew0/chapter3/animation__dna_replication__quiz_1_.html iew0/chapter3/animation__dna_replication__quiz_1_.html

23 Do Now!!  Please complete the worksheet in front of you!

24 Objectives  To define RNA  To identify the different types of RNA  To define transcription and translation  To define RNA  To identify the different types of RNA  To define transcription and translation

25 So why do we NEED DNA??

26 We need to make RNA to make proteins!!  What is RNA?  Ribonucleic Acid  How is it different from DNA?  Single stranded  Indefinite shape  Uses “uracil”  Contains Ribose  What is RNA?  Ribonucleic Acid  How is it different from DNA?  Single stranded  Indefinite shape  Uses “uracil”  Contains Ribose

27 Types of RNA  Linear  Located in both the nucleus and the cytoplasm  Brings genetic code from DNA to the ribosome to make protein (in cytoplasm)  Contains codons (every 3 letters, ex. AUG is 1 codon) 1. M essenger RNA ( m RNA):

28 Types of RNA  2. R ibosomal ( r RNA):  Located within the ribosome  Helps make the structure of the ribosome  2. R ibosomal ( r RNA):  Located within the ribosome  Helps make the structure of the ribosome

29 Types of RNA  3. T ransfer ( t RNA)  Located in the cytoplasm  Clover-like loop structure  Brings amino acids (attached to top of tRNA) to ribosome to help build proteins  Contains anticodon (3 letter sequence at bottom of tRNA, complements codon)  3. T ransfer ( t RNA)  Located in the cytoplasm  Clover-like loop structure  Brings amino acids (attached to top of tRNA) to ribosome to help build proteins  Contains anticodon (3 letter sequence at bottom of tRNA, complements codon)

30 The Central Dogma!  DNA RNA Protein  Transcription:  Occurs in nucleus  Create (transcribe) mRNA from DNA template  Translation:  Occurs in cytoplasm  Takes mRNA and makes proteins with the help of tRNA and ribosomes.  DNA RNA Protein  Transcription:  Occurs in nucleus  Create (transcribe) mRNA from DNA template  Translation:  Occurs in cytoplasm  Takes mRNA and makes proteins with the help of tRNA and ribosomes.

31 Do Now!! o Please take out your worksheet from last class and finish!

32 Objectives  To identify the steps of transcription.  To understand the process of transcription and how mRNA is made.  To identify the steps of transcription.  To understand the process of transcription and how mRNA is made.

33 Transcription o Gene: a distinct sequence of nucleotides o Determines your traits o Only individual genes are transcribed, not a whole DNA molecule o Occurs in the nucleus o Produces mRNA o Gene: a distinct sequence of nucleotides o Determines your traits o Only individual genes are transcribed, not a whole DNA molecule o Occurs in the nucleus o Produces mRNA

34 Transcription  Step 1: DNA molecule unwinds and separates just like in replication:  RNA polymerase: enzyme that unwinds the DNA and assembles new nucleotides (makes RNA strand).  Step 1: DNA molecule unwinds and separates just like in replication:  RNA polymerase: enzyme that unwinds the DNA and assembles new nucleotides (makes RNA strand).

35 Transcription  Step 2: RNA nucleotides match up with their complimentary bases on the DNA template strand:  RNA polymerase assembles these nucleotides  Creates a single stranded mRNA molecule  Practice: Write the complimentary mRNA strand from this DNA  ATCGATGGCAAGCTA  Step 2: RNA nucleotides match up with their complimentary bases on the DNA template strand:  RNA polymerase assembles these nucleotides  Creates a single stranded mRNA molecule  Practice: Write the complimentary mRNA strand from this DNA  ATCGATGGCAAGCTA

36 Transcription  Step 3: mRNA detaches once entire gene is done and DNA rewinds:  mRNA strand leaves nucleus through pores  Goes to cytoplasm to help ribosomes make proteins  *Delivers directions from DNA for how to make proteins  Step 3: mRNA detaches once entire gene is done and DNA rewinds:  mRNA strand leaves nucleus through pores  Goes to cytoplasm to help ribosomes make proteins  *Delivers directions from DNA for how to make proteins *Many copies of RNA can be made from the same gene in a short period of time.

37 Transcription Video  

38 Do Now!!  With a partner, please complete the worksheet in front of you!

39 Do Now!!  What is the “Central Dogma”?  What is transcription?  Please transcribe the DNA sequence below: T A C C G A A T C G T A C G G A C T  What is the “Central Dogma”?  What is transcription?  Please transcribe the DNA sequence below: T A C C G A A T C G T A C G G A C T

40 Objectives  To define translation  To identify the steps of translation  To practice building amino acid sequences to form proteins  To define translation  To identify the steps of translation  To practice building amino acid sequences to form proteins

41 Translation  What happens in the steps before translation?  What happens in translation?  Where does this happen?  What happens in the steps before translation?  What happens in translation?  Where does this happen?

42 Translation  Step 1: Translation begins when a ribosome attaches to the beginning of an mRNA molecule.  *Translation MUST START AT THE LETTERS “AUG”:  This is the START codon  * Every 3 letters on the mRNA is called a “ Codon ” that codes for a specific amino acid.

43 CODON BINGO!!

44 Do Now!!  What is translation?  Where does translation take place?  Write the amino acid sequence this mRNA strand would form: A U G C G G C U A A U U  What is translation?  Where does translation take place?  Write the amino acid sequence this mRNA strand would form: A U G C G G C U A A U U

45 Objectives  To identify the steps of translation  To practice the process of protein synthesis  To identify the steps of translation  To practice the process of protein synthesis

46 Translation  Step 2: A tRNA molecule carrying an amino acid matches up to a complementary codon in the mRNA on the ribosome:  *tRNA molecules contain “ Anticodons” which are 3 bases on bottom of tRNA  Anticodons compliment codons on mRNA

47 Translation  Step 3: The ribosome attaches one amino acid to another as it moves along the mRNA molecule.  Amino acids are attached by PEPTIDE BONDS.

48 Translation  Step 4: The tRNA molecules are released after the amino acids they carry are attached to the growing chain of amino acids.  Return to cytoplasm to pick up another amino acid  Step 4: The tRNA molecules are released after the amino acids they carry are attached to the growing chain of amino acids.  Return to cytoplasm to pick up another amino acid

49 Translation  Step 5: The ribosome completes the translation when it reaches a stop codon:  The newly made protein is then released.  Step 5: The ribosome completes the translation when it reaches a stop codon:  The newly made protein is then released.

50 Do Now!!  Please complete the worksheet in front of you!

51 Objectives  To define genetic mutation  To identify the different types of genetic mutations  To define genetic mutation  To identify the different types of genetic mutations

52 What is a mutation?  Mutation: a permanent change in a cell’s DNA  Errors can occur when DNA is copied  UV light, X-rays, chemicals, etc. can cause mutations in DNA  Mutation: a permanent change in a cell’s DNA  Errors can occur when DNA is copied  UV light, X-rays, chemicals, etc. can cause mutations in DNA

53 Types of mutations  Substitution – Exchanges one base for another.  Normal: ACAG A G  Mutated: ACAG G G  Insertion – Extra base pairs are inserted.  Normal: AATGAG  Mutated: AATG TGG AG  Substitution – Exchanges one base for another.  Normal: ACAG A G  Mutated: ACAG G G  Insertion – Extra base pairs are inserted.  Normal: AATGAG  Mutated: AATG TGG AG

54 Types of mutations (cont.)  Deletion - Section of DNA is lost or deleted.  Normal: CTGGAG  Mutated: CT___AG  Frameshift- Message is no longer read correctly.  Normal: THE FAT CAT ATE THE BIG RAT  Mutated: HEF ATC ATA TET HEB IGR AT  Deletion - Section of DNA is lost or deleted.  Normal: CTGGAG  Mutated: CT___AG  Frameshift- Message is no longer read correctly.  Normal: THE FAT CAT ATE THE BIG RAT  Mutated: HEF ATC ATA TET HEB IGR AT

55  Cells have different ways to repair mistakes:  Proofreading enzymes can correct mismatched base pairs  EX: DNA polymerase, exonuclease What happens when there is a mutation?

56 Do Now!!  What are the three kinds of mutations?  What is a frameshift?  Are all mutations bad?  What are the three kinds of mutations?  What is a frameshift?  Are all mutations bad?

57 Objectives  To discuss the effects of genetic mutations on protein synthesis  To complete a review protein synthesis worksheet  To simulate genetic mutations in a lab activity  To discuss the effects of genetic mutations on protein synthesis  To complete a review protein synthesis worksheet  To simulate genetic mutations in a lab activity

58 Mutations can have different effects 1.The mutation has no effect: o Amino acids have more than 1 code 2.The effect of a mutation is minor: o Could affect skin/eye/hair pigmentation 3.The effect of a mutation is great: o Genetic disorder/disease 1.The mutation has no effect: o Amino acids have more than 1 code 2.The effect of a mutation is minor: o Could affect skin/eye/hair pigmentation 3.The effect of a mutation is great: o Genetic disorder/disease

59 Genetic disorders  Sometimes passed from parents to offspring:  Sickle Cell Anemia  Cystic Fibrosis (CF)  Hemophilia  Tay- Sachs Disease  Huntington’s Disease (HD)  Cancer  Sometimes passed from parents to offspring:  Sickle Cell Anemia  Cystic Fibrosis (CF)  Hemophilia  Tay- Sachs Disease  Huntington’s Disease (HD)  Cancer

60  Mutation occurs on gene that codes for hemoglobin:  Hemoglobin – a protein that carries oxygen in red blood cells  Substitution mutation causes 1 amino acid to be replaced with another Sickle cell anemia


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