1 MUTATIONS
2 Chromosome Review… In normal diploid organisms, two copies of each chromosome are present in every somatic (body) cell (2n) One from mom, one from dad The last set are the sex chromosomes These may or may not be homologous Polyploid cells have multiple copies of one or more chromosome pairs Tri-somy 21 (Down’s Syndrome) Klinefelter’s Syndrome (XXY) Monoploid cells have one or more unpaired chromosomes Turner’s Syndrome (X)
3 2 chromatids make up 1 chromosomeEach autosome chromosome is paired with it’s homologous mate The 23rd pair is the sex chromosomes. XX=Female XY=Male Normally: 46 total (23 pairs)
4 Chromosome Number Many different disorders which are caused by polyploidy or monoploidy YOU have to know 3! Down’s Syndrome (Tri-somy 21) Klinefelter’s Syndrome Turner’s Syndrome
5 Down’s Syndrome
6 Klinefelter’s Syndrome
7 Turner’s Syndrome
8 Duplication (Amplification)Gene Mutations Occur within a chromosome/chromatid: Point Mutation Insertion Deletion Duplication (Amplification) Inversion Translocation
9 Point Mutation Substitution (Point Mutation) THE FAT CAT ATE THE RATTHE FAT CAT ATE THE HAT MAY screw up one amino acid
10 Insertion Insertion THE FAT CAT ATE THE RAT THE FAT CAT XAT ETH ERA T
11 Deletion Deletion THE FAT CAT ATE THE RAT THE FAT ATA TET HER AT
12 Duplication (Amplification)
13 Inversion
14 Translocation
15 What Causes Mutations? There are many ways in which DNA can become mutated Nature! When DNA is copied When Chromosomes separate in anaphase Mutagenic Agents Radiation Chemicals Ultra Violet Light Cigarettes Viruses & Bacteria
16 Can Mutations be Inherited?Yes and No! For a Mutation to be inherited, it must be in a gamete Egg or Sperm If it’s in an autosomal cell, it is not heritable! I cannot give my baby skin cancer… I can give my baby Down Syndrome (tri-somy 21 is due to non- disjunction in the gamete)
17 Then what?????? So, there’s a mutation in the DNA… Then what? So what?Here’s where we start to tie ALLLLLLLL sorts of stuff together!
18 PROTEIN SYNTHESIS
19 DNA & RNA DNA is the Master Plan…The “Recipe Book” made up of nucleotides DNA cannot leave the nucleus Double stranded – too big! mRNA is a copy of the DNA message Single stranded – just right! RNA travels to the Ribosome The Ribosome reads 3 Nucleotides at a time Codon The Codon “codes” for a specific amino acid tRNA brings the amino acid to the ribosome So, the sequence of the DNA nucleotides determines the sequence of the amino acids!
20 DNA-Deoxyribonucleic AcidDNA makes up genes Sequences of nucleotide bases Remember nucleotides??? Sun-House-Pool? Genes code for polypeptides (proteins) Proteins are used to build cells and do much of the work inside cells Proteins make YOU…YOU!
21 Genes & Proteins Proteins are made of amino acids linked together by peptide bonds (aka polypeptides) Remember? Amino Acids are the monomer of Proteins… They resemble a butterfly 20 different amino acids exist
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23 DNA Begins the Process DNA is found inside the nucleusDNA is the instruction booklet for making every Protein the cell needs Proteins, however, are made in the cytoplasm of cells by ribosomes Ribosomes may be free in the cytoplasm (cytosol) or attached to the surface of rough ER Both are Outside of the Nucleus!
24 Start with DNA DNA‘s code (message) must be copied and taken out of the nucleus mRNA is the copy that leaves the nucleus In the cytoplasm, this code must be read so amino acids can be bonded together to make the correct polypeptides (proteins) This entire process is called PROTEIN SYNTHESIS
25 Roles of DNA and RNA DNA is the MASTER PLAN – the Entire Cook BookRNA is the BLUEPRINT of a portion of the Master Plan – the Recipe to be Made
26 RNA Differs from DNA – Remember?RNA has a sugar ribose DNA has a sugar deoxyribose
27 Other Differences RNA contains the base uracil (U) DNA has thymine (T)RNA is small and single-stranded DNA is large and is double-stranded Double Helix
28 Structure of RNA Like DNA, RNA is a polymer of nucleotides. In an RNA nucleotide, the sugar ribose is attached to a phosphate molecule and to a base, either G, U, A, or C. Notice that in RNA, the base uracil replaces thymine as one of the pyrimidine bases. RNA is single-stranded, whereas DNA is double-stranded.
29 Three Types of RNA . Messenger RNA (mRNA) - copies DNA code & carries the genetic information to the ribosomes Ribosomal RNA (rRNA) - makes up the ribosomes Transfer RNA (tRNA) - transfers amino acids to the ribosomes where proteins are synthesized You only need to know mRNA and tRNA
30 TRANSCRIPTION & TRANSLATIONTwo Steps… TRANSCRIPTION & TRANSLATION
31 Transcription Copy Messenger RNA (mRNA)Transcription happens in the Nucleus DNA unzips & unwinds mRNA copies the DNA code & leaves through nuclear pores mRNA Contains the Nitrogen Bases A, G, C, U ( no T )
32 Transcription (Copy) Happens in the NucleusDNA unzips & unwinds Enzyme RNA Polymerase begins the process of making mRNA The unpaired DNA nucleotides are used as a template for mRNA
33 Transcription - Messenger RNA (mRNA)Inside the nucleus – complementary mRNA nucleotides are paired up with the DNA template This makes a copy of the DNA sequence to make a specific protein mRNA carries the information for the protein out of the nucleus to find a ribosome
34 Remember the Complementary Bases?On DNA: A-T C-G On RNA: A-U All Thugs Carry Guns All Underachievers Can’t Graduate
35 Transcription ExampleDNA sequence: TAC GGA CAT AAC ACC TGC ATC mRNA sequence AUG CCU GUA UUG UGG ACG UAG Every point where DNA has the nucleotide Adenine (A) mRNA matches it with Uracil (U) Why? So our body knows which is the original template (DNA) and which is the transcribed copy (mRNA)
36 mRNA carries the messagemRNA carries the information for the protein out of the nucleus through the pores in the nuclear membrane
37 mRNA finds a Ribosome In the cytoplasm, the mRNA locates a ribosome so the message can be translated and the protein made Remember – Ribosomes are the site of protein synthesis!
38 Translation – Happens at the RibosomemRNA brings the transcribed (copied) message to the Ribosome (in the Cytoplasm) The Ribosome reads the mRNA nucleotide sequence 3 bases at a time (called a codon) tRNA brings the correct amino acid to the Ribosome based on the codons tRNA has an “anti-codon” based on complementary base pairing All Underachievers Can’t Graduate!
39 Translation - Transfer RNA (tRNA)Clover-leaf shape Molecule with an attachment site at one end for a specific amino acid Opposite end has three nucleotide bases called the anticodon Which pair with the codon on the mRNA Acts like a “taxi” for the amino acid
40 Transfer RNA MET amino acid attachment site U A C anticodon Translates the nucleotide language into an amino acid language To create a polypeptide
41 Codons and Anticodons The 3 bases of an anticodon are complementary to the 3 bases of a codon on the mRNA Example: Codon ACU Anticodon UGA U G A A C U
42 This is Translation The Ribosome reads the codons… tRNA taxis over the correct amino acids
43 The Genetic Code A codon (3 nucleotides) calls for a specific amino acid An amino acid may have more than one codon There are 20 amino acids, but 64 possible codons Some codons tell the ribosome to start and stop translating AUG – methionine - start codon UAA, UAG, or UGA – stop codons
44 The Universal mRNA Codon ChartHow do WE know which amino acid is correct? Use the codon chart! Start with the first base Move to the second base… Finish with the third!
45 The Genetic Code You can use this codon chart too!But, the Regents likes the first one… Read from the center to the outside Example: AUG codes for Methionine (the “start” codon)
46 Name the Amino Acids CCC? _________ UGA? _________ CAC? _________GCA? _________ AGA? _________ CGU? _________
47 Name the Amino Acids GGG? _________ UCA? _________ CAU? _________GCA? _________ AAA? _________ CGG? _________
48 What do these codons have to do with proteins?Each codon represents an amino acid that will be bonded together to form a protein Proteins are made of hundreds of amino acids in a specific sequence When they get “out of order” a mutation occurs Long string of amino acids will form
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