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Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Structure of DNA Nucleic acid Subunits = nucleotides In DNA 5 carbon sugar = deoxyribose.

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Presentation on theme: "Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Structure of DNA Nucleic acid Subunits = nucleotides In DNA 5 carbon sugar = deoxyribose."— Presentation transcript:

1 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Structure of DNA Nucleic acid Subunits = nucleotides In DNA 5 carbon sugar = deoxyribose Phosphate group Nitrogenous base – Adenine, guanine, cytosine, thymine Bonds between sugar and phosphate group - backbone

2 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Double-helix model Antiparallel strands Run in opposite directions Allows bases to touch Hydrogen bonds Weak Between specific bases Base pairing Only certain bases bond A to T C to G Together 2 bases = base pair

3 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis What does DNA do? Makes more DNA Makes RNA – Makes proteins Building blocks of life

4 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis DNA 5-carbon sugar – deoxyribose Phosphate group Bases: A, C, G, T Double-stranded “Master plan” Stays in nucleus RNA 5-carbon sugar – ribose Phosphate group Bases: A, C, G, U Single-stranded “Blueprints” Made in nucleus, but used in cytoplasm

5 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Role of RNA Disposable copy of DNA Makes proteins from amino acids Types – Messenger (mRNA) Instructions for assembly Brings info. from nucleus to rest of cell – Ribosomal (rRNA) Several with proteins make ribosomes Where proteins are assembled – Transfer (tRNA) Carries amino acids to ribosomes Specific for an amino acid

6 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis RNA Synthesis Transcription – DNA made into RNA – Occurs in nucleus RNA polymerase – Binds to a promotor region Specific base sequence on DNA – Separates DNA strands – Uses one strand as a template – Attaches complementary bases Except no T – Until it reaches a “stop” sequence Creates pre-mRNA

7 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis RNA Editing A lot of “useless” bases in our DNA that ends up in the RNA – Introns – Enzymes cut these sections out – Recent research Leaves exons – Information used Creates mRNA – Leaves the nucleus

8 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Genetic Code Bases are read in sets of 3 = codon – Represents a specific amino acid – Some amino acids have more than one codon Start and stop codons – “Punctuation” – Start = AUG = methionine – 3 different stop codons No amino acid, just stops

9 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis

10 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Translation mRNA leaves nucleus Attaches to a ribosome “Reads” codons tRNA – Has anticodon sequence – Complementary to codon sequence – Brings in specific amino acid Ribosome moves to next codon New tRNA comes in – Amino acids bond – Old tRNA leaves – Ribosome moves to next codon….

11 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Keeps adding amino acids Forming polypeptide bonds Reaches stop codon – No amino acid added – Translation stops – Polypeptide chain released Further folding to form protein Other products recycled and reused

12 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis

13 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis

14 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Central Dogma – How do Genes Work? DNA (genes)  RNA  proteins Viruses different – RNA  DNA Genetic code is universal – Same bases – Read as codons – Codons = same amino acids

15 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Mutations Mistakes – Often caught/fixed by enzymes – Occasionally “slip” through – Passed on to offspring of that cell Point mutations – Substitution Frameshift mutations – Insertion – Deletion THE FAT CAT ATE HIS HAT THE SFA TCA TAT EHI SHA THE FAT ATA THE ISH

16 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Chromosomal Mutations Change number of structure of chromosomes More DNA/genes involved Deletion Duplication Inversion Translocation

17 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Cause Mutations Random – Accumulate over time Mutagens – Chemical – Physical – Interfere with base-pairing – Weaken DNA

18 Lesson Overview Lesson Overview Ribosomes and Protein Synthesis Helpful vs. Harmful Most are neutral Create genetic variation Harmful – Change protein structure – Change gene activity – Disrupt normal activities – Examples Cancers Sickle cell disease Beneficial – New trait is helpful for survival – Pesticide resistance – Increase human bone strength and density – Resistance to HIV – Polyploidy Larger, stronger, seedless plants


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