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Semester 2, Day 8

Semester 2, Day 8. Cell Specialization and Gene Expression. Agenda. Review Central Dogma Turn in HW (Packets 11.4-11.5) Quiz on Central Dogma Lecture on Cell Specialization and Mutations Reading/Work Time. Review. What is the definition and diagram of the central dogma?

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Semester 2, Day 8

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  1. Semester 2, Day 8 Cell Specialization and Gene Expression

  2. Agenda • Review Central Dogma • Turn in HW (Packets 11.4-11.5) • Quiz on Central Dogma • Lecture on Cell Specialization and Mutations • Reading/Work Time

  3. Review • What is the definition and diagram of the central dogma? • What are the roles of DNA, RNA and protein in the central dogma? • What is the first “step” of the central dogma? Know the steps! • What is the second “step” of the central dogma? Know the steps! • What is a codon? Be able to use scientific language! • Which amino acid do all proteins begin with? (Hint: look at the genetic code chart) • If given a strand of DNA, can you determine what the mRNA strand should be? (Hint: don’t use T, use U!) • With that mRNA strand, be able to use the genetic code chart to determine the chain of amino acids. (Remember: which amino acid comes first???)

  4. Homework Due • Annotate the packet • Sections 11.4-11.5 • Do all concept checks • Chapter 11 Review • #3-6, 12, 14, 15, 19, 20, 22-24

  5. Cell Specialization & Gene Expression • We have 100 trillion cells, but they don’t all look the same (200 types): Epithelial (Skin) Cells Red Blood Cells Neuron Cell Sperm Cell Muscle Cell

  6. Cell Specialization & Gene Expression • All of these cells contain the same exact copy of DNA (except sperm), BUT: Definitions **Gene: a portion of DNA that codes for a protein **Gene Expression: the proteins formed by the decoding of specific genes in a cell Same DNA, but only some genes are expressed Image Source: questgarden.com

  7. Cell Specialization & Gene Expression • Zygote: first cell of an organism Morula (16-64 cells) Day 0 All of these cells are TOTIPOTENT: capable of differentiating (specializing) into any and all types of cells Image Source: www.bbc.co.uk Image Source: commons.wikimedia.org

  8. Cell Specialization& Gene Expression Blastocyst(70-100 cells) **Stem cell therapy can use embryoblast cells! Embryoblast cells are PLURIPOTENT: capable of differentiating into the cells of one of three groups. Image Source: www.boundless.com Image Source: www.scq.ubc.ca

  9. Mutations & Gene Expression • Mutation: A change in a DNA sequence. May or may not affect gene expression (the protein). • Point Mutation • T H E / F A T / C A T / A T E / T H E / R A TT H E / F A T / K A T / A T E / T H E / R A T • T H E / F A T / C A T / A T E / T H E / R A TT H E / F A T / B A T / A T E / T H E / R A T Message still sounds the same “Silent Mutation” Message sounds different Not Silent

  10. Mutations & Gene Expression Recall: 64 codons, only 20 amino acids. Image Source: waynesword.palomar.edu

  11. Mutations & Gene Expression • Point Mutations (cont.) • Normal: • Point (Silent): • Point (not silent): Recall: 64 codons, only 20 amino acids; helps prevent protein changes! Just one amino acid change can change an entire protein!

  12. Mutations & Gene Expression

  13. Mutations & Gene Expression

  14. Mutations & Gene Expression • Frameshift Mutations: insertion or deletion of nucleotide(s) results in the reading of codons to shift. • T H E / F A T / C A T / A T E / T H E / R A TT H E / F A E / T C A / T A T / E T H / E R A / T • T H E / F A T / C A T / A T E / T H E / R A TT H E / A T C / A T A / T E T / H E R / A T Letters after insertion are shifted to the right Insertion All Nonsense = Message Destroyed Letters after insertion are shifted to the left Deletion All Nonsense = Message Destroyed

  15. Mutations & Gene Expression • Frameshift Mutations (cont.) • Normal: • Frameshift Insertion: • Frameshift Deletion: Completely Different! No Stop Completely Different!

  16. Mutations & Gene Expression • Which is more destructive? Point OR Frameshift Can be a “silent mutation” or only changes one amino acid Changes MANY amino acids

  17. Reading/Work Time • Section 11.3 • Cornell Notes • #1-6 • Chapter 11 Assessment • #2, 4, 12, 13, 14, 25

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