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Agenda

Agenda. Today, doing labs 8 and 9a. Informal Lab Report: Due in 1 Week! See the worksheet and insructions last week. Microworlds: 6 new and 4 old Microworlds are due in 2 weeks!! Time to work on it next week, maybe some today depending on your speed today.

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Agenda

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  1. Agenda • Today, doing labs 8 and 9a. Informal Lab Report: • Due in 1 Week! See the worksheet and insructions last week. Microworlds: • 6 new and 4 old Microworlds are due in 2 weeks!! Time to work on it next week, maybe some today depending on your speed today. • Strawberries, onion root & whitefish mitotic slides are available for Microworlds.

  2. Lab 9a: Cell Cycle and Mitosis • Read background in lab carefully • You should get this info in lecture

  3. Cell Cycle: • Interphase: G1, S, G2 • Cell may renter cell cycle or leave cell cycle (G0) • DNA replicated in S • Nuclear division =Mitosis • Cell division =cytokinesis G2 S Mitosis G1 Cytokinesis G0

  4. MITOSIS ANIMATION Actual MITOSIS photography

  5. Lab 9a: Cell Cycle and Mitosis • CELL CYCLE = entire life of cell, including division • Interphase = not dividing • Mitosis = nuclear division • Cytokinesis = cell division

  6. Interphase (before Mitosis) • EVENTS: • G1: Cell grows and prepares to copy DNA • S: Cell copies its DNA • G2: Cell prepares to divide • APPEARANCE: • Chromatin (DNA) not condensed into chromosomes – WHY? • Nuclear envelope present

  7. MITOTIC PHASES • Mitosis • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis

  8. Prophase EVENTS: 1. Chromatin condenses into chromosomes 2. Chromatids visible 3. Nuclear envelope dissolves 4. Centrioles (Spindle fibers) move to opposite poles APPEARANCE: • Nucleus looks blotchy (chromosomes) • Nuclear envelope dissolves

  9. Metaphase EVENTS: • Chromosomes line up in center of cell APPEARANCE: • Dark chromosomes lined up in center of cell • No nucleus

  10. Anaphase EVENTS: 1. Spindle fibers shorten 2. Chromosomes are pulled to opposite poles of cell APPEARANCE: • Two sets of chromosomes visibly separated from each other

  11. Telophase EVENTS: 1. Chromosomes unwind 2. New nuclear envelope reforms APPEARANCE: • Two dark areas of chromatin present at opposite ends

  12. Cytokinesis EVENTS: • Animals: Daughter cells pinch apart at cleavage furrow • Plants: Cell plate forms in center of cell APPEARANCE: • Two new (usually smaller) cells form

  13. Cell Division in Plants Plants differ from animals • Plant cells have no centrioles • Plant cells differ in Cytokinesis: • a cell wall forms between the dividing cells • called a cell plate

  14. Mitosis Review

  15. Lab 9a: Mitosis Ex. 1: Modeling Mitosis with either Clay (1a) or Pop Beads (1b). Only do 1a or 1b. Ex.2: Observing mitosis in plant cell slides • Practice this f/ lab quiz & final! Ex.3: Observing mitosis in whitefish cells • May instead answer which is easier plant or animal? Why? Ex.4: Estimating time spent in each phase

  16. Lab 8, Ex. 4: Estimating the time spent in each phase of Mitosis • Get 3 other people’s data (100 cells total) • Calculate the percent time spent in each phase • (If you have 5 cells/100 in metaphase, then the cells spend ~5% of the time in metaphase.) • Check your answer. If its off, you need to spend more time identify the phases! • Identify the phase for 25 cells

  17. Lab 8, Exercise 1: DNA Extraction • You can extract DNA from practically everything • Strawberries, peas, your lab partner’s brain!

  18. The Lysis Buffer • Contains water and a buffer • A Detergent • to dissolve the membranes so we can extract DNA • The cell wall is not a problem as DNA in water can move through it • A Salt • Causes proteins and carbohydrates to precipitate out of solution • We only want DNA

  19. DNA Extraction • Since your lab partner may object to your isolating brain DNA, we’ll use strawberries • Squash strawberry to increase the surface area exposed to detergent • It simply makes smaller pieces

  20. DNA Extraction • Add lysis buffer and continue squashing • Filter mixture through filter paper (coffee filter) • The DNA will be in the filtrate solution you capture

  21. DNA Extraction • Pour ice-cold alcohol (equal volume to strawberry filtrate) down side of tube to precipitate DNA • Keep it cold!

  22. DNA Extraction • It will appear like slimy snot between the alcohol-water interphase • Skip steps 13-14, viewing your DNA under the microscope.

  23. If desired, here are two Home DNA Extraction sites: • http://www.pbs.org/wgbh/nova/teachers/activities/2809_genome.html • http://biology.about.com/c/ht/00/07/How_Extract_DNA_Human0962932481.htm

  24. Lab8, Exercise 2: Transcription, Translation, Mutation Practice Second base C A U G UAU U UCU UUU UGU Cys Phe Tyr C UAC UGC UCC UUC Ser U UUA UCA Stop A A UAA Stop UGA Leu G UGG Trp UCG UUG Stop UAG U CAU CCU CUU CGU His CUC C CCC CGU CAC Leu Pro Arg C A CUA CCA CAA CGA Gln G CUG CGG CCG CAG First base Third base U AUU ACU AAU AGU Ser Asn AUC lle C ACC AAC AGC Thr A A AUA ACA AGA AAA Arg Lys Met or start G AUG AAG ACG AGG U GUU GCU GAU GGU Asp C GUC GCC GAC GGC G Val Gly Ala A GCA GUA GAA GGA Glu GUG GCG G GAG GGG GAG • Follow directions • Remember base-pairing rules: • DNA  DNA • DNA  RNA • Know how to use this table but do not memorize it!

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