Agenda

• REMINDER: Lab Report is due NEXT WEEK • 10 more Microworlds entries due in 2 weeks!!

Will have time to work on it next week• Today, we may be doing lab 8 and 9a.

Exercise 2: Transcription, Translation, Mutation Practice

• Follow directions• Remember base-pairing

rules:– DNA DNA– DNA RNA

• Remember how to use this table

Second base

Firs

t bas

e

Thir

d ba

se

UUUU C A G

GAA

C

U

U

U

C

AC

A

G

G

UCAG

U

C

A

G

UUC

UUA

UUG

CUU

CUC

CUA

CUG

AUU

AUC

AUA

Leu

lle

AUG Met orstart

GUU

GUC

GUA

GUG

Val Ala

Thr

GCG

GCA

GCC

GCU

ACG

ACA

ACC

ACU

Pro

CCG

CCA

CCC

CCU

UCG

UCA

UCC

UCU

Ser

Tyr CysUAU

UAC

UAA

UAG

CAU

CAC

CAA

CAG

His

Gln

Stop

Stop

UGU

UGC

UGA

UGG Trp

Stop

Arg

CGU

CGU

CGA

CGG

Asn

Lys

Asp

Glu

Gly

Arg

SerAAU AGU

AAC

AAA

AAG

GAU

GAG

AGC

AGA

AGG

GGU

GGC

GGG

Phe

Leu

GAC

GAA

GAG

GGA

Part 3: Cell Cycle and Mitosis

• Read background in lab carefully

• We will go over this info in lecture

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

G1

S

G2

Mitosis

Cytokinesis

G0

MITOSIS ANIMATION

Actual MITOSIS photography

Part 3: Cell Cycle and Mitosis

• CELL CYCLE = entire life of cell, including division– Interphase = not dividing– Mitosis = nuclear

division– Cytokinesis = cell

division

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

MITOTIC PHASES

• Mitosis– Prophase– Metaphase– Anaphase– Telophase

• Cytokinesis

ProphaseEVENTS:

1. Chromatin condenses into chromosomes

2. Chromatids visible3. Nuclear envelope dissolves4. Centrioles (Spindle fibers)

move to opposite poles

APPEARANCE: • Nucleus looks blotchy

(chromosomes)• Nuclear envelope dissolves

Metaphase

EVENTS: 1. Chromosomes line up

in center of cell

APPEARANCE: • Dark chromosomes

lined up in center of cell

• No nucleus

Anaphase

EVENTS: 1. Spindle fibers shorten2. Chromosomes are pulled to

opposite poles of cell

APPEARANCE: • Two sets of chromosomes

visibly separated from each other

Telophase

EVENTS: 1. Chromosomes unwind2. New nuclear envelope

reforms

APPEARANCE: • Two dark areas of chromatin

present at opposite ends

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

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

Mitosis Review

Part 3: Mitosis

A. Modeling Mitosis with Playdoh

B. Observing mitosis in plant cell slides– Practice you’ll do this

on a quiz

C. Estimating time spent in each phase

Part 3: Mitosis

C. Estimating time spent in each phase– Identify the phase for 25 cells– 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.)

Part 1: DNA Extraction

• You can extract DNA from practically everything

• Strawberries, peas, your lab partner’s brain!

1. Make lysis buffer• Add Water• Add Detergent– To extract DNA, we need to dissolve the membranes– Why not the cell wall?

1. Make lysis buffer

• Water• Detergent• Add Salt– Causes proteins and

carbohydrates to precipitate out of solution

– We only want DNA

2. 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

2. DNA extraction

• Add lysis buffer and continue squashing

2. DNA extraction

• Filter mixture through filter paper

• The DNA will be in the filtrate solution you capture

2. DNA extraction

• Pour ice-cold alcohol (equal volume to strawberry filtrate) down side of tube to precipitate DNA

• Keep it cold!

2. DNA extraction

• DNA is is not soluble in alcohol and will precipitate out of solution

• It will appear like slimy snot between the alcohol-water interphase

Home DNA Extraction

• http://www.pbs.org/wgbh/nova/teachers/activities/2809_genome.html

• http://biology.about.com/c/ht/00/07/How_Extract_DNA_Human0962932481.htm