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.

Lab 9a: Cell Cycle and Mitosis

• Read background in lab carefully

• You should get 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

Lab 9a: 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

Lab 9a: Mitosis

• 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

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

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

Lab 8, Exercise 1: DNA Extraction

• You can extract DNA from practically everything

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

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

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

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

DNA Extraction

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

• Keep it cold!

DNA Extraction

• Skip steps 13-14, viewing your DNA under the microscope.

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

If desired, here are two Home DNA Extraction sites:• http://www.pbs.org/wgbh/nova/teachers/acti

vities/2809_genome.html• http://biology.about.com/c/ht/00/07/

How_Extract_DNA_Human0962932481.htm

Lab8, Exercise 2: Transcription, Translation, Mutation Practice

• Follow directions• Remember base-pairing

rules:– DNA DNA– DNA RNA

• Know how to use this table but do not memorize it!

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