Bellwork 2-4-20141. Look at the two different populations of

organisms below:a. Which one is asexual and which one is sexual?b. Which one has variety and which once does not?

A B

Missed work!!

• If you finish an assignment that was incomplete when I put in homework grades, turn it into the basket!

• All in class work can be completed for full credit! Find a friend in the class if you are missing a lot of work!

• Check grades

Vocab Review• Chromosome – two chromatids put together, one

complete set of information• Sister chromatids – make up a chromosome, half of

the information • Homologous chromosomes – multiple pairs of

chromosomes (two chromatids each), some from mom and some from dad

Exploring Meiosis I

• You will be exploring meiosis I on your own with your NEW lab group today

• Following the guidelines at each lab bench, model EACH step of meiosis with the colored beads and chalk

• After each step, YOU MUST GET CHECKED and then draw the step on your worksheet with colored pencils

Your models

Chromatid Chromosome

Replication **You will have 4 of these in total,all different colors!

Check your drawings!

Once you are done…

• Separate sheet of paper• Homework if not done in class…– Describe the steps of meiosis using COMPLETE

SENTENCES

Bellwork 2-5-2014

1. At which stage in meiosis I does the exchange of information occur?

2. How many cells does meiosis I create?3. Are the products of meiosis I identical or is

there variety?

Meiosis

Meiosis: Unit Vocabulary

meiosis tetrad haploid

diploid somatic cell

homologous pair gamete zygote

crossing over Prophase I and II Metaphase I and II

Anaphase I and II Telophase I and II genetic recombination

sexual reproduction asexual reproduction independent assortment

Meiosis Video

• http://www.youtube.com/watch?v=wrxY4hjMDfk

How much information?Whole set of DNA = 2n DiploidHalf set =

How to remember:Half – Haploid

Di = 2

n haploid

How much information?

Talk with your neighbor:Are chromatids haploid or diploid?Are chromosomes (pair of sister chromosomes) haploid or diploid?

n – haploid!

2n – diploid!

Interphase

Draw and label the centrioles on your Drawing

How much information?2n!! Diploid

DNA replication

Prophase ITetrads form and crossing over occurs

Label the tetrads in your picture &where crossing over happens

Prophase INow we have double the amount of information in the cell…n or 2n??2n - Diploid!!!

Tetrads & Crossing Over

Tetrads – close association of sister chromatids on homologous chromosomes

Crossing Over:Homologous chromosomes exchange small pieces, resulting in new chromosomes!

Metaphase I

Homologouschromosomes line up at the

metaphase plate

How much info?2n – Diploid!

Anaphase IHomologous chromosomes move to opposite ends of the cellIndependent assortment occurs creating new combinations!

How much info?2n – Diploid!

Independent Assortment

Chromosomes from mom & dad RANDOMLY move to one side or the other

Telophase I

Cell walls begin to pinch inwards

2n – Diploid!How much info?

(Cytokinesis I)Two daughter cells pinch offTalk to your neighbor…How do they compare to one another?n (haploid) or 2n (diploid?

Why does genetic recombination matter?

• Your turn!!! You will get two homologous chromosomes with your partner that look like this…

Yellow:

White: Red: Green:

What traits do each potential individuals have?

Why does genetic recombination matter?

• Cross over at the indicated positions below

Yellow:

White: Red: Green:

Now what traits do each potential individuals have?

Why does genetic recombination matter?

• Cross over at the indicated positions below

Yellow:

White: Red: Green:

Now what traits do each potential individuals have?

Prophase IIBeginning with the end products of meiosis IIChromosomes are condensed and prepare for another divisionNo crossing over!!n or 2n?

Metaphase IIChromosomes line up at the metaphase plateMore similar to mitosis this timeNot homologouspairs any longern or 2n?

Anaphase II

Chromatids move to either end of the celln or 2n?

Telophase II

Chromatids separate to individual cellsn or 2n?

(Cytokinesis)Individual cells formn or 2n?Talk with your neighbor:How do the cells compare to each other?How do they compare to the products of meiosis I?

What do we call these cells?These cells are called gametes labelEggs in femalesSperm in males n or 2n?They are haploid!!!Get half of information from mom, half from dad

Fertilization – Making babies!

Sperm + Egg = Zygote

Mitosis vs. Meiosis

# of divisions:

# of divisions:

Products: Products:

Variety? Variety?

Meiosis Card Sort

Order the 11 cards to show the progress from a single cell in interphase and progressing to 4 haploid sex cells

Funny Meiosis Video

• http://www.youtube.com/watch?v=iCL6d0OwKt8

Slate Quiz!

• Look at the pictures on the following slides & name the stage of meiosis!

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