Meiosis Meiosis and and

MitosisMitosis

What is Mitosis for?• 1. Reproduction in favorable conditions.• 2. Growth and Development• 3. Tissue repair and cell

replacement

• If an organism had the ability to reproduce sexually or asexually, which would they choose?

• This is NOT mitosis, what is it?

G1 check point

G2 check point

• 90% of cells are:___

• Whatif less than 90%?

• What is Cancer?

• G2 check-point

• Cyclin

• Cdk

• MPF = ?

•What if a cell in G1 of interphase were fused with a cell in metaphase?

MITOSIS: What phase is this cell most likely in?How many chromosomes?

Would you see chromatin here?

How many centromeres?

How many sister chromatids?

Draw this cell in Anaphase.

How many kinetochores?

How many spindle fibers will it take to move all of the chromosomes during metaphase and anaphase?

What is the 2n number for this cell?What is the n number for this cell?

How many chromosomes?

How many chromatids?

What do the blue lines represent? What are they made of?

The Kinetochores are very important here because…

In which phase do spindle fibers start attaching to the kinetochores?

In which specific phases (or parts of phases) will you find sister chromatids?

Anaphase

Is this DNA in the chromosome or chromatin phase?

•What phase of mitosis?

•Is this animal or plant?

•What is this process called?

• And in a plant, how is it different?

Chromosome Number

• Different # for different species

• Full set = 2n=Diploid• n =• full set= 46 in humans • 1 pair from mother, 23• 1 pair from father, 23• Humans= 23 pairs or• 46 total

Homologous Chromosomes are the pairs

Autosomes & Sex Chromosomes

Autosomes = # 1-22 for all traits except sex

Sex chromosomes = Pair # 23 XX(female) orXY(male) XXX? XXY? XYY? X?

Meiotic Cells……..

• Divide twice to• 1/2 chromosome

number…WHY?

• “Haploid” n

• Sperm or eggs only

2n

2n2n

nn nn

2n doubled DNA = X’s

ImmatureEgg or Sperm still in the gonads

Meiosis I PMAT

Meiosis II PMAT

• How many differences can you come up with between meiosis and mitosis?

• 2 stages (PMAT,PMAT)

• 4 daughter cells formed• Crossing over (when?)• Random assortment• 2 different metaphases• Not clones• Haploid (not diploid)

MEIOSIS

• What is the longest phase of meiosis? why?

• What is synapsis? Chiasmata or chiasma?What is a tetrad?

• What is so important about what has happened here?

• Check out Metaphase I & II, what is different?

• What is the 2n number of this species?

• What is the n number?

I

II

• What might this cell look like in prophase I?

• in metaphase I of meiosis?• in prophase II?• What might each daughter

cell look like after meiosis II?

• Is there a different daughter cell outcome that could have happened?

• What would each daughter cell look like after mitosis?

2n = ____

p.230

2n n Alternate 2n & nanimals fungi, algae plants, algae

KARYOTYPE:Down Syndrome= 3 of #21

Klinefelter’s = XXY

•LAB 3A, pages 31-40LAB 3A, pages 31-40 will be due in about 1 ½ weeks (around 10/25). We will hand in 3A with 3B when it is complete.

•Start now!Start now!