Meiosis and Mitosis

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?

G2 check point G1 check point

90% of cells are:___ What if less than 90%? What is Cancer?

What if a cell in G1 of interphase were fused with a cell in metaphase? G2 check- point Cyclin Cdk MPF = ?

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?

Anaphase 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

•What phase of mitosis? •Is this animal or plant? •What is this process called? • And in a plant, how is it different? Is this DNA in the chromosome or chromatin phase?

Chromosome Number Homologous Chromosomes are the pairs 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

Autosomes & Sex Chromosomes Autosomes = # 1-22 for all traits except sex Sex chromosomes = Pair # 23 XX(female) or XY(male) XXX? XXY? XYY? X?

Meiotic Cells…….. 2n Divide twice to 1/2 chromosome number…WHY? Immature Egg or Sperm still in the gonads 2n Divide twice to 1/2 chromosome number…WHY? “Haploid” n Sperm or eggs only 2n doubled DNA = X’s Meiosis I PMAT 2n 2n Meiosis II PMAT n n n n

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? II

2n = ____ 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 & n animals fungi, algae plants, algae

KARYOTYPE: Down Syndrome= 3 of #21

Klinefelter’s = XXY

LAB 3A, pages 31-40 will be due in about 1 ½ weeks (around 10/25) LAB 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!