Unit 7- Cell Division

Suppie siteshttp://micro.magnet.fsu.edu/micro/gallery/mitosis/mitosis.htmlhttp://www.cellsalive.com/mitosis.htm

One of the characteristics to all life is the ability to reproduce. This is directly related to cell division in one if its forms- mitosis or meiosis

Uses of Mitosis and Meiosis

Usually mitosis is an asexual process while meiosis is related to sexual reproduction. However we will see that different strategies exisat in different parts of the biological world.

Mitosis MeiosisLocation

Use in animals

Ploidy Pattern

Cycle

** Most of the time cells are not dividing and occupy a stage commonly called “Interphase”. Here is where they perform their normal cell functions.

** During interphase preparations are being made for the next division.

1

The Cell Cycle-

The life of a given cell follows a set pattern -

Events in the Cycle-

Mitosis-

Cytokinesis-

Interphase-

2

Gap 1

Gap 2

Mitosis

Cytokinesis

Synthesis Phase

Controls on the Division

The system is regulated by the building of activation proteins called __________.

CdK- cyclin dependent kinases-

3

Enough CdK combines with Mitotic Cyclin to make MPF-

G1 checkpoint

End of S- G1

Comparison of Dividing and Non-Dividing Cells

Dividing Cells Non- Dividing Cells

stage

DNA form

Nucleus

Nucleolus

Centrosome

Cytoplasm

Forms of DNA in Cells- (ask about the tape measure analogy)

Chromatin-

Chromosomes-

a typical chromosome has 2 sister chromatids bound by a centromere the sister chromatids are homologs composition 60% Nucleoprotein, 35 % DNA and 5% RNA the centromere has the kinetochore- point of attachment for the spindle

fibers

Chromosomes are made in a series of progressive steps.

Histones-

Nucleosome-

Scaffolding Proteins-

4

5

Ploidy Number- defn:

Ploidy is shown with a Karyotype-

Humans have

n= 2n=

Types of Ploidy-

n = haplopid or monoploid-

2n = diploid-

Polyploids-

3n= triploid4n = tetraploid

Polyploid crops-

6

Alternation of Generations

At some point in their life cycles all organisms will perform mitosis and meiosis in a cycle called A of G.

Animals

Plants

7

Meiosis in

gonads

Spores n

Mitosis

Meiosis

Mitosis

Gametes n

Gametes nGametes n

Gametes n

Zygote 2n

Fertilization and recombination

Fertilization and recombination to 2n

Growth and Maturation into diploid 2n organism

Growth and Maturation into diploid organism

Gametophyte Generation

Sporophyte Generation

Growth and Maturation into HAPLOID 1n organism

Sporophyte Generation

Gametophyte Generation

Fungi

8

Zygote2n

Meiosis

Mitosis

Gametes N

Gametes N

Fertilization and recombination to

2N

Mitosis

Spores n

Growth and Maturation into HAPLOID 1n organism

Sporophyte Generation

Gametophyte Generation

The Stages of Mitosis

Interphase- While not officially a stage of mitosis most texts treat it as such

Features-1. 2. 3. 4.

Activity-1.

2. 3.

Prophase- the first stage of true mitosis

Features-1. 2. 3.

Activities-1.

2.

3.

9

Metaphase- the most distinct phase

Anaphase- separation of the chromatids

10

Features-1.

2.

Activities-1.

Features-1. 2.

Activities-1.

2.

Telophase- making of the daughter cells

Cytokinesis-

Cell plate-

11

Features-1. 2.

Activities-1.2.3.

Limits to Mitosis-

Growth factors- secreted by cells to influence their neighbors to divide

Plant growth factors are cytokinins .

Wound repair diagram

12

Damage to tissue creates a gap in cells

Rapid Mitosis stops

Cells proliferate and fill in gap

Growth Factors join receptors on cells and start cascades of CdK/cyclin metabolism

Rapid Mitosis

Neighbor cells secrete growth factors

Cells differentiate into functioning tissues

Dividing cells attach to basement substrate

Resources are consumed to the point of shortage

Cancers-

Cancer: defn-

13

Transformation-

Metastasis-

OR

Cancer terms-

Malignant tumor-

Benign tumor-

Mutagens-

Oncogenes-

Oncology

Therapy Rationale-

Meiosis

Meiosis is cell division with a reduction of ploidy number and is often called Reduction Division

Mitosis occurs in the ____________ in animals to make ______________.

Male Female gonadFunctional unitAccessory Steroid HormoneGameteName for Process

Meiosis is a Two Step Process

Meiosis I- reduction division –

Meiosis II- proliferation-

14

Meiosis I- Reduction Division

1x 2n 2x 1n

Interphase-

15

Prophase I-

Metaphase I-Synapsis- TETRADS

Anaphase I-

Telophase I-

Meiosis II- Proliferation

2x 1n 4x 1n

16

Cytokinesis and Interkinesis

Metaphase II

Telophase II

Anaphase II

Prophase II-

Another Overview of Meiosis

17

Spermatogenesis- Male Meiosis

-occurs in the ____________

-seminiferous tubules

-Sertoli cells-

Leydig or Interstitial Cells-

18

Spermatogonia2n

SpermN

Secondary Spermatocytes

1n

Primary Spermatocytes2n

Spermatidsn

Activated at puberty by hormones

Meiosis I

Meiosis II

Maturation

Parts of a Sperm

Acrosome-

Pronucleus-

Collar-

Tail

Meiotic recombination

19

Oogenesis- Female Meiosis

-occurs in the __________

Follicle-

Corpus luteum-

Menstrual cycle-

Ovulation-

Hormones involved-

Pituitary- LH and FSH-

Estrogen- estradiol-

Progesterone

Picked up by placenta if pregnancy occurs

20

21

Oogonia2n

First Polar Body1n

Second Polar Body1n

Secondary Oocyte1n

Primary Oocyte2n

Ootid1n

Ovum1n

Meiosis Ifinishes

Meiosis II

Mature at around birth

Prophase 1-

Puberty

Unequal cell division

Unequal cell division

Zona Pellucida-