Ch. 10 : Cell Division and Growth

10-1: Cell Reproduction

Why do cells divide? How is DNA packaged in the nucleus? How do cells prepare for division?

Cells are busy making more cells.

The reproduction of cells allows

you to grow and heal.

Cell reproduce to : Control cell size (many smaller cells are more

efficient than one large cell)Surface area to volume ratio for supplies, proteins and

control by nucleusMake new cells

Growth in multicellular organismsDevelopmentreplace

RepairWounds

Reproduce If you are single celled

Chromosomes

DNA is a long thin, coiled molecule.

DNA is a chemicalDNA’s job is to store and

transfer informationDNA is made of

nucleotides, each human cell has DNA totaling 6 billion nucleotide pairs!

Chromosome structure

DNA in a eukaryotic nucleus is thin and uncoiled – it is called chromatin. Chromatin is available for the cell to use as information

When the eukaryotic cell divides the DNA must be copied, packaged and move to new nuclei. The packaged format is called chromatids and chromosomes. This is only for cell division.

Chromosome structure

ProkaryotesOne chromosomeCircularNo nucleusplasmids

EukaryotesMany (humans have 23

pairs or 46)Linear Inside nuclear

membraneDNA is copied into RNA

DNA

DNA is a long thin chemical chain, made of nucleotides, in the form of a double helix.

DNA wrapped around protein is called chromatin and chromatin coiled into visible threads is a chromosome.

After DNA copies each part is called a chromatid and they travel together connected at a structure called a centromere.

Chromosome numbers

Normal humans have 23 pairs of chromosomes ( 46 total).

22 pairs are autosomes, regular chromosomes

The 23rd pair is called the sex chromosomes and determines your gender X X means a female X Y means a male

Preparing for divisionProkaryotes – “Binary Fission”

Copy one chromosomeMembrane indentsWall forms2 gentically identical cells

Eukaryotes – “Mitosis”S of interphase (Interphase = G1, S and G2)All chromosomes are copiedNuclear membrane dissolvesOther organelles and structures are copied and formed Then enters MITOSIS which is nuclear division

Vocabulary

Homologous chromosomes are the two copies of each autosome, same size and same shape and same genes in the same locations.

Karyotypes pictures of your chromosomes from a microscope (WBC) and arranged in order from longest to shortest.

Karyotype

More vocabulary

Diploid cells/ diploid number cells that contain both chromosomes from each homologous pair. ( 23 pairs, or 46 total, in humans) . All of our cells that are NOT egg or sperm.

Haploid cells/ haploid number cells that only contain one from each pair for 23 total chromosomes. These cells would include eggs, sperm and cells like pollen and spores in plants and fungi. They are reproductive cells, as opposed to body (somatic) cells.

10-2: Mitosis

What are the phases of the eukaryotic cell cycle?

What are the stages of mitosis? How does cytokinesis occur?

The events of the cycle ensure that new cells

will be just like the old cell.

10-2: Eukaryotic Cell CycleBinary fission the division of prokaryotic

cells (bacteria) into two new cells.Mitosis cell division in eukaryotic cells

that results in two new, identical, diploid cells. (skin cell makes new skin cells)

Meiosis division in specialized eukaryotic cells that reduces the number of chromosomes to haploid - creating reproductive cells.

Mitosis Review

Steps of Mitosis Interphase: grow, copy DNA Prophase: chromosomes and

structures visible Pro-metaphase: spindle

complete Metaphase: chromosomes

aligned at equator Anaphase: chromosomes and

copies separate and move Telophase: new nuclei form Cytokinesis: cytoplasm and

organelles are divided. Cell plate is formed in plant cells xxxx

Mitosis occurring in root cells of onion

10-3: Regulation

Environmental and genetic cluesChemicalsContact InhibitionCheck points

8-3 MEIOSIS

“reduction division”Produces reproductive cells, that are

haploid and are generically called gametesCells still do Interphase, one and only one

time to copy the chromosomesThen they divide twice, producing four

cells. . . . This reduces the number of chromosomes – ½ from each parent

Meiosis terminology

Synapsis pairing of homologous chromosomes that only occurs during meiosis. Chromsome #1 and its copy chromatid and the OTHER chromosome #1 and its copy chromosome pair up. Creating a group of four

Tetrad group of four. “Pairs of pairs” of chromosomes.

Crossing over some times adjacent pieces of chromsomes break and re-align with another part of the tetrad.

Terminology continued

Genetic recombination as a result of crossing over eggs and sperm can give offspring different combinations than that of the parent. Grandma has brown hair and blue eyesGrandpa has blonde hair and brown eyesMom has brown hair and brown eyes but could

give the child an egg with the information for Child = blonde hair and brown eyes

End of vocabularyIndependent Assortment each chromsome

pair goes to the gametes without the influence of the other chromosomes – can get grandmas info. for # 4 and grandpas info for # 17.

Spermatogenesis – process where specialized cells create sperm

Oogenesis – process where specialized cells make ova (eggs)

Asexual reproduction – offspring are produced by one parent through mitosis

Sexual reproduction – offspring are produced by union of egg and sperm. Requires meiosis.