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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.
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
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.
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