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Ch 10 and 11Ch 10 and 11
Cell Reproduction,
Mitosis
•Diffusion•DNA•Surface area to volume ratio
Limits on Cell Size
Cell Cycle•The sequence of growth and division of a cell•Divided into Stages:•Interphase•Mitosis•http://www.cellsalive.com/cell_cycle.htm
Cell Growth
INTERPHASE•Divided into Stages•G1 stage (Growth)•Rapid growth•High protein production
•S stage (synthesis)•DNA made•Chromosomes replicates
•G2 stage (Growth)•Other organelles are made•Cell prepares for mitosis
•Majority of the cell’s life is spent in Interphase
CHROMOSOME2 Main Parts•Sister Chromatids•Two halves of the doubled structure of a chromosome
•Centromere•Structure that holds sister chromatids together
Homologous Pair
Centromeres (DNA)
Sister ChromatidsnonSister Chromatids
• Cell reproduction in which 2 identical cells or daughter cells are made from 1 parent cell• Mitosis results in the growth and
repair of the body cells or somatic cells (such as skin, bone, muscles, or liver cell).
• http://www.cellsalive.com/mitosis.htm
What is Mitosis?
Prophase•Centrioles pull apart•Spindle fibers form•Nuclear membrane disappears
Centrioles
Spindle fibers
Nuclear envelope
•Chromosomes attach the spindle fibers•Chromosomes line up at the center of the cell
fibers
chromosomes
centriolesMETAPHASE
ANAPHASE•Centromeres spilt and sister chromatids are pulled to opposite poles•Cytoplasm pinches inward
Sister chromatids
centrioles
Spindle fibers
TELOPHASE•Spindle fibers break down•Nuclear membrane reappear•2 identical cells formed•Cytokinesis occurs•(cell splits)
Nuclear envelope
Regulation of the Cell cycle
• Enzymes (proteins) monitor a cell’s progress from phase to phase during the cell cycle
• Enzymes are necessary to begin and drive the Cell cycle• Enzyme production is directed by genes
located on the chromosomes
Internal and External Regulation of the Cell cycle
• Internal Regulation-proteins that respond to events inside the cell; they allow the cell cycle to proceed only when certain processes have happened inside the cell properly
• Ex: prevents anaphase until all chromosomes are attached to the mitotic spindle
• External Regulation- proteins that respond to events outside of the cell; they speed up or slow down the cell cycle
• Example: prevents excess growth of the cell by using chemical messengers (signals) such as hormones (proteins)
Causes of Cancer• Cancer is the result of
uncontrolled cell division• Can be both genetic &
environmental
• Environmental factors such as cigarette smoke;
• air pollution; water pollution & exposure to ultraviolet radiation can cause Cancer• Cancer may also be
caused by viral infections
Cancer Prevention
• Diets low in fat & high in fiber content reduce the risk of cancer• Vitamins & minerals may also help
prevent cancers• Daily exercise & not smoking
TYPES of ASEXUAL REPRODUCTION
3rd set of ch 10 and 11 notes
• Asexual Reproduction is the production of new organisms without the fusion of nuclei of two specialized sex cells• Mitotic Cell Divisions – the new
organisms are genetically identical to the parent• 1Diploid Cell(2n) 2 Diploid Cells(2n)
Binary Fission (evenly)• The nucleus
divides by mitosis along with cytoplasm to make 2 daughter cells that have the same # of chromosomes
Ex: amoeba, paramecium, (protists)
Budding• The division of cytoplasm
is unequal so 1 daughter cells is larger than the other• Ex: hydra, yeast
Sporulation• Spores are made in
large amounts that surround themselves with tough coats, large #s• Ex: bread mold, fungi,
bacteria
Vegetative Propogation-new plants are made from roots, stems, or leaves of
the parent plant
• Cutting-new plants develop from cut end of plant, plant stem• Ex: coleus,
geraniums
• Bulb-underground stem made from existing bulbs• Ex: onions,
tulips, lilys
•Tuber-underground stem with food stored in it•Ex: potato
• Runner-horizontal stem close to the ground• Ex: Strawberry
• Grafting- cut twig attached to trunk or branch of another• Ex: flowers,
seedless fruits
Regeneration (unspecializes=invertebrates)
• Replacement or regrowth of lost or damaged body parts• Ex: lobster,
starfish
44thth set of notes set of notes
• Process of nuclear division that reduces the # of chromosomes by half• It is involved in SEXUAL reproduction• It results in haploid(1n) eggs and
sperm (animals) and spores that later lead to egg and sperm (plants) [gametes]
• It has 2 nuclear divisions : Meiosis I and Meiosis II• Also called
Gametogensis(Spermatogenesis – sperm (testes) and Oogenesis-eggs (ovaries))
• Nuclear membrane and nucleolus disappears
• Synapsis occurs (pairing of homologous chromosomes) & crossing-over occurs
• Tetrad forms (packets of 2 chromosomes)
tetrad
Crossing-over
• Homologous chromosomes attach to spindle fibers and move to the equator of the cell
• Disjunction occurs (homologous chromosomes separate and move to opposite poles)
• Cytokinesis occurs• 2 daughter cells form• Nuclear membrane
reappears
• Centrioles reappear• Similar to mitosis
• Chromosomes attach to spindle fibers and move to equator of cell
• Chromosomes split at centromere• Chromosomes
move to opposite poles
• Cytokinesis occurs in both cells• Nuclear membrane reappears• 4 cells formed• Males – 4 sperm cells• Females-1 egg cell & 3 polar bodies
Fertilization and Development
5th set of notes for ch 10 and 11
Fertilization and Development
• Fertilization is the union of a monoploid (n) sperm nucleus with a monoploid (n) egg nucleus to form a zygote (2n) cell, the fertilized egg
2 Types of Fertilization:
1. Internal fertilization is the union of sperm and egg in the moist reproductive tract of the female.
2. External fertilization is the union of sperms and egg outside the body of the female; usually done in water.
Stages of development:
• Development begins when the zygote undergoes a rapid series of mitotic cell divisions called cleavage.
1.
2.
3. 4. 8 cells
5. Ball of cells-stem cells
6. Blastula
• Blastula the formation of a hollow ball made up of one single layer of cells.• Gastrulation the process in which
one side of the blastula pushes inward or indents; resulting in an embryonic stage called the gastrula
Gastuala consists of 3 germ layers:
1. Enduderm inner layer that gives rise to the organs
2. Ectoderm outer layer that gives rise to the skin and nervous system
3. Mesoderm middle layer that forms bonds between the ectoderm and endoderm; gives rise to the muscles, bone, and blood.
• Differentiation and Growth result as the germ layers differentiate to form various cells of the body from stem cells
2 types of Development:
• External Development occurs outside the female’s body; the embryo often obtains food in the form of yolk. Examples: birds, reptiles• Internal Development involves the
growth of the embryo inside of the female; occurs in most mammals
–In all mammals the young are nourished after birth by milk from the mother’s mammary glands
3 types of Mammals
• Placental mammals embryo develops in the uterus of the female. Ex:humans
• Marsupial mammals pouched mammals. Ex: kangaroos
• Monotreme mammals egg laying mammals. Ex: duck billed platypus