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 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

CHROMOSOME 2 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 Chromatids nonSister 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). 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 centrioles METAPHASE

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 3 rd 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

4 th 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 5 th 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.

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