cell reproduction, mitosis. diffusion dna surface area to volume ratio limits on cell size

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