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Cell Growth and Reproduction






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Cell Growth and Reproduction. Biology Agriculture. Cell Growth. All cells come in different sizes and shapes. Diffusion in fast and effective over short distances. It become slow and inefficient over long distances.
Cell Growth and Reproduction

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Cell growth and reproduction l.jpgSlide 1

Cell Growth and Reproduction

Biology Agriculture

Cell growth l.jpgSlide 2

Cell Growth

  • All cells come in different sizes and shapes.

  • Diffusion in fast and effective over short distances.

    • It become slow and inefficient over long distances.

  • If a cell and a mitochondria 20cm in diameter – it would take months before it would receive molecules that entered the cell membrane.

Cell growth3 l.jpgSlide 3

Cell Growth

  • Surface area-to-volume ratio

    • Area: the surface included in a set of lines.

    • Volume: space occupied as measured in cubic inches.

    • Ratio: the relationship in quantity, amount, or size between two or more things.

Cell growth4 l.jpgSlide 4

Cell Growth

  • Due to the surface area-to-volume ratio cells divide before they become to large.

  • DNA is what directs the cell when it is becoming to large.

Cell reproduction l.jpgSlide 5

Cell Reproduction

  • Cell division in necessary to form multi-cellular organisms.

  • Asexual Reproduction:

    • Production of offspring from one parent cell.

  • Sexual Reproduction:

    • Formation of offspring from the union of two gamete cells .

Asexual reproduction l.jpgSlide 6

Asexual Reproduction

  • Steps:

    • Chromosomes duplicate (called replication)

    • Both attach to a site located in the cell

    • They are forced apart.

      • Cell membrane constricts them till they separate.

Asexual reproduction7 l.jpgSlide 7

Asexual Reproduction

  • Some examples include:

    • Strawberry Runners

    • Potatoes

    • Star Fish

Sexual reproduction l.jpgSlide 8

Sexual Reproduction

  • Results from the joining of two highly specialized cells.

    • Sperm Cells

    • Ovum Cells or Egg Cell

  • Fertilization:

    • Sperm cell and ovum combine to form a Zygote.

Chromosomes l.jpgSlide 9

Chromosomes

  • Chromatids:

    • Long strands of DNA.

  • Chromosomes:

    • Made of two sister chromatids.

  • Held together by a centromere

Diploid 2n cells l.jpgSlide 10

Diploid (2n) Cells

  • A cell with two of each kind of chromosomes are called Diploid Cells.

Haploid n cells l.jpgSlide 11

Haploid (n) Cells

  • A cell with one kind of each chromosome is called a Haploid cell.

Mitosis l.jpgSlide 12

Mitosis

  • Cells undergo mitosis as they reach their maximum cell size.

  • There are four steps in mitosis:

    • Prophase

    • Metaphase

    • Anaphase

    • Telophase

Mitosis13 l.jpgSlide 13

Mitosis:

  • Stage 1 – Prophase.

  • Chromatids coil up into visible chromosomes.

  • Nucleus Disappears

  • Centrioles migrate to the polar ends of the cell

  • Spindle Fibers begin to form.

Mitosis14 l.jpgSlide 14

Mitosis:

  • Stage 2 – Metaphase

  • Chromosomes become attached to the spindle fibers by their centromeres.

  • They are lined up across the center of the cell.

Mitosis15 l.jpgSlide 15

Mitosis:

  • Stage 3 – Anaphase

  • Sister chromatids begin to separate

  • Chromatids are pulled apart, and separate from each other.

Mitosis16 l.jpgSlide 16

Mitosis:

  • Stage 4 – Telophase

  • New cells prepare for their new existence.

  • Chromosomes uncoil and direct metabolic activity

  • Spindle Fibers break down

  • Nucleolus reappears

  • Double membrane forms between them

Mitosis17 l.jpgSlide 17

Mitosis

  • Cytokinesis

    • Animals – Plasma Membrane pinches in along the equator of the cell.

Mitosis18 l.jpgSlide 18

Mitosis

  • Cytokinesis

    • Plants - Cell Plate is laid across the equator.

    • Cell walls form around the plate

Results of mitosis l.jpgSlide 19

Results of Mitosis

  • As a result,

    • Each daughter cell receives and exact copy of the chromosomes present in the parent cell.

    • They copy their chromosomes during Interphase.

    • They become a diploid cell 2n

    • The process can then start over.

Results of mitosis20 l.jpgSlide 20

Results of Mitosis

  • Process that guarantees that genetic continuity.

  • The two new cells formed will carry out the same functions of the parent cell.

  • They will grow and divide just like the parent cells.

Results of mitosis21 l.jpgSlide 21

Results of Mitosis

  • As a result of cell division we have groups of cells working together, until they create and organism, i.e.

    • Cells

    • Tissues

    • Organs

    • Organs Systems

    • Organisms

The cell cycle l.jpgSlide 22

The Cell Cycle

  • Cell Cycle:

    • The sequence of growth and division in the cell.

  • A cell goes though two periods:

    • A period of growth

    • A period of division

The cell cycle23 l.jpgSlide 23

The Cell Cycle

Prepare for cell division

2 hours

Mitosis 1 hour

DNA Synthesis and Replication

10 Hours

INTERPHASE

Rapid Growth and Metabolic Activity

9 hours

Interphase l.jpgSlide 24

Interphase

  • The busiest part of the cell cycle

    • Part I: Cell grows and protein production is high.

    • Part II: Cell copies its chromosomes

    • Part III: Parts manufactured for cell division.

The cell cycle25 l.jpgSlide 25

The Cell Cycle

  • The cell cycle is controlled by;

    • Proteins

    • Enzymes

    • Area – to – Volume Ratio

  • Occasionally, cells lose control.

    • Cancer, malignant growth resulting from uncontrolled cell division.

Cancer a mistake in the cell cycle l.jpgSlide 26

Cancer – A mistake in the cell cycle!

  • Tumors

    • Masses of tissue that deprive normal cells of nutrients.

  • Cancer is the second leading cause of death in the United States, exceeded only by heart disease.

Meiosis l.jpgSlide 27

Meiosis

  • Meiosis forms haploid daughter cells from diploid parent cells.

  • Meiosis is divided into two parts;

    • Meiosis I

    • Meiosis II

Meiosis i l.jpgSlide 28

Meiosis I

  • Synapsis

    • Homologous Chromosomes line up next to each other.

    • Forming a structure called a tetrad.

Meiosis i29 l.jpgSlide 29

Meiosis I

  • Meiosis I is divided into four stages;

    • Prophase I

    • Metaphase I

    • Anaphase I

    • Telophase I

Meiosis i30 l.jpgSlide 30

Meiosis I

  • Prophase I

    • Homologous Chromosomes are formed

    • Spindle fibers form

    • Tetrads are visible and have lined up along the equator.

Meiosis i31 l.jpgSlide 31

Meiosis I

  • Metaphase I

    • Each tetrad becomes attached to the spindle fibers

Meiosis i32 l.jpgSlide 32

Meiosis I

  • Anaphase I

    • Homologous chromosomes are pulled apart.

    • One pair goes to the on polar end while the other goes to the other end.

Meiosis i33 l.jpgSlide 33

Meiosis I

  • Telophase I

    • Cytokinesis takes place.

    • The cell divides.

Meiosis i34 l.jpgSlide 34

Meiosis I

  • At the end of Meiosis I;

    • One chromosome from each parent cell is present in the daughter cell.

  • Meiosis I is a reductive division;

    • Reduce the chromosomes from diploid (2n) to a haploid (n).

Meiosis ii l.jpgSlide 35

Meiosis II

  • Each daughter cell produced in Meiosis I undergoes another division.

  • Meiosis II is very similar to Mitosis except, it is not proceeded by a replication of the chromosomes.

Meiosis ii36 l.jpgSlide 36

Meiosis II

  • There are four stages;

    • Prophase II

    • Metaphase II

    • Anaphase II

    • Telophase II

Meiosis ii37 l.jpgSlide 37

Meiosis II

  • Resulting in;

    • Four daughter cells

    • Each daughter cell produced is haploid.

    • Each cell has four chromosomes.

    • One from each of the homologous pairs of parent cells.

Meiosis ii38 l.jpgSlide 38

Meiosis II

  • Prophase II

    • New spindle fibers form around the chromosomes.

Meiosis ii39 l.jpgSlide 39

Meiosis II

  • Metaphase II

    • Chromosomes line up along the equator.

    • Attach the centromere to the spindle fibers

Meiosis ii40 l.jpgSlide 40

Meiosis II

  • Anaphase II

    • The centromere divides and the chromatids separate.

    • Each chromatids becomes it on chromosomes with their own centromere.

Meiosis ii41 l.jpgSlide 41

Meiosis II

  • Telophase II

    • The nuclear envelope forms around each set of chromosomes.

    • Cell undergoes Cytokinesis.

Meiosis why l.jpgSlide 42

Meiosis – Why?

  • The result;

    • Cells used for reproduction

      • Sperm Cells

      • Ovum Cells


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