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Reproduction. T he Cell Theor y. The 4 main points of the cell theory are: All living organisms are made of one or more cells Cells are the basic unit of structure and function in all organisms All cells come from previously existing cells

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Reproduction

Reproduction


T he cell theor y

The Cell Theory

  • The 4 main points of the cell theory are:

    • All living organisms are made of one or more cells

    • Cells are the basic unit of structure and function in all organisms

    • All cells come from previously existing cells

    • Organisms are controlled by single cells working together


Animal cells

Animal Cells


Plant cells

Plant Cells


So what s the difference

So what’s the difference?

  • Plant cells – rigid cell wall which provides structure and support for the cell

  • Plant cells – have chloroplasts that enable them to make their own food through photosynthesis


Organelles

Organelles

A typical cell has many organelles, specialized structures that perform specific functions in the cell

Nucleus – the control center of the cell

Nuclear Membrane – encloses the cells genetic material or DNA (Deoxyribonucleic Acid)

Nucleolus – darker area within the nucleus that makes ribosome parts


Cell organelles continued

Cell Organelles Continued…

Ribosomes – small, cell structures involved in the making of proteins

Cell Membrane – the membrane that holds all the cell contents together

Cytoplasm – the gel-like substance within the cell that supports the structures of the cell


Cell organelles continued1

Cell Organelles Continued…

Endoplasmic Reticulum – transports materials to different parts of the cell

Mitochondrion – an oval-shaped organelle that makes energy for a cell to use. The power-house of the cell

Golgi Body – packages and moves (secretes) waste out of a cell

Vacuole – stores water, food, wastes and other materials in the cell

Lysosome – breaks down food, wastes and worn-out cell parts


Cell division

Cell Division

Part One: Mitosis


In the nucleus

In the nucleus

  • In non-dividing cells, the genetic material is stored as thin DNA super coils called CHROMATIN

  • When a cell divides, the chromatin will shorten and thicken into CHROMOSOMES

  • One strand of a double stranded chromosome is called a CHROMATID


Draw a double stranded chromosome label chromosome chromatid and centromere

Draw a double stranded chromosome. Label chromosome, chromatid and centromere

Chromatid

Chromosome

Chromatid

Centromere


Mitosis

Mitosis

  • MITOSIS: a process by which the nucleus of a cell divides while maintaining the chromosome number

    • One cell  two cells

    • New cells have identical genetic material (DNA) of the parent cell

  • Four stages of division (Prophase, Metaphase, Anaphase and Telophase - PMAT) plus a period of growth and metabolism called Interphase


The cell cycle

The Cell Cycle


Phase one prophase

Phase One: Prophase

  • Chromatin contracts and becomes visible (spaghetti). It is now called CHROMOSOMES

  • Each is a double chromosome with a pair of SISTER chromatids which are joined to each other by a centromere

  • Chromosomes begin to move towards the equator (center) of the cell

  • Nuclear membrane disintegrates (breaks down)

  • CENTRIOLES will form SPINDLE FIBERS that will attach to each centromere and move around the chromosomes


Prophase

Prophase


Phase two metaphase

Phase Two: Metaphase

  • The centromeres of each chromosome line up along equator ( looks like praying hands)

  • Centromeres divide so the doubled chromosomes become two identical single stranded sister chromatids

  • Centrioles are now at the poles of the cell and are attached to each centromere by spindle fibers


Metaphase

Metaphase


Phase three anaphase

Phase Three: Anaphase

  • The spindle fibers begin to shorten and the chromosomes begin moving to opposite ends or poles of the cell (fingers)

  • Each side gets one chromatid from each double stranded chromosome


Anaphase

chromosomes

Anaphase


Phase four telophase

Phase Four: Telophase

  • Begins when single stranded chromosomes reach the poles

  • Chromosomes uncoil and turn into chromatin

  • Nuclear membrane reappears

  • Reverse of prophase

  • Division of the cytoplasm or CYTOKINESIS is completed by pinching off in animals or by building a cell wall in plants


Telophase

Telophase


Interphase

Interphase

  • Period between divisions

  • Longest part of the cell cycle

  • Cell is growing and metabolizing

  • Nuclear membrane present

  • Genetic information in the form of chromatin and cannot be seen with a microscope

  • Before division each strand of DNA will replicate (copy) itself to become double stranded

  • Near the end of interphase the DNA begins to condense (shorten)


Interphase1

Interphase


What s the point of mitosis

What’s the point of Mitosis?

  • Mitosis creates identical copies of cells for:

    • 1. growth

    • 2. Repair/regeneration of damaged tissue

    • 3. Asexual reproduction (animals) or vegetative reproduction (plants)


Asexual reproduction

Asexual Reproduction

  • Reproduction that involves only one parent; parent and offspring have identical genetics

  • No special reproductive cells or organs used to create offspring

  • Occurs through mitosis and cytokinesis

  • Both single and multi-celled organisms, plants and simple animals can reproduce asexually

  • In multi-cellular organisms, the offspring develop from undifferentiated, unspecialized cells from the parent

  • Usually a rapid form of reproduction


Binary fission

Binary Fission

  • Simplest form of asexual reproduction

  • Parent divides into two approximately equal sized daughter cells

  • Bacteria: circular chromosome attaches to plasma membrane then replicates, cell wall separates each copy

  • Protozoa: eg. Amoeba become circular and use mitosis


Budding

Budding

  • New individuals develop from small outgrowths of the parent (buds)

  • May develop colonies (sponges) or break off to be individuals (hydra, yeast)

  • Some organisms can both bud and reproduce sexually


Spores

Spores

  • Specialized single cells that are released from the parent organism, germinate and grow by mitosis

  • New cells differentiate to form a new organism

  • Can reproduce quickly and in large quantities

  • Often have thick protective coats

  • Eg. Fungi, algae, protozoa


Regeneration

Regeneration

  • The ability to regrow lost body parts

  • Some animals can regrow entire new organisms from parts

  • Ability to regenerate decreases as organisms increase complexity

  • Even simple organisms that can regenerate entire organisms generally prefer to utilize a differentmethod to reproduce


Vegetative reproduction

Vegetative reproduction

  • MERISTEM: area on plant with unspecialized cells (cells that can become any kind of cell) that frequently divide using mitosis

  • Meristematic cells can be found in the vegetative structures of a plant (roots, stems, leaves)

  • Given proper treatment, meristem cells can reproduce mitoticlly then differentiate into new independent plants

  • Structures include bulbs, corms, tubers, runners, rhizomes

  • Can also be artificially propagated using cuttings, layerings or grafting


Reproduction

Bulb

  • short underground stem with thickened storage leaves

  • small new bulbs sprout from the old ones

  • Eg. onions, tulips


Reproduction

Corm

  • short underground stems with no fleshy leaves

  • Eg. gladiolas, crocuses


Tuber

Tuber

  • enlarged part of an underground stem that contains stored food

  • potatoes (eyes are tiny buds)


Runner

Runner

  • AKA stolon

  • is a stem that runs sideways and contains buds

  • Eg. strawberry


Rhizome

Rhizome

  • a stem that grows sideways under the ground

  • ferns, irises


Cutting

Cutting

  • a stem, root or leaf cutting used to make a new plant


Layering

Layering

  • part of a stem is bent and covered in soil

  • once it roots the original can be cut off

  • Eg. raspberries, roses


Grafting

Grafting

  • stem or bud removed from one plant and permanently joined to another plant

  • Eg. grapes and many seedless fruits


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