Cell structure chapter 3
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Cell Structure Chapter 3. By Mr. Kling. Cell - The smallest unit capable of carrying out all the functions of life . Examples of Cells. Amoeba Proteus. Plant Stem. Bacteria. Red Blood Cell. Nerve Cell. Discovery of the Cell.

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Cell Structure Chapter 3

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Cell StructureChapter 3

By

Mr. Kling


  • Cell- The smallest unit capable of carrying out all the functions of life.


Examples of Cells

Amoeba Proteus

Plant Stem

Bacteria

Red Blood Cell

Nerve Cell


Discovery of the Cell

  • The English scientist RobertHooke used one of the first microscopes to observe a thin slice of cork in 1665. He saw a lot of little boxes, which reminded him of the small rooms where monks lived. He called then cells.

  • In 1675, the Dutchscientist Anton van Leeuwenhoek used a microscope to look at a sample of clear pond water and saw single celled organisms.


Formation of The Cell Theory

  • In 1838, a Germanbotanist,MatthiasSchleidenconcluded that all plants were entirely composed of cells.

  • In 1839, the German zoologist TheodorSchwannconcluded that animals were entirely composed of cells.

  • In 1855, the German physician RudolphVirchow determined (while studying how disease affects living things) that cells only come from other cells.

  • These 3 scientists are credited, together, as creating the cell theory.


The Cell Theory

  • All living things are composed of 1 or more cells.

  • In organisms, cells are the basicunitsof structure and function.

  • Cells come only from existing cells.


History of Cells

  • The first cells had no separate, internal parts (organelles). They are called prokaryotes.

  • These were the only living things to exist for the first 2 billion years on Earth.

  • Prokaryotes are the mostcommon type of cells on Earth.

  • Prokaryotes are very small (1-15 um).

  • Example: bacteria


History of Cells

  • About 1.5 billion years ago, cells developed a nucleus and other membrane-bound cell parts (organelles). The cells are called eukaryotes.

  • Eukaryotes can be larger (2-2,000 um).

  • Early eukaryotes were single-celled (unicellular).

  • Eventually, many eukaryotic cells joined together and formed multicellular (many celled) organisms.

  • Each cell is able to specializein certain activities.

  • Examples: nerve cells carry messages muscle cells contract the outside of the cell membrane.


Two Types of Cells

  • Prokaryotic

  • Eukaryotic


Prokaryotic

  • Do not have structures surrounded by membranes

  • Few internal structures

  • One-celled organisms, Bacteria

http://library.thinkquest.org/C004535/prokaryotic_cells.html


Eukaryotic

  • Contain organelles surrounded by membranes

  • Most living organisms

Plant

Animal

http://library.thinkquest.org/C004535/eukaryotic_cells.html


Cell Size

  • Cells must be small.

  • There are approximately 100 trillion (100,000,000,000,000) cells in the human body.


Why are cells so small?

  • Surface-to-Volume ratio

    • Food, water, oxygen, and other materials must enter through the surface. Waste products must leave through the surface.

    • As a cell grows, its volume increases morerapidly than its surface area does.

    • As a cell size increases, it takes longer for information and materials to reach their destination. Small cells are more efficient.


Eukaryotic Cell Parts (Organelles)

  • Animal Cell Parts

  • Cell Membrane- The outer bilipid boundary of a cell. Also called the plasma membrane.

  • Cytoplasm- The jelly-like fluid in a cell.

  • Ribosomes- Site of protein synthesis.

  • Endoplasmic Reticulum- A folded membrane system used for a molecular transport in the cell. There are 2 types of ER, smooth and rough. Rough ER has lots of ribosomes.

  • Golgi Apparatus- Secretes waste products.

  • Mitochondria- Site of aerobic respiration in cells.

  • The energy distribution center of the cell.

  • Lysosomes- Site of the cellular digestion.

  • Microtubules- Long, slender, tube-shaped organelles that help give the cell shape and support.


Animal Cell Parts (continued)

  • Microfilaments- Fine, threadlike organelles that help give the cell shape and support.

  • Cilia- Hair-like structures on the outside of the cell that help the cell move. Example: The cilia that surround a paramecium.

  • Flagella- Hair-like structure that helps the cell move. Example: The tail of a sperm cell.

  • Nucleus- Contains most of the cell’s DNA.

  • Nuclear Envelope- The membrane that surrounds the nucleus.

  • Chromatin- The DNA and proteins in the nucleus of a nondividing cell.

  • Chromosome- DNA in a coiled, rod-shaped form that occurs during cell division.

  • Nucleolus- Site in the nucleus where ribosomes are created.


Plant Cell Parts

  • Plant cells have all the parts of animal cell, plus a few more.

    • The additions:

      • Cell Wall- A strong, rigid layer on the outside of the cell membrane.

      • Vacuoles- A fluid-filled cavity that stores waste products. In a mature plant cell, the vacuole typically takes up 90% of the volume.

      • Plastids- An organelle in which food or pigments are stored. There are 3 types:

        • Chloroplasts- Contain chlorophyll.

        • Chromoplasts- Contain orange carotenes, yellow xanthophylls, and various red pigments.

        • Leucoplasts- Store food such as starches, proteins and lipids. Especially common in potato tubers.


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