Biology

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PATTERNS IN NATURE – Summary Notes

1. ORGANISMS ARE MADE OF CELLS THAT HAVE SIMILAR STRUCTURAL CHARACTERISTICS

1.1 Outline the historical development of the cell theory, in particular, the contributions of Robert Hooke and Robert Brown

The Cell Theory states that:
All living things are made of cells (Theodor Schwann & Matthias Schleiden) Cells are the basic structural and functional unit of organisms (Theodor Schwann) All cells come from pre-existing cells (Rudolf Virchow)

The historical development of the cell theory:
1485 – Leonardo Da Vinci used glass lenses to study small objects 1600 – the first compound microscope was made by Hans and Zacharias Janssen 1665 – Robert Hooke observed cork cells using a compound microscope and described ‘cells distinct from one another’ 1676 – Anton von Leeuwenhoek described unicellular organisms in pond water 1831 – Robert Brown – observed the nucleus in plant and animal cells 1839 – Schleiden and Schwann formulated the cell theory that all living things are made up of cells. Schwann was the first scientist to see yeast cells producing new cells 1858 – Virchow stated that where a cell exists, there must be pre-existing cells 1880 – Walter Flemming described cell division from observations on living and stained cells

1.2 Describe evidence to support the cell theory
The evidence supporting the cell theory accumulated over a period of 600 years as the technology developed. The use of microscopic lenses to study living matter eventually provided enough data to establish the cell theory. Little boxes distinct from one another (‘cells’) seen by Robert Hooke in 1665 Living microorganisms in pond water seen under the microscope (1676) It was suggested that all organisms are made of cells (1824) The nucleus in plant cells described by Robert Brown (1827)

More evidence accumulated for the idea that all organisms are made of cells. This included seeing yeast cells budding and producing new cells. From then the cell was regarded as the building blocks of life (1838) In the twentieth century the Cell Theory was supported by the identification of call structures and their functions and the discovery of cellular mechanisms and processes.

1.3 Discuss the significance of technological advances to developments in the cell theory Improvements in the microscope have enabled us to see the cell better and learn more about and develop the cell theory For example the development of the light microscope enabled Hooke to see that living things were made up of cells Biological stains used to view cells dividing, verifying the way cells reproduced

1.4 Identify cell organelles seen with current light and electron microscopes LIGHT MICROSCOPE
ELECTRON MICROSCOPE
Nucleus
Mitochondria
Chloroplast
Endoplasmic Reticulum
Vacuole
Ribosomes
Cell wall/ membrane
Lysosomes

1.5 Describe the relationship between the structure of cell organelles and their function ORGANELLE
FUNCTION
Cell
the basic unit of all living things, mage up of protoplasm (cytoplasm and a nucleus) surrounded by a cell membrane and, in plants and some organisms, a cell wall Cell membrane
the boundary surrounding the cell that controls what enters and leaves the cell. Cell wall
(not present in animal cells) gives the cell strength and a strong structure. It is made of layers of cellulose fibers interspersed with other carbohydrates. Centriole
an organelle present in animal cells, responsible for forming fibers called the spindle during cell division Chlorophyll
green pigment found in all green plant cells, responsible for light capture in photosynthesis Chloroplasts
organelles found in plant cells containing chlorophyll. Chloroplasts make glucose for the plant through photosynthesis Endoplasmic Reticulum
a system of parallel membranes running through the cell the transports material through the cell. The rough endoplasmic reticulum is covered with ribosomes that create proteins Golgi Body
apparatus for...
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