cells: basic structures & functions
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Cells: Basic Structures & Functions. Historical Timeline of The Cell and Development of The Cell Theory. Hooke observes dead plant cells under a microscope and names them “cells”. Virchow, german medical doctor, looks at cells dividng under a microscope. Leeuwenhooke first to look at - PowerPoint PPT PresentationTRANSCRIPT
Cells: Basic Structures & Functions
Historical Timeline of The Cell and Development of The Cell Theory
Early 1600’s
1665 1670
1838
1839
1855
Invention of the microscope
Hooke observes dead plant cells
under a microscope and nam
es them
“cells”
Leeuwenhooke first to look at
living things through am
icroscope
Schleiden, a botanist, concludesthat all plants m
ust be made
of cells.
Schwann, a zoologist, concludes
the same about anim
als, allm
ust be made of cells.
Virchow, germ
an medical doctor,
looks at cells dividng undera m
icroscope.
In 1665, Robert Hooke used a microscope to examine a thin slice of cork (dead plant cell walls).
What he saw looked like small boxes.
Hooke is responsible for naming cells.
Hooke called them “CELLS” because they looked like the small rooms that monks lived in called Cells.
Anton van Leeuwenhoek In 1673, Leeuwenhoek (a Dutch microscope
maker), was first to view organisms (living things) in pond water.
Leeuwenhoek used a simple, handheld microscope to view pond water & scrapings from his teeth
Cell Theory Nearly a century after Hooke’s
findings, several other scientist’s discoveries led to the formation of the cell theory.
Beginning of the Cell Theory In 1838, a German
botanist named Matthias Schleiden concluded that all plants were made of cells
Schleiden is a cofounder of the cell theory
In 1839, a German zoologist named Theodore Schwann concluded that all animals were made of cells
Schwann also cofounded the cell theory
In 1855, a German medical doctor named Rudolph Virchow observed, under the microscope, cells dividing
He reasoned that all cells come from other pre-existing cells by cell division
CELL THEORY IS FORMED All living things are made of cells
Cells are the basic unit of structure and function in all living organisms (basic unit of life)
Cells come from the reproduction of existing cells (cell division)
Discoveries Since the Cell Theory In 1970, American biologist,
Lynn Margulis, provided evidence that some organelles within cells were at one time free living cells themselves
Supporting evidence included organelles with their own DNA
Chloroplast and Mitochondria
Simple or Complex Cells
Although ALL living things are made of cells, organisms may be:
Unicellular – composed of one cell Multicellular- composed of many cells
that may organize into tissues, etc.
Types of Cells Living organisms are made of either
prokaryotic or eukaryotic cells – the two major kinds of cells which can be distinguished by structural organization
Prokaryotes – The first Cells Cells that lack a nucleus or membrane-
bound organelles Includes bacteria Simplest type of cell Single, circular chromosome
No nucleus, DNA scattered through center of the cell.
Surrounded by cell membrane & cell wall made of (peptidoglycan)
Contain ribosomes (no membrane) in their
cytoplasm to make proteins
Examples of bacteria:
E.coli, Streptococcus
Eukaryotes Cells that HAVE a true nucleus and
membrane-bound organelles
Includes protists, fungi, plants, and animals
More complex type of cells
Eukaryotes contain 3 basic cell structures:
Nucleus
Cell Membrane
Cytoplasm with organelles
Two Main Types of Eukaryotic Cells
Plant Cell
Animal Cell
Cell Boundaries
Cell Wall Outer boundary in bacteria, plant and
fungi cells NOT found in animal cells Primary function: provide support and
structure
Plasma Membrane
Also call the cell membrane Found in ALL cells Primary function: maintain
homeostatsis Provides protection from environment Regulates exchange with the
environment Selectively permeable
Controls what enters and what does not
Plasma MembraneComposed of 3 Biomolecules:1. Lipids
Phospholipids make up the phospholipid bilayer Hydrophillic head and hydrophobic tails Two phospholipids orient themselves tail to tail
to form the phospholipid bilayer Cholesterol
Found in plasma membrane of animal cells Provides stabilization
Plasma Membrane
2. Carbohydrates “ID tags” to identify cells
3. Proteins Embedded in the phospholipid bilayer Function: serve as channels and pumps
for transport in and out of cell
Plasma Membrane
Plasma Membrane