a tour of the cell. anton van leeuwenhoek (1600’s) credit for the first microscope looked at pond...
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A Tour of the Cell
• Anton Van Leeuwenhoek (1600’s)
• Credit for the first microscope
• Looked at pond water and saw “wee beasties”
Robert Hooke• Observed plant
stems, wood, and cork (1600’s)
• Saw all the tiny chambers and called them CELLS
• What cell part did Hooke observe?
• Cell Wall
Robert Brown (1833)
• Observed that cells had a dark structure within plant cells
• Brown observed the nucleus and stated that all cells have nuclei (at this time no one knew that the nucleus has DNA)
Matthias Schleiden (1838)• Stated that all plants
are made of Cells
• Made many observations of plants around the area
Theodor Schwann (1839)• Stated that all animals are made of
Cells
• Observed many animal tissues
Rudolf Virchow (1855)• Stated that all cells come from pre-
existing cells• Cells arise from the division of pre-
existing cells
The Cell Theory
Microscopes Provide the Windows to the World of the Cell
The Cell Theory• All living things are
composed of cells
• Cells are the basic unit of structure and function in living things
• All cells come from pre-existing cells
A Prokaryotic Cell
Figure 7.1 The size range of cells
The SizeRange ofCells
Cell SizesAverage Animal Cell – 15 microns
Average Plant Cell – 40 microns
Average Eukaryotic Cell :10-100 microns
Average Prokaryotic Cell: 1-10 microns
An Electron Microscope
Geometric Relationships Explain Why Most Cells Are Microscopic
Overview of an Animal Cell
Human Cheek Cells
Overview of a Plant Cell
Onion Epithelial Cells
Animal Cell’s Cell Membrane
Cell or Plasma Membrane
•“Fluid Mosaic” Model• Lipid Bilayer (made of phospholipids)•Proteins embedded throughout•Semi-permeable or Selectively Permeable
Cell Wall• provides support to the
perimeter of plant cells, some protists, and bacterial cells
The Plasma Membrane
The Nucleus and Its Envelope
Nuclear Envelope/Membrane
•Double Membrane that surrounds the nucleus•Lined with pores•Supported by nuclear lamina
Nucleolus•Inside the nucleus•Site of ribosome and rRNA synthesis
Ribosomes
Endoplasmic Reticulum (ER)
Endoplasmic Reticulum(ER)
•Rough ER •Intercellular transport of materials, particularly proteins; site where proteins leave ribosomes and are chemically modified
Smooth ER• breaks down toxic substances, • regulates Ca levels, • synthesizes steroids and other lipids
The Golgi Apparatus
Golgi Apparatus•Modifies proteins and other substances from the ER for export from the cell
Lysosomes
Lysosomes•Digest cellular waste and foreign substances•Breakdown of lipids, carbohydrates, and proteins
The Formation and Functions of Lysosomes
Plasma membrane expandsby fusion of vesicles; proteinsare secreted from cell
Transport vesicle carriesproteins to plasma membrane for secretion
Lysosome availablefor fusion with anothervesicle for digestion
4 5 6
Nuclear envelope isconnected to rough ER, which is also continuous
with smooth ER
Nucleus
Rough ER
Smooth ERcis Golgi
trans Golgi
Membranes and proteinsproduced by the ER flow in
the form of transport vesiclesto the Golgi
Nuclear envelop
Golgi pinches off transport Vesicles and other vesicles
that give rise to lysosomes and Vacuoles
1
3
2
Plasmamembrane
• Relationships among organelles of the endomembrane system
Figure 6.16
Peroxisomes•Contain an assortment of enzymes that perform such roles as detoxification of alcohol, breaking down of fatty acids•Produces H2O2 in the process
Peroxisomes
The Chloroplast, Site of Photosynthesis
Plastids•May be called chromoplasts or leukoplasts•Store starch, fat or contain pigments suchas chlorophyll or carotenoids to capture energy from the sun
The Mitochondrion
MitochondrionSite of cellular respirationand synthesis of ATP,a source of chemical energy for the cell
The Plant Cell Vacuole
Vacuoles•Store water, salts, proteins, carbohydrates, or enzymes
The Cytoskeleton
Cytoskeleton•Protein strands that give the cell its shape and size•Helps organize the location of organelles and their activities
There are three main typesof fibers the make up the cytoskeleton: 1) Microtubules 2) Microfilaments 3) Intermediate Filaments
Microtubules•Are made of the protein tubulin•Shape and support the cell•Are responsible for the separation of chromosomes during cell division
Centrosome Containing a Pair of Centrioles
Centrioles•Appear during mitosis in animal cells; are composedof nine sets of triplet microtubules in a ring
Centrosome•Area from which the centrioles radiate during mitosis
Figure 7.24 Ultrastructure of a eukaryotic flagellum or cilium
Ultrastructure of a Cilium or flagellum
Cilia and Flagella•In eukaryotes, a specializedarrangement (“9 + 2”) of microtubules is responsible for the beating of flagella and cilia•The protein, dynein, is responsible for the movement
How Dynein “WalkingMoves Cilia and Flagella
A Comparison of the Beating of Flagella and Cilia
The microtubule assembly of a cilium or flagellum is anchored in the cell by a Basal Body, which is structurally identical to a centriole.
Sea Urchin Sperm
Microfilaments and Motility
Microfilaments also aid in •Cell motility (Ex: pseudopodia)•Cell division (cleavage furrowformation)•Cytoplasmic Streaming
A Structural Role of Microfilaments
Microfilaments•Made of the protein actin •Located in the cytoplasm of most eukaryotic cells•Works with myosin to cause muscle cell contractions
Intermediate Filaments
•Anchor nucleus and other organelles•Reinforces cell shape •Make up nuclear lamina that lines the interior of the nuclear envelope
Plant Cell Walls
Intercellular Junctions in Animal Tissues
Extracellular matrix (ECM)
1)What are the two major
types of electron microscopes?
2) All cells are classified as
either _______ or _____.
3) Under the microscope, bacteria are typically measured in ___________ (units).
4) Two similarities between plant and animal cells are. . .. two differences are . . ..
5) The term used to describe the fact that the cell membrane allows some materials in and keeps others out is. . .
6) The lipid bilayer of the cell membrane is made of:
1)The organelle that packages proteins for export from the cell is the . . .
2) Cellular respiration occurs in the ___________ and energy is made in the form of ________.
3) The major difference between a prokaryotic and eukaryotic cell is that a prokaryotic cell lacks a/an:
4) The oldest cells on earth are ______ cells. They evolved . . . . years ago.
What characteristic of the cell membrane allows some molecules into the cell and keeps other out?
The primary purpose of the cellwall is..
The cell membrane is composed primarily of. .
Why is the cell membrane referred to as a “fluid mosaicmodel”?
Since some molecules can passthrough the cell membrane and others cannot it is termed. .
If a molecule is too big to get through the cell membrane, it mustenter through _________ channels.
The centers of protein synthesis in the cell are the _________.
Describe the role of the cytoskeleton in the cell.
Name two different things stored by vacuoles.
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