introduction to cells intro to cells - phsbio2201 -...
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Intro to Cells
Key Concept: Cells are the basic unit of life.
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Introduction to CellsCells are the basic units of organismsCells can only be observed under microscope
Basic types of cells:
Animal Cell Plant Cell Bacterial Cell
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Cell Theory
The cell theory grew out of the work of many scientists and improvements in the microscope.
3 principles of the Cell Theory:
1. The cell is the basic unit of life.
2. All living things are made of cells.
3. All cells are made from other living cells.
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Scientists who contributed to cell theory
• Hooke: first to identify cells & name them
• Leeuwenhoek: developed better lenses for microscope
• Schleiden: said that plants were made of cells
• Schwann: said that animals were made of cells
• Virchow: said that all cells come from other living cells (all cells reproduce)
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All Cells:
• Microscopic
• Enclosed by a membrane
• Filled with cytoplasm
• Have DNA
Bacterium(colored SEM; magnification 8800x)
cell membrane
cytoplasm
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There are 2 types of cells:
1. Prokaryotic Cells
2.Eukaryotic Cells
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� Prokaryotes include bacteria & lack a nucleus or membrane-bound structures called organelles (“Pro = no”)
�Eukaryotes include most other cells & have a nucleus and membrane-bound organelles (“Euk has a nuk”)
Cells May be Prokaryotic or Eukaryotic
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Prokaryotes (bacteria)•No nucleus or organelles
•Has a Cell membrane & cell wall
• Contain ribosomes (no membrane) to make proteins in their cytoplasm
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Two Main Types of Eukaryotic Cells
Plant Cell Animal Cell10
Number of CellsOrganisms may be:• Unicellular –composed of one cell (prok & euk)• Multicellular-composed of many cells that are organized (euk only)
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Eukaryotic Cell
Contain 3 basic cell structures:
• Cell Membrane
• Nucleus
• Cytoplasm with organelles
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Basic Structure of a Cell
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• Outer covering of cell
• Made of protein and phospholipids
• Selectively permeable---
Cell membrane
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Controls the normal activities of the cell
Bound by a nuclear membrane (function?)
Contains chromosomes
Nucleus
Each cell has fixed number of chromosomes that carry genes that give the cell its characteristics
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Nucleolus
Inside the nucleus; makes ribosomes16
Jelly-like substance enclosed by cell membrane
Provides a medium for chemical reactions to take place
Cytoplasm
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Organelles
Very small size
Can only be observed under a microscope
Have specific functions
Found throughout cytoplasm
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Organelles Found in ALL Eukaryotic Cells
Examples of Organelles include:
Endoplasmic reticulum, Ribosomes, Nucleolus, Golgi Bodies, Lysosomes, Mitochondria, Vacuoles, Chloroplasts,
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Endoplasmic Reticulum: internal membrane system (“highway”)
Smooth ER lacks ribosomes & makes lipids & carbohydrates
Rough ER has ribosomes on its surface which make proteins to EXPORT
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Ribosomes• Make proteins to be used inside the
cell, while others leave the cell• Some are attached to the Rough ER
while others float freely in the cytoplasm
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Golgi Bodies
Process, Sort, & Deliver proteins
(Modifies/Packages/Transports) 22
Lysosome
digests & gets rid of wastes or foreign materials like bacteria/viruses; recycles
worn-out cell parts
*not found in plant cells*
VESICLES• Small sacs that transport
materials from place to place
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*Rod shape*Site of Cellular respiration*has its own DNA
Mitochondrion( mitochondria )
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*Burn sugars to produce energy (ATP)*Active cells like muscles have more mitochondria
Mitochondria
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Vacuoles• Used to store
food and water• There are
many, small vacuoles in animals cells only; only one large one in plant cells
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Cytoskeleton• Framework/structure of cell• Movement of parts of cell• 2 parts:
– Microtubules—thick tubes; make up centrioles
– Microfilaments—thin tubes; make up cilia & flagella
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Special Cell Structures
• Cilia—short, hair-like projections; used for movement (locomotion)
• Flagella—long, whip-like projection; moves organism/cell in one direction
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Organelles found in PLANT cells
only
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• Contain the green pigment chlorophyll
• Converts light energy into chemical energy (glucose)
• Process called photosynthesis
Chloroplast
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• Have a large central vacuole
• Stores sugars, proteins, minerals, wastes, & pigments
Vacuole
Plant Cell
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• Protects
• Gives shape to cell
• Made of cellulose
– Strong and rigid– Found in plant, fungi, and bacteria
• Freely permeable
Cell wall
Plant Cell
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Organelles found in ANIMAL cells
only
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mitochondrion
nucleus
glycogen
granule
cell
membrane
cytoplasm Animal cell
No cell wall or chloroplastStores glycogen in the cytoplasm for food energy
vacuole
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Animal Cell Organelles
• Help cell divide• Near the nucleus• Paired structures
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Different kinds of plant cells
Onion Epidermal Cells
Root Hair Cell
root hair
Guard Cells
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Different kinds of animal cells
white blood cell
red blood cell
cheek cellssperm
nerve cell
muscle cell
Amoeba
Paramecium 38
Similarities between plant cells and animal cells
Both have a cell membrane surrounding the cytoplasm
Both eukaryotic
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Differences between plant cells and animal cells
Animal cells Plant cells
Relatively smaller in size
Irregular shape
No cell wall
Relatively larger in size
Regular shape
Cell wall present
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Animal cells Plant cells
Vacuole small or absent
Glycogen as food storage
Centrioles present
Large central vacuole
Starch as food storage
Centrioles absent
Differences between Plant Cells and Animal Cells
Cell Song Video
https://www.youtube.com/watch/?v=rABKB5aS
2Zg
Animal Cell DiagramLETTER NAME OF ORGANELLE
A CELL MEMBRANE
B CYTOPLASM
C NUCLEUS
D NUCLEOLUS
G RIBOSOMES
H MITOCHONDRIA
I NUCLEAR ENVELOPE OR MEMBRANE
J1 ROUGH ENDOPLASMIC RETICULUM
J2 SMOOTH ENDOPLASMIC RETICULUM
K GOLGI APPARATUS
L LYSOSOME
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Plant Cell DiagramLETTER NAME OF ORGANELLE
A CELL WALL
C CYTOPLASM
E RIBOSOME
F1 ROUGH ENDOPLASMIC RETICULUM
F2 SMOOTH ENDOPLASMIC RETICULUM
G MITOCHONDRIA
H CHLOROPLAST
M GOLGI APPARATUS
N NUCLEUS
J CENTRAL VACUOLE
B CELL MEMBRANE