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1
Basic Structure of a Cell
copyright cmassengale
2
Review Facts Review Facts About Living About Living
ThingsThings
copyright cmassengale
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What Are the Main What Are the Main Characteristics of Characteristics of
organisms?organisms?1. Made of CELLS2. Require ENERGY (food)3. REPRODUCE4. Maintain HOMEOSTASIS5. RESPOND to environment6. GROW and DEVELOP7. RESPIRATION - exchange materials
with surroundings (water, wastes, gases)
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LEVELS OF ORGANIZATIONLEVELS OF ORGANIZATION
Nonliving Levels:
1.ATOM (element)
2.MOLECULE (compounds like
carbohydrates & proteins)
3.ORGANELLES (nucleus, ER, Golgi
…)
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LEVELS OF ORGANIZATIONLEVELS OF ORGANIZATION
Living Levels:
1.CELL (makes up ALL organisms)
2.TISSUE (cells working together
3.ORGAN (heart, brain, stomach …)
4.ORGAN SYSTEMS (respiratory, circulatory
…)
5.ORGANISM
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LEVELS OF ORGANIZATIONLEVELS OF ORGANIZATIONLiving Levels continued:1.POPULATION (one species in an area)2.COMMUNITY (several populations in
an area3.ECOSYSTEM (forest, prairie …)4.BIOME (Tundra, Tropical Rain forest…)5.BIOSPHERE (all living and nonliving
things on Earth)
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History of Cells & the History of Cells & the Cell TheoryCell Theory
Cell Specializationcopyright cmassengale
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First to View CellsFirst to View Cells• 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
copyright cmassengale
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First to View CellsFirst to View Cells•Hooke is
responsible for naming cells
•Hooke called them “CELLS” because they looked like the small rooms that monks lived in called Cells copyright cmassengale
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Anton van Leeuwenhoek
• In 1673, Leeuwenhoek (a Dutch microscope maker), was first to view organism (living things)
• Leeuwenhoek used a simple, handheld microscope to view pond water & scrapings from his teeth
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Beginning of the Cell Beginning of the Cell TheoryTheory
• In 1838, a German botanist named Matthias Schleiden concluded that all plants were made of cells
•Schleiden is a co-founder of the cell theory
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Beginning of the Cell Beginning of the Cell TheoryTheory
• In 1839, a German zoologist named Theodore Schwann concluded that all animals were made of cells
•Schwann also co-founded the cell theory
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Beginning of the Cell Beginning of the Cell TheoryTheory
• 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 divisioncopyright cmassengale
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CELL THEORY
•All living things are made of cells
•Cells are the basic unit of structure and function in an organism (basic unit of life)
•Cells come from the reproduction of existing cells (cell division)
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Number of CellsNumber of CellsAlthough 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.
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Multicellular OrganismsMulticellular Organisms• Cells in multicellular organisms
often specialize (take on different shapes & functions)
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Specialized Animal CellsMuscle cells Red blood cells
Cheek cells
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Specialized Plant Cells
Xylem cellsPollen
Stomata and Guard Cells
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Organization Organization Levels of LifeLevels of Life
Atoms to OrganismsAtoms to Organisms
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ATOMS MOLECULES ORGANELLES
Nonliving LevelsNonliving Levels
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CELLS – life starts here
TISSUES – Similar cells working together
Living LevelsLiving Levels
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ORGANSORGAN SYSTEMS ORGANISM
Different tissuesworking together
Different organsworking together
More Living LevelsMore Living Levels
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Simple or Complex Simple or Complex CellsCells
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Prokaryotes – The first Prokaryotes – The first CellsCells
• Cells that lack a nucleus or membrane-bound organelles
• Includes Archaea and Bacteria• Simplest type of cell• Single, circular chromosome
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Eukaryotes
• Cells that HAVE a nucleus and membrane-bound organelles
• Includes protists, fungi, plants, and animals
• These are more complex cells
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Eukaryotic Cell
Contain 3 basic cell structures:
•Nucleus•Cell Membrane•Cytoplasm with
organelles
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Two Main Types of Eukaryotic Cells
Plant Cell
Animal Cell
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Cell SizeQuestion:
Are the cells in an elephant bigger, smaller, or about the same size as those in a mouse?
About the same size, but …
The elephant has MANY MORE cells than a mouse!
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OrganellesOrganelles
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OrganellesOrganelles
•Very small (Microscopic)•Perform various functions for
a cell•Found in the cytoplasm•May or may not be
membrane-bound
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Animal Cell OrganellesAnimal Cell Organelles
NucleolusNucleus
Nuclear envelope
Ribosome (attached)Ribosome (free)
Cell Membrane
Rough endoplasmic reticulum
Golgi apparatus
Mitochondrion
Smooth endoplasmicreticulum
Centrioles
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Plant Cell OrganellesPlant Cell Organelles
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•Lies immediately against the cell wall in plant cells
•Pushes out against the cell wall to maintain cell shape
Cell Membrane in PlantsCell Membrane in PlantsCell membrane
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•Nonliving layer•Found in plants, fungi, & bacteria
•Made of cellulose in plants
•Made of peptidoglycan in bacteria
•Made of chitin in Fungi
Cell wallCell WallCell Wall
copyright cmassengale
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Cell WallCell Wall• Supports and
protects cell• Found outside of
the cell membrane
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•Jelly-like substance enclosed by cell membrane
•Provides a medium for chemical reactions to take place
Cytoplasm of a Cytoplasm of a Cell Cell
cytoplasm
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•Contains organelles to carry out specific jobs
•Found in ALL cells
More on CytoplasmMore on Cytoplasmcytoplasm
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•Controls the normal activities of the cell
•Contains the DNA in chromosomes
•Bounded by a nuclear envelope (membrane) with pores
•Usually the largest organelle
The Control Organelle - The Control Organelle - NucleusNucleus
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•Each cell has fixed number of chromosomes that carry genes
•Genes control cell characteristics
Nucleus
More on the More on the NucleusNucleus
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Inside the Nucleus -The genetic material (DNA) is
found
DNA is spread out And appears as
CHROMATINin non-dividing cells
DNA is condensed & wrapped around proteins forming
as CHROMOSOMES in dividing cells
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What Does DNA do?What Does DNA do?DNA is the hereditary
material of the cell
Genes that make up the DNA molecule code for different proteins
copyright cmassengale
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Nucleolus
• Inside nucleusInside nucleus• Cell may have Cell may have 1 1
to 3to 3 nucleoli nucleoli• DisappearsDisappears
when cell when cell dividesdivides
• Makes Makes ribosomesribosomes that that make proteinsmake proteins
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CytoskeletonCytoskeleton• Helps cell maintain
cell shape• Also help move
organelles around• Made of proteins• Microfilaments are
threadlike & made of ACTIN
• Microtubules are tubelike & made of TUBULIN
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CytoskeletonCytoskeleton
MICROTUBULES
MICROFILAMENTS
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CentriolesCentrioles• Found only in animal
cells• Paired structures
near nucleus• Made of bundle of
microtubules• Appear during cell
division forming mitotic spindle
• Help to pull chromosome pairs apart to opposite ends of the cell
copyright cmassengale
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Centrioles & the Mitotic Centrioles & the Mitotic SpindleSpindle
Made of MICROTUBULES (Tubulin)
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MitochondrionMitochondrion(plural = mitochondria)(plural = mitochondria)
• “Powerhouse” of the cell
• Generate cellular energy (ATP)
• More active cells like muscle cells have MORE mitochondria
• Both plants & animal cells have mitochondria
• Site of CELLULAR RESPIRATION (burning glucose)
copyright cmassengale
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MITOCHONDRIASurrounded by a
DOUBLE membrane
Folded inner membrane called CRISTAE (increases surface areafor more chemical Reactions)
Has its own DNA
Interior called MATRIXcopyright cmassengale
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Interesting Fact ---Interesting Fact ---
• Mitochondria Come from cytoplasm in the EGG cell during fertilization
Therefore …• You inherit your
mitochondria from your mother!copyright cmassengale
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Rod shape
Cell PowerhouseCell Powerhouse
Mitochondrion( mitochondria )
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What do mitochondria What do mitochondria do?do?
Burns glucose to release energy (ATP)
Stores energy as ATP
“Power plant” of the cell
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Endoplasmic Reticulum - EREndoplasmic Reticulum - ER
Two kinds of ER ---ROUGH & SMOOTH
• Network of hollow membrane tubules• Connects to nuclear envelope & cell
membrane• Functions in Synthesis of cell products
& Transport
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Rough Endoplasmic Reticulum Rough Endoplasmic Reticulum (Rough ER)(Rough ER)
• Has ribosomes on its surface
• Makes membrane proteins and proteins for EXPORT out of cell
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Rough Endoplasmic Rough Endoplasmic Reticulum (Rough ER)Reticulum (Rough ER)
• Proteins are made by ribosomes on ER surface
• They are then threaded into the interior of the Rough ER to be modified and transported
copyright cmassengale
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Smooth Endoplasmic Smooth Endoplasmic ReticulumReticulum
• Smooth ER lacks ribosomes on its surface
• Is attached to the ends of rough ER
• Makes cell products that are USED INSIDE the cell
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Functions of the Smooth Functions of the Smooth ERER• Makes membrane
lipids (steroids)• Regulates calcium
(muscle cells)• Destroys toxic
substances (Liver)
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RibosomesRibosomes• Made of PROTEINS and rRNA• “Protein factories” for cell• Join amino acids to make proteins• Process called protein synthesis
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RibosomesRibosomes
Can be attached to Rough ER
OR
Be free (unattached
) in the cytoplasm
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Golgi BodiesGolgi Bodies• Stacks of Stacks of flattened flattened
sacssacs• Have a shipping side Have a shipping side
((trans facetrans face) and ) and receiving side (receiving side (cis cis faceface))
• Receive Receive proteinsproteins made by ERmade by ER
• Transport vesiclesTransport vesicles with modified with modified proteins pinch off the proteins pinch off the endsends
Transport
vesicle
CIS
TRANS
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Golgi BodiesGolgi BodiesLook like a stack of pancakes
Modify, sort, & packagemolecules from ERfor storage OR transport out of cell
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GolgiGolgi
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Golgi AnimationGolgi Animation
Materials are transported from Rough ER to Golgi to the cell membrane by
VESICLEScopyright cmassengale
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LysosomesLysosomes• Contain Contain digestive digestive
enzymesenzymes• Break down Break down food, food,
bacteria,bacteria, and and worn out worn out cell partscell parts for cells for cells
• Programmed forProgrammed for cell cell death (AUTOLYSIS)death (AUTOLYSIS)
• Lyse (break open) & Lyse (break open) & release enzymesrelease enzymes to to break down & recycle break down & recycle cell parts)cell parts)
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Lysosome DigestionLysosome Digestion
• Cells take in food by phagocytosis
• Lysosomes digest the food & get rid of wastes
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Cilia & FlagellaCilia & Flagella
• Made of protein tubes called microtubules
• Microtubules arranged (9 + 2 arrangement)
• Function in moving cells, in moving fluids, or in small particles across the cell surface
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Cilia & FlagellaCilia & Flagella
• Cilia are shorter and more numerous on cells
• Flagella are longer and fewer (usually 1-3) on cells
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Cell Movement with Cilia Cell Movement with Cilia & Flagella& Flagella
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Cilia Moving Away Dust Particles Cilia Moving Away Dust Particles from the Lungsfrom the Lungs
Respiratory SystemRespiratory System
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VacuolesVacuoles• Fluid filled sacks for storage• Small or absent in animal cells• Plant cells have a large Central Vacuole• No vacuoles in bacterial cells
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VacuolesVacuoles
• In plants, they store Cell Sap
• Includes storage of sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes
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Contractile Contractile VacuoleVacuole
• Found in unicellular protists like paramecia
• Regulate water intake by pumping out excess (homeostasis)
• Keeps the cell from lysing (bursting)
Contractile vacuole animation
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ChloroplastsChloroplasts• Found only in producers (organisms
containing chlorophyll)• Use energy from sunlight to make
own food (glucose)• Energy from sun stored in the
Chemical Bonds of Sugars
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ChloroplastsChloroplasts• Surrounded by DOUBLE
membrane• Outer membrane smooth• Inner membrane
modified into sacs called Thylakoids
• Thylakoids in stacks called Grana & interconnected
• Stroma – gel like material surrounding thylakoids
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ChloroplastsChloroplasts
• Contains its own DNA
• Contains enzymes & pigments for Photosynthesis
• Never in animal or bacterial cells
• Photosynthesis – food making process
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Factors Affecting Cell Size
• Surface area (plasma membrane surface) is determined by multiplying length times width (L x W)
• Volume of a cell is determined by multiplying length times width times height (L x W x H)
• Therefore, Volume increases FASTER than the surface area
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Cell Size•When the surface area is no
longer great enough to get rid of all the wastes and to get in enough food and water, then the cell must divide
•Therefore, the cells of an organism are close in size
copyright cmassengale
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Cell SizeQuestion:
Are the cells in an elephant bigger, smaller, or about the same size as those in a mouse?
About the same size, but …
The elephant has MANY MORE cells than a mouse!
copyright cmassengale
78copyright cmassengale