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CellsObjectives:•List scientists who contributed to the cell theory •List the components of the cell theory •Compare prokaryote and eukaryote cells •Label a plant and an animal cell •Know the functions of cell organelles
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LEVELS OF ORGANIZATIONLEVELS OF ORGANIZATION
Nonliving Levels:
ATOM (element)
MOLECULE (compounds like
carbohydrates & proteins)
ORGANELLES (nucleus, ER, Golgi …)
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LEVELS OF ORGANIZATIONLEVELS OF ORGANIZATION
Living Levels:
CELL (makes up ALL organisms)
TISSUE (cells working together
ORGAN (heart, brain, stomach …)
ORGAN SYSTEMS (respiratory, circulatory …)
ORGANISM (living individual)
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LEVELS OF ORGANIZATIONLEVELS OF ORGANIZATION
Living Levels continued:
POPULATION (one species in an area)
COMMUNITY (several populations in an area
ECOSYSTEM (forest, prairie …)
BIOME (Tundra, Tropical Rain forest…)
BIOSPHERE (all living and nonliving things on Earth)
Early Contributions
Robert Hooke - First person to see cells and give them their name, he was looking at cork and noted that he saw "a great many boxes” that looked like the cells that monks lived in. (1665)
Anton van Leeuwenhoek - Observed first living cells in pond water and scrapings from his teeth, which he called "animalcules" (1673)
Early Contributionso Theodore Schwann - zoologist who observed tissues
of animals and concluded they had cells. Also the cofounder of the Cell Theory (1839)
o Mattias Schleiden - botanist, observed tissues of plants and said they contained cells. Also the cofounder of the Cell Theory ( 1845)
o Rudolf Virchow – observed under the microscope, cells dividing and concluded that cells come from pre-existing cells and that all living things are made of cells (1850 )
The Cell Theory
1. Every living organism is made of one or more cells.
2. The cell is the basic unit of structure and function. It is the smallest unit that can perform life functions.
3. All cells arise from pre-existing cells. * Why is the Cell
Theory called a Theory and not a Fact?
Cell Features
ALL cells have these parts
Ribosomes- make protein for use by the organism
Cytoplasm- fluid material within cell
DNA- genetic material
Cytoskeleton- internal framework of cell
Cell Membrane- outer boundary, some things can cross the cell membrane
Comprehension Checkpoint
Answer true or false
1. Robert Hooke was the first person to see cells.
2. Bacteria cells have a cell membrane.
3. The Cell Theory was developed by a single scientist.
4. Plant cells have cytoplasm
5. Cells taken from fungi do not have DNA.
6. Cells can only come from pre-existing cells.
7. It only took five years to develop the Cell Theory.
Prokaryote Cells The first cells to inhabit the earth Simple cells Only example: Bacteria These cells do NOT have a nucleus, their DNA is circular and
floats in the cytoplasm Nucleoid region (center) contains the DNA Surrounded by cell membrane & cell wall
(peptidoglycan) Contain ribosomes in their cytoplasm to make proteins
Some bacteria have a tail-like structure called a flagella, that helps it to move
A capsule surrounds some bacteria and helps them avoid the body’s immune system
pilliDNA
Ribosomes
Cell membraneCell wall
Bacterial Images
Bacteria that causes Anthrax
Eukaryotic Cells True Cells
Complex
Cells found in plants, animals, protists and fungi
The cell is composed of 4 main parts:
1. Cell membrane
2. Cytoplasm (cytosol and organelles, except nucleus)
3. Nucleus- “control center” of cell, houses DNA
4. Membrane Bound Organelles- small structures that carry out specific functions (“little organs”). Shape determines function.
Other VocabProtoplasm (nucleus and cytoplasm)
Cytosol (fluid part of cytoplasm)
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Two Main Types of Eukaryotic Cells
Plant Cell
Animal Cell
Cheek Cells Seen Through Microscope
Nucleus Controls the normal activities of the
cell
Usually found at center of cell and the largest organelle in animal cells
Has a nuclear membrane/envelope & nuclear pores
Contains cell’s DNA in one of 2 forms
chromatin - DNA bound to proteins and spread out (non-dividing cell)
chromosomes - condensed structures DNA wrapped around proteins, seen in dividing cell
Also contains an organelle called nucleolus - which makes the cell’s ribosomes (disappears when cells divide)
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•Jelly-like substance enclosed by cell membrane
•Provides a medium for chemical reactions to take place
• Contains organelles to carry out specific jobs
CytoplasmCytoplasmcytoplasm
Cell Organelles
Mitochondria – this is the cell’s energy center. It turns food into a chemical energy called ATP during Cellular Respiration
More active cells like muscle cells have MORE mitochondria
The mitochondria is sometimes called the “powerhouse” of the cell
Has its own DNA
Interior called Matrix
Outer Membrane
Folded Inner Membrane called Cristae to increase surface area for chemical reactions
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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!
Cell Organelles
Golgi Apparatus – receive proteins from ER to modify/processes, package and secrete proteins. It is comparable to a factory or a post office.
*A vesicle forms with Golgi to transport substances outside cell.
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GolgiGolgi
copyright cmassengale
Cell Organelles
Lysosome – Contains digestive enzymes, breaks down food, bacteria and worn out cell parts
Programmed for cell death (autolysis), "suicide sac”
Lyse (break open) and release digestive enzymes to break down and recycle cell parts
Cell Organelles
Endoplasmic Reticulum (ER) – Connects to nuclear envelope and cell membrane
Functions in Synthesis of cell products and Transport, "intracellular highway".
-Rough ER contains many ribosomes & is involved in protein synthesis
-Smooth ER (ribosomes not found on surface) Makes membrane lipids
(steroids) Regulates calcium (muscle
cells) Destroys toxic substances
(Liver)
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Cell OrganellesCell Organelles
Ribosomes are made of proteins and rRNA where protein synthesis occurs by joining amino acids together
Can be attached to Rough ER or be Free (unattached) in the cytoplasm
Cell Organelles
Cytoskeleton – Helps cell maintain support & shape; movement microtubules-hollow structures; also
-help build cilia flagella microfilaments-threadlike
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Cell OrganellesCell Organelles Centrioles are 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
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CentriolesCentrioles & the Mitotic & the Mitotic SpindleSpindle
Made of MICROTUBULES (Tubulin)
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Cell OrganellesCell Organelles
Cilia are shorter and more numerous on cells
Flagella are longer and fewer (usually 1-3) on cells
Function in moving cells, in moving fluids, or in small particles across the cell surface
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Cell Movement with Cell Movement with Cilia Cilia & Flagella& Flagella
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Cilia Cilia Moving Away Dust Particles Moving Away Dust Particles from the Lungsfrom the Lungs
Respiratory SystemRespiratory System
Cell Membrane
Selectively permeable ; it regulates what comes into the cell and what leaves the cell
It is composed of a double layer of phospholipids with proteins embedded throughout
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Cell or Plasma MembraneCell or Plasma Membrane
Outsideof cell
Insideof cell(cytoplasm)
Cellmembrane
Proteins
Proteinchannel Lipid bilayer
Carbohydratechains
Composed of double layer of phospholipids and proteins
Surrounds outside of ALL cellsControls what enters or leaves the cellLiving layer
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PhospholipidsPhospholipidsHeads contain glycerol &
phosphate and are hydrophilic (attract water)
Tails are made of fatty acids and are hydrophobic (repel water)
Make up a bilayer where tails point inward toward each other
Can move laterally to allow small molecules (O2, CO2, & H2O to enter)
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The Cell Membrane is FluidThe Cell Membrane is Fluid
Molecules in cell membranes are constantly moving and changing
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Cell Membrane ProteinsCell Membrane Proteins
Proteins help move large molecules or aid in cell recognition
Peripheral proteins are attached on the surface (inner or outer)
Integral proteins are embedded completely through the membrane
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Recognize “self”
GLYCOPROTEINSGLYCOPROTEINS
Glycoproteins have carbohydrate tails to act as markers for cell recognition
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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
Plant Cells
Have additional structures
CELL WALL – surrounds membrane & provides additional support
CHLOROPLASTS – contain green pigment, function in photosynthesis
CENTRAL VACUOLE – large water container in center of cell
LACK Centrioles
Plant Cell
Can you identify all the parts?
Anacharis Cells Viewed With a Microscope
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o Cell Wall- Nonliving layer found in plants, fungi, & bacteria
o Made of cellulose in plants, peptidoglycan in bacteria and chitin in Fungi
o Supports and protects cell
o Found outside of the cell membrane
Cell wall
Cell OrganellesCell Organelles
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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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Chloroplasts
Surrounded by DOUBLE membrane
Outer membrane smoothInner membrane modified
into sacs called Thylakoids
Thylakoids in stacks called Grana & interconnected
Stroma– gel like material surrounding thylakoids
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Chloroplasts
Contains its own DNA
Contains enzymes & pigments for Photosynthesis
Never in animal or bacterial cells
Photosynthesis – food making process
Cell Organelles
Vacuole – storage area for sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes, plant cells usually have a large central vacuole
Small or absent in animal cells
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Contractile Contractile VacuoleVacuoleFound in unicellular
protists like paramecia
Regulate water intake by pumping out excess (homeostasis)
Keeps the cell from lysing (bursting)
Contractile vacuole animation
Organelles with DNA In 1970, American biologist, Lynn Margulis, provided
evidence that some organelles within cells were at one time free living cells themselves
Supporting evidence- Mitochondria and chloroplasts have their own DNA (separate from the nucleus)
This supports the ENDOSYMBIOSIS THEORY which states that eukaryotic cells evolved when prokaryote cells engulfed or absorbed other cells.
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Multicellular Organisms
Cells in multicellular organisms often specialize (take on different shapes & functions)
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Cell Specialization
Cells in a multi-cellular organism become specialized by turning different genes on and off
This is known as DIFFERENTIATION
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Specialized Animal Cells
Muscle cells Red blood cells
Cheek cells