SOL BIO 4.a-c
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The cell theory is the unifying theme in biology because it emphasizes the similarity of all living things.
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All organisms are composed of one or more cells.
Cells are the smallest living units of all living organisms.
Cells arise only by division of a previously existing cell.
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Cells contain specialized structures to perform functions necessary for life.
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Cellular activities necessary for life include chemical reactions that facilitate:
 acquiring energy
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 reproduction adaptation maintaining homeostasis
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All cells contain:
Genetic material
 single circular molecule of DNA in prokaryotes
 double helix located in nucleus in eukaryotes
Cytoplasm jelly-like substance that fills the cells interior
Phospholipids
Plasma membrane encloses the cell
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– phospholipid bilayer
Membrane proteins 4

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Cell structure is one of the ways in which organisms differ from each other.
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2 Types of Cells
• Prokaryote
• Eukaryote
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Earth’s first cells were prokaryotes.
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The simplest life forms are the prokaryotes.
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Prokaryotic cells exist in two major forms: eubacteria and archaebacteria.
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Prokaryotes are the Earth’s most abundant inhabitants. They can survive in a wide range of environments and obtain energy in a variety of ways.
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Prokaryotes are cells that lack a nucleus and membrane bound organelles.
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Some use flagellum for locomotion
ALL are UNICELLULAR
Bacteria and related microorganisms are prokaryotes
Rotary motor
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• Eukaryotes arose from prokaryotes and developed into larger more complex organisms.
• Eukaryotes are cells that contain a nucleus and organelles surrounded by a membrane, such as mitochondria and chloroplasts.
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• Can be both unicellular or multi-cellular
• Examples of eukaryotes are:
• All fungus, plant, and animal cells
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Most cells are relatively small because as size increases, volume increases much more rapidly.
 longer diffusion time
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 Cellular differences between plant and animal cells
 Plants have:
 a cell wall
 Chloroplast
 Large vacuole
 Animal cells do not have these structures
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Endosymbiotic theory suggests that eukaryotes arose from a symbiotic relationship between various prokaryotes.
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Heterotrophic bacteria became mitochondria.
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Cyanobacteria became chloroplasts.
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Host cell was a large eukaryotic cell.
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Eukaryotic cell
Prokaryotic cell is engulfed
Prokaryotic cell
Symbiosis
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Cell specialization occurs during the development of a multi-cellular organism.
The genetic information necessary for all cellular functions remains in each cell but may not be used.
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Stores genetic material
Contains DNA site where RNA is made
Nucleolus: Chromatin and ribosomal subunits
Nuclear envelope:
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Double membrane with pores
Largest organelle
BRAIN of the cell – controls protein synthesis
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Ribosomes are RNA-protein complexes composed of two subunits that join and attach to messenger
RNA.
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 site of protein synthesis assembled in nucleolus
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They can be found alone in the cytoplasm or attached to the endoplasmic reticulum.
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Alone in cytoplasmmakes proteins for use within the cell
Attached to RER- makes proteins for export out of the cell
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 transports materials through the cell
• Rough ER studded with ribosomes
• Attached to nuclear membrane
• site of protein synthesis and processing
• Smooth ER lacks ribosomes
• site of synthesis of phospholipids and the packaging of proteins into vesicles
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 collection of Golgi bodies
• Stacked flattened sacks
• Site where cell products are packaged for export
• Proteins are modified by being combined with fats or carbohydrates
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Vesicles then pinch off from the Golgi body to be secreted
(outside the cell)
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Involved in the production of lysosomes
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 vesicles produced by the
Golgi apparatus.
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Lysosomes contain digestive enzymes and are involved in intracellular digestion of food particles, disease causing bacteria and worn out cell parts
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Found in PLANT and ANMAL cells
The vacuole acts a container, storing water and dissolved particles
Plants have a large central vacuole for water storage
Unicellular animals can use contractile vacuoles for movement
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"Powerhouse of the cell" - cellular metabolism
Structure- outer and inner membranes, cristae
Found in both plant and animal cells
Very active cells have more mitochondria
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•Chloroplasts are larger and more complex than mitochondria
•Contain green pigment called chlorophyll that absorbs sunlight in the first step of photosynthesis
•Found ONLY in PLANTS
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•controls what enters and leaves the cell
•Found in
cells
•Phospholipid bilayer with transport proteins, and cholesterol (for flexibility)
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•provides support
•Found in and
cells
•Made from cellulose
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Long slender protein tubes and fibers that extend from the nucleus to the plasma membrane.
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The cytoskeleton contains three types of elements responsible for cell shape, movement within the cell, and movement of the cell:
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Actin filaments
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Microtubules
Intermediate filaments
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•Cylindrical structures found near the nucleus
•Made of hollow, tubular structures arranged in bundles
•Important in cell division
•Found ONLY in ANIMAL cells
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HAVE:
Cell Wall
LARGE vacuoles
Chloroplasts
DO NOT HAVE:
Centrioles
PLANT
CELL
Cell membrane
Mitochondria
Golgi apparatus
Nucleus
Cytoskeleton
Ribosomes
Endoplasmic reticulum
Lysosomes
ANIMAL
CELL
HAVE:
Centrioles
DO NOT HAVE:
Cell Wall
LARGE vacuoles
Chloroplasts
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