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Cells
Chapter 7
Page 168 - 197
Cell Theory
Types of Cells
Organelles
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Cell Theory
Cells are the basic units of life
All living things have cells
All cells come from preexisting cells
Cells hold genetic information – DNA
Cells have a membrane that encloses and protects it from its surroundings
Cells divide and produce more cells through mitosis
Types of Cells
• Prokaryote – has no nucleus or organelles
- usually unicellular (1 cell)
- bacteria & viruses
• Eukaryote – has a nucleus and organelles
- usually multicellular (↑ 1 cell)
- plants & animals
• Both have a cell membrane & cytoplasm
Key for Organelles
• = what the organelles are made of
1. = functions of the organelles
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Cell Membrane
Thin flexible barrier made of a lipid bilayer that surrounds cells
Lipid bilayer – 2 layers of lipids with proteins embedded in it with CHO chains
attached
Regulates what comes in & out of cell
Protection
support
Cell Wall
• Rigid layer outside of cell membrane
• Made of carbohydrates & protein
• Found only in plant cells
1. Provides support & protection to the cell
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Nucleus
Large organelle surrounded by a nuclear envelope
Contains DNA
Controls all cell activities
DNA made here
Nucleolus
• Small dense region inside the nucleus
1. Makes ribosomes
Chromatin
• Granular material that consists of DNA
• Found in the nucleus
1. Condenses to form chromosomes when the cell divides
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Chromosome
Thread like structures that contain genetic information
Passes genetic information from one generation to the next
Units of heredity
Cytoplasm
• Jellylike substance outside of nucleus but enclosed by the cell membrane
• Where all organelles are found
1. Gives cell its shape
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Mitochondria
Peanut shaped organelle enclosed by 2 membranes (inner & outer)
Only inherited from your mom!
Converts the chemical energy stored in food into compounds that the cell can use
for energy
“powerhouse” “energy maker”
Golgi Complex
• Stacks of membranes closely packed together
1. modify, sort, & package proteins & other materials from the endoplasmic reticulum
(ER) for storage in the cell or for secretion out of the cell
• Small particles of RNA & protein
• Found throughout the cytoplasm
• 2 types – free & attached
Ribosome
1. Makes proteins
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Smooth Endoplasmic Reticulum Smooth (ER)
Internal membrane system without ribosomes
Contains enzymes
Makes lipids
Transports materials inside cell
Rough Endoplasmic Reticulum
Rough (ER)
• Internal membrane system with ribosome's attached
• Surrounds the nucleus
1. Synthesis of proteins from ribosomes
• Located near the nucleus
• Made of microtubules
1. Helps with cell division
Centrioles
Cytoskeleton
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Network of protein filaments
Made of microfilaments & microtubules
Help support cell
Maintains its shape
Helps materials move within the cell
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Small organelle filled with enzymes
Found only in animal cell
Eats or breakdown lipids, carbohydrates, & proteins
Removes junk from cell
Breakdown old organelles
Lysosome
Chloroplast
• Large stacks of membranes
• Found only in plant cells
1. Capture energy from sunlight & converts it into chemical energy - Photosynthesis
Vacuole
• Storage saclike structures
• Found only in plant cells
1. Stores water, food, salts, Carbohydrates, proteins & wastes
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Specialized vacuole
Contractile vacuole
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Pumps excess water out of cells
Helps maintain homeostasis
DIFFUSION – when particles tend to move from an area of higher concentration to an area of lower
concentration.
When the concentration is the same on both sides of the membrane – EQUILIBRIUM is reached
DOES NOT REQUIRE ENERGY
Even when EQUILIBRIUM is
reached, particles will continue to move across the membrane in both
direction
Is no further change to the CONCENTRATION
Osmosis – diffusion of water across a membrane
Water moves from higher concentration to lower concentration
Water will tend to move across a membrane until EQUILIBRIUM is reached.
ISOTONIC = “same strength”
- SAME CONCENTRATION
HYPERTONIC = “above strength”
- MORE CONCENTRATION
HYPOTONIC = “below strength”
- LESS CONCENTRATION
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FACILITATED DIFFUSION
Some molecules can not freely pass through the cell membrane
PROTEINS in membrane will help or “FACILITATE” the movement of these molecules
Proteins act like CHANNELS OR “TUNNELS” so the molecules can pass in and out of cell
Even though it is fast & specific,
IT IS STILL DIFFUSION
SO IT DOES NOT REQUIRE ENERGY
ACTIVE TRANSPORT
When particles move from a lesser concentration to a higher concentration
OPPOSITE of DIFFUSION
REQUIRES ENERGY
Carried out by transport protein or “pumps” that are in the membrane