Cell Structures and Function
Concept 6.4-6.6
Organelles
mini organs with a specific function
6.1 pg 110-114
All living organisms are made of cells.
Scientist contributions
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Robert Hooke- observed cork – dead
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Anton van Leeuwenhoek- pond water
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Tiny room-cells
Animicules- simple microscopes
Schleiden and Schwann
Plant and Animals have cells
Cell Theory
1. All living things have cells
2. Cell is the basic unit of structure and
function.
3. Cells come from other cells.
Cell division- mitosis- body cells
 Reduction division- meiosis- sex cells-egg
and sperm.
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Importance of Microscopes
Light microscopes- magnifies up to
1000x.
Can see bacteria- diameter of 1-2um.
 Cannot see smaller cell organelles
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Electron Microscopes- use electron
beams- can magnify 1,000,000 x
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SEM- Scanning Electron Microscope
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Surface- 3D detail
TEM- Transmission Electron Microscope
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Internal detail of cell structures
Two Main types of Cells
Prokaryote- bacteria and archaea
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no membrane bound nucleus
Only ribosomes, lacks most organelles
Contains DNA in a center region.
Much smaller than eukaryotic cells
Earlier in fossil record.
Eukaryote- protists,fungi,plants, animals
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Membrane bound nucleus
Membrane bound organelles
100 x larger than prokaryotic cells
Appeared later
Plant vs Animal Cells
Similar:
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Nucleus, cytoplasm, cell
membrane,organelles
Differences:
Plants- cell wall, definite shape
chloroplasts, large central vacuole.
 Animals- no cells wall, smaller vacuoles.
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Nuclear Structures
Nucleus
Control center of the cell
 Spherical
 DNA-Deoxyribonucleic Acid
 Chromatin- DNA attached to proteinsform long fibers.
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Nuclear envelope (membrane)
Surrounds the nucleus
 Double layer membrane
 Pores –thousands for substances (RNA)
to move into the cytoplasm.
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Nucleolus
Inside the nucleus.
 Not visible when the cell is dividing.
 Site of ribosomal RNA production.
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Cytoplasmic Structures
Cytoplasm
Between the nucleus and plasma(cell)
membrane.
 Gel-like fluid.
 Consists of cytosol and organelles.
 Many organelles are enclosed by
membranes.
 Cytosol is mainly water.
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Centrioles
Found in animal cells
 Paired cylindrical organelles near the
nucleus.
 Involved in cellular division???
 Lie at right angles to each other.
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Chloroplasts
Found in plant cells.
 Contain green pigment chlorophyll.
 Site of photosynthesis
 Disks- thylakoids – solar “power packs”
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Cytoskeleton
Fiber network in the cytoplasm.
 Changing structural pattern.
 Composed of:
 Microtubules Straight, hollow tubes.
 Shape, rigidity, organization
 Microfilaments Thinner, solid rods
 Allows cell to move and change
shape.
 Amoeba- pseudopodia.
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Ribosomes
Made of RNA and proteins.
 Thousands in every cell.
 Site of protein manufacture.
 Bound ribosomes:
 Bound to the endoplasmic reticulum
(ER)
 Make proteins for membranes.
 Make proteins for export
 Free ribosomes:
 Suspended in the cytoplasm
 Make proteins that remain in
cytoplasm.
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Endoplasmic reticulum (ER)
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Network of membranes connected to the
nuclear membrane
Transport system of the cell.
 Rough ER
 Bound ribosomes• produce proteins inserted into
membranes and exported out thru
vesicles.
 Found in salivary glands.
 Smooth ER No ribosomes
 Lipid building
 Found in ovaries/testes
 Produce sex hormones
Golgi apparatusProcessing and shipping center
 Flattened stacks
 One side-receiving dock- vesicles of
proteins from ER.
 Golgi apparatus refines and modifies.
 Shipping side- sends finished product via
vesicles to other parts of the cell.
 Some vesicles fuse with plasma
membrane to release products outside of
the cell.
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Lysosome Digestive plant of animal cell.
 Digest proteins, lipids, and carbs.
 Membrane sacs with digestive enzymes.
 3 functions Fuse with food vacuoles to digest
food
 Destroy harmful bacteria.
 Recycle damaged organelles.
 If a lysosome explodes the cell breaks
down.
Mitochodria Power house of the cell
 Site of cellular respiration; results in
ATP.
 ATP= adenosine triphosphate- high
energy molecule.
 Plant and animal cells
 Structure- envelope with 2 membranes.
 Cristae- internal folds, provide more
sites for cellular respiration.
 Unique genetic structure; contains DNA
 Remnant genetic info, from bacteria
 Humans- mitochondria from Mom.
Vacuoles Membrane sacs for storage
 Undigested nutrients, digestion,
waste removal.
 Contractile vacuoles Pump out excess water in singlecelled organisms.
 Central vacuole- largest organelle in
plants.
 Stores salts, absorbs water to expand
cell.
 Pigments of flower petals.
 Poisons in leaf cells.
Surface Structures
Cell wall Plant cells; also algae, fungi and
bacteria.
 Outside of cell membrane.
 Protects.
 Maintains cell shape.
 Provides support.
 Cellulose in plant cell wall.
 cellulose- tough carbohydrate.
 Wood, paper.
Plasma (cell) membraneThin outer boundary of the cell.
 Regulates chemicals in/out of the cell.
 Semipermeable.
 Fluid-like.
 Proteins surrounded by a phospholipid
bi-layer.
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Movement Structures
FlagellaLong, thin whip-like structure
 Projects from the cell.
 Propels by “S” shaped motion.
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CiliaShorter, more numerous than flagella.
 Composed of microtubules.
 Moves the cell in “back and forth”
motion
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