unit 3 - cells chapter 7 cell structure & function
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Unit 3 - CellsChapter 7
Cell Structure & Function
Brief history
• Hooke (1660’s)
• Leeuwenhoek (1670’s)
• Schleiden & Schwann(1830’s)
• Virchow (1850’s)
Cell Theory(based on 200+ years of discoveries)
• A. all living things are composed of cells
• B. cells are the basic unit of structure & function of all living things
• C. new cells are produced from existing cells
Cell Types
Prokaryotic cells = smallest, no true nucleus,
ribosomes only Ex: bacteria
• Eukaryotic cells = – large, multicellular, true nucleus,
many specialized organelles
– ex: protists, fungi, plants & animals
• 1. Nucleus = • directs cell activities• a) N. Envelope
(with pores)outer
boundary• b) Chromosomes =
(contain DNA)carry genetic code
• c) Nucleolus(contain RNA)produces ribosomes
chromatin
• 2. Endoplasmic reticulum = an interconnecting system of “pathways,” for transport
May be Rough ER(with ribosomes)or Smooth ER(without ribosomes)
• 3. Ribosomes =small bodies on ERto produce protein
4. Golgi = flattened compartments with vesiclesfor secretion (packaging & shipping)
5. Lysosomes = small filled sacs,for digestion
6. Vacuoles = large, “hollow” sacs (in plants)for storing liquids
7. Mitochondria = rod-shaped with folds,for releasing energy (ATP) by respiration
8. Chloroplasts = oval with green pigmentfor making food by photosynthesis
9. Cytoskeleton = hollow fibers• for support & shape• to move cytoplasm
10. Plasma Membrane – outer boundary of cytoplasmSemipermiable (only certain molecules enter & leave)
Outsideof cell
Insideof cell(cytoplasm)
Cellmembrane
Proteins
Proteinchannel Lipid bilayer
Carbohydratechains
a. Phospholipid bilayer• a double layer that is an effective barrier for
most molecules• 1) Hydrophobic =
“water fearing” center tails prevent most things from entering
• 2) Hydrophilic = “water loving”
heads attract water to edges of membrane
b. Embedded Proteins• 1) Channels
“gates” to interior for transporting into & out of cytoplasm
• 2) Receptors “windows” for gathering information about cell surroundings
• 3) Markers “name tags” that identify type of cell to others
current
(Concentration gradient)
Passive or Active transport?
Passive vs Active transport:which requires energy output?
Passive Transport
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c. Types of passive transport
• 1) Diffusion• random spread of
molecules from higher to lower concentration
• Examples?
• 2) Osmosis
• Diffusion of water through a membrane
• Examples?
3) Types of osmotic solutions
• a) Hypertonic• More solutes = less water = water moves
out & cell shrinks• b) Hypotonic• Less solutes = more water = water moves
in & cell expands• c) Isotonic• Equal solutes & water, so equal movement
of water & cell is stable
Types of solutions
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Plant cells in Isotonic solution
Cells in various solutions
LYSE
TURGID
NORMAL
FLACCID
PLASMOLYZE
Plant, fungus, algae, bacteria
animal
Hypotonic Isotonic Hypertonic
Types of Active Transport
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4. Types of Active Transport
• a. Endocytosis • cell brings particles into cytoplasm
• 1) Pinocytosis • small particles
(liquids) are brought in by vesicles
• 2) Phagocytosis• large particles
(food or bacteria) are surrounded & engulfed by cell membrane
• Examples = an ameba feeding &
• a white blood cell destroying an invader
• b. Exocytosis cell deposits
particles outside of cytoplasm
• 1) Secretion = cell products given off
• 2) Excretion = wastes products given off