Transcript Unit 3 - Cells

Unit 3 - Cells
Chapter 7
Cell Structure & Function
Brief history
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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 ER
to produce protein
4. Golgi =
flattened compartments with vesicles
for 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 pigment
for making food by photosynthesis
9. Cytoskeleton = hollow fibers
• for support & shape
• to move cytoplasm
10. Plasma Membrane –
outer boundary of cytoplasm
Semipermiable
(only certain molecules enter & leave)
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
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
Passive or Active transport?
current
(Concentration gradient)
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
Click here to view Filmclip
Plant cells in
Isotonic solution
Cells in various solutions
Hypotonic
LYSE
Isotonic
NORMAL
Hypertonic
animal
PLASMOLYZE
Plant,
fungus,
algae,
bacteria
TURGID
FLACCID
Types of Active Transport
Click here to view flimclip
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