Transcript Cells - nimitz126

Cells
Inside and Out
Cell Theory

English scientist Robert Hooke used a
crude microscope to look at a slice of
cork.
 He
saw little boxes that reminded him of the
small rooms that monks lived in – Cells
Cell Theory

Later the observations of scientists
Schleiden, Schwann and Virchow led to
what we call the Cell Theory:
 All
living things are composed of one or
more cells
 Cells are the basic units of structure and
function in organisms
 All cells arise from existing cells
Size Chart
Atom
Molecule
Organelle
Cell
Tissue
Organ
Organ System
Organism
Population
Community
Ecosystem
Cell Size


Having many small cells is more efficient
than having a few large cells
Small cells have larger surface to volume
ratios than large ones
 So,
substance exchange is faster in small
cells than in large.
Surface to Volume Ratio
Example
 Surface area Equation on a cube
 L2 X 6
 Volume Equation of a cube
 L2 X H
Magnification
Light microscope
 Visible light passes through object
 A Lens magnifies the image
Magnification
 Making an image seem larger than what it
is
Resolution
 What measures the clarity of an object
 What limits a particular type of scope
Magnification
 Electron Microscope
 100,000 X
magnification power
 Scanning Electron
Microscope (SEM)
 Allows for better
resolutions on the
surface of an
object
 Shows object in
3D
 Good for
observing living
organisms
Magnification
 Electron
Microscopes
 Transmission
Electron
Microscope (TEM)
 Observer to sees
through cells
 allows the observer to
see specimen's
internal structure
Features Common to All Cells

Cell Membrane
 All
cells share this outer boundary
 This membrane encloses and separates the
interior of the cell – the cytoplasm
 The cell membrane also regulates what
enters and leaves the cell
Features Common to All Cells
 Cytoplasm (Cyto= cell, -plasm= formative
material)
 Everything between plasma membrane and nucleus
or nucleoid region.
 Cytoskeleton (Cyto= cell, -skeleton= structural
framework)
 Structure made of microfibers & microtubules
within the cytoplasm that suspends the cells
structures
 Most cells have ribosomes
 Cellular Structures on which proteins are made
Prokaryotes

Bacteria Cells
 Have


no nucleus
Evolved before eukaryotic cells
Structures Common to Prokaryotes
 Nucleoid
region- where the chromosome is
 ribosomes- protein synthesis
 Cell membrane- “gate keeper”
 Cell wall (different than plants)- support
 Some have capsules outside wall- resistance
to antibiotics
 Pili- exchange of genetic info
 Flagella- movement
Prokaryotes
Eukaryotes
 Plant and Animal Cells
 Cells are more complex than prokaryotic cells
 Much like Prokaryotes Eukaryotic Cells
 have a cell wall (plants/protists/fungi)
 have a plasma membrane
 have Cytoplasm
 have ribosomes
 But within their cytoplasm eukaryotes have
 Organelles
 Cytosol - fluid in cytoplasm
Major Organelles to know
 Cytoskeleton- support & protection
 Cell membrane- “gate keeper” controls what enters or
leaves the cell
 Nucleus- holds the chromosomes, directs cell
 Endoplasmic Reticulum- transport & protein formation
 Golgi Apparatus- packages things
 Lysosomes- hold digestive enzymes, “suicide sac”
 Vesicles- storage
 Mitochondria- “Power house” respiration, ATP energy
 Cell Wall- support, protection
 Chloroplasts- photosynthesis, make glucose
 Central Vacuole- storage, especially of water
 Ribosomes- protein making
Cytoskeleton
 Provides interior
framework to support
cell
 Made of network of
protein fibers tied to
the plasma
membrane.
Cytoskeleton
 There are three kinds of cytoskeleton fibers
 Microfilaments (or Actin Fibers)
 Made of protein actin
 Works in the shape and movement of a cell
 Microtubules
 Tiny tubules made up tubulin protein
 Highway for transportation of info. from nucleus to parts of
the cell
 Intermediate Fibers
 Rope-like fibers where enzymes and ribosomes anchor in
the cell
Cell Membrane
 Phospholipid bilayer -
barrier separating inside of cell
(cytoplasm) from outside
 Selectively permeable (penetrable) - controls what
enters & leaves cell
Proteins Embedded in the
Plasma Membrane


** Proteins are macromolecules made of amino
acids
Some proteins embed in the plasma membrane
 Enzymes
 Transport
Proteins
 Receptor Proteins

Must have both polar & non polar ends to embed
in the membrane
Nucleus
 Nucleus and mitochondria contain genes
 Nucleus consists of:
 Envelope
 Double membrane
 Pores let messages in and out
 Chromatin
 DNA
 Protein
 Nucleolus
 Produces rRNA
 rRNA with proteins makes up ribosomes
Nucleus
Endoplasmic Reticulum (endo =
Inside, plasm = formed material)

Major system of internal membranesmove proteins and other stuff through cell
 Is
a lipid bilayer with embedded proteins
 Makes steroids, lipids
 Detoxifies chemicals
Endoplasmic Reticulum (ER)
 Rough ER
 Has ribosomes embedded so looks “rough”
 Processes proteins
 Smooth ER
 No ribosomes embedded so looks “smooth”
 Makes lipids and breaks down toxic chemicals
Golgi Apparatus/Lysosomes
 Golgi Apparatus
 Flattened pancake like membrane-bound sacs- the packaging
distribution center of the cell
Lysosomes/Vesicles
Lysosomes (lyso-breaking, -some=body)
• Small spherical organelles• hold digestive enzymes
Work with Golgi to produce, package and
distribute protiens
Vesicles
• Small bubble-like membrane bound sacs
• carry material from ER to Golgi and out of cell
Some will become lysosomes
Here’s the Protein Flow
Mitochondria
 Harvests energy from organic compound
(sugars) to make ATP
 ATP: energy “Money” in the cells
 Cellular respiration
 Most eukaryote cells contain mitochondria
 Double membrane
 Big bag stuffed in smaller bag
 Folds of inner bag = cristae
 Space inside inner bag called matrix
 Holds enzymes and DNA
 This DNA ONLY inherited from mom
Mitochondria
Organelles Common to Plants


Plants contain all of the organelles now
mentioned plus more
Organelles Only in Plants (not animals)
 Cell
Wall
 Chloroplast
 Central Vacuole
Cell Wall
 Surrounds the cell membrane
 Made of proteins and carbohydrates
 Cellulose - polysaccharide(poly=many,
saccharide=sugars) cellulose can NOT be digested
by all us, but some can.
 Supports and Maintains the shape of a cell
 Protects from damage
Chloroplasts
 Plant cells contain mitochondria to produce the
energy “bucks” (ATP), AND they contain
chloroplasts to make the glucose the
mitochondria “burns” to make the ATP
 Chloroplasts use light energy to convert carbon
dioxide and water into sugar, oxygen and
energy (ATP)
 Also found in algae and some protozoans.
 Chloroplasts
 have two membranes
 have enzymes & DNA
Chloroplasts
Central Vacuole



Largest organelle in a plant cell
Contains ions (charged atoms), nutrients
(macromolecules), and wastes
When full, makes cell rigid which enables
the plant to stand upright.
Plant Cell
The Endosymbiotic Hypothesis
Evolution of the Eukaryotic cell
– (with mitochondria and
chloroplasts)
Theory: one large prokaryotic
cell ingested another which
became mitochondria and/or
chloroplast in the now
eukaryotic cell.
Evidence
Both are similar to bacteria in size
and shape
Both have a double membrane
 Outer from being taken into cell
 Inner from original bacterial cell
Contain DNA in loop like bacteria
Contain ribosomes - make
proteins
RNA in ribosomes like bacterial
cells
The Endosymbiotic Theory