Transcript CELLS & the ORGANELLES

CELLS & the ORGANELLES
Prokaryote vs. Eukaryote
Animal vs. Plant
Early Microscopes
• Robert Hooke (1665)
 Coined the term “cell” (Why?)
 looking at cork, he saw little boxes
 Is cork alive?
• Anton von Leeuwenhoek (1674)
 saw living cells in pond water
Cell Discoveries
• Matthias Schleiden (1838)
 Plants are made of cells
• Theodor Schwann (1839)
Animals are made of cells
• Rudolf Virchow (1855)
 Saw dividing cells
 new living cells come from
pre-existing cells
The Cell Theory
1. All living things made of cells.
2. Cell are the basic unit of structure &
function for life.
3. Cells can only arise from pre-existing
living cells
Specialization
• Unicellular organisms  living organisms
that are only ONE cell
– Examples: bacteria, algae, protists, yeast
• Multicellular organisms  any organism
that is made of more than one cell
– Evolved later
Kingdoms and Domains
Three Domain System
Bacteria
Archaea
Eukarya
Six Kingdom System
Bacteria
Archaea
(based on rRNA evidence)
(based on rRNA evidence)
Protista
Fungi
Plantae
Animalia
Traditional Five Kingdom System
Monera
Protista
Fungi
Plantae
Animalia
Humans = 5%
Prokaryote vs. Eukaryote
All cells have a membrane, cytoplasm, DNA & ribosomes
• Prokaryotic Cells
– DNA not bound by a
membrane… no “true
nucleus”
– Usually smaller, simple
– No membrane bound
parts (organelles)
– Ex: bacteria
• Eukaryotic Cells
– Membrane bound
nucleus
– Larger, complex,
internal organization
– Have internal
membrane bound
structures
– Ex: you, plants, algae
Can unicellular organisms be eukaryotic?
What does that mean?
Do prokaryotes have DNA?
What is an example of a prokaryote?
Are prokaryotes considered to be alive?
Why do we need to understand cells?
Each organelle has a specific job that needs to
be performed. The more we understand
their jobs, the better we can understand life.
Basic Cell Structures
• Cell membrane
• Nucleus
-nucleolus
-nuclear
envelope
• Cytoplasm
Organelles
•
Very small size
•
Can only be observed under a microscope
•
Have specific functions
•
Found throughout cytoplasm
•
Include:
Cytoplasm, Nucleus, ribosomes, endoplasmic reticulum,
Golgi apparatus, lysosomes, vacuoles, mitochondria, chloroplasts (plants
only), cytoskeleton, centrioles (Animal only)
The Nucleus:
Control center of the cell, houses genetic material
Nucleolus
• Is a small
dense region in
the nucleus
• Makes
ribosomes,
which make
proteins
RIBOSOMES
• Free floating in
cytoplasm
or
• Attached to ER
• “reads” RNA code
from DNA to
assemble proteins
• “protein factory”
ENDOPLASMIC RETICULUM
• Internal membrane
• Lipid parts of the cell
membrane made here
• Makes proteins etc.
for shipment out of
cell
• Can be “Rough” or
Smooth
GOLGI APPARATUS
• Modifies, sorts,
packages proteins
and other products
• Destination
– storage in cell
– export out of cell
• Customizes
• Adds lipids, carbs to
protein
LYSOSOMES
• Small, enzyme-filled
organelles
• Digests material for
use or disposal
• Tay Sachs disease
has dysfunctional
lysosomes in neural
cells which allows fats
to accumulate
MITOCHONDRIA
• Convert food into
usable energy
• Have an outer & inner
membrane
• Has its own DNA!
– Inherited from your
mom
CHLOROPLASTS
• Capture sunlight &
convert it to energy
– Photosynthesis
• Have 2 membranes
• Contain the green
pigment chlorophyll
• Has its own DNA!
VACUOLES
• Stores materials
• Water, salts, protein,
carbs
• Largest in plants
– Gives turgor pressure
• May not be present in
animals
CYTOSKELETON
• Structural support
& transport
MICROFILAMENTS
Actin – threadlike
protein
MICROTUBULES
Tubulins – protein
basis of cilia & flagella
CENTRIOLES
• Help in the process of
cell division
• Only in Animals
PLANTS V. ANIMALS
• CELL WALLS
• LARGE VACUOLE
• CHLOROPLASTS
• CENTRIOLES
• NO central VACUOLE
• NO CHLOROPLASTS
Awesome cell clip
• http://www.youtube.com/watch?v=kxSLw1
LMvgk
Cooperation Among Cells
UNICELLULAR: Each individual cell is its own
organism, but may form:
- Colonies – Volvox, colonial algae
- Biofilms – Bacteria on teeth, plaque
• What are the advantages of cooperating?
Disadvantages?
MULTICELLULAR
• Cells are specialized (specific roles)
- eventually form tissues  organs  systems
• What are our specialized cell types?
Volvox
http://www.youtube.com/watch?v=-V7LTyJuAy4&feature=related
Colonies of Bacteria
Cell to Cell Connections
• Cells in same tissue communicate with each
other through junctions
– Tight junction : membranes are fused, stitched
together; no passage
– Desmosomes: protein fibers that anchor in
cytoplasm of neighboring cells
• – allow passage of materials
– Gap junction : Channels formed by donut-shaped
proteins btwn cells ; yes passage
– Pits & Plasmodesmata : (plants) cell walls
perforated with pits, strands of cytoplasm
(plasmodesmata) run through pits connecting cells
Can you find the connection?
Extracellular Matrix
• Solution of macromolecules
(proteins & carbs) that
surround cells in a tissue
– Secreted by the cell itself
to the space outside
• Holds cells together
• Allows them to migrate &
interact
• May regulate behavior in
cells
• Ex: collagen
Question
• You are not feeling well so you go to the
doctor. She swabs your throat and grows
the bacteria in the lab to identify.
• She discovers that it is Streptococcus
pneumoniae, a common but harmful
bacteria.
• When she looks in her microscope, does
she see a nucleus in this organism? Why
or why not?
Question
• You got a bad rash at sports camp. The doctor has prescribed
you a cream that she says will help break down the cell wall of
the organism that is growing on your skin.
• Do you have a bacterial infection or a fungal infection? Or do
you need more information?
• Will this cream injure your skin cells in the same way? Why or
why not?
Question
• Trace the path of protein production from
DNA to export.