Transcript Cells - SchoolRack

Unit 4
Discovery of Cells
• Anton van
Leeuwenhoek:
• Made improvements
to the simple
microscope in 1648
– Saw microscopic
critters in pond
water 1674
Discovery of Cells
• Robert Hooke
• 1st person to see
cells & identify
them – saw cell
walls in cork 1665;
• He gave ‘cells’
their name!
2 Types of Cells
•Prokaryotic Cells
and
•Eukaryotes Cells
Prokaryotes
• The cell DOES NOT
have a “true” nucleus;
Tend to be smaller than
Eukaryotes
Not as many organelles
as Eukaryotes
– Ex: All bacteria
Eukaryotes
• The cell HAS a “true”
nucleus
– Eukaryotes contain
organelles which are
special structures that
perform important
cellular functions
– Ex: All
plants,
animals, fungi, &
protists
Similarities and Differences in
Prokaryotes and Eukaryotes
Prokaryotes
Both
Cell membrane
Contain DNA
Cytoplasm
Ribosomes
Eukaryotes
Nucleus
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles
Mitochondria
Cytoskeleton
Cell Organelles 1
• Tiny structures inside the cell that perform
functions
• The organelles are to the cell as the
organs are to the whole body
• Cells  Tissues  Organs  Organ
Systems  Organism
NUCLEUS
• The control center of the cell
• contains DNA, chromatin, &
chromosomes
• DNA contains coded
instructions needed to make
proteins
• Chromosomes are threadlike structures that contain
genetic material
CYTOPLASM
• Gel-like material
in the cell
• organelles are
suspended in the
cytoplasm
Ribosomes
• Makes proteins
with the help of
RNA and
Amino Acids
Endoplasmic Reticulum
• Moves materials
around the cell
• Assembly of Lipids
• Assists with Protein
Synthesis
• Rough ER: contains
ribosomes
• Smooth ER: no
ribosomes
Mitochondria:
• “Power-house” of the cell
• makes ATP (energy);
found in both plants &
animals
– Converts food into
compounds that the
cell uses for growth,
development, and
movement
Chloroplasts:
• Converts energy from
sunlight into chemical
energy by
photosynthesis
–Found only in
plants, bacteria,
and some
protists
Golgi Apparatus
• Sorts &
Packages
proteins from
the ER
Vacuole
• Stores water, salts,
protein, & carbs
– Plant cells have a
single large vacuole
(stores water)
– Animal cells have
many small
vacuoles
Lysosomes:
• Contains
enzymes to
digest waste
Cytoskeleton
• helps the cell
maintain its shape
– Contains
microfilaments &
microtubules
Cell Wall
Provides
support and
protection for
the cell; found
in plant cells
and bacteria
Cell Membrane
• Regulates what
enters and leaves
the cell; found in
both plant & animal
cells
– Composed of a
Lipid bilayer
(contains lipids
and proteins)
Outside
of cell
Lipid Bilayer
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
Animal Cell – rounder shape;
no cell wall; no chloroplasts
How a school is like a cell
Just as the Administrative assistant controls
what enters and leaves the school, so the plasma
membrane regulates what leaves and enters the
cell.
Just as the princible directs all operations that go on in
the school, so the nucleus and DNA controls all cell
activities and what proteins will be made.
Just as the school floor holds all the desks and every
thing that’s on it, so the cytoplasm is were all the
organelles and activities are found.
Just as the cafeteria kitchen is the place were the
workers do their job making food, so the ER is the
place were the ribosomes do their job of
assemabling proteins
Just as the janitors clean up all the trash around the
school and recycles the things that can still be used, so
the so the lysosomes break down the cell waste so the
different parts can be reused.
Just as the support beams, walls, ceilings, floors,
bricks, and cement support the school building, so the
cytoskeleton supports and maintains the shape of the
cell.
Just like lunch provides the students with energy to do
there work, so the mitochondria are the source of ATP
that is used for energy in cell processes.
Just as composting breaks down garbage from the
students in the school, so the peroxisomes break
down hazardous material such as hydrogen peroxide.
Just as the storage closets in the classrooms store
material, so the smooth ER (edoplasmic reticulum)
stores steroids and ions.
Just as the teacher directs the students into the
auditorium for an assembly, so the necleolous directs
the assembly of proteins with in the cell necleus.
Just as the buses drive kids to and from school, so the
centrosome is were microtubes carry out transportation.