Download THE CELL

THE CELL
“The smallest unit that can carry
out all the processes of life.”
Scientists Who Discovered
the Cell
Discovery of the Cell
 ROBERT HOOKE
 First to observe cells.
 He examined cork
cells.
 “These little boxes
reminded him of the
small rooms in which
monks lived, so he
called them cells.”
Discovery of the Cell
 Anton van Leeuwenhoek – First person
to examine living cells & father of
microscopy
 Matthias Schleiden – “All plants are
composed of cells.”
 Theodore Schwann – “All animals are
composed of cells.”
 Rudolf Virchow – “All cells come from
existing cells.”
The Cell Theory
 Schleiden, Schwann, & Virchow
 All living things are composed of one or
more cells.
 Cells are organisms’ basic units of
structure & function.
 Cells come from existing cells.
CELL DIVERSITY
1. Size
 Cells range in size
from .2 um to 2 m.
 Average plant &
animal cells are 10 to
50 um in diameter.
2. Shape
 Cuboidal & spherical.
3. Internal Organization
 Different Organelles
TYPES OF CELLS
 Eukaryotes –
Contains a nucleus
and membrane-bound
organelles.
 Prokaryotes – Lacks
a nucleus. (bacteria)
 Organelle – A cell
component that
performs specific
functions in the cell.
ORGANELLES
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Nucleus
Cell Membrane
Cytoplasm
Ribosomes
Rough Endoplasmic
Reticulum
 Smooth Endoplasmic
Reticulum
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Golgi Apparatus
Mitochondria
Lysosomes
Cytoskeleton Microtubules &
Microfilaments
 Cilia
 Flagella
The Nucleus
 Directs activities of
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the cell.
Contains DNA.
Nucleolus – synthesis
of ribosomes.
Nuclear pores
Nuclear envelope
Nucleoplasm
DNA
 Deoxyribonucleic acid
 Encodes information
important for the
synthesis of proteins.
CYTOPLASM
 Contains various
organs in the cell
 Gelatin-like fluid
called cytosol which
has dissolved salts,
minerals, and organic
molecules
CELL MEMBRANE
 Made of lipids &
proteins.
 Provides shape &
flexibility.
 Selectively
Permeable - a
complex barrier that
keeps out some
molecules & allows
others through.
RIBOSOMES
 Carry out protein
synthesis.
 Attached ribosomes attached to Rough
ER; produce proteins
to be exported by the
cell.
 Free ribosomes produce proteins for
the cell.
ENDOPLASMIC RETICULUM
 Rough Endoplasmic
Reticulum - (ER) - A
membrane system
covered with
ribosomes; aids in
protein synthesis.
 Smooth ER - Few or
no ribosomes;
intracellular pathway
for proteins.
GOLGI APPARATUS
 System of
membranes.
 Processing,
packaging, &
secreting organelle
of the cell.
MITOCHONDRIA
 “Powerhouse of the
cell.”
 Carries out cellular
respiration.
LYSOSOMES
 Contains digestive
enzymes.
 Digests food &
disease-causing
bacteria.
CYTOSKELETON
 Provides a structural
framework for the cell.
 Microtubules - long,
slender protein tubes
 Microfilaments - fine
protein threads.
CILIA & FLAGELLA
 Function in movement.
 Composed of proteins.
 Cilia - small & hair-like; covers entire
surface of the cell.
 Flagella - long & slender; found singly or in
pairs.
VACUOLES
 Store substances
inside the cell.
 Plant cells have large
central vacuoles.
CENTRIOLES
 Structure that
appears during
animal cell division
CELL WALL
 Only in plant cells
 Lies outside the cell
membrane
 Supports and protects
the plant
PLASTIDS
 Convert solar energy
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into chemical energy.
Chloroplast - contain
green pigments
Leucoplast - store
food, such as
starches.
Chromoplast synthesize & store
other pigments.
Plant cells only!!
CHLOROPLASTS
 Found in plant cells
only
 Where the energy of
sunlight is converted
into chemical energy
during photosynthesis
 Contain green
pigment called
chlorophyll
DIFFERENCES BETWEEN PLANT &
ANIMAL CELLS
 ANIMAL CELLS
 Centrioles
 Small vacuoles
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PLANT CELLS
Plastids
Large central vacuole
Cell Wall