Transcript Chapter 2
Chapter 2
Section 2-3
Cells the Unit of Life
• Cells – smallest units that carry on all the
activities and functions of a living thing
• Microscopes – instruments that enlarge tiny
things
- have one or more lenses to aid
in enlarging small things
Microscopes
• Zacharias Janssen
Dutch
– Made reading glasses
– Put two magnifying
lenses together
• Compound – two or
more lenses
Microscopes
• Simple – one lens
-magnifying
glass
• Anton van Leeuwenhoek
• Dutch scientist
• Simple micro used glass
bead for a lens
• Magnified up to 270X
What did van Leeuwenhoek see?
Animalcules – coined
term of pond creatures
found by van
Leeuwenhoek.
The Compound Light Microscope
• Lets light pass through an object and then
through two or more lenses
Objective lens – eye piece
power of 10X
Body Tube – holds eyepiece
Revolving Nosepiece – holds second objectives
Arm – used to safely carry microscope
Stage – place slide over hole to receive light
Stage clips – holds slide in place
Diaphragm – controls amount of light
Coarse adjustment knob – use first to focus image NEVER
use after image is focused
Fine adjustment knob – use second for finer focus
Light source – light
Base – bottom of microscope
• Stereo microscope – 3D view of image
•
- used to view thick objects
or whole objects like an insect
•
- has two ocular eyepieces
• Electron Microscope – for
objects too small to be
viewed through a
compound light
microscope
•
- uses
magnetic field to bend
beams of electrons
•
- can
magnify one million times
Electron microscope images
• Robert Hooke –
– Thin slice of cork
– Looked like tiny empty
boxes - cells
– Drawing of cork cells
– Dead – no organic
material inside of them
Schleiden and Schwann
• German scientists who
discovered all living
things –plant and
animal- are made of
cells.
• Rudolph Virchow
– Theory that cells come
from other living cells
– They divide to form
new cells
The Cell Theory
• All organisms are made of one or more cells.
• Cells are the basic unit of structure and
function of all organisms.
• All cells come from other living cells.
Section 2-4
Cell Organization
• Prokaryotic cells – no
membrane around the
nuclear material
– Ex. Bacteria
• Eukaryotic cells –
have a nucleus with a
membrane around it
– Ex. Plant and animal
Cytoskeleton
Framework of
fibers which helps
cell :
maintain
shape
stretches
and contracts with
cell
supports cell
Cell membrane
• Outer layer of cell
• Flexible
• Allows material to go
into and out of cell
• Semipermeable
• Made of double layer
lipids (fats) with
protein in the middle.
Nucleus
• Directs the activity in the
cell
• Nuclear membrane –
membrane that holds the
nuclear material inside
the nucleus
• Chromatin – genetic
material (DNA)
• Nucleolus – makes
ribosomes
•
RNA-protein recipe
Cytoplasm
• Jelly material inside
cell
• Held in by cell
membrane
• Constantly streaming
• Allows other
organelles to hang
suspended in cyto
Endoplasmic reticulum
ER
• Folded membrane
• From nucleus to cell
membrane
• Moves material
around the cell
• Train tracks of cell
Endoplasmic reticulum
• Rough ER – contains
ribosomes
• Smooth ER – no
ribosomes
- makes
lipids (stored
energy)
Ribosomes
• Makes proteins
• Found on ER
– Rough ER
• Receives messages
from nucleus about
how to make and
kinds of proteins
• Some found scattered
in cyto
Mitochondria
• Powerhouse of cell
• Food is broken down
• Energy is released
Golgi Apparatus
• Stacks of flattened
membranes
• Package proteins
• Moves proteins
outside of the cell or
to areas in cell that
need them.
Lysosomes
• Containers of
chemicals that digest
wastes
• Digest worn out cell
parts
• Breakdown food
• Helps to breakdown
dead cells
Vacuoles
• Storage containers of
the cell
• H2O
• Food
• waste
• Plant cells – very large
vacuoles
– Helps to keep plant
rigid
Centrioles
• Found in animal cells
only
• Hollow tubular
structures arranged in
a bundle
• Used in animal cell
reproduction
Plant Cell
• Cell wall – rigid
structure outside of
the cell membrane it
gives plant;
•
support
•
protection
•
shape
• chloroplasts –
contains chlorophyll
• Light sensitive
• Helps light to produce
sugar for plant
Organelles of the Animal Cell
Bacteria cell
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Prokaryotic
Cell wall- capsule
Cytoplasm
Chromosome
No nuclear membrane
ribosomes