Download NOTES: 7.1 - Intro to Cells

NOTES: 7.1 Introduction
to the Cell
1. All living things are composed of 1 or
more cells.
2. Cells are the basic unit of structure &
function in living things.
3. New cells are produced from
existing cells.
MICROSCOPES
1. Light Microscope
2. Electron Microscope (1940’s)
•
Scanning Electron Microscope
•
Transmission Electron Microscope
Light Microscope
• works by passing visible light
through a thin section of
specimen and then through
glass lenses
• magnification about 1000x 1500x
Electron Microscope (1940’s)
• uses electron beams which
have shorter wavelengths
of light (so you can see
smaller objects…more
detail)
• magnification up to
500,000x
Electron Microscope
1. Scanning Electron Microscope
– electron beam scans the surface of
a specimen
– useful for studying the surface of
specimen in 3-D
2. Transmission Electron
Microscope
– electrons transmitted through
specimen
– used to study internal cell structure
Disadvantages to EM…
• can only view dead cells (preparation
steps kill living cells)
• very expensive
zooxanthellae cells
cultured from coral
Aiptasia pulchella in a
Scanning Electron
Microscope
ALL CELLS:
• have a cell membrane
• have cytoplasm
• have ribosomes
• can reproduce & contain
genetic material
CELLS CAN BE CLASSIFIED AS:
1. PROKARYOTES
See… no nucleus!!!
2. EUKARYOTES
See… a nucleus!!!
PROKARYOTES
• oldest cells (3.5 billion
years)
EUKARYOTES
• “newer” cells (1.5 billion
years)
PROKARYOTES
EUKARYOTES
• oldest cells (3.5 billion
years)
• “newer” cells (1.5 billion
years)
• single celled
• single or multicellular
PROKARYOTES
EUKARYOTES
• oldest cells (3.5 billion
years)
• “newer” cells (1.5 billion
years)
• single celled
• single or multicellular
• lack nucleus &
membrane-bound
organelles
• have a “true” nucleus &
membrane-bound
organelles
PROKARYOTES
EUKARYOTES
• oldest cells (3.5 billion
years)
• “newer” cells (1.5 billion
years)
• single celled
• single or multicellular
• lack nucleus &
membrane-bound
organelles
• have a “true” nucleus &
membrane-bound
organelles
• genetic material in a
single, circular molecule
• genetic material
organized and in nucleus
PROKARYOTES
EUKARYOTES
• oldest cells (3.5 billion
years)
• “newer” cells (1.5 billion
years)
• single celled
• single or multicellular
• lack nucleus &
membrane-bound
organelles
• have a “true” nucleus &
membrane-bound
organelles
• genetic material in a
single, circular molecule
• genetic material
organized and in nucleus
• small (1-2 µm)
• larger (2-1000 µm)
PROKARYOTES
EUKARYOTES
• oldest cells (3.5 billion
years)
• “newer” cells (1.5 billion
years)
• single celled
• single or multicellular
• lack nucleus &
membrane-bound
organelles
• have a “true” nucleus &
membrane-bound
organelles
• genetic material in a
single, circular molecule
• genetic material
organized and in nucleus
• small (1-2 µm)
• larger (2-1000 µm)
• Domains Bacteria &
Archaea (bacteria)
• Kingdoms Protista, Fungi,
Plantae, Animalia
NUCLEUS
• membrane-bound organelle
in eukaryotic cells;
• contains the cell’s DNA
– enclosed by a nuclear
envelope
– contains all of the information
for cell to function