Cells: why they are important
• All living things are made of one or more
cells.
• Cells are the smallest functional unit of
living things.
• The basic unit of life
• The structure and function of cells relates
to the structure and function of the entire
organism.
Types of Cells
• Prokayrotic  Bacteria
• Eukaryotic  Everything else
– Plants
– Animals
– Fungi
– Algae
– protists
A Prototypical/Generic Cell
3
3 Major Eukaryotic Cell Parts
The major parts of the cell include
• Plasma membrane — the outer boundary of the cell,
controls/regulates what enters or exits cell
• Cytoplasm — within PM, performs most cell activities
• Nucleus— contains & protects DNA; “control center” of cell
Plasma Membrane
Cytoplasm
Nucleus
You will observe and compare the
VISIBLE structure among:
• Human Cheek Cell (animal cell)
• Elodea Cell (plant cell)
• Onion Cell (plant cell)
• Have one person at each table set up
different slide and then look at eachothers
microscopes.
Human Cheek Cell—animal cell
Elodea Cell: a plant cell
(from leaf/above ground part of plant)
Onion Cell: plant cell
(from below ground plant part)
Plant Cell Parts
Cell Wall
Cell/Plasma membrane
Vacuole
Chloroplast
Nucleus
Euks v. Proks
Eukaryotic
• Large
• DNA within nucleus
• Many different organelles
Prokaryotic
• Very small
• No nucleus, DNA ‘exposed’
• Very few organelles
Typical eukaryotic cell
Typical prokaryotic cell
Animal
Plasma
Membrane
Cytoplasm
Cell wall
Nucleus
Vacuole
chloroplast
BIG or small
Elodea
Onion
prokaryote
Mitosis and the Cell Theory:
• Cells only come from pre-existing cells (part of cell theory)
• Existing cells must divide to create new cells
– Growth or replacement of damaged/dead cells
• New cells need all the DNA/genetic information
the original cell had
• DNA must be copied, then divided equally, then
cell can divide.
Mitotic Cell Division
– Replication = copying DNA
– Mitosis = separation of duplicated chromosomes
– Cytokinesis = division of cytoplasm and separation of
two cells
– Results in two daughter cells, each with a complete
set of DNA that is identical to one another and
identical to the original cell (genetically identical)
1 copy of each
chromosome
1 copy of each
chromosome
2 copy of each
chromosome
1 copy of each
chromosome
Replication of DNA during
S-phase of interphase
• Mitosis divides/separate
the two copies of identical
chromosomes
Parent/mother cell
• Cytokinesis divides up
the cytoplasm contents
daughter cells: each with one
copy of each chromosome,
genetically identical to the
mother cell
The Cell Cycle
Interphase
Prophase
Metaphase
Anaphase
telophase
Daughter cells
in interphase
no nucleus
Cell Cycle Stages made simple
•
•
•
•
•
Interphase = nucleus visible, not chromosomes
Prophase = chromosomes in a clump
Metaphase = chromosomes in a line
Anaphase = chromosomes in two clumps
Telophase = chromosomes in two clumps;
cytokinesis visible
Mitosis identification game
http://www.biology.arizona.edu/cel
l_bio/activities/cell_cycle/01.html