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

3

A Prototypical/Generic Cell

3 Major Eukaryotic Cell PartsThe 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 Elodea Onion prokaryote

Plasma Membrane

Cytoplasm

Cell wall

Nucleus

Vacuole

chloroplast

BIG or small

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

2 copy of each chromosome

Replication of DNA during S-phase of interphase

1 copy of each chromosome

1 copy of each chromosome

• Mitosis divides/separate the two copies of identical chromosomes

• Cytokinesis divides up the cytoplasm contentsParent/mother cell

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

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

no n

ucle

us

Mitosis identification game

http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/

01.html