Objectives
• List the components of the cell theory
• Compare prokaryote and eukaryote cells
• Compare & contrast a plant and an animal cell
• Know the functions of cell organelles
Early Contributions
• Anton van Leeuwenhoek –
• Made 1st microscope
• Observed living cells called "animalcules“
• Robert Hooke • Observed tiny units in cork and named them “cells”
• Theodore Schwann - zoologist who observed tissues of
animals had cells (1839)
• Mattias Schleiden - botanist, observed tissues of plants
contained cells ( 1845)
The Cell Theory
1. All organisms are
composed of one or more
cells
2. The cell is the basic
unit of structure and
functions of living things
3. All cells come from
pre-existing cells
The cell is the Basic Unit of
Life
• Cell is basic unit of life
• Unicellular organisms are
made of one cell only
• The cells of multicellular
organisms are specialized to
perform different functions
Levels of Organization
CELLS
(muscle cells, nerve cells)
TISSUES
ORGANS
(muscle, epithelium)
(heart, lungs, stomach)
SYSTEMS
ORGANISM
(circulatory system)
(human)
Common Cell Features
ALL CELLS have these parts:
• Ribosomes – make protein for use by the organism
(protein synthesis)
• Cytoplasm – fluid material within cell; carbohydrate
and water based solution that suspends all internal
parts of the cell
• DNA – genetic blueprint; is a nucleic acid
• Cell Membrane – outer boundary of cells, determines
what goes in and out , semipermeable, made up of a
phospholipid bilayer
Two Types of Cells:
Prokaryote and Eukaryotes
Prokaryote Cells
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The first cells to inhabit the earth
Smallest and simplest cells
Always a single–celled organism
Bacteria
These cells do NOT have a nucleus
No membrane-bound organelles
DNA is circular and floats in the cytoplasm
Have a cell wall
Many have flagella – long, threadlike structures that
protrude from the cell’s surface and enable movement
(whip-like tail)
A capsule surrounds
some bacteria and helps
them avoid the body’s
immune system and cling
to almost anything (teeth,
skin, and food)
Prokaryotic Cell
Bacteria Images
Bacteria that causes Anthrax
Eukaryotic Cells
• Cells found in plants, animals, protists,
and fungi
• Have a Nucleus
• Have membrane-bound organelles
• Larger cells than prokaryotes
• More complex
• DNA is linear
• Evolved from prokaryotes
Eukaryotic Cell
Animal Cell
• 1. cell (plasma) membrane –
thin, transparent, 2-layered, semi-permeable
(porous), flexible
-controls what enters and leaves cell
-separates cell from its environment
2. nucleus –
command center of the cell; most cells have only one;
some have >1
DNA: (one of two forms)
a) chromatin – mass of thread-like fibers
scattered through the nucleus (normal)
b) chromosomes – compact chromatin (when
dividing)
-direct & store instructions for all cell
functions and control inheritance of traits
c) nuclear membrane –
2-layered, semi-permeable, porous,
surrounds nucleus
d) nucleolus – cell may have 1 or 2; produce
granules rich in RNA, each granule will
become part of a ribosome
e) nucleoplasm - fluid within the nucleus
* 3. cytoplasm – jelly-like fluid outside
nucleus, but within cell
-transports chemical substances within
the cell
4. endoplasmic reticulum – network of
interconnected membranes (ER)
-storage, separation, and transport of
substances made within the cell (mostly
proteins)
a) rough ER – dotted with ribosomes
b) smooth ER – no ribosomes
5. Golgi apparatus (body) – stack of flattened
membranes where proteins are packaged
and distributed
6. vacuole – clear, fluid-filled sac; used for
storage
7. lysosome – small sac filled with powerful
chemicals which break down food
molecules and digest old organelles;
surrounded by a membrane
8. mitochondria – “powerhouse” of the cell;
bean-shaped; one of the largest and most
numerous; site of cellular respiration
Cytoskeleton
9. microtubules – long, thin, hollow cylinders;
in cytoplasm, they support cell (shape) or
are arranged in bundles in other structures
(like cilia, flagella, or centrioles* - only in
animal cells)
10. microfilaments – tiny-threadlike fibers made
of protein; contract like muscle cells for
movement
11. ribosomes – tiny, round bodies involved
in protein synthesis from amino acids
Plant Cell
-have a cell wall composed of cellulose
(provides structure and support)
-contain chloroplasts – function in photosynthesis
(football shaped), starch
granules – spherical, function in food storage,
and carotens – contain orange pigments; spherical
-plant cells are rectangular in shape (animal cells are
spherical)
-have a large water vacuole which provides turgor
pressure