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General Biology lab
Lab 4
The Cell (Part A(
Definition
• The word cell comes from the Latin word
"cella", meaning "small room".
• The cell
– is the basic unit of all living things
• They are often referred to as "the building
blocks of life".
Characteristics Of Cell
 Several characteristics that are common to all cells, such as the
presence of a cell membrane, Cytoplasm, DNA, Ribosomes, not all
cells are the same.
 Cells arise from other cells through cellular division.
 Cells carry genetic material passed to daughter cells during cellular
division.
 All organisms are composed of one or more cells.
Prokaryotic cell
Eukaryotic cell
Smaller and simpler
Bigger and complex
The nuclear material is not envelope
by nuclear membrane
Genetic material is enclosed by nuclear
membrane .
Lack of many organelles
Contain organelles
Eubacteria and Archeabacteria
Plant , Animal , Fungi and protists
Single cell
Multicellular
Ribosomes 70s
10 µm in size
30s +50s
Ribosomes 80s
100 µm in size
40s+60s
 Bacteria
– are microscopic, single celled prokaryotic
cells.
 Habitat of bacteria
– Bacteria can be found virtually everywhere.
– They are in the air, the soil, and water, and in and on plants and
animals
• Some bacteria cause disease, but most
are actually helpful.
• Because of their small size, it is impossible
to see details inside bacterial cell with the
light microscope.
• Shape of bacteria
1. Rods
2. Sphere
3. Spirals
• They generally consist of
• Plasma membrane :
– The laminar structure that surrounds the cytoplasm of all cells .
• DNA
– This single chromosome is located in a region of the cell called the
nucleoid
• Ribosomes
– This organelle is where the last stages of protein synthesis take
place.
• Flagella
– Some bacteria also have tail-like structures called flagella help
bacteria move.
• Cell wall
– made of peptidoglycan ,keeps the cell from exploding if it absorbs
too much water. The flagella are attached to it.
• The cytoplasm
– The region located between the plasma membrane and the nucleus.
It contains fluid with organelles.
Bacteria in yogurt
Kingdom Protista
• Include protozoa and algae .
• protozoa
– Protozoa in Greek mean first animal .
– Unicellular eukaryotes
– Include Rhizopoda , Euglenozoa , Ciliphora .
Rhizopoda (Amoeba)
Amoeba
 Microscopic single celled(Unicellular) organisms
that possess pseudopods.
Habitat of Amoeba
 Free living organism found in fresh water .
Amorphous cell
 is a type of cell or organism which has the
ability to alter its shape.
 Lacks a rigid outer cell wall .
 The nucleus in the center of the cell .
Movement
– Move by pseudo pods (false feet)
– Pseudo pods are the temporary protrusion formed by streaming
of cytoplasm .
Nutrition
– Pseudopods can also be used to engulf food in a process called
phagocytosis
Euglenozoa (euglena)
Euglena
• Genus of single-celled flagellate protists
• that possess eye spot (photoreceptor) is
located near the site flagellum.
• Movement
– Move by flagellum (it is a long, thin, whip-like projection that
is used for locomotion).
• Nutrition
– This genus can be both autotrophic and heterotrophic
(Mixotrophic ).
– These cells contain chloroplasts for photosynthesis and they
may also engulf food by phagocytosis when light not available
Ciliphora (paramecium)
• Is a genus of unicellular ciliated protozoan
• Known as “slipper animalcules”
• Have two nucleolus
Habitat of paramecium
• Paramecia are widespread in freshwater,
brackish, and marine environments and
are often very abundant in ponds.
• Movement
– Paramecia propel themselves by whiplash movements of their
cilia.
– Cilia : hair-like structures which are arranged in tightly spaced
rows around the outside of their body
• Nutrition
– They get their nutrients through phagocytosis.