Type of cells
 Lab-5 Sunday 3/1/2016
The cell
The cell is the basic structural and functional unit of all known living organisms. It
is the smallest unit of life that is classified as a living thing, and is often called the
building block of life.
Organisms can be classified as unicellular (consisting of a single cell; including
most bacteria) or multicellular (including plants and animals). Humans contain
about 10 trillion (1013) cells. Most plant and animal cells are between 1 and
100 µm and therefore are visible only under the microscope.
The cell was discovered by Robert Hooke in 1665. In 1835, before the final cell
theory was developed.
The word cell comes from the Latin cellula, meaning "a small room". The
descriptive term for the smallest living biological structure was coined by Robert
Hooke in a book he published in 1665 when he compared the cork cells he saw
through his microscope to the small rooms monks lived in.
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Prokaryotic cells
Pro = “before”, karyon = “nucleus”
The first living organisms to evolve are primarily distinguished by the fact that
they lack a membrane-bound nucleus. In fact, the only membrane in prokaryotic
cells is the plasma membrane--the outer boundary of the cell itself.
Their genetic material is naked within the cytoplasm, ribosomes their only type
of organelle.
Prokaryotes are most always single-celled, except when they exist in colonies.
These ancestral cells, now represented by members of the domains Archaea
and Bacteria, reproduce by means of binary fission, duplicating their genetic
material and then essentially splitting to form two daughter cells identical to the
parent.
Domain Archaea
Methanosarcina mazei, an archaeon
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Domain Bacteria
E.coli, a bacterium
Features of Prokaryotes
 Prokaryote cells are smaller and simpler
 Commonly known as (bacteria), archaea, cyanobacteria.
 1–10 µm in size.
 Single-celled(unicellular) or
 Filamentous (strings of single cells).
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Prokaryotic cell
Diagram
Prokaryotic cell structure
Prokaryote cells are simply built (example: E. coli)
Capsule: slimy outer coating.
Cell wall: tougher middle layer.
Cell membrane: delicate inner skin.
Cytoplasm: inner liquid filling.
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DNA in one big loop.
Pilli: for sticking to things.
Flagella: for swimming.
Ribosomes: for building proteins.
Prokaryote lifestyle
 Unicellular: all alone.
 Colony: forms a film.
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 Filamentous: forms a chain of cells.
Prokaryote Feeding
 Photosynthetic: energy from sunlight.
 Disease-causing: feed on living things.
 Decomposers: feed on dead things.
Eukaryotic Cells
 Eu = “true”, karyon = “nucleus”
 The most noticeable feature that differentiates these more complex cells
from prokaryotes is the presence of a nucleus, a double membrane-bound
control center separating the genetic material, DNA (deoxyribonucleic acid),
from the rest of the cell.
 In addition to the plasma membrane, eukaryotic cells contain internal
membrane-bound structures called organelles. Organelles, such as
mitochondria and chloroplasts, are both believed to have evolved from
prokaryotes that began living symbiotically within eukaryotic cells.
 Eukaryotic cells can reproduce in one of several ways, including meiosis
(sexual reproduction) and mitosis (cell division producing identical daughter
cells).
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Features of Eukaryotes
 Eukaryotes are bigger and more complicated
 Have organelles.
 Have chromosomes.
 Can be multicellular.
 Include animal and plant cells, protists, slime molds, algae, fungi.
Domain Eukarya; Kingdom Protists
Paramecium, a unicellular protozoan
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Domain Eukarya; Kingdom Fungi
Coprinus, a shaggy mane mushroom
Domain Eukarya; Kingdom Plants
Passiflora, passion flower, a flowering plant
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Eukaryotic cell
Nerve cell
Eukaryotic cell
Muscle cell
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Eukaryotic cell
Epithelial cell
Eukaryotic Cell
Diagram
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Organelles are membrane-bound cell parts
 Mini “organs” that have unique structures and functions.
 Located in cytoplasm.
Cell Structures
Cell membrane
Delicate lipid and protein skin around cytoplasm.
Found in all cells.
Nucleus
A membrane-bound sac evolved to store the cell’s chromosomes (DNA).
Has pores: holes.
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Nucleolus
Inside nucleus.
Location of ribosome factory.
Contains (RNA).
Mitochondrion
Makes the cell’s energy.
The more energy the cell needs, the more mitochondria it has.
Ribosomes
Build proteins from amino acids in cytoplasm.
May be free-floating, or May be attached to ER.
Made of RNA.
Endoplasmic Reticulum (ER)
May be smooth (SER): builds lipids and carbohydrates
May be rough (RER): stores proteins made by attached ribosomes.
Golgi Complex
Takes in sacs of raw material from ER.
Sends out sacs containing finished cell products.
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Lysosomes
Sacs filled with digestive enzymes.
Digest worn out cell parts.
Digest food absorbed by cell.
Centrioles
Pair of bundled tubes.
Organize cell division.
Cytoskeleton
Made of microtubules.
Found throughout cytoplasm.
Gives shape to cell & moves organelles around inside.
Eukaryote cells can be multicellular
 The whole cell can be specialized for one job.
 Cells can work together as tissues.
 Tissues can work together as organs.
 Organs can work together as system.
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Differences between Prokaryotic & Eukaryotic cells
Prokaryotic Cells
Eukaryotic cells
Small cells 1–10 µm
Larger cells 10–100 µm
Always unicellular
Often multicellular
No nucleus or any membrane-bound organelles
Always have nucleus and other membrane-bound organelles
DNA is circular, without proteins
DNA is linear and associated with proteins to form chromatin
Ribosomes are small (80S)
Ribosomes are large (100S)
No cytoskeleton
Always have a cytoskeleton
Cell division is by binary fission
Cell division is by mitosis or meiosis
Reproduction is always asexual
Reproduction is asexual or sexual
L.A. SURA SALAH
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