2.1 Prokaryotic & Eukaryotic Cells

8/3/2019 2.1 Prokaryotic & Eukaryotic Cells

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CHAPTER 2.0:

CELL AS A UNIT OF LIFESUB-TOPIC 2.1:

PROKARYOTIC ANDEUKARYOTIC CELLS


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At the end of this topic, students will be able to :

Describe and compare the structures of

prokaryotic and eukaryotic cells

Learning Outcome


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KEY-CONCEPT / TERMS

Prokaryotic cells

Eukaryotic cells

Photosynthesis

Plant cell and Animal cell


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Cells

Smallest living unit

Most are microscopic


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Cell Size


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Characteristics of All Cells

A surrounding membrane

Protoplasm cell contents in thick fluid

Organelles structures for cell function Control center with DNA


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Cell Types

Prokaryotic

Eukaryotic


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PROKARYOTIC AND

EUKARYOTIC CELLSProkaryotic Cells

Prokaryotes pro, before; karyon, nucleus

A prokaryote is a single-celled organism

Very small (less than 5 - 10 micrometers long)

lack of membrane-bound organelles and

has a single chromosome circular in shape

E.g: bacteria, cyanobacteria


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Pili (singular, pilus):attach to surface and toexchange the geneticmaterial (conjugation).

Capsule: polysaccharideor protein coatingsecreted outside theircell wall

Structure of prokaryotic cells


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Cell wall: wall

surrounding theirplasma membrane,made of peptidoglycanto maintain the shapeand protect the cell.

Plasma membrane:made up of

phospholipids forexchange of wasteproduct and nutrients.


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Ribosomes: tinyorganelles found in largenumbers in the

cytoplasm Naked DNA: single,

circular strand of DNA


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Eukaryotic cells

The eukaryote eu, true Larger than prokaryotic, diameter 10-100

micrometer.

Membrane-bound nuclei Have linear strands of DNA within their nuclei Have many membrane-bound organelles with large

ribosomes

May have flagella or cilia cellulose cell wall (plant) E.g: Protists, fungi, animal and plants


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Anatomy of the animal cell


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Animal cell Plant cell


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Eukaryotic cells however are notall alike.

Each type of cell has a few uniqueorganelles not found in the other.

Plant cells for example containchloroplast, plastids and centralvacuole which are not found in theanimal cells.

Animal cells have centrioles


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Animal cell Bounded by plasma

membrane The nucleus is identical

to that in the plant cells

Structure of animal and plant cells


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Centrosome (a region)consisting centriolesoccurs beside the

nuclues. Contain organelles of

various types but nochloroplasts


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Plant cells

Surrounded by cell wallcomposed of cellulose,

The nucleus control anddirect the activities ofthe cell


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The nucleus surrounded

by nuclear membrane The cytoplasm is

bounded by a plasmamembrane and is

pressed firmly againstthe cell wall by a largefluid-filled vacuole


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The vacuole is boundedby a specializedmembrane calledtonoplast

Chloroplasts are the siteof photosynthesis.

They contain chlorophyll(green pigment)


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Starch granules occur inchloroplast

The cytoplasm also

contain stored foodsubstance such as oildroplets.


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There are cytoplasmicconnections between

cells calledplasmodesmata


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Differences between plant and animal cellsFeature Plant cell Animal cell

Cell wall Present Absent

Plasmodesmata Present Absent

Chloroplast Present Absent

Vacuole Large,permanent

Small, temporary

Reserve food Starch Glycogen


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Comparison between Prokaryotic and

Eukaryotic cellsCell structure Prokaryote Plant Animal

Cell wall (peptidoglycan ) (cellulose) none

Plasma membrane Nucleus none

DNA circular linear linear

Nucleolus none


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Cell structure Prokaryote Plant Animal

Central vacuole none none

Flagellum /cillium with

9 + 2 microtubular array

none


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Cell structure Prokaryote Plant Animal

Ribosome

Membrane-boundorganelles

none

Photosynthetic pigment none


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Feature Prokaryote EukaryoteOrganisms Bacteria Protists, fungi, plants and

animals

Cell size 0.5-10 m 10-100 m

Cell division binary fission Mitosis,meiosis

Geneticmaterial

DNA is circular,liesfree in cytoplasm

DNA is naked

DNA is linear and locatedin nucleus

DNA is associates withprotein to formchromosomes

Differences between Prokayotes andDifferences between Prokayotes andEukaryotesEukaryotes


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Respiration Mesosome inbacteria.

Insidemitochondria

Photosynthesis Photosyntheticbacteria takes placeon membrane

Plant cell : takeplace inchloroplast

Feature Prokaryote Eukaryote


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Organelles No membrane-

bound organelle

Membrane-bound

organelles present

Cell walls Peptidoglycan is

main strengtheningcompound of cellwalls

Compound of cell wall

inPlant cell: cellulose

Flagella Simple, nomicrotubules

Complex, with 9+2arrangement ofmicrotubules

Feature Prokaryote Eukaryote

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2.1 Prokaryotic & Eukaryotic Cells