Prokaryotic Cel寡s

Prokaryotes are organisms that are composed of p「okaryotic ce=s, P「oka「yotes

a「e the smaIiest and simpIest ceIis, A p「okaryote is a single-Ceiled organism that

lacks a nuc!eus and othe「 intemal compartments, Because prokaryotes iack

many specialized inte「naI compartments, they camot carry out many specialized

functions (hence why they are simp!e「), and because they iack these st「uctures,

they a「e much sma=er than eukaryotes (thei「 size is usua=y about O,5-2 um).

Prokaryotes are the most primi[ive of ce=s (meaning they are the oidest and

Simp!est), and [hey lived a=east 3.5 b冊On yearS agO. For nea「ly 2 b冊on years,

P「Okaryotes were the onIy organisms on Ea巾h. The most familia「 examp!e of

P「Okaryotes is bacteria.

1n prokaryotic ce=s, the cytop!asm is everything inside the ce!看membrane"

P「okaryotes have a ce!! wall su「rounding thei「 Ceil memb「ane" The cel! wa旧s

Very impo巾ant because it gives prokaryotic ce=s their shape, The ceii wa= is

typica=y made up of poIysaccha「ides connected by sho巾Chains of amino acids・

P「okaryotes also have a cytoske!eton, but it is very simpIe and aides in ce11

movement. Many (not a=) prokaryotes also have a fIagella, Which are Iong,

th「eadIike st「uctu「es that protrude f「om the cell’s surface to enabIe the ce旧o

move at faste「 speeds.

丁he ce= wa旧s often times cove「ed by a capsuIe, Which is also made out of

POlysaccharides. The capsule is very sticky, and a=ows the prokaryote to stick toteeth, Skin, food, intestjnes, etC, Prokaryotes may also have a piius, Which a「e

S[icky p「Qjections.

The DNA shape of p「oka「yotes is different than eukaryotes because it consists of

a single, CircuIa「 mo!ecule of DNA. The DNA is aIso f「ee and Ioose within the ce=

because it is not housed in a nucieus (remember, One Ofthe most definitive

featu「es of a prokaryotic ceIIs is the fact that i=acks a nucleus)"

◎ 201 2 Vanessa Jason BjoIogy Roots www.bioiogyイOOtS,COm

Eukaryotic Ce音ls

Eukaryotes a「e organisms that are made up of eukaryotic celIs, Eukaryotic ceils

Were the first ceIIs to appear on ea巾h that had speciaiized inte「nai

COmPa正ments. Eukaryotic ce!Is evo!ved about 2,5 b冊on yea「s ago, and

euka「yotic celIs are defined by having a nucleus。

丁he specia=zed inte「naI compa巾ments that a「e found in eukaryotic ceIis are

known as “organe=es” meaning “!軸e organs”, The「e a「e many d肺e「ent

Organe=es in euka「yotic ce!Is, and they a「e defined as a st「ucture that ca「ries out

SPeCific activities in the ce!I. Exampies of organelles are mitochondria,

endopIasmic reticu!um, and the Go!gi body, tO name a few.

一n Eukaryotic ce一一S, the cytoplasm is de軸ed as everything in-side the ceIl

memb「ane and outside ofthe nucIeus. The cytoso=s the fIuid that is contained in

the cytopIasm. The cytoskeleton of euka「yotic ce=s is very compIex and supports

the cell’s shape and movement葛

Euka「yo[ic ce=s a「e very iarge in comparison to othe「 fypes Qf ce11s (about lO

um). Eukaryotic ce=s are aIso ve「y complex compa「ed to othe「 ce=s because

they contain many specia!ized organe!les that each has a spec胴c function.

丁hough aII ce=s have DNA, euka「yotic ce=s are the oniy cei! type that has an

Organei看e known as the nucIeus (as mentioned above)" The nucIeus houses and

P「OteCtS the DNA.

Exampies of euka「yotic ce=s are animal ce!Is, Piant ce!ls, and some p「otists such

as paramecium,

◎ 201 2 Vanessa Jason BioIogy Roots www.bio10gy-「OOtS.COm