Transcript المحاضرة الثالثة عشر Thirteenth lecture

Lecture 13: The Classification of Living
Organisms ‫تصنيف الكائنات الحية‬
Taxonomy ‫علم التصنيف‬
 Taxonomy: is that branch of biology, concerned with the grouping
and naming ‫ تسمية‬of organisms.
 The modern taxonomic system was developed by the Swedish
botanist Carolus Linnaeus ‫( كارلوس لينيوس‬1707-1788).
 He classified all known organisms into two large kingdoms:
a) Kingdom Plantae ‫المملكة النباتية‬
b) Kingdom Animalia ‫المملكة الحيوانية‬
 Linnaeus developed a 7 level classification system based on
similarities between organisms.
Kingdom Phylum Class Order Family Genus Species
‫مملكة‬
‫شعبة‬
‫طائفة‬
‫رتبة‬
‫عائلة‬
‫جنس‬
‫نوع‬
 Linnaeus classified species as the smallest unit.
 Species is a Latin word meaning “kind” or “appearance” ‫الشكل الظاهري‬
 Differences between species based on:
a) Morphological differences ‫اختالفات شكلية‬
b)The potential to interbreed ‫ القدرة على التزاوج‬with each other in
nature to produce fertile offspring ‫نسل خصيب‬
 Robert Whittaker ‫ روبرت وايتكر‬in 1969 proposed five kingdoms:
1) Kingdom: Animalia
‫مملكة الحيوان‬
3) Kingdom: Fungi
‫مملكة الفطريات‬
2) Kingdom: Plantae
‫مملكة النبات‬
5) Kingdom: Monera
‫مملكة البدائيات‬
4) Kingdom: Protista
‫مملكة الطالئعيات‬
Binomial nomenclature ‫التسمية الثنائية‬
 Developed by Carolus Linnaeus.
 Binomial nomenclature consists of two names:
 The first name is the organism’s genus
 The second name is the organism’s species
What rules are used to write scientific names?
1. The first letter of the genus is always capitalized.
2. The first letter of the species is always lowercase.
3. Scientific names of organisms are always italicized or
underlined.
For example, Linnaeus assigned to humans the scientific
name Homo sapiens, which means “wise man ‫”اإلنسان العاقل‬.
Systematic position of human ‫الوضع التقسيمي لإلنسان‬
Kingdom: Animalia ‫المملكة الحيوانية‬
Phylum:
Chordata ‫شعبة الحبليات‬
Class:
Mammalia ‫طائفة الثدييات‬
Order:
Primates ‫رتبة الرئيسيات‬
Family:
Hominidae ‫عائلة البشر‬
Genus:
Homo
Species:
sapiens
‫الجنس البشري‬
‫اإلنسان‬
First: Kingdom of Monera ‫مملكة البدائيات‬
 All the organisms of this kingdom are prokaryotes ‫بدائية النواة‬. This
means all cells do not have nuclear membrane.
 They are unicellular organisms ‫كائنات وحيدة الخلية‬
 The kingdom is divided into two groups, a) Bacteria and b) Archaea.
 Monera exist in habitats ‫ الموطن‬that are too cold, too hot, too salty, too
acidic, or too alkaline.
Classification of Kingdom Monera Based on
Mode of Nutrition ‫طريقة التغذية‬
1) Autotrophs ‫ذاتي التغذية‬
2) Heterotrophs ‫غير ذاتي التغذية‬
a) Saprophyte
‫ترمم‬
b) Parasitism
‫تطفل‬
c) Symbiosis
‫تكافل‬
i) Mutualism ii) Commensalism
‫تقايض‬
‫تعايش‬
 Autotrophic bacteria: bacteria which prepare their own food.
 Heterotrophic bacteria: bacteria which are dependent on other
organisms for their food.
 Parasitic bacteria: bacteria obtain their food from the tissues of
living organisms (host ‫ )العائل‬and cause harm to the host.
 Saprophytic bacteria: bacteria obtain their food from dead
organic matter.
 Mutualism: a relationship between individuals of different
species in which both individuals benefit.
 Commensalism: a relationship between individuals of different
species in which one organism benefits without affecting the
other
A) Bacteria
 Bacteria can be classified by shape into
Bacillus ‫عصوية‬, Coccus ‫ كروية‬or Spirillum
‫حلزونية‬.
 Different types of diseases are caused by
bacteria include: cholera, many sexually
diseases ‫األمراض الجنسية‬, and certain types
of food poisoning ‫التسمم الغذائي‬
 However, more bacteria are beneficial
‫مفيدة‬.
o Bacteria
in our intestines ‫أمعائنا‬
produce important vitamins.
o Bacteria recycle CO2 and other
chemical elements between organic
matter and the soil and atmosphere.
B) Archaea
Archaea can be classified into:
a)- Halophiles ‫محب للملوحة‬
 live in saline waters (high salt
concentrations) as the Great Salt
Lake and the Dead Sea.
 Some species require an extremely
salty environment to grow.
b)- Thermophiles ‫محب للحرارة‬
 live in hot environments (hot
springs).
 The optimum temperatures for
most thermophiles are 60 - 80°C.