A)- Prokaryotes

It includes two Major Domains: Archaea and Bacteria It includes two Major Domains: Archaea and Bacteria Prokaryotes are single-celled organisms that do not have a membrane-bound nucleus, and can live in nearly every environment on Earth. Prokaryotes are single-celled organisms that do not have a membrane-bound nucleus, and can live in nearly every environment on Earth. Although tiny, prokaryotes differ greatly in their genetic traits, their modes of nutrition, however, their habitats are similar. Although tiny, prokaryotes differ greatly in their genetic traits, their modes of nutrition, however, their habitats are similar. Based on genetic differences, prokaryotes are grouped in two domains: Domain Archaea and Domain Bacteria. Based on genetic differences, prokaryotes are grouped in two domains: Domain Archaea and Domain Bacteria.

1. Domain: Archaea can be classified into: Archaea are extremophiles, “ مُحب للظروف القاسية ” of extreme environments and can be classified into: a)- Extreme halophiles مُحب للملوحة : live in such saline places as the Great Salt Lake and the Dead Sea. live in such saline places as the Great Salt Lake and the Dead Sea. Some species require an extremely salty شديدة الملوحة environment to grow. Some species require an extremely salty شديدة الملوحة environment to grow. b)- Extreme thermophiles مُحب للحرارة live in hot environments. The optimum temperatures for most thermophiles are °C. The optimum temperatures for most thermophiles are °C.

غشاء بلازمى الجدار الخلوى شبه نواة الريبوزومات الكبسولة الأسواط Bacteria occur in many shapes and sizes. Most bacteria have one of three basic shapes: rod-shaped, sphere-shaped, or spiral-shaped. 2. Domain: Bacteria

Prokaryotic Cell Capsule Cell Wall Plasma membrane Cytoplasm ( Cytosol ) Nucleoid Ribosomes

Bacteria occur in many shapes and sizes. Most bacteria have one of three basic shapes: rod-shaped, sphere-shaped, or spiral-shaped. Bacteria occur in many shapes and sizes. Most bacteria have one of three basic shapes: rod-shaped, sphere-shaped, or spiral-shaped. Spiral shaped bacteria are called spirilla (singular, spirillum). Spiral shaped bacteria are called spirilla (singular, spirillum). Sphere-shaped bacteria are called cocci (singular, coccus). An example of cocci is Micrococcus luteus. Cocci that form chains similar to a string of beads are called streptococci. Sphere-shaped bacteria are called cocci (singular, coccus). An example of cocci is Micrococcus luteus. Cocci that form chains similar to a string of beads are called streptococci. Rod-shaped bacteria are called bacilli (singular, bacillus). An example of bacilli is Escherichia coli. Rod-shaped bacteria are called bacilli (singular, bacillus). An example of bacilli is Escherichia coli. Shapes of Bacteria

It is a tool for identifying تعريف specific bacteria, based on differences in their cell walls. A)- Gram-positive ( Gram +ve ) bacteria: A)- Gram-positive ( Gram +ve ) bacteria: violet- تـُصبغ بنفسجيا Their cell walls have large amounts كمية كبيرة of peptidoglycans that react with Gram’s stain (appear violet- stained تـُصبغ بنفسجيا ). The Gram’s stain: صبغة جرام

B)- Gram-negative B)- Gram-negative ( Gram -ve ) bacteria: تظهر الصبغة their cell walls have no or small amount of peptidoglycan. So, do not react or very weakly react with Gram’s stain (do not appear stained لا تظهر الصبغة ) The Gram’s stain: صبغة جرام

Gram Stain Gram Stain Most species of bacteria are classified into two categories based on the structure of their cell walls as determined by a technique called the Gram stain. Most species of bacteria are classified into two categories based on the structure of their cell walls as determined by a technique called the Gram stain. 1.Gram-positive bacteria have a thick layer of peptidoglycan in their cell wall, and they appear purple under a microscope after the Gram-staining procedure. 2.Gram-negative bacteria have a thin layer of peptidoglycan in their cell wall, and they appear reddish- pink under a microscope after the Gram-staining procedure. The Gram’s stain: صبغة جرام

Gram Staining of Bacteria Gram +ve bacteria: have Large amount of peptidoglycan that stained violet ( most of them are non-pathogenic غير ممرضة ). Gram +ve bacteria: have Large amount of peptidoglycan that stained violet ( most of them are non-pathogenic غير ممرضة ). Gram –ve bacteria: Have small amount or no peptidoglycan (no staining) ( most of them are pathogenic ممرضة ). Gram –ve bacteria: Have small amount or no peptidoglycan (no staining) ( most of them are pathogenic ممرضة ). Gram-negative species are pathogenic ( ممرضة ) more threatening ( أكثر خطورة ) than gram-positive species. Gram-negative species are pathogenic ( ممرضة ) more threatening ( أكثر خطورة ) than gram-positive species. Gram-negative bacteria are commonly more resistant ( أكثر ممانعة ) than gram-positive species to antibiotics للمضادات الحياتية. Gram-negative bacteria are commonly more resistant ( أكثر ممانعة ) than gram-positive species to antibiotics للمضادات الحياتية.

Many prokaryotes (bacteria) secrete a sticky protective layer called capsule outside the cell wall. Many prokaryotes (bacteria) secrete a sticky protective layer called capsule outside the cell wall. Capsule has the following functions وظائف : Capsule has the following functions وظائف : 1. Adhere bacteria cells to their substratum. 1. Adhere تثبيت bacteria cells to their substratum السطح. 2. Increase bacteria resistance to host defenses. 2. Increase bacteria resistance المقاومة to host defenses مناعة العائل. 3. Stickتلصق ) ) bacterial cells together when live as colonies. 4. Protect bacterial cell. 4. Protect تحمى bacterial cell. I - the bacterial capsule

In all prokaryotes, the functions of the cell wall are as following: تحافط 1. maintains تحافط the shape of the cell, الحماية الطبيعية توفر 2. affords physical protection الحماية الطبيعية توفر ( إنفجار ) البيئة ذات التركيز الأسموزي المنخفض 3. prevents the cell from bursting ( إنفجار ) in a hypotonic environment البيئة ذات التركيز الأسموزي المنخفض. peptidoglycan Most bacterial cell walls contain peptidoglycan ( a polymer of modified sugars cross-linked by short polypeptides ). ( تـفـتـقـد ) The walls of Archaea lack ( تـفـتـقـد ) peptidoglycan. II - The bacterial cell wall

Structural Characteristics of a Bacterial Cell

Prokaryotes reproduce ( تـتـكاثر ) only a sexually ( لا جنسيا ) by binary fission ( الإنقسـام الثـنائي البسيط ). A single cell produce a colony of offspring. Reproduction of Bacteria التكاثر في البكتريا

Nutrition of Prokaryotes Nutrition of Prokaryotes التغذية في الأحياء الدقيقة Prokaryotes are grouped into four categories according to how they obtain energy and carbonProkaryotes are grouped (صُنٍفـَت) into four categories (أنواع) according to how they obtain energy and carbon Nutrition refers to how an organism obtains energy and a carbon source from the environment to build the organic molecules of its cells.

Phototrophs ضوئية التغذية Phototrophs ( ضوئية التغذية ): Organisms that obtain energy from light. Chemotrophs كيميائية التغذية Chemotrophs ( كيميائية التغذية ): Organisms that obtain energy from chemicals in their environment. Autotrophs ذاتية التغذية Autotrophs ( ذاتية التغذية ): Organisms that use CO 2 as a carbon source. Heterotrophs متعدد التغذية Heterotrophs ( متعدد التغذية ): Organisms that use organic nutrients as a carbon source. Nutrition of Prokaryotes Nutrition of Prokaryotes التغذية فى الأحياء الدقيقة

 Photoautotrophs light energyCO 2  Photoautotrophs (ذاتية التغذية الضوئية): use light energy as energy source, and CO 2 as carbon source to synthesis (تخلق) organic compounds.  Chemoautotrophs inorganic substancesCO 2  Chemoautotrophs ذاتية التغذية الكيميائية)): use chemical inorganic substances as energy source, and CO 2 as a carbon source.  Photoheterotrophs use lightorganic substances  Photoheterotrophs (متعدد التغذية الضوئية): use light as energy source, and organic substances as carbon source.  Chemoheterotrophs  Chemoheterotrophs (متعدد التغذية الكيميائية): organic substances use organic substances as a source for both energy and carbon. There are four major modes of nutrition

Prokaryotic modes of nutrition Based on Carbon source and Energy source that can be used by a prokaryote organism to synthesize organic compounds. AutotrophsHeterotrophs Photo- autotroph Chemo- autotroph Chemo- Heterotroph Photo- Heterotroph CO 2 as Carbon Source Organic compounds as Carbon Source - Light as energy source -CO 2 as C source - Light as energy source -CO 2 as C source - Chemicals as energy source -CO 2 as C source - Chemicals as energy source -CO 2 as C source - Light as energy source -Organic compounds as C source - Light as energy source -Organic compounds as C source - Chemicals as energy source - Organic compounds as C source - Chemicals as energy source - Organic compounds as C source Prokaryotes