General Animal Biology Zoology 145 course General Animal Biology For Premedical Student 1430-1431H

The Cell Types of cells متقدمة بدائية Eukaryotic Prokaryotic Cellulae (Small room) The Organism’s Basic Unit of Structure and Function متقدمة بدائية Types of cells Eukaryotic Prokaryotic All other forms of life Micro-organisms الكائنات الدقيقة

Cell Theory 1- All organisms are composed of one or more of cells. 2- Cell is the basic unit of life. 3- The new cell arises only from pre- existing cell.

1). Prokaryotic and eukaryotic cells differ in size and complexity Similarities أوجه التشابه All cells are surrounded by a plasma membrane غشاء بلازمى. The semi-fluid substance المادة النصف سائلة within the cell is called “cytosol”, السيتوبلازم containing the cell organelles عِضيات الخلية. All cells contain chromosomes which have genes in the form of DNA. All cells have tiny organelles عضيات صغيرة called “Ribosomes” that make proteins. Page 112

1). Prokaryotic and eukaryotic cells differ in size and complexity Differences أوجه الإختلاف A major difference الفرق الأساسى between prokaryotic and eukaryotic cells is the location of chromosomes موضع الصبغيات. In an eukaryotic cell, chromosomes are contained in a true nucleus (النواة ). In a prokaryotic cell, the DNA is concentrated in the nucleoid (شـبه نواة) without a membrane ( بدون غـشاء) separating it from the rest of the cell. In prokaryotic cell, DNA is a single strand (أحادى الشريط) or double strand (ثنائى الشريط) DNA. But in eukaryotic cell, DNA is double strand. Page 112

الكائنات وحيدة الخلية ذات النواة البدائية (A)- Prokaryotes الكائنات وحيدة الخلية ذات النواة البدائية Micro-organisms الأحياء الدقيقة Page 112, 526

Prokaryotes Bacteria Archaea Types of Prokaryotes - Exist in extreme environments البيئات القاسية (hot and salty) - Exist in most environments They are differing in some other structural, biochemical and physiological characteristics صفات Page 526

Prokaryotes 1- Bacteria

شبه نواة الريبوزومات الكبسولة الأسواط Fig. 7.4 The prokaryotic cell is much simpler in structure, lacking a nucleus and the other membrane-enclosed organelles of the eukaryotic cell. Page 112 غشاء بلازمى الجدار الخلوى شبه نواة الريبوزومات الكبسولة الأسواط

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

A) the bacterial capsule Many prokaryotes (bacteria) secrete a sticky protective layer called capsule outside the cell wall, which has the following functions وظائف: Adhere تثبيت bacteria cells to their substratum السطح. Increase bacteria resistance المقاومة to host defenses مناعة العائل. Stickتلصق) ) bacterial cells together when live as colonies. Protect تحمى bacterial cell. Fig. 27.6

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

The Gram’s stain: صبغة جرام It is a tool for identifying تعريف specific bacteria, based on differences in their cell walls. A)- Gram-positive (Gram +ve) bacteria: Their cell walls have large amounts كمية كبيرة of peptidoglycans that react with Gram’s stain (appear violet-stained تـُصبغ بنفسجيا). Fig. 27.5a Page 529

The Gram’s stain: صبغة جرام B)- Gram-negative (Gram -ve) bacteria: 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) Fig. 27.5b Page 529

Gram Staining of Bacteria Gram +ve bacteria: have Large amount of peptidoglycan that stained violet (non-pathogenic غير ممرضة). Gram –ve bacteria: Have small amount or no peptidoglycan (no staining) (pathogenic ممرضة). 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.

Reproduction of Bacteria التكاثر فى البكتريا Prokaryotes reproduce (تـتـكاثر) only asexually (لا جنسيا) by binary fission (الإنقسـام الثـنائى البسيط). A single cell produce a colony of offspring. Fig. 27.9 Page 531

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

Nutrition of Prokaryotes التغذية فى الأحياء الدقيقة Phototrophs (ضوئية التغذية): Organisms that obtain energy from light. Chemotrophs (كيميائية التغذية): Organisms that obtain energy from chemicals in their environment. Autotrophs (ذاتية التغذية): Organisms that use CO2 as a carbon source. Heterotrophs (متعدد التغذية): Organisms that use organic nutrients as a carbon source.

There are four major modes of nutrition Photoautotrophs (ذاتية التغذية الضوئية): use light energy as energy source, and CO2 as carbon source to synthesis (تخلق) organic compounds. Chemoautotrophs ذاتية التغذية الكيميائية)): use chemical inorganic substances as energy source, and CO2 as a carbon source. Photoheterotrophs (متعدد التغذية الضوئية): use light as energy source, and organic substances as carbon source. Chemoheterotrophs (متعدد التغذية الكيميائية): use organic substances as a source for both energy and carbon.

Organic compounds as Carbon Source Prokaryotic modes of nutrition Based on Carbon source and Energy source that can be used by a prokaryote organism to synthesise organic compounds. Prokaryotes Page 532 Autotrophs Heterotrophs CO2 as Carbon Source Organic compounds as Carbon Source Photo-autotroph Chemo-autotroph Photo-Heterotroph Chemo-Heterotroph - Light as energy source -CO2 as C source - Chemicals as energy source -CO2 as C source - Light as energy source -Organic compounds as C source - Chemicals as energy source - Organic compounds as C source