1 Cell Organelles Continuous……..

2 The Cytoskeleton الهيكل الخلوى Pages A network of fibresrovide structural support تدعيم to the cell extending throughout تمتد خلالthe cytoplasm A network of fibres شبكة من الالياف that provide structural support تدعيم to the cell extending throughout تمتد خلالthe cytoplasm

3 Cytoskeleton Page Responsible for cell motilityحركة, and separation of chromosome during cell divisionانفصال الكروموسومات اثناء الانقسام الخلوي. () (Tubulin protein) Support cell motility and transport materials within the cellنقل المواد داخل الخلية. () (Actin protein) Support the cell shape and fixing position of organelles. () (Fibrous protein) Microfilaments Intermediatefilaments Microtubules ThickThinMiddleسميكة رفيعةمتوسطة أنيبيبات دقيقة ألياف دقيقة ألياف متوسطة

4 Page 127

5 The cytoskeleton is dynamicمتحرك, dismantling يتفككin one part and reassembling يتجمعin another to change cell shapeيغير شكل الخلية.The cytoskeleton is dynamicمتحرك, dismantling يتفككin one part and reassembling يتجمعin another to change cell shapeيغير شكل الخلية. Functions of the cytoskeleton 1. The cytoskeleton provides mechanical supportدعم and maintains shape of the cellيحافظ على شكل الخلية. 2. The cytoskeleton also plays a major roleيلعب دور اساسي in cell motility حركة الخلية by interacting الاتصال مع motor proteins البروتين الحركى 2. The cytoskeleton also plays a major roleيلعب دور اساسي in cell motility حركة الخلية by interacting الاتصال مع motor proteins البروتين الحركى. Interactions of motor proteins and the cytoskeleton circulates تدور materials الموادwithin the cell. 3. Interactions of motor proteins and the cytoskeleton circulates تدور materials الموادwithin the cell. Motor molecules also carry organelles تحمل العضياتto various destinationsأماكن العمل by the cytoskeleton. 4. Motor molecules also carry organelles تحمل العضياتto various destinationsأماكن العمل by the cytoskeleton. Fig. 7.21a, Page 126 The Cytoskeleton الهيكل الخلوى

6 Microtubule Motor Protein Organelle P Energy Microtubules functions as tracks قضيب that guide motor proteins carrying organelles to their destination. Microtubules functions as tracks قضيب that guide motor proteins carrying organelles to their destination المكان المستهدف. e.g. They move chromosomes during cell division

7 Fig. 7.22, Page 128 الجسم المركزيCentrosome الجسم المركزيCentrosome In animal cells, the centrosome has a pair of centriolesزوج من السنتريولات, each with 9 triplets of microtubulesIn animal cells, the centrosome has a pair of centriolesزوج من السنتريولات, each with 9 triplets of microtubules تسعة مجموعات كل منها مكون من ثلاثة أنيبيبات (9 + 0 pattern ) arranged in a ring مُرتبة دائريا. تسعة مجموعات كل منها مكون من ثلاثة أنيبيبات (9 + 0 pattern ) arranged in a ring مُرتبة دائريا. During cell division the Centrioles replicate تتضاعف.During cell division the Centrioles replicate تتضاعف.

8 Microtubules are the central structural supports both cilia الأهداب and flagella الأسواط. –Both can move unicellular and small multicellular organisms by propellingدفع الماء water outside the organism. Fig. 7.23, Page 129 Cilia and Flagella Cilia usually occur in large numbers on the cell surface.Cilia usually occur in large numbers on the cell surface. Flagella usually occur in just one or a few per cell.Flagella usually occur in just one or a few per cell.

9 cilia flagellum

10 Fig  Both cilia and flagella have the same ultrastructure التركيب الدقيق.  Both have a core مركز of microtubules surrounded by محاطة ب the plasma membrane.  9-doublets (9 + 2 pattern) تسعة مجموعات كل منها مكون من أنيبيبتان of microtubules arrangedمرتبة aroundحول a pair زوج at the centerالمركز.  The outer doublets are also connected by motor proteins.  The structurecilium and flagellum is identical to that of centriole.  The structure of cilium and flagellum is identical to that of centriole.  Cilia and flagella are formed of arms of a motor protein of arms of a motor protein (dynein بروتين الداينين).

11 7- Cell membrane Fig. 7.6, Page 113, and Fig Page 133 The plasma membrane functions as a selective barrier حاجز إختيارى that allows passage of oxygen, nutrients, and wastes for the whole volume of the cell.The plasma membrane functions as a selective barrier حاجز إختيارى that allows passage of oxygen, nutrients, and wastes for the whole volume of the cell.

12 Cell membrane Composed of lipids (phospholipids) and proteins Lipid layer contains hydrophilic and hydrophobic regions Phospholipid Hydrophilic مُحب للماء Hydrophobic كاره للماء Proteins Carbohydrate chains Fig. 7.6 Page 113, and Fig Page 138

13 Term ProkaryotesEukaryotes Size1-10 µm in diameter µm in diameter Cell wallExistedIn plant cell ( not animal cell ) nucleus No nuclear envelope but Nucleoid True nucleus exists with nuclear envelope DNA As fibre in the nucleoid region ( plasmids in some cases ) As Chromatin ( DNA and protein ) Specialized Organells Most of them are absentAll are existed Cell division By Binary FissionMeiotic and/or Mitotic Comparison between Prokaryotes and Eukaryotes