B- Eukaryotic CellB- Eukaryotic Cell

Fig. 7.11, Page 119

3)- The endoplasmic reticulum (ER) manufacturers membranes and performs many other biosynthetic functions

• The ER includes membranous tubules

• There are two types of ER that differ in structure and function.

1. Smooth ER looks smoothناعمة because it lacks ribosomes.

2. Rough ER looks rough because ribosomes خشنة(bound ribosomes) are attached to its outside.

• The smooth ER: اإلندوبالزم الناعمة يالشبكة ة- It synthesizes lipids دهون (oils, phospholipids,

and steroids) including the sex hormones الجنسية .الهرمونات

- Extensive بكثرة in the liver, it helps detoxify توجدالسام األثر إبطال

drugs المخدرات and poisons السموم

• The rough ER: الخشنة اإلندوبالزمية الشبكة - is especially abundant متوفرة in those cells that

secrete proteins البروتينات as it containsتفرزribosomes.

• Many transport vesicles ناقلة from the ER أوعيةtravel to the Golgi apparatus for modification تطوير of their contents.

• The Golgi function is manufacturing تصنيع, warehousing تغليف, sorting تَـج1هيز (Packaging), and shipping نقل materials to outside the cell.

• The Golgi apparatus is especially extensive in cells specialized for secretion اإلفراز في .المتخصصة

4)- Golgi apparatus: finishes, sorts تُـج8هز, packaging and ships وتنقل cell products تغلف

Fig. 7.12, Page 120

وعاء ناقل

• The lysosome is a membrane-bounded sac كيسof enzymes that digests macromolecules.

5)- Lysosomes الم=حللة are digestive األجسامcomponents

Fig. 7.13a, Page 121

Lysosomal enzymes work best at pH = 5 (acidic).

The lysosomal enzymes are synthesized by rough ER and then transferred to إلى .the Golgi then to lysosomes تنقل

Function of Lysozomal enzymes

1) They hydrolyse يحللproteins, fats, polysaccharides, and nucleic

acids.

2) Can destroy the cell by autodigestion (autophagy) الذاتى .الهضم

3) Can fuse with food vacuoles الغذائية to digest food, (when a الفجوة

food item is brought into the cell by phagocytosis).

4) Can digestتهضم another organelle. This process of autophagy

called recycling which renews the cell

Lysozomal enzymes

Fig. 7.14, Page 122

• Vesicles أوعـية and vacuoles فجوات are membrane-bound sacs أغشية ذات with أكياسvaried functions.

1. Food vacuoles غذائية .from phagocytosis, fuse with lysosomes ,فجوة

2. Contractile vacuoles منقبضة found in freshwater protists, pump , فجوةexcess water out of the cell.

3. Central vacuoles مركزية .are found in many mature plant cells فجوة

6)- Vacuoles: الفجوات have diverse functions متنوعة الخلية in cell maintenanceوظائف على للحفاظ

Figs. 7.15 & 166, Page 123

الفجوة المركذية

خلية نباتية

خلية حيوانية

7)- Peroxisomes contain enzymes that transfer hydrogen from various substrates to

oxygen

Functions of peroxisomes

1- Hydrogen peroxide (H2O2) is a poison, but the peroxisome has enzyme

that converts H2O2 to water.

2- Some peroxisomes break fatty acids تكسر الدهنية downاألحماضto smaller molecules that are transported to mitochondria for fuel الطاقة .إلنتاج

3- They detoxify مىNالس المفعول alcohol and يبطلother harmful compounds. Thus, it exists

extensively in the liver cells

8)- Mitochondria:Thy are the main energy producers الطاقة of منتجي

cells as they make energy الطاقة that cells can use for

work.

• Mitochondria are the sites of cellular

respiration,

• generating جb ,of sugars هدم ATP from the catabolism تُـنت

fats, and other fuels طاقة مصادر in the presence of

oxygen األكسجين وجود . في

• Almost all eukaryotic cells have mitochondria.

• Mitochondria are mobileمتحركة and move around the

cell along tracksمسارات in the cytoskeleton هيكل

. الخلية

• Mitochondria have a smooth outer membrane ناعم خارجي and غشاءa highly folded inner membrane منثني داخلي forming cristaeغشاء.نتوءات

• The inner membrane enclosesيحيط the mitochondrial matrix, a fluid-filled space with DNA, ribosome, and enzymes.

Fig. 7.17, Page 124