B- Eukaryotic Cell

1. B- Eukaryotic Cell

2. 3- The Endomembrane System • The endoplasmic reticulumالشبكة الإندوبلازمية manufacturers membranes and performs many other biosynthetic functions • The Golgi apparatusجهاز جولـﭽـىfinishes, sorts, and ships cell products • The Lysosomesاليسوزوماتare digestive compartments • The Vacuolesالفجواتhave diverse functions in cell maintenance

3. A)-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. • Smooth ER looks smoothناعمة because it lacks ribosomes. • Rough ER looks rough خشنة because ribosomes (bound ribosomes) are attached to its outside. Fig. 7.11, Page 119

4. The smooth ER:الشبكة الإندوبلازمية الناعمة - It is rich in enzymes and plays a role in metabolic processes. - Its enzymes synthesize lipids دهون (oils, phospholipids, and steroids) including the sex hormones الهرمونات الجنسية. - Extensive توجد بكثرةin the liver, it helps detoxify إبطال الأثر السام drugs المخدرات and poisons السموم • The rough ER:الشبكة الإندوبلازمية الخشنة - is especially abundant متوفرة in those cells that secrete proteins as it contains ribosomes. - These secretory proteins are packaged in transport vesicles that carry them to their next stage.

5. B)- Golgi apparatus:finishes, sorts تـُجَهز, packaging and ships تغلف وتنقل cell products • Many transport vesicles أوعية ناقلة from the ER travel to the Golgi apparatus for modification تطوير of their contents. • The Golgi function is manufacturing تصنيع, warehousing تغليف, sorting تـَجْهيز (Packaging), and shipping نقلmaterials to outside the cell. • The Golgi apparatus is especially extensive in cells specialized for secretionخلايا إفرازية. • The Golgi also manufactures pectin and polysaccharides.

6. وعاء ناقل Fig. 7.12, Page 120

7. C)- Lysosomesالأجسام المُحللةare digestive components • The lysosome is a membrane-bounded sac كيسof enzymes that digests macromolecules. Fig. 7.13a, Page 121

8. Lysozomal enzymes Lysosomal enzymes work best at pH = 5 (acidic). The lysosomal enzymes are synthesized by rough ER and then transferred to تنقل إلى the Golgi then to lysosomes. Function of Lysozomal enzymes • They hydrolyse يحللproteins, fats, polysaccharides, and nucleic acids. • Can destroy the cell by autodigestion (autophagy) الهضم الذاتى. • Can fuse with food vacuoles الفحجوة الغذائية to digest food, (when a food item is brought into the cell by phagocytosis). • Can also fuse with another organelle or part of the cytosol. This process of autophagycalled recycling which renews the cell

9. Fig. 7.14, Page 122

10. D)- Vacuoles: الفجواتhave diverse functions وظائف متنوعةin cell maintenance للحفاظ على الخلية • Vesicles أوعـية and vacuoles فجوات are membrane-bound sacs أكياس ذات أغشية with varied functions. • Food vacuoles فجوة غذائية, from phagocytosis, fuse with lysosomes. • Contractile vacuoles فجوة منقبضة, found in freshwater protists, pump excess water out of the cell. • Central vacuolesفجوة مركزية are found in many mature plant cells.

11. خلية نباتية الفجوة المركذية خلية حيوانية Figs. 7.15 & 166, Page 123

12. Other Membranous Organelles A)- 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 down to smaller molecules that are transported to mitochondria for fuel لإنتاج الطاقة. 3- They detoxify يبطل المفعول السُّمى alcohol and other harmfulcompounds. Thus, it exists extensively in the liver cells

13. Other Membranous Organelles B)- Mitochondria:Thy are the main energy transformers of cells as they convert energy to fuel الطاقة that cells can use for work. • Mitochondria are the sites of cellular respiration, • generating تـُنتِجATP from the catabolism هدم of sugars, fats, and other fuels مصادر طاقة in the presence of oxygen. • Almost all eukaryotic cells have mitochondria. • Mitochondria and chloroplasts are mobile and move around the cell along tracks in the cytoskeleton.

14. Mitochondria have a smooth outer membrane and a highly folded inner membrane forming cristae نتوءات. • The inner membrane encloses the mitochondrial matrix, a fluid-filled space with DNA, ribosomes, and enzymes. Fig. 7.17, Page 124