B- Eukaryotic Cell

B- Eukaryotic Cell
Internal membranes ‫ أغشية داخلية‬compartmentalize
‫ تحدد أعضاء وظيفية‬the functions of a eukaryotic cell
An eukaryotic cell has internal membranes, which partition ‫ تـقـســم‬the cell
into compartments ‫أعضاء وظيفية‬.
These membranes also participate in metabolism as many enzymes are
built into membranes.
The general structure of a biological membrane is a double layer ‫ثنائى الطبقات‬
of phospholipids and diverse proteins ‫بروتينات متنوعة‬.
Each type of membrane has a unique combination ‫ تركيب مـمـيـ!ز‬of lipids and
proteins for its specific functions.
Page 114
For example, those in the membranes of mitochondria function in
cellular respiration.
B- Eukaryotic Cell
Eu: True
Karyon: Nucleus
Animal Cell
Plant Cell
What are the functions of cell organelles ?
Compare between Animal and Plant cell?
Page 114 - 115
‫المادة الوراثية‬
‫الشبكة الندوبلزمية‬
‫الجدار النووى‬
‫سوط حركى‬
‫جسم مركزى‬
‫حهاز جولـﭽـى‬
‫غشاء بلزمى‬
‫حلمات دقيقة‬
‫جسم ‪J‬محلل‬
‫الهيكل الخلوى‬
‫‪Fig. 7.7, Page 114‬‬
‫فجوة مركزية‬
‫بلستيدة خضراء‬
‫الجدار الخلوى‬
‫ثقوب بينية‬
‫‪Fig. 7.8, Page 115‬‬
‫‪The Cell Organelles‬‬
1. The nucleus:
Contains the cell’s genetic library ‫المحتوى الـﭽينى‬
The nucleus contains most of the genes in an
eukaryotic cell.
The nucleus is separated from the cytoplasm by a
double membrane ‫ غشاء مزدوج‬called nuclear membrane.
The nuclear membrane contains pores ‫ ثقوب‬that allow
large macromolecules and particles to pass through.
The nuclear membrane ‫ الغلف النووى‬is maintaining the shape
of the nucleus
Fig. 7.9, Page 116
The nucleus contains “chromatin fiber” ‫الخيوط الكروماتينية‬
which is the DNA associated with proteins.
When the cell prepares to divide, the chromatin
fibers coil up ‫ تلتف‬to be seen as “chromosomes”.
Each eukaryotic species has a characteristic number
of chromosomes ‫رقم مميـ!ز من الكروموسومات‬.
- A typical human cell has 46 chromosomes, but sex cells (eggs and
sperm) have only 23 chromosomes.
The nucleus directs protein synthesis by synthesizing
messenger RNA (mRNA).
– The mRNA travels to the cytoplasm and combines with
ribosomes to translate its genetic message into the
primary structure of a specific protein.
Nucleolus is a dark region involved in production
2. Ribosomes:
build the cell’s proteins
Ribosomes contain rRNA and protein.
A ribosome is composed of two subunits ‫ وحدتين‬that combine ‫ تتحد‬to
carry out protein synthesis ‫تخليق البروتين‬.
Fig. 7.10, Page 117
In the nucleolus, ribosomal RNA (rRNA) is synthesized
and assembled with proteins from the cytoplasm to
form ribosomal subunits.
The subunits pass from the nuclear pores to the
cytoplasm where they combine to form ribosomes.
Cell types that synthesize large quantities of proteins
(e.g., pancreas) have large numbers of ribosomes.
Types of Ribosomes:-
Free ribosomes are suspended ‫ معلق‬in the cytosol and
synthesize proteins that function within the cytosol.
Bound ribosomes are attached to ‫ ملتصق بـ‬the outside of the
endoplasmic reticulum.
These synthesize proteins that are either included into
membranes or for secretion outside the cell.