Lecture 3: The Cell The Cell Theory The cell theory states that: In 1838, the German botanist Matthias Schleiden concluded that all plants were composed of cells In 1839, Theodor Schwann concluded the same thing for animals In 1855, Rudolf Virchow noted that all cells come from other cells The cell theory states that: all living organisms are made of one or more cells, cells are the basic units of structure and function, and cells come only from pre-existing cells. A cell is the smallest unit that can carry on all of the processes of life

All Protists, Fungi, Plants and Animals Types of cells بدائية النواة حقيقية النواة Prokaryotes Eukaryotes Bacteria and Archaea All Protists, Fungi, Plants and Animals

Prokaryotic and eukaryotic cells A) 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.

Prokaryotic and eukaryotic cells B) Differences أوجه الإختلاف A major difference الفرق الأساسي between prokaryotic and eukaryotic cells is the location of chromosomes موضع الصبغيات In an eukaryotic cell, chromosomes are contained in a true nucleus (النواة) with nuclear membrane غشاء نووي. In a prokaryotic cell, the DNA is concentrated in the nucleoid (شـبه نواة) without a nuclear membrane separating it from the rest of the cell. In prokaryotic cell, DNA is a single strand (أحادى الشريط) or double strand (ثنائي الشريط), but in eukaryotic cell, DNA is double strand.

Comparison between Prokaryotes and Eukaryotes Term Prokaryotes Eukaryotes Size 1-10 µm in diameter 10-100 µm in diameter Cell wall Existed In plant cell (not animal cell) nucleus No nuclear membrane but Nucleoid True nucleus exists with nuclear membrane DNA As fibre in the nucleoid region (plasmids in some cases) As Chromatin (DNA and protein) Specializeorganells Most of them are absent All are existed Cell division By binary fission Meiotic and/or Mitotic

Types of Prokaryotes Prokaryotes Bacteria Archaea 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

Bacteria

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

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

Eukaryotes An eukaryotic cell has internal membranes, which partition تـُقـَســم the cell into compartments أجزاء مستقلة. These membranes also participate in metabolism as many enzymes are built into membranes. The general structure of a biological membrane is a double layer ثنائي الطبقات of phospholipids and diverse proteinsبروتينات متنوعة. Each type of membrane has a unique combination تركيب مـُمـَيـٍز of lipids and proteins for its specific functions. For example, those in the membranes of mitochondria function in cellular respiration.

Eukaryotes Animal Cell Plant Cell Eu: True Karyon: Nucleus Animal Cell Plant Cell Compare between Animal and Plant cell? What are the functions of cell organelles ?

الشبكة الإندوبلازمية الكروماتين نوية النواة سوط حركى الغلاف النووى خشنه ناعمه جسم مركزى ريبوسوم حهاز جولـﭽـي حلمات دقيقة غشاء بلازمي ميتوكوندريا جسم مُحلل الهيكل الخلوى

فجوة مركزية بلاستيدة خضراء الجدار الخلوى ثقوب بينية