The Eukaryotic Cell PDF

The Eukaryotic cell Pamela BL  To understand the morphology of the human body, there is a need to learn about: Cells Tissues Organs Systems  To understand the human body, the student must learn Microscopic(histological)structure of the of each individual cell Macroscopic appear...

The Eukaryotic cell Pamela BL  To understand the morphology of the human body, there is a need to learn about: Cells Tissues Organs Systems  To understand the human body, the student must learn Microscopic(histological)structure of the of each individual cell Macroscopic appearance(gross) of organs and systems(their shape, location and how they are relate to each other in the body)  The study of individual cells is called cell biology(cytology). Cytology, science of the cell where one learns To recognize different types of cells To understand organization and structure of cells in terms of their functions. The study of morphological features of different cells and their arrangement in tissues and organs is called histology.  In histology, the part of an organ or tissue to be studied is collected, and the portion that is collected is referred to as a specimen. In our laboratories, most specimens that are used for histology are collected from an animal which usually bears great similarities with human tissue.  The cell: general overview The cell is the smallest living unit of the body Cells…..tissues…..organs…..systems. The cell is made up of 3 compartments: Nucleus Cytoplasm Plasma membrane  The size, shape and function of mammalian cells vary from cell to cell. Our bodies are made up of different cells of various shapes and sizes. That is why we study cells to know their functional differences in different tissues and organs  The differences in functions make the cell to express specific morphological features that makes it different. Cells cannot survive independently, they depend on external source of nutrients and oxygen for sustaining their life. Nutrients are used as a source of energy as well as the raw materials for synthesis of new molecules.  Cellular functions performed by some specialized cells Type of cell Function performed Glandular cells Secretion of materials(in form of hormones, enzymes and growth factors) Muscle cells Contraction that gives rise to locomotion and peristalsis Neuron Initiation and conduction of nerve impulses White blood cells Recognition and elimination of pathogens Oligodendrocytes and Shwann cells Myelination of nerve axons Osteoblasts Bone formation, formation of bone matrix and calcification Osteoclasts Secrete hydrolytic enzymes, that destroy bone tissue Adipocytes Storage of fat Fibroblasts Facilitate wound healing and tissue repair  Types of cells There are two types of cells: Prokaryotic cells Eukaryotic cells Prokaryotic cells are primitive unicellular cells o Generally small o Have no nuclei, therefore their hereditary materials lie freely in the cytoplasm. Continued…prokaryoti c cells o Have few or no organelles o Membrane bound organelles are absent o Replicate quickly by binary fission.  Eukaryotic cells: o Complex cells found in higher plants and animals o They form multicellular bodies o Are also characteristic of protozoa such as amoeba and malaria parasite  The Eukaryotic cell: Consists of the nucleus, and cytoplasm bounded by the plasma membrane The nucleus is surrounded by the nuclear envelope, and contains chromosomes and the nucleolus. The cytoplasm contains cell organelles(membrane bound and non membrane bound organelles) and cytoplasmic inclusions.  Differences between prokaryotic cells and eukaryotic cells Cell differences Prokaryotic cells Eukaryotic cells Cell size Small cells Large cells Nucleus Absent present Cytoplasm Contains metabolic Complex cytoplasm substances, few or no containing both membrane organelles, membrane bound and non membrane bound organelles usually bound organelles not present Nature of DNA Short, circular, not bound Long double helix molecule to histone proteins bound to histone and non histone proteins Mode of replication By binary fission Reproduce via mitosis and meiosis in germ cells  Differences between prokaryotic cells and eukaryotic cells Cell differences Prokaryotic cells Eukaryotic cells Nature of existence Form unicellular organism Exists in multicellular organisms Intermediate filaments absent present Exocytosis and endocytosis absent present Ribosomes Smaller in size Larger in size metabolism Anaerobic and aerobic aerobic