Eukaryotic Cell PDF

Eukaryotic cell Vincent Rodrigues  The cell Cell is the structural, functional and biological unit of a living organism (building blocks of life) Study of cells – cytology or cell biology Prokaryotic cell: Found in bacteria Small and don’t have membrane bound n...

Eukaryotic cell Vincent Rodrigues  The cell Cell is the structural, functional and biological unit of a living organism (building blocks of life) Study of cells – cytology or cell biology Prokaryotic cell: Found in bacteria Small and don’t have membrane bound nucleus Eukaryotic cell: Large, have a distinct nucleus surrounded by a nuclear membrane Eg- animal cells, plant cells Vincent Rodrigues  Animal cell Adult humans have around 100 trillion cells in the body There are different types of cells Cells of epithelium – epithelial cells Cells of connective tissue – fibroblast cells Cells of bones – osteocytes Cells of cartilages – chondrocytes Cells of muscle – muscle cells or myocytes Cells of nervous tissue – nerve cells or neurons Cells of blood – white blood cells, red blood cells Vincent Rodrigues  Structure of a cell: The cell has a covering called cell or plasma membrane Interior of cell contains nucleus and cytoplasm Cytoplasm Nucleolus Ribosomes Nucleus Cell Membrane Mitochondria Rough Endoplasmic Smooth Endoplasmic Reticulum Reticulum Golgi Bodies Centrioles Nuclear membrane with nuclear pores Vincent Rodrigues  Plasma membrane Also known as cell membrane or plasmalemma Outer covering of cell It separates the cell from the extracellular space and fluid It is made up of phospholipid, protein, carbohydrate and cholesterol molecules Functions as a selective barrier that regulates the passage of certain materials into and out of the cell Facilitates the transport of specific molecules  Impermeable membrane – substances can not cross a membrane Freely permeable membrane – substances can cross the membrane without difficulty Selectively permeable membrane – allows certain substances to pass Some cells present the extension of cell membrane – microvilli, cilia and flagellum Microvilli – seen in the cells lining intestine Cilia – seen in the cells lining the trachea Flagellum – long projection, seen in the sperms Vincent Rodrigues  Cytoplasm: Part of the cell between the plasma membrane and the nuclear envelope Clear in color and has a gel-like appearance Mainly made up of water Also contains proteins, carbohydrates, lipids, enzymes, sodium, potassium, phosphates, magnesium, bicarbonates and vitamins Also contains cell organelles like mitochondria, golgi apparatus, endoplasmic reticulum, ribosomes, lysosomes, centrioles and microtubules Helps to move materials around the cell and also dissolves cellular waste Vincent Rodrigues  Mitochondria: Rod-shaped organelles that can be considered the power generators of the cell Sites of production of high energy compounds like adenosine triphosphate (ATP) Convert oxygen and nutrients into ATP Their number in a cell depends upon the metabolic requirements of that cell Vincent Rodrigues  Contain outer and inner membranes Inner membrane is thrown into folds called cristae Cristae divide the interior into compartments Intermembrane space is the narrow gap between the two membranes Matrix is the part enclosed by the innermost membrane. Several of the steps in cellular respiration occur in the matrix due to its high concentration of enzymes Vincent Rodrigues  Endoplasmic reticulum: Is a network of tubules Synthesizes proteins, carbohydrates and lipids Also involved in the storage and transport of these structures Two types of endoplasmic reticulum - Rough and smooth endoplasmic reticulum  Rough endoplasmic reticulum: Rough because it contains ribosomes Protein is synthesized here Smooth endoplasmic reticulum: Without ribosomes Involved in carbohydrate and lipid metabolism Vincent Rodrigues  Golgi apparatus (Golgi complex) Consists of a stack of flattened membrane discs called cisternae Number of cisternae vary from 3 to 10 Usually located close to the cell nucleus It is the distribution and shipping department for the cell's chemical products It modifies proteins and lipids (fats) that have been built in the endoplasmic reticulum and prepares them for export outside of the cell or for transport to other locations in the cell Vincent Rodrigues  Ribosomes: Granule shaped structures Contain RNA Manufacture proteins using information provided by the DNA of the nucleus Two types of ribosomes Free ribosomes – scattered in the cytoplasm Fixed ribosomes – attached to the endoplasmic reticulum  Lysosomes: These are roughly spherical bodies bounded by a single membrane Contain hydrolytic enzymes like acid phosphatase Responsible for intracellular digestive process Responsible for breakdown of materials ingested by the cells Digestion compartments for cellular materials that have exceeded their lifetime or are otherwise no longer useful These break down cellular waste products, fats, carbohydrates, proteins, and other macromolecules into simple compounds Found in all animal cells, but are most numerous in disease-fighting cells, such as white blood cells, macrophages Vincent Rodrigues  Centrioles: Animal cell contains pair of centrioles They are cylindrical structures, made up of short microtubules Each centriole contains 9 groups of microtubules These take major role during cell division Microtubules: These are tubular structures made up of protiens They give stability to the cell They are required for cell division  Nucleus: Is the administrative center of the cell Stores the cell's hereditary material - DNA Coordinates the cell's activities like growth, metabolism, protein synthesis, and reproduction (cell division) Generally there is only one nucleus per cell, but there are exceptions (muscle cell) A double-layered membrane, the nuclear envelope, separates the contents of the nucleus from the cellular cytoplasm The envelope is perforated with tiny holes called nuclear pores  These pores regulate the passage of molecules between the nucleus and cytoplasm The semifluid matrix found inside the nucleus is called nucleoplasm The nucleus contains – nucleolus and chromatin Nucleolus: Membrane-less organelle within the Nucleolus nucleus - manufactures ribosomes Under microscope it looks like a large dark spot within the nucleus Nucleus may contain up to four nucleoli  Chromatin: Made up of network of threadlike structures called chromosomes Most of the human cells contain 46 chromosomes Chromatid The sperms and ovum contain 23 Centromere chromosomes each The chromosomes contain DNA The chromosomes contain 2 parts Chromatid - elongated thread like part Centromere – is a node like part situated near the centre of chromosome Vincent Rodrigues