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Transcript of CELL Topics Cell structure Cell structure Cell function Cell function Cellular organization Cellular...

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CELL Topics Cell structure Cell structure Cell function Cell function Cellular organization Cellular organization Cellular metabolism Cellular metabolism (by Dr. Amjad Ali Khan) Slide 2 Introduction The cell is the structural and functional basic unit of life. The cell is the structural and functional basic unit of life. It was discovered by Robert Hooke and is the functional unit of all known living organisms. It was discovered by Robert Hooke and is the functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. Slide 3 Introduction Some organisms, such as most bacteria, are unicellular (consist of a single cell). Some organisms, such as most bacteria, are unicellular (consist of a single cell). Other organisms, such as humans, are multicellular. Other organisms, such as humans, are multicellular. Humans have about 100 trillion or 10 14 cells; a typical cell size is 10 m (micrometer) and a typical cell mass is 1 nanogram. Humans have about 100 trillion or 10 14 cells; a typical cell size is 10 m (micrometer) and a typical cell mass is 1 nanogram. Slide 4 Types of Cells There are two types of cells: There are two types of cells: prokaryotic and eukaryotic Prokaryotic cells are usually independent, while eukaryotic cells are often found in multicellular organisms. Prokaryotic cells are usually independent, while eukaryotic cells are often found in multicellular organisms. Slide 5 Prokaryotic Cell The prokaryote cell is simpler, and therefore smaller, than a eukaryote cell, lacking a nucleus and most of the other organelles of eukaryotes. The prokaryote cell is simpler, and therefore smaller, than a eukaryote cell, lacking a nucleus and most of the other organelles of eukaryotes. Nuclear material of prokaryotic cell consist of a single chromosome which is in direct contact with cytoplasm. Here the undefined nuclear region in the cytoplasm is called nucleoid. Nuclear material of prokaryotic cell consist of a single chromosome which is in direct contact with cytoplasm. Here the undefined nuclear region in the cytoplasm is called nucleoid. Slide 6 On the outside, flagella and pili may be present. These facilitate the movement and communication between cells. On the outside, flagella and pili may be present. These facilitate the movement and communication between cells. Enclosing the cell is the cell envelope generally consisting of a cell wall covering a plasma membrane Enclosing the cell is the cell envelope generally consisting of a cell wall covering a plasma membrane Slide 7 General structure of a Prokaryotic cell Slide 8 Cell Eukaryotic Cell Eukaryotic cells are far more advanced and complex than a Prokaryotic cell. Eukaryotic cells are far more advanced and complex than a Prokaryotic cell. Eukaryotic cell can be as much as 1000 times bigger in size than a prokaryotic cell. Eukaryotic cell can be as much as 1000 times bigger in size than a prokaryotic cell. eukaryotic cells contain membrane-bound compartments (organelles) in which specific metabolic activities take place. eukaryotic cells contain membrane-bound compartments (organelles) in which specific metabolic activities take place. Slide 9 Most important among these is a nucleus, a membrane bound compartment that contains DNA. This nucleus gives the eukaryote its name, which means "true nucleus. Most important among these is a nucleus, a membrane bound compartment that contains DNA. This nucleus gives the eukaryote its name, which means "true nucleus. There are some differences in the structure and function of animal and plant cells. Though both cells are eukaryotic. There are some differences in the structure and function of animal and plant cells. Though both cells are eukaryotic. Slide 10 In the cytoplasm the eukaryotic cell contains many organelles such as: In the cytoplasm the eukaryotic cell contains many organelles such as: Mitochondria Mitochondria Endoplasmic reticulum (rough and smooth) Endoplasmic reticulum (rough and smooth) Golgi bodies Golgi bodies Lysosomes Lysosomes Peroxisomes Peroxisomes Ribosomes Ribosomes Chloroplast (found in plant cells) Chloroplast (found in plant cells) Vacuole Vacuole centriole centriole Slide 11 Simple structure of a eukaryotic cell Slide 12 Eukaryotic cell organelles There are several types of organelles in a cell. There are several types of organelles in a cell. Some (such as the nucleus and golg apparatus) are typically solitary, while others (such as mitochondria, peroxisomes and lysosomes) can be numerous (hundreds to thousands). Some (such as the nucleus and golg apparatus) are typically solitary, while others (such as mitochondria, peroxisomes and lysosomes) can be numerous (hundreds to thousands). The cytosol is the gelatinous fluid that fills the cell and surrounds the organelles. The cytosol is the gelatinous fluid that fills the cell and surrounds the organelles. Slide 13 Nucleus The cell nucleus is the most conspicuous organelle found in a eukaryotic cell. It contains the chromosomes, The cell nucleus is the most conspicuous organelle found in a eukaryotic cell. It contains the chromosomes, The nucleus is spherical and separated from the cytoplasm by a double membrane called the nuclear envelope. The nucleus is spherical and separated from the cytoplasm by a double membrane called the nuclear envelope. The nuclear envelope isolates and protects a cell's DNA The nuclear envelope isolates and protects a cell's DNA Slide 14 The nucleolus is a specialized region within the nucleus where ribosome subunits are assembled. The nucleolus is a specialized region within the nucleus where ribosome subunits are assembled. In prokaryotes, DNA processing takes place in the In prokaryotes, DNA processing takes place in the cytoplasm. cytoplasm. Slide 15 Mitochondria Mitochondria play a critical role in generating energy in the eukaryotic cell so it is also called power house of a cell. Mitochondria play a critical role in generating energy in the eukaryotic cell so it is also called power house of a cell. Mitochondria are self-replicating organelles that occur in various numbers, shapes, and sizes in the cytoplasm of all eukaryotic cells. Mitochondria are self-replicating organelles that occur in various numbers, shapes, and sizes in the cytoplasm of all eukaryotic cells. Mitochondria multiply by splitting in two. Mitochondria multiply by splitting in two. Respiration occurs in the cell mitochondria. Respiration occurs in the cell mitochondria. Slide 16 General structure of Mitochondria Slide 17 Endoplasmic reticulum The endoplasmic reticulum (ER) is the transport network for molecules targeted for certain modifications and specific destinations. The endoplasmic reticulum (ER) is the transport network for molecules targeted for certain modifications and specific destinations. The ER has two forms: the rough ER, which has ribosomes on its surface and secretes proteins into the cytoplasm, and the smooth ER, which lacks them. The ER has two forms: the rough ER, which has ribosomes on its surface and secretes proteins into the cytoplasm, and the smooth ER, which lacks them. Slide 18 Endoplasmic Reticulum Slide 19 Golgi apparatus The primary function of the Golgi apparatus is to process and package the macromolecules such as proteins and lipids that are synthesized by the cell. The primary function of the Golgi apparatus is to process and package the macromolecules such as proteins and lipids that are synthesized by the cell. It is particularly important in the processing of proteins for secretion. It is particularly important in the processing of proteins for secretion. It consists of -cis and -trans faces It consists of -cis and -trans faces Slide 20 Golgi apparatus Slide 21 Ribosomes The ribosome is a large complex of RNA and protein molecules. The ribosome is a large complex of RNA and protein molecules. They each consist of two subunits, and act as an assembly line where RNA from the nucleus is used to synthesize proteins from amino acids. They each consist of two subunits, and act as an assembly line where RNA from the nucleus is used to synthesize proteins from amino acids. Slide 22 Ribosomes Ribosomes can be found either floating freely or bound to endoplas- mic reticulum in eukaryotes, or the cell membrane in prokaryotes). Ribosomes can be found either floating freely or bound to endoplas- mic reticulum in eukaryotes, or the cell membrane in prokaryotes). In prokaryotic cells 70S ribosomes are present while in eukaryotic cells 80S ribosomes are present In prokaryotic cells 70S ribosomes are present while in eukaryotic cells 80S ribosomes are present Slide 23 Lysosomes Lysosomes contain digestive enzymes. They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria. Lysosomes contain digestive enzymes. They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria. These organelles (lysosomes and peroxisomes) are often called a "suicide bag" because of their ability to detonate and destroy the cell. These organelles (lysosomes and peroxisomes) are often called a "suicide bag" because of their ability to detonate and destroy the cell. Slide 24 Vacuoles Vacuoles store food and waste. Some vacuoles store extra water. Vacuoles store food and waste. Some vacuoles store extra water. The vacuoles of eukaryotic cells are usually larger in those of plants than animals. The vacuoles of eukaryotic cells are usually larger in those of plants than animals. Slide 25 Centriole In animal cells, centrioles are short cylinders present near the nucleus. In animal cells, centrioles are short cylinders present near the nucleus. There is always one pair of centrioles near the nucleus. There is always