Cell Physiology By Dr Vani Gupta Robert Hooke

Cell Physiology By Dr. Vani Gupta

�Robert Hooke (mid-600 s) observed cell in cork § Cell is the basic structural, functional and biological unit § Cell- The smallest unit of life that can replicate independently, and are often called the "building blocks of life"

Structure of Cell • Each cell is formed by a cell body and membrane covering the cell body called cell membrane. • Cell body has two part a- Nucleus b-Cytoplasm • Cell membrane

Structure Of Animal Cell

Structure of Plant Cell

Cell Size

Characteristics of Cell �A surrounding membrane �Protoplasm – cell contents in thick fluid �Organelles – structures for cell function �Control center with DNA

Cell Membrane § The cell membrane surround the cell; work as gatekeeper. membrane serves to separate and protect a cell from its surrounding environment § also known as plasma membrane or plasma lemma § selectively permeable and able to regulate what enters and exits the cell. § Cell membrane is composed of three type of substance 1 -Protein-55% 2 -Lipid-40% 3 -Carbohydrate-5%

Cell membrane

Structure of Cell Membrane- cell membrane is called unit membrane. Electron microscope study reveals three layer of cell membrane v One central electron-lucent layer-protein layer v Two electron dense layer-lipid layer.

Cytoplasm- Gel-like fluid that take up most of the space inside the cell containing organelles components of cytoplasm � Interconnected filaments & fibers � Fluid = cytosol � Organelles (not nucleus) � storage substances

Microtubules �Filamentous intracellular structure with 20 -30 nm in diameter that are responsible for various kinds of movements in all eukaryotic cells. �Microtubules are composed of a single type of globular protein tubulin. Function of microtubules � Long rigid shape - which enables microtubules to support other structures within the cell �Ability to generate movement - various kinds of movements in all eukaryotic cells. both within cells (conveyer belts) and of the whole cells themselves ( microtubules that form structures such as cilia and flagella). �Role in nucleic and cell division (Spindle –Mitosis, centiole movements)

�Inter mediate Filaments: Forms network around nucleus extend towards periphery. �Diameter- 10 nm. �Rope like polymer �Five Classes: 1. Keratins (epithelial Cells) 2. Glial filaments (Astreocytes). 3. Neurofilaments(nerve cells). 4. vimentin 5. desmin (muscle fibers)

�Microfilaments: Long fine thread like 3 -6 nm. �Non tubular contractile proteins. (actin & myosin) Ectoplasm-Actin Endoplasm- Actin & myosin Functions: structural strength. Resistance against pulling force Cellular Movements- contraction, gliding, cytokinesis.

Nucleus v Nucleus control center of cell, is the largest organelle. v Double membrane Nucleus Contains � Chromosomes � Nucleolus Function of nucleus v Control of all activities of the cell v Synthesis of RNA v Sending genetic instruction to cytoplasm for protein synthesis v Formation of subunits of ribosome v Control of cell division v Storage of hereditary information in genes

Mitochondria � Known as power house, bound by double membrane � Have their own DNA � 0. 5 -1. 0 micron. � Cristae � Matrix Function of mitochondria • Production of energy • Synthesis of ATP • Initiation of apoptosis Cytochrome C Caspases • Storage of Ca & Detoxification of Ammonia.

Endoplasmic Reticulum Endoplasmic reticulum (ER)- an interconnected network of tubules, vesicles, and cisternae within cells. The phospholipid membrane encloses a space, the cisternal space (or lumen), from the cytosol, which is continuous with the perinuclear space. Two types �Rough endoplasmic reticulum �Smooth endoplasmic reticulum

�Ribosome-15 nm dot like without membrane. � 35% protein & 65% RNA. �Functions: Protein Factories. �Bound Ribosome- Enzyme, Hormone, lysosomal protein & cell membrane protein. �Free Ribosome-Hb , peroxisomal & mitochondrial protein.

Rough endoplasmic reticulum Smooth endoplasmic reticulum �Ribosomes attached to surface �No attached ribosomes �Has enzymes that help build molecules � Manufacture proteins � Not all ribosomes attached to rough ER �May modify proteins from ribosomes � Carbohydrates � Lipids

Function of Rough endoplasmic Function of Smooth endoplasmic reticulum v Synthesis of protein v Degradation of worn out organelles v v Synthesis of lipid and steroids Role in cellular metabolism Storage and metabolism of calcium Catabolism and detoxification of toxic substance

Golgi Apparatus � The Golgi apparatus also known as the Golgi complex, Golgi body, or simply the Golgi, is an found in most eukaryotic cells. � Involved in synthesis of plant cell wall � Labeling, Packaging & shipping station of cell Golgi Apparatus Functional mechanism: 1. Molecules come in vesicles 2. Vesicles fuse with Golgi membrane 3. Molecules may be modified by Golgi 4. Molecules pinched-off in separate vesicle 5. Vesicle leaves Golgi apparatus 6. Vesicles may combine with plasma membrane to secrete contents

Lysosomes � Lysosomes - cellular organelles which contain acid hydrolase enzymes to break up waste materials and cellular debris. They are found in animal cells, while in yeast and plants the same roles are performed by lytic vacuoles. � � � Some (50) important enzymes found within lysosomes include: Lipase, which digest lipids Amylase, which digests amylose, starch, and maltodextrins Proteases, which digest proteins Nucleases, which digest nucleic acids phosphoric acid monoesters. � � � Functions of Lysosomes Aid in cell renewal Break down old cell parts (autography) Digests invaders (hetrography) Secretary-Perforin, Granzymes, Melanin, Serotonin

Vacuoles vacuole- membrane-bound organelle which is present in all plant and fungal cells and some protist, animal and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution , though in certain cases they may contain solids which have been engulfed. Function of Vacuole � Isolating materials that might be harmful or a threat to the cell � Containing waste products � Containing water in plant cells � Maintaining internal hydrostatic pressure or turgor within the cell � Maintaining an acidic internal p. H � Containing small molecules � Exporting unwanted substances from the cell

MULTIPLE CHOICE QUESTIONS

Q-1 The maximum size of a cell is limited by �a. its need for enough surface area for exchange with its environment. �b. the number of organelles that can be packed inside. �c. the materials needed to build it. �d. the amount of flexibility it needs to be able to move. �e. the amount of food it needs to survive Ans –a

�Q-2 Generally accepted features of biological membrane include all of the following except �a-asymmetric arrangement of lipid �b-rapid diffusion of inorganic ions across lipid bilayer �c- lateral diffusion of lipid �d-lateral diffusion of integral and peripheral proteins. Ans-b

Q-3 the major function /feature of the golgi apparatus in eukaryotic cells are �a-its carries out glycosylation of the proteins being transported �b-it is the major protein sorting centre of the cell �c-it forms secretary vesicles in its trans compartment �d-all of the above Ans-d

Q-4 which one of the following organelles is enclosed by a single membrane �a-mitochondria �b-nucleus �c-chloroplast �d-lysosome Ans-d

Q-5 A distinctive features of the lysosome is that it has �a- a lower p. H than cytoplasm �b- a reduced hydrolase activity �c- DNA �d- ribosome Ans-a

�Q 6 - The following are membranous cell organelles except �a- mitochondria �b- cell membrane �c- microtubules �d- lysosomes �E-secretory vesicles Ans-c

�Q 7 -The organoids that can duplicate themselves are �a- Ribosomes �b- Lysosomes �c- Mitochondria �d- Golgi apparatus �e- none of the above Ans-c

�Q 8 - The number of mitochondria present in a cell depends on its �a- size �b- shape �c- energy requirements �d- capability of division �E- none of the above Ans-c

�Q 9 - To enter or leave a cell, substances must pass through �a. a microtubule. �b. the Golgi apparatus. �c. a ribosome. �d. the nucleus. �e. the plasma membrane Ans-e

Q. 10 -The largest cell in human body �a- lymphocytes �b- fat cells �c- RBCs �d- Mature ova Ans-a