Cell organelles

Presentation of

Working of Cell Organelles

INTRODUCTION

Types of cell

Organelles of cell

Working of organelles

Types of Cell

1.Eukaryotic cell

2.Prokaryotic cell

Types of Cell

Eukaryotic cell

Eukaryotic cells are found in the

kingdoms Protista, Plantae,

Fungi, and Animalia.

They have a nucleus and

membrane enclosed organelles.

Eukaryotic cells contain well

defined cellular organelles

such as:

Nucleus

Mitochondria

Endoplasmic reticulum

Golgi apparatus

Peroxisomes

Lysosomes

Plastids

Vacuoles

centrosome

The nucleus is the largest cellular organelle in animals. In mammalian cells, the average diameter of the nucleus is approximately 6 micrometers (μm), which occupies about 10% of the total cell volume. The viscous liquid within it is called nucleoplasm, and is similar in composition to the cytosol found outside the nucleus. It appears as a dense, roughly spherical organelle.

Nucleu

s

function of nucleus

The cell 'Nucleus' controls all cell activity by regulating what proteins are made. The cell contains DNA and transmits messages by eating, movement, and reproduction. This is a large organelle that is easily seen with a light microscope

In electron micrographs of cells, mitochondria appears as – rods, spheres or filamentous bodies.

Size: 0.5µm -1µm

in diameter

up to 7µm

in length

MITOCHONDRIA

Working of mitochondria

Mitochondria convert oxygen, and the sugar, fat and protein from foods to useable energy. The body uses that energy for daily function and growth.

make energy from sugar + O2 = ATP

Cytoplasm of eukaryotic cells contain a network of interconnecting membranes.

This extensive structure is called endoplasmic reticulum.

This is of two type:-

1.Smoth ER

2.Rough ER

ENDOPLASMIC RETICULUM

Rough Endoplasmic Reticulum

These membranes enclose a lumen.

In this lumen newly synthesized proteins are modified.

Rough appearance is due to the presence of ribosomes attached on its cytosolic side(outer side).

These ribosomes are involved in the biosynthesis of proteins.

Smooth Endoplasmic Reticulum

Smooth Endoplasmic Reticulum

Smooth endoplasmic reticulum is involved in lipid synthesis.

Cholesterol synthesis

Steroid hormones synthesis.

Detoxification of endogenous and exogenous substances.

The enzyme system involved in detoxification is called Microsomal Cytochrome P450 monooxygenasesystem(xenobiotic metabolism).

Golgi complex is a network of flattened smooth membranous sacs- cisternae and vesicles.

These are responsible for the secretion of proteins from the cells(hormones, plasma proteins, and digestive enzymes).

It works in combination with ER.

Working of Golgi apparatus

Golgi apparatus packages macromolecules for secretion and transportation outside the cell. It produces vesicles that encloses the macrolecules and transports it to the plasma membrane.

It works with the rough and smooth endoplasmic reticulum

These are responsible for the intracellular digestion of both intra and extracellular substances.

They have a single limiting membrane.

They have an acidic pH- 5

They have a group of enzymes called Hydrolases.

Working of Lysosomes

Lysosomes contain acid hydrolase enzymes to break up waste materials and cellular debris. Lysosomes fuse with vacuoles and dispense their enzymes into the vacuoles, digesting their contents.

Called Peroxisomes because of their ability to produce or utilize H2O2.

They are small, oval or spherical in shape.

They have a fine network of tubules in their matrix.

About 50 enzymes have been identified.

The number of enzymes fluctuates according to the function of the cells.

PEROXISOMES

Working of peroxisome

A major function of the peroxisome is the breakdown of fatty acid molecules, in a process called beta-oxidation. In this process, the fatty acids are broken down two carbons at a time, converted to Acetyl-CoA, which is then transported back to the cytosol for further use. In animal cells, beta-oxidation can also occur in the mitochondria. In yeast and plant cells, this process is exclusive for the peroxisome.

The plastid (Greek: πλαστός; plastós: formed, molded –plural plastids) is a major organelle found in the cells ofplants and algae. Plastids are the site of manufacture and storage of important chemical compounds used by the cell. They often contain pigments used in photosynthesis, and the types of pigments present can change or determine the cell's color. They possess a double-stranded DNA molecule, which is circular, like that of prokaryotes.

Plastid

1. Leucoplast: These are colourless plastids. They store the food of the plant body in the form of starch, proteins and fat. They are mostly present in the storage cell as in the roots and underground stem.

2. Chloroplast: These are green coloured plastids because of the presence of the chlorophyll. They occur abundantly in green leaves and also in green parts of the shoot. They trap the solar energy which is used for manufacturing food. So, they are the sites of Photosynthesis.

3. Chromoplast: These are colored plastids. They provide colour to fruit and plants. So they help in pollination and fuit dispersal.

Plastid types

Function of plastids:

• Chloroplast traps the solar energy and transform in to the chemical energy of carbohydrate using water and CO2 this process is called photosynthesis.

• Chloroplast impart colors to the different flowers which have to attract insects for pollination.

• Leucoplasts store food in the form of starch.

A vacuole is a membrane-bound organelle which is present in all plant and fungal cells and some protist, animal and bacterial cells.

vacuole

Function of vacuole

Isolating materials that might be harmful or a threat to the cell

Containing waste products

Maintaining internal hydrostatic pressure or turgor within the cell

Maintaining an acidic internal pH

Containing small molecules

Exporting unwanted substances from the cell

In cell biology, the centrosome is an organelle that serves as the main microtubule organizing center of the animal cell as well as a regulator of cell-cycle progression.

centrosome

Function of Centrosomes

It is the center of production of microtubules, the thin filamentous structures in the cell.

Centrosomes and the associated microtubules determine the directional growth of certain types of cells such as neurons, where the direction and point of growth of axons are determined by these cells.

They are known as the chief microtubule organizing centers of the animal cells.They are responsible for the initiation of cytokinesis, or splitting up of the mother cell into two.

In the absence of centrosomes, it has been observed that cytokinesis does not initiate even after the completion of mitosis.

They organize the primary cilia that are present on the epithelial cells of the kidney, the olfactory receptors, the lining of the stomach, and rod cells in the eyes.

Thank you………