bio chp 4

Homework chap 4 by Shivam Deotare

Q.1 discribe the major organells and there functions in animal cell ?

Ans:cell include mitochondria,endoplasmic reticulum ,golgi body and others.

1-mitochondria -energy factories,self replicating,membrane bound.Producing NADH and ATP.It is powerhouse of cell.

Mitochondria are quite variable in shape.they are rod shaped organelles that ranges in length from 0.2-3.0um.

They are the site of the areobic respirat

2-ER-it is a intracellular highway. Protein synthesized at ribosome.

connect nuclear envolope to cell membranes.

Trannsport materials from or through the cell.

3-Ribosome-composed of two sub units. That attach to the mRNA at beginning of protein synthesis.

It is made up of large and small sub units

Large unit is made up of 45 protein and 3RNA.

Small unit is made of 33 protein and 1 RNA.

Diameter is about 30 nm.

4-Golgi bodies-series of flanttend sacs.

It pakage proteins produced on RER.

It is just visibale in light microscope.

It has two sites that are Trans and Cis.

It is processing ,packaging and secreting organelle of cell.

5- Lysosomes-

intracellular digestion.

It contain digestive enzymes.

Function is digestion.

It is called suicide bags.

Q.2what compose the cells cytoskeleton?and what are their functions?

Ans:

Intermediate filaments are a part of the cytoskeleton of all animals. These filaments, averaging 10 nanometers in diameter, are more stable (strongly bound) than actin filaments, and heterogeneous constituents of the cytoskeleton. Like actin filaments, they function in the maintenance of cell-shape by bearing tension (microtubules, by contrast, resist compression but can also bear tension during mitosis and during the positioning of the centrosome). Intermediate filaments organize the internal tridimensional structure of the cell, anchoring organelles and serving as structural components of the nuclear lamina. They also participate in some cell-cell and cell-matrix junctions. Nuclear lamina exist in all animals and all tissues. Some animals like the fruit fly do not have any cytoplasmic intermediate filaments. In those animals that express cytoplasmic intermediate filaments, these are tissue specific.[4]Different intermediate filaments are:

made of vimentins. Vimentin intermediate filaments are in general present in mesenchymal cells.

made of keratin. Keratin is present in general in epithelial cells. neurofilaments of neural cells.

made of lamin, giving structural support to the nuclear envelope.