Skill 6.2 Identify the structures and functions of cellular organelles

Skill 6.2 Identify the structures and functions of cellular organelles. 

The nucleus is the brain of the cell that contains all of the cell s genetic information. The chromosomes consist of chromatin, which is a complex of DNA and proteins. The chromosomes are tightly coiled to conserve space while providing a large surface area. The nucleus is the site of transcription of the DNA into RNA. The nucleolus is where ribosomes are made. There is at least one of these dark-staining bodies inside the nucleus of most eukaryotes. The nuclear envelope is two membranes separated by a narrow space. The envelope contains many pores that let RNA out of the nucleus. 

Ribosomes are the site for protein synthesis. Ribosomes may be free floating in the cytoplasm or attached to the endoplasmic reticulum. There may be up to a half a million ribosomes in a cell, depending on how much protein is made by the cell. 

The endoplasmic reticulum (ER) is folded and provides a large surface area. It is the roadway of the cell and allows for transport of materials through and out of the cell. There are two types of ER. Smooth endoplasmic reticulum contains no ribosomes on their surface. This is the site of lipid synthesis. Rough endoplasmic reticulum has ribosomes on their surface. They aid in the synthesis of proteins that are membrane bound or destined for secretion. 

Many of the products made in the ER proceed on to the Golgi apparatus. The Golgi apparatus functions to sort, modify, and package molecules that are made in the other parts of the cell (like the ER). These molecules are either sent out of the cell or to other organelles within the cell. The Golgi apparatus is a stacked structure to increase the surface area. 

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