Climate Zones Objectives: 1. Describe Earth's major climate zones. 2. Explain how climate zones are characterized. Notes: According to the three cell convection model of each hemisphere the Earth neatly separates itself into three distinct climate zones; the polar, temperate, and the tropical zones.limate Zones Objectives: 1. Describe Earth's major climate zones. 2. Explain how climate zones are characterized. Notes: According to the three cell convection model of each hemisphere the Earth neatly separates itself into three distinct climate zones; the polar, temperate, and the tropical zones.
The nucleus is a large roundish organelle. It is bounded by a double membrane which has numerous pores. Inside the nucleus are chromosomes and a dark region called a nucleolus which makes ribosomes. (Ribosomes are necessary for protein synthesis.)
The nucleolus is a region of the nucleus in which three of these rRNA genes occur. Inside the nucleus the RNA and protein molecules are assembled into two subunits, which leave the nucleus, again through nuclear pore complexes. Once in the cytoplasm, the two subunits are combined to form the functional ribosome. A ribosome contains RNA and proteins. The following description applies to eukaryotes (plants, animals, and fungi).