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.)
In eukaryotes, ribosomes form in the nucleolus, a structure inside the cellâs nucleus. As ribosomal proteins enter the nucleus, they join with four rRNA strands to create a complete ribosome. The subunits exit the nucleus through pores and begin protein synthesis in the cytoplasm of the cell. In prokaryotes, proteins combine with three rRNA strands. Since prokaryotes do not have a membrane-bound nucleus, ribosomes form within the cytoplasm.