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.)
You might recall that a ribosome is a cell organelle that helps in assembling chains of amino acids. It's made of ribosomal RNA, or rRNA, and protein. Ribosomes are located on the rough endoplasmic reticulum, or RER, that surrounds a cell's nucleus. In fact, ribosomes are the reason that the RER is called rough; they give the endoplasmic reticulum a rough appearance when viewed under a microscope.