Cells (Chapter 3)

Question 1

1) Describe the main parts of a cell.

Answer 1

• Cell membrane: surrounds the cell and forms the outer boundary of the cell.
• Cytoplasm: a thick fluid that fills the inside of the cell and the suspended structures it contains.
• Organelles: structures suspended in the cytoplasm that carry out particular functions.
• Cytosol: the liquid part of the cytoplasm.
• Cytoskeleton: internal scaffolding of protein fibers within the cytoplasm.
• Inclusions: chemical substances occurring as granules or liquid droplets in the cytoplasm.

Question 2

2) Explain the difference between the cytosol and the cytoplasm.

Answer 2

Cytoplasm is the jelly-like or watery material inside the cell membrane in which the organelles are suspended. The cytosol is the liquid part of the cytoplasm (75-90% water) with a complex mixture of dissolved substances.

Question 3

3) What are organelles?

Answer 3

Organelles are the structures within the cell. There are a number of different types of organelles and each is specialized for a particular function. Many of the organelles are formed by the cell’s internal membrane.

Question 4

4) Describe the functions of the following organelles: Mitochondria, Endoplasmic Reticulum, Ribosomes, Nucleus

Answer 4

• Mitochondria (the power house of the cell) releases energy for the cell through the process of cellular respiration.
• Endoplasmic Reticulum: provides a surface on which chemical reactions can occur. The channels between the paired membranes are used for fat storage or transport of materials. (Rough endoplasmic reticulum have ribosomes attached.)
• Ribosomes: amino acids are joined together at the ribosomes to make more proteins.
• Nucleus: contains the genetic material, mostly DNA, separated from the cytoplasm by a nuclear membrane. The membrane is double and has gaps (nuclear pores) through which large molecules can pass. An area called the nucleolus is composed mainly of RNA. the DNA and nucleolus are suspended in a jelly-like nucleoplasm.