The Cell_Chapter 6

1. What is the function and the structure of a cell?

The cell is the basic functional unit of all living things. The cell membrane bounds the cell and encloses the nucleus and cytoplasm. The cytoplasm consists of specialized bodies called organelles suspended in a fluid, called cytosol, which consists %75-90 of water and dissolves substances like proteins and carbohydrates.

2. What is the differences and similarities of prokaryotic and eukaryotic cells?

Eukaryotic organisms include all living things except bacteria and archaea. In eukaryotic cell, DNA is found in the nucleus with a double membrane but in prokaryotic cell the DNA is found in nucleoid, which does not have a membrane. Eukaryotic cells are much bigger than prokaryotic cells. Prokaryotic cells are lacking a true nucleus and the other membrane-closed organelles of the eukaryotic cell.

3. Identify the structures and functions of cell organelles.

. The plasma membrane separates internal events from the external environment and controls the movement of materials into and out of the cell. The plasma membrane is a double phospholipid membrane with the polar hydrophilic heads and the nonpolar hydrophobic tails to the inside of the membrane.

. The nucleus is bounded by the nuclear envelope, a phospholipid bilayer like plasma membrane has. The nucleus contains DNA. Nucleus is the brain of the cell.

. Ribosome makes proteins. They can be free in cytosol or bounded to rough endoplasmic reticulum or nuclear envelope.

. Endoplasmic reticulum is active in membrane synthesis and other synthesis and metabolic process. It has 2 regions, which are rough and smooth. Smooth ER has no ribosome.

. Golgi Apparatus is active in synthesis, modification, sorting and secretion of cell products. They function to modify and package proteins and lipids into vesicles, which move materials between organelles and the plasma membrane.

. Lysosome is the digestive organelle where macromolecules are hydrolyzed. They do not occur in plant cells.

. Periximose produces hydrogen peroxide as a by-product then converts it to water.

. Mitochondrion is the organelle where cellular respiration occurs and most ATP (obtained from carbohydrate) is generated.

. Chloroplast makes the process of photosynthesis. (convertion of energy of sunlight into the chemical energy stored in sugar molecules.) They do not occur in animal cells.

. Cell wall maintains the shape and protects cell from mechanical damage, made of cellulose, polysaccharides and proteins. It is found in plants, fungi, protists and bacteria. They are outside the membrane.

. Vacuole is the large membrane-bounded vesicle in plants. They digest, store, waste disposal, balance water and protect the cell.

Video about the organelles :

http://www.youtube.com/watch?v=T30PvdRJoR4&feature=PlayList&p=A99C8A255510C861&playnext=1&playnext_from=PL&index=11

5 main facts about this chapter :

. The plasma membrane is made of Phospholipids, proteins, cholesterol and glycocalyx.

. In an eukaryotic cell; the genetic information (DNA) is kept in the nucleus but carried out by the ribosomes in the cytosol.

. There are 4 intercellular junctions in animal tissues, and one in plant cells. Plasmodesmata in plant cells, and tight junctions, desmosomes, gap junctions in animal cells.

. To study cells, biologists use microscopes and the tools of biochemistry.

. Mitochondria and chloroplast change energy from one to another.

In this chapter, we learnt about organelles, their structures and functions. We learnt the differences between eukaryotic and prokaryotic cells but also between animal and plant cells. We know there are different kinds of microscopes such as light and electronic microscopy.