... functions, a substance can be concentrated in an area or excluded from an area. In addition, the plasma membrane at the cell's boundary must serve a third function - communication with other cells. The cell's boundary membrane provides this cell-to-cell communication via glycoprotein surface markers. The phospholipid bilayer, because of its non-polar, hydrophobic tails, is a barrier to many large ... opposite direction (high to low concentration), moving against a concentration gradient isn't easy. It's a lot like pushing a rock up a hill - it takes energy. Other proteins function as door...

• Word Count: 10700
• Approx Pages: 43
• Grade Level: High School

... the area between the nucleus and the cell membrane. The cytoplasm contains other important structures in the cell. Structures inside the cell are called organelles. An organelle is a tiny structure in the cell that preforms a special function within the cell. The mitochondria is greatly important to the cell. In animals, the mitochondria changes the ... also have a structure besides the vacuole called the plastid. The plastid also stores food as well as pigments for the plant. The cytoskeleton in a cell is the frame work that holds the cell together and gives it their shape. The cytosk...

• Word Count: 4152
• Approx Pages: 17
• Grade Level: High School

... organism's cells. Each chromosome is made up of fine strands of deoxyribonucleic acids, or DNA. The information carried on the DNA determines the cells function within the organism. Sex cells are the only cells that contain a complete DNA map of the organism, therefore, "the structure of a ... DNA molecule or combination of DNA molecules determines the shape, form, and function of the [organism's] offspring " (Lewin 1). DNA discovery is attributed to the research of three scientists, Francis Crick, Maurice Wilkins, and James Dewey Watson ... engineering, specifically, gene therapy. The ...

• Word Count: 3104
• Approx Pages: 12
• Has Bibliography
• Grade Level: High School

... on a symbiont relationship with another prokaryote. The aerobic prokaryote was enclosed by the bacterium's cell surface membrane in the process of endocytosis, which is made easy by the absence of a cell wall in the bacterium. The aerobic prokaryote wasn't digested but continued to function inside the other cell. The host cell received energy that the aerobic prokaryote released. The mitochondrion that was forming had everything ... He also observed that high birthrates and a shortage of life's necessities forced organisms into a constant "struggle for existence," both against the enviro...

• Word Count: 2685
• Approx Pages: 11
• Has Bibliography
• Grade Level: High School