Cell Structure Chapter 7

Chapter 7: Cell Structure

Cell Structure

Cell Structure in Eukaryotic Cells

Cells are the basic unit of life, and understanding their structure is essential to understanding their function. In eukaryotic cells, the main components are the nucleus and the cytoplasm.

Nucleus

The nucleus is the control center of the cell, housing the cell's DNA and directing the synthesis of ribosomes and proteins ((https://halleyhosting.com/sci/soph/cells/eukaryotic.htm)). It is surrounded by the nuclear envelope, a double membrane structure that controls the passage of ions, molecules, and RNA between the nucleoplasm and the cytoplasm ((https://rwu.pressbooks.pub/bio103/chapter/introduction-to-cells/)).

Cytoplasm

The cytoplasm is the entire region of a cell between the plasma membrane and the nuclear envelope. It is made up of organelles suspended in the gel-like cytosol, the cytoskeleton, and various chemicals ((https://rwu.pressbooks.pub/bio103/chapter/introduction-to-cells/)). The cytoplasm consists of 70 to 80 percent water, but it has a semi-solid consistency due to the proteins within it. Many metabolic reactions take place in the cytoplasm ((https://rwu.pressbooks.pub/bio103/chapter/introduction-to-cells/)).

Organelles in the Cytoplasm

Eukaryotic cells are highly compartmentalized into structures called organelles, each with a specialized function. Some of the main organelles in the cytoplasm include:

• Rough ER (Endoplasmic Reticulum): This organelle is studded with ribosomes, which are responsible for protein synthesis ((https://rwu.pressbooks.pub/bio103/chapter/introduction-to-cells/)).
• Smooth ER: This organelle has a smooth surface and does not have ribosomes. It is involved in lipid synthesis and other metabolic processes ((https://rwu.pressbooks.pub/bio103/chapter/introduction-to-cells/)).
• Mitochondria: Often referred to as the "powerhouse of the cell", mitochondria are oval-shaped organelles with their own DNA and ribosomes. They produce ATP, the energy currency of the cell, through cellular respiration ((https://halleyhosting.com/sci/soph/cells/eukaryotic.htm) &(https://rwu.pressbooks.pub/bio103/chapter/introduction-to-cells/)).
• Golgi Apparatus: This organelle modifies, sorts, and packages proteins and lipids, preparing them for transport to their final destinations in the cell ((https://rwu.pressbooks.pub/bio103/chapter/introduction-to-cells/)).
• Lysosomes: These organelles contain digestive enzymes that break down lipids, carbohydrates, and proteins, playing a role in cellular recycling and "cellular suicide" ((https://www.etsu.edu/uschool/faculty/tadlockd/documents/bio_chp7sec2show.pdf)).

Chromosomes and Chromatin

Chromosomes are structures within the nucleus made up of DNA, the hereditary material ((https://rwu.pressbooks.pub/bio103/chapter/introduction-to-cells/)). DNA in the nucleus is usually seen as chromatin, which is a long, thin string of DNA ((https://www.etsu.edu/uschool/faculty/tadlockd/documents/bio_chp7sec2show.pdf)). When a cell divides, the chromatin condenses into shorter, thicker chromosomes, which contain the genetic information (DNA) passed to the offspring ((https://www.etsu.edu/uschool/faculty/tadlockd/documents/bio_chp7sec2show.pdf)).