User:RyanPF/Bio Ch4

1. Explain how cell therapy may help heal hearts damaged by heart attacks.
Cells are taken from elsewhere in the patient's body and delivered to the heart. The cells usually are immature muscle cells from the patient's thigh. The cells are multiplied in a lab and injected directly into the heart's scar tissue.

2. Explain why cells are fundamental to biology.

 * Cells are the smallest entity that exhibits all the characteristics of life.
 * Cells are as fundamental to biology as atoms are to chemistry.
 * An understanding of cell structure and function is essential to understanding most human disease.

Light microscopes vs. electron microscopes
Electron microscopes can resolve much smaller objects. Electron: 0.2 nanometers. Light: 0.2 micrometers.

Scanning electron microscopes vs. transmission electron microscopes
SEM is for looking at the surface of a cell. TEM is for looking at the internal structure of a cell.

Magnification vs. resolution
Magnification makes an object look bigger than it actually is. Resolving power makes an object clearer, and shows two objects as separate.

Prokaryotic cells vs. eukaryotic cells
Prokaryotic cells are simpler; bacteria and archaea. Eukaryotic cells are more complex; everything else.

Plant cells vs. animal cells

 * Lysosomes and centrioles are not found in plant cells
 * Plant cells have a rigid cell wall, chloroplasts, and a central vacuole not found in animal cells

4. Describe the structure of the plasma membrane and the other membranes of the cell. Explain why this structure is called a fluid mosaic.
Mostly lipids and proteins... phospholipids. Hydrophilic (water-loving) heads on the outside, hydrophobic (water-hating) tails on the inside. Forms a phospholipid bilayer, protecting tails from water. Called fluid because the molecules can move freely past one another and mosaic because of the diversity of proteins that float in the phospholipids.

5. Compare the structures and functions of a plant cell wall and the extracellular matrix of an animal cell.
Cell walls protects the cells, maintain their shape, and keep the cells from absorbing too much water. Very strong. The extracellular matrix is just a sticky coat that holds the cell together.

6. Explain how the genetic information in the nucleus is used to direct the production of proteins in the cytoplasm.

 * 1) DNA transfers its info to a molecule called messenger RNA. (mRNA)
 * 2) The mRNA exits through pores in the nuclear envelope and binds with ribosomes in the cytoplasm.
 * 3) As a ribosome moves along the mRNA, the genetic message is translated into a protein of specific amino acid sequence.

rough endoplasmic reticulum
One of the main manufacturing facilities within a cell. The roughness is ribosomes on the outside of the ER membrane. One function is producing new membrane.

smooth endoplasmic reticulum
One of the main manufacturing facilities within a cell. Has no ribosomes. Synthesizes lipids, including steroids. Detoxifies drugs and poisons, increases tolerance.

Golgi apparatus
Receives, refines, stores, and distributes chemical products of the cell. Receives products from the ER in transport vesicles on one side, ships out on other side.

lysosomes
Breaks down, digests macromolecules like proteins, polysaccharides, fats, nucleic acids.

vacuoles
Membranous sacs that bud from the ER, Golgi, or plasma membrane. Aid in breakdown of molecules, among other things.

Chloroplasts

 * Found in plant cells
 * Perform photosynthesis
 * The grana are interconnected stacks that trap light energy and convert it to chemical energy

Mitochondria

 * Found in animal cells
 * Harvests energy from sugars and other foods and converts to ATP energy
 * Mitochondrion (singular form)

9. Describe the functions of the cytoskeletion
It is both the skeleton and the "muscles" for the cell. Can rearrange itself to move around like an amoeba.

Flagella (singular, flagellum)

 * Long
 * Propel the cell forward with a whip-like movement.
 * Often occur singly. (Only one in a group)

Cilia (singular, cilium)

 * Shorter than flagella
 * Propel the cell with coordinated back-and-forth motion
 * Come in large groups

10. Describe the properties of phospholipids that suggest that they were part of the first cell membranes.

 * Were probably among the organic molecules that formed from chemical reactions on early Earth before the emergence of life.
 * Could have spontaneously self-assembled into simple membranes
 * This assembly doesn't require genes or any other information except the intrinsic properties of the phospholipids themselves.