Flashcards in Chapter 3 - Cells Deck (7)
What is a cell?
A cell is the basic unit of life, nothing smaller than a cell is alive. A cell is defined as the smallest, basic unit of life that is responsible for all of life's processes.” Cells are the structural, functional, and biological units of all living beings. A cell can replicate itself independently. Hence, they are known as the building blocks of life.
Why are most cells small?
Because they are smaller, they can efficiently absorb enough food. When a cell doubles in size the volume increases much more than the surface area, which is why large cells cannot receive enough food efficiently for their volume. information within small cells is transmitted more quickly and efficiently than within larger cells. The nucleus or "command center" of the cell initiates cellular activity by converting genetic information into functional molecules, such as proteins. These proteins and other molecules are then directed around the cell to perform specific functions. The larger the cell, the longer these proteins and other cellular processes will take to carry out their functions. This is quite energy expensive and a less than ideal situation; therefore, cells tend to be relatively small.
What do prokaryotic and eukaryotic cells have in common?
Prokaryotic cells lack a nucleus, whereas eukaryotic cells posses a nucleus. The prokaryotic group includes two groups of bacteria: the eubacteria and archaebacteria. The eukaryotic group are the animals, plants and fungi, as well as some singled-celled organisms called protists. Both types of cells have plasma membrane, an outer membrane that regulates what enters and exits a cell. All types of cells contain cytoplasm, which is a semifluid medium containing cytosol, a mixture of water and various types of molecules and organelles. Both eukaryotic and prokaryotic cells contain organelles.
How are cells organized?
Cells are organized into tissues, and tissues form organs. Organs are organized into organ systems such as the skeletal and muscular systems. An organism is made up of four levels of organization: cells, tissues, organs, and organ systems, atoms are organized into molecules, molecules into organelles, and organelles into cells.
How do things move across the plasma membrane?
Move within the cell 's cytosol by diffusion, and certain materials move through the plasma membrane by diffusion. Diffusion is the random movement of molecule from an area of higher concentration to an area of lower concentration, until there is an equal amount of distribution. Diffusion is the passive movement for molecules to enter or exit and cell. Molecules can cross the plasma membrane, they are able to move both directions. The net movement will be from the region of higher concentration to the region of lower concentration until equilibrium is achieved.
What is the role of an enzyme in a metabolic reaction?
The main role of enzymes during metabolic reactions is to assist in transferring electrons from one molecule to another. Some enzymes help to break down large nutrient molecules, such as proteins, fats, and carbohydrates, into smaller molecules. Each enzyme can promote only one type of chemical reaction. The compounds on which the enzyme acts are called substrates.