Cells Course Study Guide

Cells Protoplasm: ● An aqueous solution of carbohydrates, proteins, lipids, nucleic acids, and inorganic salts surrounded by a cell membrane. Organelles ● Microscopic structures within the cell having a special function or capacity. ○ Ribosomes ■ Submicroscopic particle attached to endoplasmic reticulum; site of protein synthesis in the cytoplasm of the cell. ○ Centrosomes ■ Tiny area near the nucleus of an animal cell; it contains two cylindrical structures called centrioles ○ Endoplasmic reticulum ■ Transport system of a cell; can be smooth or rough. ○ Mitochondria ■ Organelle that supplies energy to the cell. ○ Lysosomes ■ Cytoplasmic organelle containing digestive enzymes. ○ Peroxisomes ■ Membranous sacs that contain oxidase enzymes. ○ Golgi apparatus ■ Membranous network that resembles a stack of pancakes; it stores and packages secretions to be secreted by the cell. ○ Cytoskeleton ■ Internal framework of the cell consisting of microtubules, intermediate filaments, and microfilaments. ○ Nucleoplasm ■ Protoplasm inside the nucleus of a cell ○ Cytoplasm ■ Protoplasm of the cell body, excluding the nucleus. ○ Chromatin ■ When a cell reaches a certain size, it divides to form two new cells. The DNA and protein are arranged in a loose and diffuse state. ○ Chromosomes ■ Nuclear material that determines hereditary characteristics. ○ Cilia ■ Protrusions from the cell membrane that move material across the cell’s surface ■ Short hair-like protrusions ○ Flagella ■ Protrusions from the cell membrane that allow the cell to move throughout the environment ■ Singular tail like protrusions. ○ Meiosis ■ Process of cell division in the sex cells ■ Ovum (from the female) and the spermatozoa (from the male) reduce their chromosomes by half. ■ When fertilization occurs, the two sex cells combine to form a simple cell ● Zygote ○ Has full set of 46 chromosomes ○ Mitosis ■ First stage is the division of the nucleus ■ Second stage is the division of the cytoplasm ■ Orderly series of steps in which the DNA in the nucleus of the cell is equally distributed into 2 daughter cells or identical nuclei ■ Phases ● Interphase ○ The cell goes through all metabolic cellular activities to help in the maintenance of homeostasis. ○ Known as the resting stage. ● Prophase ○ The two pairs of centrioles start to separate toward the opposite ends of the cell. ○ An array of cytoplasmic microtubules form between them. ○ The nucleus disappears ● Metaphase ○ Nuclear membrane has dissolved completely. ○ Chromatid pairs arranged in a single file. ○ One chromatid pair per spindle fiber between the two centrioles. ● Anaphase ○ The chromatid pairs separate and are pulled apart by the shortening spindle fibers toward the centrioles. ○ The two chromatids of each replicated chromosome are now fully separated ● Telophase ○ The chromosomes migrate to the opposite poles of the cell. ○ They start to uncoil ○ The nuclear membrane and and the nucleus reappear ○ When cytoplasmic division is finished, two new daughter cells are formed. ○ Cell death ■ Necrosis ● Name given to unprogrammed death of cells and living tissue. ● There are many causes of necrosis ○ Injury, infection, cancer, infarction, toxins, and inflammation. ■ Apoptosis ● Orderly process by which cells intentionally die. ● The cell itself initiates, regulates, and executes its death with an elaborate arsenal of cellular and molecular activity. ○ Osmosis ■ The diffusion of water or any other solvent molecule through a selectively permeable membrane.