Chapter 4: the Cell (Anatomy & Division) Flashcards
3 major regions of animal cells
nucleus, plasma membrane, cytoplasm
nucleus
Control center of the cell; necessary for reproduction; contains DNA
chromatin
threadlike form of DNA loosely dispersed throughout the nucleus
chromosomes
coiled and condescend chromatin when the cell is in the process of forming daughter cells
nucleoli
contained in the nucleus; composed of proteins and RNA; assembly sites for ribosomes
ribosomes
protein synthesizing factories
nuclear envelope
double layered porous membrane that binds the nucleus; has large nuclear pores
nuclear pore
protein complexes regulate nuclear pores and determine what passes through the membrane
plasma membrane
separates cell contents from the surrounding environment. Fluid mosaic model- bilayer of phospholipid molecules. Selectively permeable.
Active transport
cell must provide energy (ATP) to power transport process.
Passive transport
transport process driven by concentration or pressure differences
Microvilli
greatly increase the surface area of the cell available for absorption or passage of materials and for the binding of signaling molecules
cytosol
fluid cytoplasmic material in the cell
organelles
literally, “small organs” highly organized to carry out specific functions; include ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, perioxisomes, mitochondria, cytoskeletal elements and centrioles
Ribosomes
densely staining, roughly spherical bodies composed of RNA and proteins. Actual sites of protein synthesis
Endoplasmic reticulum (ER)
highly folded system of membranous tubules and cisterns that extends throughout the cytoplasm; continuous with the nuclear envelope
Rough ER
studded with ribosomes; external face synthesizes phospholipid and cholesterol synthesis
Smooth ER
no function in protein synthesis; site of steroid and lipid synthesis, lipid metabolism and drug detoxification
Golgi apparatus
stack of flattened sacks with bulbous ends; packages proteins or other substances for export
Lysosomes
various sized membranous sacs containing digestive enzymes; digest worn out cell organelles and foreign substances entering the cell
Peroxisomes
small lysosome like membraneous sacs containing oxidase enzymes that detoxify alcohol, hydrogen peroxide and other harmful chemicals
Mitochondria
rod shaped bodies with double membrane wall; inner membrane is made into folds (cristae); contain enzymes that produce ATP; the “powerhouses of the cell”
cytoskeletal elements
form internal scaffolding called the cytoskeleton that supports and moves substances within the cell; includes microfilaments, intermediate filaments and microtubules
microtubules
organize the cytoskeleton and form spindle during cell division
microfilaments
ribbon and cordlike; actin; shorten and relax to form elongated shape; important in cell mobility
intermediate filaments
act as internal guy wires to resist mechanical pulling forces acting on cells
Centrioles
paired, cylindrical bodies that lie at right angles to each other; direct the formation of miotic spindle during cell division; form the bases of cilia and flagella
Cell life cycle
consists of two stages - interphase and cell division
Interphase
longer period during which the cell grows and carries on normal activites
Cell division
when the cell reproduces itself by dividing; DNA is copied exactly; consists of mitosis and cytokinesis
Mitosis
division of the copied DNA of the mother cell to two daughter cells
Cytokinesis
division of the cytoplasm; begins when mitosis is nearly complete; in some instances of mitosis, cytokinesis does not occur; this leads to the formation of binucleate or multinucleate cells.
Meiosis
specialized type of nuclear division that occurs only in the reproductive organs (testes or ovaries). Yields 4 daughter nuclei that differ genetically from the mother cell
Phases of Mitosis (4)
1) Prophase, 2) metaphase, 3) Anaphase, 4) telophase
