Chapter 1 Flashcards
What is a cell?
The basic unit from which living organisms are made, consisting of an aqueous solution of organic molecules enclosed by a membrane. All cells arise from existing cells, usually by a process of division into two.
What is the plasma membrane?
this is what encloses the cell and separates the inside of the cell from the outside of the cell. The plasma membrane consists of a lipid bilayer which contains proteins and sterols. (5 nm thick)
What is cytoplasm?
Cytoplasm- contents of a cell that are contained within its plasma membrane but (in eukaryotes) outside of nucleus.
What is cytosol?
contents of the main compartment of cytoplasm, excluding the memrane-bounded organelles
What is the nucleus?
this a large structure that contains DNA organized into chromosomes. DNA is the genetic material. Is enclosed by a double membrane (nuclear envelope)
What is an organelle?
a discrete structure or subcompartment of a eukaryotic cell that is specialized to carry out a particular function; especially a cellular substructure that is visible in the light microscope
What is the endosybiotic theory?
It is thought that both mitochondria and chloroplasts originated following engulfment of bacteria. Both mitochondria and chloroplasts resemble bacteria in many ways (contain their own DNA, reproduce themselves) and it is thought that these organelles derive from bacteria that were engulfed by ancestral eukaryotic cells.
What is the endoplasmic reticulum?
maze-like, membrane-bounded compartment in the cytoplasm of eukaryotes
- produces materials for export
- rough ER- protein synthesis
- smooth ER- membrane synthesis
What is the golgi apparatus?
stacks of flattened membrane-bounded sacs
- receives molecules made in the ER and modifies them- then directs them to exterior of the cell or other cellular compartments
- glycolysis of proteins occurs here
What are lysosomes
small organelles that contain hydrolases for breakdown (digestion) of materials
What are peroxisomes?
small organelles that provide a contained environment for the generation and degradation of hydrogen peroxide. The hydrogen peroxide for oxidation of organic molecules
What are vesicles?
small membrane-bounded organelles in the cytoplasm- often ferry material between different organelles and to the exterior of the cell. Vesicles pinch off from one organelle and then fuse with another. Portions of the PM can invaginate and then pinch off (enclosing extracellular material) – called endocytosis. The reverse can occur, when vesicles fuse with the PM to release intracellular contents to the outside (exocytosis)
What is the cytoskeleton?
- the cytoplasm also contains molecules that give it structure- these molecules are polymers that can undergo polymerization (to get bigger) or depolymerization (to shrink)- these are long filamentous strands of protein.
Actin- thinnest filaments- microfilaments- in all eukaryotic cells (lots in muscle- for contraction)
Microtubules- thickest filaments- form hollow tubes-are reorganized in diving cells to form spindle apparatus to separate chromosomes during mitosis and meiosis; also in cilia and flagella
Intermediate filaments –intermediate in size- strengthen the cell mechanically (not in plant cells)
What makes cells different?
- size (bacteria much smaller than animal egg)
- shape- often related to the function
- chemical requirements (aerobic vs anaerobic)
What makes cells similar?
made of same set of molecules
perform gylcolosis
have genetic code
