← make up of a cell Test
5 Written Questions
5 Matching Questions
- gap junctions
- tight junctions
- nuclear membrane
- a is a double membrane between the two membranes is a fluid-filled "moat" or space. encloses a jellylike fliud called nucleoplasm.
- b are impermeable junctions that bind cells together into leakproof sheets that prevent substances from passing throught the extracellular space between cells. these junctions keep digestive enzymes from seeping into the bloodstream.
- c are tiny, bilobed, dark bodies made of proteins and one variety of RNA, called ribosomal RNA. ribosomes are the actual sites of protein synthesis in the cell.
- d commonly seen in the heart and between embryonic cells, function mainly to allow communication. neighboring cells are connected by connexons.
- e are anchoring junctions that prevent cells subjected to mechanical stress from being pulled apart. such as skin cells. these junctions are buttonlike thickenings of adjacent plasma membranes (plaques).
5 Multiple Choice Questions
- vary structurally depending on their roles. tight junctions, desmosomes, gap junctions.
- is a fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment.
- are chemical substances that may or may not be present, depending on the specific cell type. they include the lipid droplets common in fat cells, glycogen gtanules abundant in liver and muscle cells, pigments such as melanin in skin and hair cells, mucus and other secretory products, and various kinds of crystals.
- are membranous sacs containing powerful oxidase enzymes that use molecular oxygen to detoxify a number of harmful or poisonous substances, including alcohol and formaldehyde, but most important function is to "disarm" dangerous free radicals.
- "network within the cytoplasm" ER is a system of fluid-filled cisterns that coil and twist through the cytoplasm. tubeles, or canals.
5 True/False Questions
mitochondria → consists of a double membrane, equal to 2 plasma membranes, placed side by side. outer membrane is smoothe and featureless, inner membrane has shelflike protrusions called cristae.
flagella → the basic biological unit of living organisms, containing a nucleus and a variety of organelles enclosed by a limiting membrane.
nucleoli → a dense central body in most cells containing the genetic material of the cell.
free radicals → are highly reactive chemicals with unpaired electrons that can scramble the structure of proteins and nucleic acids.
chromatin → when a cell is not dividing, its DNA is combined with protein and forms a loose network of bumpy threads.