Ch. 4 Flashcards
What is magnification?
the ratio of an object’s image size to its real size
how close a specimen is
What is resolution?
a measure of the clarity of an image
how clear a specimen appears
What is the total magnification of a light microscope?
1000x
What is the total magnification of an electron microscope?
1-50x million
What is a scanning microscope? (SEM)
used to scan the surface of a sample so as to study its topography
What is a transmission electron microscope? (TEM)
used to study the internal structure of cells through thin slices of the specimen
What are the smallest objects observable using microscopes?
atoms
What are the 3 tenants of cell theory?
- Cells are the basic unit of life
- All living things are composed of one or more cells
- New cells come from pre-existing cells
What is the function of the plasma membrane?
- provides shape and structure for the cell
- acts as a selective barrier that regulates the cell’s chemical composition
What is the plasma membrane composed of?
a phospholipid bilayer
Why are cells small in size?
- to maintain a high surface area to volume ratio
- allows cell to carry out functions quickly and efficiently
Why is maintaining a high surface area to volume ratio important?
- the ratio gets smaller as cell gets larger
- if the cell grows beyond a certain limit, not enough material will be able to cross the membrane fast enough
What are 4 characteristics of prokaryotes?
- simple and unicellular
- no nucleus or membrane-bound organelles
- circular DNA
- divides using binary fission
What are 4 characteristics of eukaryotes?
- complex and multicellular
- clear nucleus and membrane-bound organelles
- linear DNA found in the nucleus
- divides using mitosis
What are organelles?
structures within cells that have specialized functions
What are fimbriae?
attachment structures on the surface of some prokaryotes
What is a nucleoid?
the region where a prokaryotic cell’s DNA is located
What are ribosomes?
complexes that synthesize protein
What is the plasma membrane?
the membrane enclosing the cytoplasm
What is the cell wall?
a rigid structure outside the plasma membrane
What is the glycocalyx?
the outer coating of many prokaryotes, consisting of a capsule or slime layer
What is a flagellum?
a locomotion organelle of some prokaryotes
What is the nucleus?
organelle that houses DNA and controls and regulates cellular activities
What is the nucleolus?
- a nonmembranous structure involved in rRNA synthesis and ribosomal subunit assembly
- found within the nucleus
Where are ribosomes found?
either free in the cytosol or bound to the rough ER or nuclear envelope
What are vesicles?
membranous sacs in the cytoplasm responsible for transporting materials and recycling waste
What is the smooth endoplasmic reticulum?
smooth ER
a network of membranous sacs and tubes responsible for lipid synthesis
contains no ribosomes, found near plasma membrane