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