CHAPTER 5 Flashcards
cell theory is an important unifying theory of biology:
-cells are the fundamental units of life
-all organisms are composed of cells
-all cells come from preexisting cells
-modern cells evolved from a common ancestor
surface area-to-volume ratio of a cell
as a cells volume increases chemical activity increases, along with the need for resources and waste removal which means they need more energy, more organelles, etc but volume increasing limits the surface area which is why cells stay small
magnification
increases apparent size
resolution
clarity of magnified object–minimum distance two objects can be apart and still be seen as two objects
two basic types of microscopes:
-light microscopes: glass lenses and light; resolution = 0.2 μm
-electron microscopes: electromagnets focus an electron beam; resolution = 0.2μm
cell membrane
outer boundary of evert cell; similar structure in all cells– a phospholipid bilayer with embedded proteins
cytoplasm
everything in the cell except the nucleus
cytosol
fluid cytoplasm not contained inside another compartment
the cell membrane
-is a selectively permeable barrier
-allows cells to maintain a constant internal environment
-is important in communication and receiving signals
-often has proteins for binding and adhering to adjacent cells
two types of cells?
-prokaryotic (bacteria and archaea): have no membrane-enclosed internal compartments
-eukaryotic (eukarya): have membrane-enclosed organelles in which different functions occur
features of prokaryotic cells?
-enclosed by a cell membrane
-DNA located in a region called the nucleoid
-cytoplasm:the rest of the cell contents
ribosome: sites of protein synthes
cytoplasm
the rest of the cell contents
ribosomes
sites of protein synthesis
prokaryotes cell wall
the cell wall is rigid on the outside of the cell membrane which helped withstand environment and gave it stronger structural support
what do bacterial cell walls contain?
-they contain peptidoglycan and some have an additional outer membrane
-some bacteria have slimy capsule of polysaccharides
bacteria that carry out photosynthesis have?
they have internal membrane system that contains the molecules needed for photosynthesis
cytoskeleton
system of protein filaments that maintain cell shape and play roles in cell movement and cell division.
-protein fibers support the shape and movement
how do some prokaryotes swim?
they use flagella (long) made of the protein flagellin; which helps with movement as well swimming, moving back and forth from propelling
pili
pili (short)are hairlike structures projecting from the cell surface. they help bacteria adhere to other cells (sticky)
fimbriae
they are shorter and they also help cells adhere to surfaces such as animal cells
eukaryotic cells
-about 10 times larger than those of prokaryotes
-membrane-enclosed organelles carry our specific functions
-most eukaryotic cells have similar organelles
organelles
-organelles were first studied using light microscopy and then electron microscopy
ribosomes
-sites of protein synthesis
-similar structure in prokaryotes and eukaryotes
-consist of two subunits: ribosomal RNA (rRNA) and more Thant 50 different protein molecules
nucleus
-usualyl the largest organelle
-contains most of the DNA
-site of DNA replicaiton
-site where gene transcription is turned on or off
-assembly of ribosomes begins in a region called the nucleolus
nucleolus
a small, generally spherical body found within the nucleus of eukaryotic cells. the site of synthesis of ribosomal RNA