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
What is the rough endoplasmic reticulum?
a network of membranous sacs and tubes that synthesizes proteins
studded with ribosomes, found near cytoplasm
What is the Golgi apparatus?
AKA Golgi body
organelle active in synthesis, modification, sorting, and secretion of cell products
UPS center of the cell
What are mitochondria?
sites of cellular respiration where most ATP is generated
What are 4 unique structures within plant cells?
- cell wall
- chloroplasts
- plasmodesmata
- central vacuole
What is a cell wall in plants?
outer layer that maintains cell shape and protects cell from mechanical damage
made of the polysaccharide cellulose
What are chloroplasts?
photosynthesis organelles that convert sunlight to chemical energy stored in glucose
What are plasmodesmata?
intracellular pores connecting adjacent plant cells, allowing for cellular communication between cells
What is a central vacuole?
used for storage, breakdown of waste, and hydrolysis
What is the nuclear envelope?
- composed of 2 membranes that surround the nucleus
- perforated with pores that regulate traffic within the cytosol
What are nuclear pores?
protein-lined channels in the nuclear envelope that regulates transportation
What is nucleoplasm?
the substance of a cell’s nucleus
serves as a suspending substance for DNA and RNA
What is chromatin?
the material that chromosomes are made of, consisting of protein, DNA, and RNA packed into a fiber
What are chromosomes?
discreet units of DNA that are found within the nucleus
single-stranded forms of condesned chromatin
What are free ribosomes?
- suspended in the cytosol
- most proteins made here function within the cytosol
What are bound ribosomes?
- attached to the ER or nuclear envelope
- make proteins destined for membrane insertion
What are the 4 functions of the endomembrane system?
- synthesis
- distribution
- storage
- import/export
What are the 6 structures of the endomembrane system?
- nuclear envelope
- ER
- Golgi apparatus
- lysosomes
- vacuoles
- plasma membrane
What are lysosomes?
organelles that digest worn-out organelles and other cell debris
What are vacuoles?
organelles that store cellular materials
What are the 6 internal compartments of mitochondria?
- outer membrane
- inner membrane
- intermediate space
- cristal membrane
- intracristal space
- mitochondrial matrix
What is the mitochondrial matrix?
the fluid that is inside the inner membrane of a mitochondrion
How many membranes do chloroplasts have?
3
2 outer membranes and 1 thylakoid membrane
What is the stroma?
dense fluid within the chloroplast surrounding the thylakoid membrane
What are grana?
- stacks of thylakoid disks in the chloroplast
- plays a role in light reactions of photosynthesis
What are thylakoids?
flattened sacs inside a chloroplast that are used to convert sunlight to energy
What is the endosymbiotic theory?
theory that mitochondria and chloroplasts originated as prokaryotic cells engulfed by host cells
later evolved into a single organism
“origin of eukaryotes”
What are 4 pieces of evidence that support the endosymbiotic theory?
- composed of 2 membranes
- contain circular DNA
- contain ribosomes
- autonomous
What is the cytoskeleton?
a network of microtubules, microfilaments, and intermediate filaments that extends throughout the cytoplasm
serves mechanical, transport, and signaling functions
What are microtubules?
hollow rods composed of tubulin that regulate cell growth and movement
What are microfilaments?
AKA actin filaments
long, thin fibers that function in cell motility
contractions, basic cell movements
What are intermediate filaments?
flexible intracellular tendons that prevent excessive stretching of cells
nylon rope!
What are cilia?
short appendages containing microtubules in eukaryotic cells
there are 2 types: primary and motile
What are motile cilia?
specialize in locomotion or moving fluid past the cell
formed in a 9+2 arrangement
What are primary cilia?
nonmotile, plays a sensory and signaling role in eukaryotes
What is the 9+2 pattern?
formation of motile cilia in which 9 doublets of microtubules are arranged in a ring with 2 single microtubules in the center
What are flagella?
long, cellular appendages specialized for locomotion in prokaryotes
What are motor proteins?
proteins that interact with cytoskeletal elements, producing cellular movement
What is the extracellular matrix? (ECM)
the meshwork surrounding animal cells
consists of glycoproteins, polysaccharides, and proteoglycons
What are tight junctions?
membranes of neighboring calls are pressed together, preventing leakage of fluid
What are anchoring junctions?
AKA desmosomes
function like rivets to fasten cells together to form strong sheets
What are gap junctions?
AKA communication junctions
provide cytoplasmic channels between cells with special membrane proteins
