CH6: TOUR OF THE CELL Flashcards
visible light is passed through a specimen and then through glass lenses
lenses refract (bend) the light so that the image is magnified and focused on an eye lens
Light Microscope
the measure of the clarity of the image or the minimum distance of two distinguishable points
resolution
visible difference in brightness between parts of the sample and the background
contrast
an image is formed by transmitting light through cell (white bg)
bright-field microscopy
rays of light are directed from the side; only light scattered by the specimen enters the lenses
dark-field microscopy
variations in density cause difference int he way various regions of the cytoplasm refract light
Phase Contrast Microscopy
Differential Interference-Contrast Microscop
filters transmit light that emitted by by fluorescently stains that bind specifically to DNA or specific protein molecules
fluorescence microscope
produces a sharper image than standard fluorescence microscopy
a computerized microscope produces optical sections that are assembled into a 3D image
confocal microscopy
allows researchers to study fine details (ultrastructure) of cells
some have resolving powers less than 1nm (magnification > 1 million X)
electron beam consists of energized electrons, which can be focused by electromagnets just as images are focused by glass lenses in a light microscope
Electron Microscope
- specimen embedded in plastic and thinly sectioned
- the electron beam passes through the specimen and falls onto a photographic plate or fluorescent screen
- focus beam of electrons through specimen
- internal structure of cells
Transmission Electron Microscope (TEM)
- the specimen is coated with gold or some other metal
- emission patterns of secondary electrons give a 3D picture of the surface
- focuses a beam of electrons onto the surface of a specimen, providing images that look 3D
Scanning Electron Microscope (SEM)
takes cells apart and separates the major organelles from one another
fractionate cells into component parts and allows scientists to determine the functions of organelles
Cell Fractionation
Domains of Prokaryotic Cells
Bacteria and Archaea
Kingdoms of Eukaryotic Cells
protists, fungi, animals, plants
Basic features of ALL cells
- plasma membrane
- cytosol (semifluid substance)
- chromosomes (carry gens)
- ribosomes (make proteins
characteristics of prokaryotic cells
- no nucleus
- no membrane-bound organelles
DNA in an unbound region in prokaryotic cells
nucleoid
lines nuclear side of envelope (inner side) and is made of proteins and maintains the shape of the nucleus
nuclear lamina
site of ribosomal RNA (rRNA) synthesis
nucleolus
what makes up the endomembrane system?
Nuclear envelope
ER
Golgi apparatus
Lysosomes
Vacuoles
Plasma membrane
small, membrane-bound sacs that play a role in transport, storage, or secretion
vesicles
what are the functions of smooth ER
synthesizes lipids
metabolizes carbs
detoxifies drugs/poisons
stores calcium ions
proteins covalently bonded to carbs; secreted by rough ER ribosomes
glycoproteins
membranous sac of digestive enzymes;
fuses with food vacuole and digests the molecules
lysosome
certain cells can engulf another cell (i.e. macrophage engulf foreign invader and breaks it down)
phagocytosis
the process where a lysosome uses enzymes to recycle the cell’s own organelles and macromolecules
autophagy
large vesicles with many purposes from ER and golgi
vacuole
large vesicle formed by phagocytosis
food vacuoles
large vesicle found in many freshwater protists that pump excess water out of cells
contractile vacuoles
large vesicles found in many mature plant cells that hold organic compounds and water
central vacuoles
part of golgi where vesicles enter
cis Golgi
golgi closest to plasma membrane
trans golgi
cellular respiration to ATP
mitochondria
photosynthesis from sunlight
chloroplasts
oxidative organelles; specialized metabolic compartments; make hydrogen peroxide (H2O2) and turn it to water
peroxisomes
mitochondria and chloroplasts share similarities with WHAT (double membrane, free ribosomes, circular DNA molecules, grow and reproduce independently)
bacteria
theory that early eukaryotes engulfed an oxygen using nonphotosynthetic prokaryotic cell and formed a relationship with the host cell
endosymbionts - mitochondria
photosynthetic prokaryote - chloroplast
endosymbiont theory
mitochondria smooth outer membrane and inner membrane folded into ________
cristae
the innermost compartment within a mitochondrion, enclosed by the inner membrane
mitochondrial matrix
green pigment in chloroplasts
chlorophyll
double-membrane organelles which are found in the cells of plants and algae, like chloroplast
plastids
roles of cytoskeleton
- support cell and maintain shape
- interacts with motor proteins to produce motility (ability to move)
- vesicles can walk on cytoskeleton
- thickest cytoskeleton (25nm)
- hollow tubes
- make of tubulin (aka tubulin polymers)
- shaping cell
- guide movement of organelles
separate chromosomes in cell division
microtubules
- thinnest cytoskeleton (7nm)
- two intertwined (wrapped around each other) strands of actin
- made of actin (aka actin filaments)
- maintain cell shape
- muscle contraction
- cell motility
- division in animal cells
- make up microvilli
microfilaments
- 8-12 nm
- fibrous proteins coiled into cables
- types of proteins (e.g. keratin)
- maintain cell shape, anchor nucleus and certain organelles
- forms nuclear lamina
- more PERMANENT that other structures
intermediate filaments
two ______ make 1 _____ which has ____ triplets of microtubules in a ring
centrioles, centrosome, 9
motor protein that drives bending movements of cillium or flagellum
its arms grab, move, release the outer microtubules
dynein
microfilaments form this 3D network inside the plasma membrane to support cell shape
cortex
cellular extensions that help cells crawl along a surface
pseudopodia
circular flow of cytoplasm within cells
cytoplasmic streaming
what cells can have cell walls
prokaryotes, fungi, and some unicellular eukaryotes (plants)
functions of plant cell wall
- protect plant cell
- maintain shape
- prevent burst in excess uptake of water
thin layer between primary cell wall and adjacent cells/secondary cell wall (in some cells, inner wall of plasmodesmata)
middle lamella
channels between adjacent plant cells (like desmosomes for plants)
small solutes and water can pass
plasmodesmata
made up of glycoproteins (collagen, proteoglycans, fibronectin) that bind to receptor proteins in membrane
- regulate cell behavior by communication through integrins
- influence gene activity in nucleus
- mechanical signaling through cytoskeleton changes that trigger chemical signals in cell
Extracellular Matrix
receptor proteins in membrane
integrins
neighboring cells adhere, interact, or communicate through direct physical contact
cell junctions
prevent leakage of extracellular fluid; mostly epithelial cells like intestine lining
tight junctions
anchor cells together
button-like; made of keratin
desmosomes
provide cytoplasmic channels between adjacent cells (allows water and small molecules to pass)
gap junctions
