section 4 Flashcards
The light microscope originally
around since the early 1600’s. Robert hooke used it to first find the description of a cell
Antoni Van Leeuwenhoek
the father of biology– was a fabric merchant who saw Robert Hooke’s work and was inspired to make his own light microscope which magnified up to 200-250x
what kinds of structures did Leeuwenhoek funk
sperm muscle cells red blood cells capillaries protists bacteria
visual angle
an angle subtended at the eye by an object
how microscopes generally work
increase the size of an image on the retina. THIS IMAGE SIZE IS GOVERNED BY VISUAL ANGLE. the size of an image is directly proportional to the visual angle
step by step how micrsoscopes work
light from larger object close to the eye hits the eye at a large visual angle producing a large image on the retina
objects a long way away or small objects make a tiny visual angle with he eye and the lense focuses a tiny image on the retina
microscopes bend light to increase the visual angle and give more info to the retina
3 main points in microscopy
- magnification: ratio of image size to real size
- resolution: min distance by which two points can be separated and still seen as two points
- contrast: diff between light and dark areas in an image. can be done wit staining or labelling certain structures within a cell
what limits light microscope
the wavelength of light. objects smaller than half the wavelength of light used to illuminate the specimens effectively hide within the wavelength and cant be resolved
cell fractination
biologists help couple structure with function- homogenize
repeated centrifugations at increasing speeds
cell components can be separated starting with largest structures which can be identified using a light microscope
differences between prokaryotes and eukaryotes
- size: E are generally 10x bigger
- arrangement of DNA: E have proper membrane bound nucelus containing DNA. P have a nuceloid region
- internal compartments: E have membrane bound organleeld and P do not
common traits of Prokaryotes and Eukaryotes
- plasma membrane
- cytosol/ cytoplasm
- chromosomes (DNA)
- ribosomes
smallest prokaryote cells
mycoplasmas
prokaryotes general info
they have a lower size limit set by requirements for DNA , cellular machinery, etc. to run essentials of life
upper size limit for eukaryotes
there is no very big unicellular organisms because of SA/V ratio
importance of SA/V ratio
cells aqquire nutrient molecules and remove waste by moving them across the cell membrane and all parts of a cell must be in molecular communication with the membrane meaning that surface area must be big enough for efficient exchange of molecules and volume must be small enough for the same reason
the natural limit of max size of a cell
the idea SA/V ratio that allows efficient molecular transfer throughout the cell. Big organisism solve this SA/V ratio bu being made of lots of tiny cells each having its own membrane and surrounded by extracellular fluid
jobs of integral/ peripherla proteins
- transportaion of hydrophillic molecules
- enzyme activity: preform metabolic processes at the edge of the cell both inside and outside
- signal transduction: signalling molecules, cause a cascade of activities to happen inside the cell like dorbells
- cell-cell recognition: recognizing other cells by binding to carb ID tags attached to membrane proteins
- intercellular joining: cells join together to make tissues. long lasting binding of cells, tight and gap juctions
- attachments to cyto and exoskeleton: give stronger framework.
glycoproteins
carbohydrate ID tags attatched to membrane protiens. This is important in blood types, immune system recognition of foreign bodies, and embryology (sorting of cells)
temeprature buffer
cholestrol. keeps particles from closely packing in cold temperatures and stabilizes them in warmer temperatures so they don’t become too leaky.
memrane proteins
integra (transmembrane) and peripheral proteins
what affects membrane fluidity
temperature and nature of hydrocarbon tails (striaght of bendy chains)
2 ways of getting through the membrane
- direct
2. through the membrane
what type of molecuels can directly dissolve through the membrane
small, hydrophobic, non polar molecuels such as o2, co2, and somewhat water even tough it is charged because it is small
what molecules have to go through the membrane
polar, charged, hydrophillic molecules have to go through TARGET SPECIFIC channel and carrier proteins
channel proteins
have a hydrophillic channel running through them. Aquaporins are a type of channel protein
carrier protein
spit out their specific molecuels that they take in and change shape. They are so specific that they wont take isomers of the same thing such as fructose and glucose
what drives osmosis and diffusion
thermal motion
net diffusion
molecules move randomly but the net movement is always down their concentration gradients until the net movement=0 because both sides are the same
is diffusion spontaneous or non spontaneous
this is a spontaneous process that requires no input of energy and is driven by the inherent thermal energy in the molecules
osmoisis
diffusion of FREE water molecules down their concentration gradient. There must be a solute dissolved in the water for there to be a water concentration gradient.
what do water molcules do with solute
they cluster around hydrophillic solutes and now those large water molecules are too big to fit through the membrane
what does a cells “fate” depend on when immersed in a solution
- precence of a cell wall
- concentration of salts in the soltuion
- concentration of salts in the cell
tonicity
the relative concentraion of solutes in the solution on either side of a semi permeable membrane. tonicity determines the direction of osmosis
characteristic of protists
can both have a cell wall or no cell wall
lysed cell
a cell in a hypotonic soltution and the cell will bust and die due to a net water movement into the cell
how do paramecium deal with the tonicity difference
they have contractile vacoules that fills up continuously with water and empties it out again
how to terrestrial animals deal with the difference in tonicity
their cells are bathed in extracellular fluid which is isotonic to the cell contents
three tonicity states for cells with walls
- turgid in a hypotonic enviroment
- flaccid in a isotonic envitoment
- plasmolysis in a hypertonic environment leads to death and is lethal
what processes are due to diffusion
BOTH movement of small uncharge molecules through the membrane AND polar, ionized molecules with the help of channel and carrier proteins
facilitated diffusion
moement of polar and ionized molecules down their concentration gradients with the help of carrier proteins
passive transport
movement of molecules against their concentration gradeints using ENERGY
which transport proteins can facilitate active transport
carrrier proteins
how is membrane poteintial like a water dam
opening the dam/ opening the channels in the membrane can power carious cell activities like muscle contration and nerve conduction
what is the equivalent of Na/K pumps in bacteria/ fungi,/ plants
proton pumps
what particles use bulk transport
large molecules like polymers, macromolecules, and food particles
how is bulk transport achieved
both exo and endocytosis use ATP and membrane bound vesicles
what molecules leave the cell via exocytosis
- neurotransmitters
- hormones
- cellulose that makes part of cell walls
- waste molecules
what are the three types of endocytosis
pinocytosis ——————GENERALLY ALL EUKARYOTES
receptor mediated——-GENERALLY ALL EUKARYOTES
phagocytosis ———–ONLY CELLS WITHOUT CELL WALLS
what is receptor mediate endocytosis
it is a concentration mechanism that selectively captures molecules of choice and brings them into the cell for processing
peroxisomes
specialized metabolic compartment bounded by a single membrane which contatains more than 50 enzymes that metabolize a wide variety of substances
what kinds of things do peroxisomes metabolize
long chani fatty acids for use in the mitochondira
amino acids
alchohol
chloroplasts
capture light energy and convert it to chemical energy to produce glucose
they have a double membrane and circular DNA and ribosomes
they grow and move and divide by binary fission
mitochondria
is the site of cellular respiration. This is where the breakdown of glucose happens and the energy released is used to regenerate ATP
unique enzymes found in the membranes or in the compartments drive cellular repsiration and regulate ATP
vacoules
large and memebrane bound storage compartments
where do vacoules come from
ER and Golgi
what types of vacoules are there
- central vacoule in plants: resivoir for organic compounds and inorganic ions and sap
- food vacoules: formed by phagocytosis
- contractile vacoules: used to maintain water balalcne
- storage vacoules: protein storage in seeds
- hydrolytic vacoules similar to vesicles for plants and fungi
endosymbiont theory
the idea that mitochondria and chloroplasts were once free living prokaryotic bacteria that were engulfed and incorporated into an acient eukaryotic cell. there were two of these events to produce plant cells.
evidence for the endosmbiont theory
- double membrane
- circular DNA
- divide and reproduce autonomously
- there are living prokaryotes that resemble both mitochondria and chloroplasts
what are the uses of the proteins that are made by ribosomes
- inserted into membranes (enzymes or transporters)
- used inside organelles (lysosome enzymes)
- secreted from the cell (digestive enzymes)
- or proteins in the cytosol that are enzymes involved in glucose metabolism
cisternae
litttle flattened discs or openings thingies found in golgi or ER
Lysosomes
digestive compartments which contain hydrolytic enzymes
where do lysosomes come from
rough ER produces hydrolytic enzymes and mebranes which are sent to the golgi for processing and bud off the trans side of the golgi as lysosomes
what is the function of lysosomes
- digestion: breakdown of macromolecules
- defense: breakdown of invaders engulfed by white blood cells
- cell maintenance: breakdown and recylcing or debris
autophagy
self eating
what is known as the biosynthetic factory of the cell
the endoplasmic reticulum
fun fact about ER
the mebranous sacs and channels are up to half of the total membrane in the cell
what is the ER attatched to
the nuclear encelope
what are the compartments of the ER called
cisternae
functions of the smooth ER
- enxymes synthesize lipids and steroids
- enzymes metabolize carbs (glycogen formation and breakdown)
- enzymes detozify poisons (harmful metabolic byproducts and excel alcohol by adding OH groups to hydrophobic substances making them more water soluble and flushing them out)
- storage of calcium in lumen (ready for Calcium requiring fuctinos such as muscle contraction)
who is the father of biology
antony van leeuwenhoek
rough ER function
- protein synthesis
- membrane factory for cell (produces phospholipids and membrane proteins)
- forms transport vesicles
how doe sthe rough ER deal with polypeptide chains
polyppetide chains produced in the ribosomes are threaded into the ER lumen through protein complex pores
they are then folded, undergo secondary processing, and are packaged in vesicles and shipped off to other locations
