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Cell Biology


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A phospholipid is an __________ molecule because it has botha hydrophilic and hydrophobic region
the number of mitochondria is coreelated with the ____
cell's level of activity
What are integral proteins?
transmembrane proteins, with hydrophobic regions. consists of 1 or more stretches of nonpolar amino acids into alpha-helixes.
perisomes do not bud like lysosomes,.....
they grow by incorporating proteins and lipids in the cytosol. and increase in number by splitting in 2.
problem w/ the all protein on top adn bottom one:
all membranes don't look the same
proteins have hydrophobic and hydrophilic, and hydrophobic was touching the water
Singer and Nicolson then said that hydrophobic parts in side, and hydrophillic outside: fluid mosaic.
The carb attached to a glycoprotein is called:
Prokaryotic cells contain:
ribosomes, capsule, cell wall, plasma membrane, nucleoid region
Golgi does what?
finishes, sorts and ships cell products
Why is cytoplasmic streaming important?
circular flow of cytoplams which enables the materials to travel faster.
if cilia or flagella extend from cells that are held in place as part of a tissue layer, they function to ________
move fluid over the surface of the tissue.
What are peripheral proteins?
not embedded into the lipid bilayer, often loosely bound to the surface of the membrane.
what does the cis face do?
what does the trans face do?
receives vesicles
ships the vesicles
What ar ethe 3 main functions of a plant cell's wall?
protection, maintians shape, prevents excessive uptake of water. hold plant up against gravity.
ER makes itself, how?
by adding proteins and phospholipids
what is a free ribosome?
suspended in cytosol, most of the proteins made will function in the cytosol.
in the centrosome, there are a pair of _____, each composed of 9 sets of 3 triplet microtubules arranged in a ring.
Microfilaments are solid, and they are built from molecules of...
actin, a globular protein. twisted double chain of actin subunits
what are the 2 poles of Golgi?
cis and trans face
on the cytoplasmic side of the plasma membrane, they are held by the _______
on the exterior side, protein sare attached to fibers of the ________
cytoskeleton, extracellular matrix
what is the basic thing that mitochondria does?
sites of cellular respiration. generates ATP by extracting energy from sugars, fats and other stuff w/ help from oxygen
Microtubules have a compression-resisting role, while the structural role of microfilaments is to:
bear tension (pulling force).
microtubules are straight and hollow rods, the wall of the hollow tube is made from a proteinc aleld:
tubulin. there is alpha-tubulin and beta-tubulin. elongates by adding tubulin molecules to it. also can be disassembled
bad thing about electron microscopy?
kills the cells, and introduce artifacts: structural features seen in micrographs that don't exist in the living cell (also in light)
what are lysosomes?
membrane-bound sac that is a digestive compartment
myosin is important because:
it acts w/ actin to contract muscle cells, and also microfilaments forms a cleavage furrow when a cell divides in 2
Vacuoles are larger/smaller than vescicles
there is an __ distribution of proteins, lipids and carbs which is determined when it is being built by the ______
asymmetric, ER
the cytoskeleton is a network of _______
fibers extending throughout the cytoplasm
integrins do what?
transmit changes in ESM to the cytoskeleton.
what do chloroplasts do?
sites of photsynthesis, converts solar energy to chemical, by absorbing sunlight
What is magnification
how much larger the object appears compared to its real size
The cristae (inner membrane that is folded) gives the inner mitochondrial membrane a __________
large surface area that enchances cellular repsiation.
What is ECM?
extracellular fluid
what are the 3 types of vaculoes?
FOod vacuole, contractile vacuole (protists), central vacuole (mature plant cells which are surrounded by the tonoplast)
muscle cells do what?
ER membrant pumps calcium ions from cytosol into the cisternal space. when the cell is stimulated, Ca rushes back across the ER membrane into the cytosol and triggers the muscle
if hydorolytic enzymes roamed around and weren't in a lysosome, the cell would:
like rivets, fastening cells together
mitochondria and chloroplasts grow and reproduce w/in the cell
semiautonomous organelles
Describe nuclear envelope
doubele membrane, each is a lipid bilayer w/ pores through it. pore complex lines each pore and regulates the entry.
Lysosomal membrane maintains low internal pH (5) by...
pumping h ions into the lumen of the lysosome.
Davson and Danielli proposed a sandwich model:
phospholipid bilayer between 2 layers of protein.
chloroplast structure:
2 membranes separted by a very narrow intermembrane space. thylakoid, granum, stroma
ribosomes are on ____ and _____
rough ER and nuclear envelope
the chloroplast is a specialized member of ______
What is a basal body?
structurally like a centriole, the microtubule assembly of cilium or flagellum is anchored in the cell.
Golgi makes certain macromolecules by itself, like:
hyaluronic acid, which helps glue animal cells together
Dna is organized along w/ proteins into_______
cell motility requires the interation of the cytoskeleton with _______
proteins called motor molecules *they move cilia and flagella) they can slide around.
Stages of plant cell wall:
primary cell wall, then between taht is the middle lamella, then secondary wall.
wood has secondary. lamells serves as cement.
cell motility refers to
changes in cell location and more limited movements of parts of the cell
Er is continuous w/...
nuclear envelope
in the future, it might be possible to treat storage diseases by ______
injecting the missing enzymes into the blood along w/ adaptor molecules that target the enzymes for engulfment by cells.
intermediate filaments are more _____ than microtubules or microfilaments
Most secretory proteins are ________, which are proteins that __________
glycoproteins, covlently bonded to carbs.
how does TEM work?
aims an electron beam through a thin section of the specimen, and uses electromagnets as lenses to focus and magnify the image by bending the paths of the electrons. then is focused on a screen
Microtubules shape and support the cell and also serve as tracks along which organelles equipped w/ motor molecules can move.
can guide secretory vesicles from Golgi to plasma membrane
Pseudopodia extend and contract through the
reversible assembly of the actin subunits.
A flagellum moves, how?
has an undulating motion that generates force int he same direction as the flagellum's axis.
Detoxification usually involves:
adding hydroxyl groups to make them more soluble to flush from the body. This is why you need more drugs to cause the same effect. (tolerance to drugs)
what are rough ER's 2 main functions?
synthesis of secretory proteins and membrane production
Both flagella and cilium have the same arrangment of microtubules:
"9+2" pattern. 9 doublets of microtubules.
Mitochondria are membrane boud, but they are NOT part of the ___
endomembrane system
what are prokaryotic cells?
no nucleus, DNA is in the nucleoid, but no membrane separates this from the rest of the cell, Bacteria and Archaea have these.
Amoeba and other protists each through
channels between walls.
put the 3 main types of fibers that make up the cytoskeleton in order of thickest to thinnest:
Microtubules, intermediate filaments, and microfilaments
what does the endomembrane system consist of?
nuclear envelope, endoplasmic reticulum, GOlgi apparatus, lysosomes, varoious kinds of vacuoles, and the plasma membrane.
microtubules grow out from a
centrosome which is a region located near the nucleus
IF a membrane is rich in phospholipids, w/ unsaturated hydrocarbons, it will be more___
Secretory proteins leave the ER in membranes of vesicales from a special region called:
transitional ER
what instrument do you use to fractionate cells?
centrifuge (really powerful ones: ultracentrifuge)
Different cisternae contain different __________
Tight Junctions
prevent leakage. keep contents of one cell separate from the other
the thylakoid membrane divides the interior of hte chloroplast into 2 compartments:
the thylakoid space and the stroma
chloroplasts are mobile!
what is ER?
membranous labyrinth that it accounts for more than half of the total membrane in many cells
what is a glyoxysomes
convert fatty acids to suagar, type of peroxisomes
The various kinds of intermediate filaments can function as the framework of the entire cytoskeleton
also can reinforce the shape and fix positions of organelles
the most recent addition to the list of possible cytoskeletal funcions is:
redulation of biochemical activities in the cell, it may trasmit mechanical forces fromthe surface of the cell to the interior
how does the nucleus control protein synthesis?
makes mRNA in the nucleus according to directions from DNA, then mRNA conveys the genetic messages to cytoplasm. Then mRNA attaches to ribsomes, where the message is translated into the primary sturcture of the protein.
the large vacuole of a plant cell develops by the coalesces of _____
smaller vacuoles.
A membrane at some critical temp. phospholipids settle into a closely packed arragnement and the membrane solidifies, this depends on...
lipid concentration.
The cytoskeleton has many functions:
gives mechanical support, aslo it is very dynamic and it changes
Smooth ER makes:
sex hormones
chromoplats are
enriched in pigments and give fruit and flowers color.
the doublets do not move, instead, the forces exerted by the ____ cause the doublets to curve, which bends the cilia or flagella
dynein arms
Functions of a plant cell vacuole
storage of organic compounds, of inorganic ions, disposal sites, pigments, poison, elongates as vacuoles get water.
what are eukaryotic cells?
true nucleus enclosed by a nuclear envelope. Protists, plants, fungi and animals
what is a peroxisome
consome oxygen and form H2O2 as a by-product to mperform various metabolic functions.
Freeze fracture tells you:
gives you both halves of the membrane, and it was cobblestone like.
lysosomes use their hydrolytic enzymes to recycle the cell's own organic material, which is called:
autophagy. (engulfs old organelles)
ER consists of...
a network of membranous tubules and sacs called: cisternae. Er separates this from the cytosol.
Hydrolytic enzymes and lysosomal membrane are made by ____ then transferred to _______
ER, a Golgi apparatus
Intermediate filaments are made up of
any time of molecular subunit under keratins. Microtubules and microtubules are consistent in diameter and composition in all eukaryotic cells.
Golgi is made of:
cisternae: like pita bread: membranous sacs, vesicles inside of it are engaged in the transfer of material between the GOlgi and other structures.
Ctyoplasm consists of:
cytosol, a semifluid medium in which organelles are in.
amyloplasts are colorless plastids that store
starch in roots and tubers
Cholesterol's role:
hinders close packing of phospholipids, and it lowers the temp. neeeded for the membrane to solidify. helps stabilize the membrane.
what are the main functions of smooth ER
synthesizes lipids, metabolism of carbs, and detoxification of drugs and poisons
thte most abundant glycoprotein int eh ECM of most animal cells is:
collagen. forms strong fibers
why can't a cell be really big?
because as an object has more surface area, there is a lot more volume. You want more surface area.
Gap juntion s( communicating junctions)
for chemical communications, connects provide cytoplasmic channels.
Light microscopes can magnify up to about _______ times the sieze of the specimen
Dynein is:
the motor molecules that makes up the arms, and it is a protein. it moves due to changes in the conformation of the protein, w/ ATP providing hte enrgy for those changes.
cell ultrastructure?
cell's anatomny as resolved by an electron microscope
how does a cilia move?
oar-like, perpendicular motion to the axis.
why does the light microscope not work all the time
limited by the wavelength of the visible light used
what are light microscopes?
visible light is passed through the specimen, and the lenses refrace the light so the image is magnified
what do ribsomes do?
sites where the cell makes proteins. Human liver cell have a lot of ribosomes. have promenient nucleolus.
3-D, used to look at the surface of a specimen.
what is cell fractionation?
separates the major organelles so that their individual functions can be studied.
what is resolving power?
measure of the clarity of the image. the minimum distance 2 points can be separated and still be distinguished as 2 separate points.
what does the nucleus contain?
most of the genes that control the eukaryotic cell
what is a bound ribosome?
attached to the outside of the endoplasmic reticulum, make proteins that are destined either for inclusion into membranes, for packaging w/in certain organelles, or export.
what are the 2 different types of electron microscopes?
Transmission electron microscope and scanning electron microscope
why is the nucleolus important?
components of ribosomes are synthesized and assembled. then pass to the cytoplasm, where they combine to form ribosomes. can be more than 1
Chromatin what does it do?
looks like a diffuse mass, but as a cell prepares to divide, it condnses and then it becomes separate structures: chromosomes. we hav e46 chromosomes
how does fractionation work?
separates parts of the cell into: the pellet: larger structures that go to the bottom, and supernatant: smaller parts of the clel above. so then you get smaller and smaller pellets
where is the nuclear lamina and what does it do?
lines the nuclear envelope, itis a netlaike array of protein filaments that maintains the shape of the nucleus. Nuclear matrix wi/in nucleus.
Electron Microscope (EM)
beam of electerons through trhe specimen. electron mbeans have shorter wavelengths than visible light

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