Biology: The cell

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The cell
The smallest unit of life capable of carrying out all life functions -can be multicellular or unicellular
theory of the cell
1. All living things are made of one or more cells
2. The basic unit of structure and function in organisms
3. All cells arise from pre-existing cells
Cell/Plasma Membrane
-A flexible covering or layer which separates the inside of the cell from its surrounding . It directs what enters and leaves the cell.
rotifer
a multicellular (organs/systems) animal
tetrahymena
a unicellular eukaryotic protozoa
coccolith
a unicellular eukaryotic phytoplankton
Imbedded proteins
polar ends of the proteins are attracted to water on either side of the membrane; non polar ends are attracted to the interior which gives "fluidity"
Marker proteins
ID, what type of cells they are to each other
Receptor proteins
bind to signal molecules outside the cell found embedded within the plasma membrane surface of a cell that receives chemical signals from outside the cell.
transport proteins
active in moving things in and out of the cell
cytoplasm
colloidal material that holds organelles in place
-the region of the cell inside the plasma membrane but outside the nucleus
cytoskeleton
protein microtubule fibers that give some support to the cell
-a kind of internal scaffolding consisting of three sorts of protein fibers; some of these can be likened to tent poles, other to monorails
-a network of protein filaments that functions in cell structure cell movement and the transport of materials within cell
-many moving and assembled or disassembled very rapidly
-divided into three parts : microfilaments, intermediate filaments and microtubules
microfilaments
-most slender of the skeletal fibers
-made of the protein actin and serve as a support or "structural " filament in almost all eukaryotic cells
-can help cells move or capture prey essentially by growing very rapidly at one end (direction of movement or extension)while decomposing rapidly at the other end (pseudopodia)
intermediate filaments
-filaments of the cytoskeleton intermediate in diameter between microfilaments and microtubules.
-these proteins are the most permanent of the cytoskeletal elements, kinda like our skeleton.
-stabilizes the positions of the nucleus and other organelles within the cell
ribosomes
organelles that direct the activity for making proteins
-produces proteins from amino acids and contains many enzymes for lysosomes
-destinations for the mRNAs
-organelles that serves as the site of protein synthesis in cell
-mRNA runs chains through hair and then the ribosome reads the chemical sequence and starts putting the amino acids specified in the order by the mRNA resulting of a chain of amino acids growing from the ribosome (aka polypeptide)
eukaryote and prokaryote
-eu means true and karyon means nucleus which prokaryote means before nucleus
Prokaryotic cells
-are either bacteria or another microscopic form of life known as archaea
-cells whose DNA is not enclosed within a nucleus
-DNA is in nucleoid region
-much smaller
-always single-celled
-only one type of organelle
Eukaryotic cells
-everything else other than bacteria and archaea are eukaryotic
-cells whose primary complement of DNA is enclosed within a nucleus
-DNA within membrane-bound nucleus
-much large-
-often multicellular
-many types of organelles
Five larger structures of the Eukaryotic cell
-cells nucleus
-other organelles that lay outside the nucleus
-the cytosol
-cytoskeleton
-plasma membrane
cytosol
a protein-rich, jelly-like fluid in which the cell's organelles are immersed (mostly water)
plasma membrane
the outer lining of the cell a microscopic membrane of lipids and proteins that forms the external boundary of the cytoplasm of a cell or encloses a vacuole, and that regulates the passage of molecules in and out of the cytoplasm.
cell size
ex. human skin cell = 40-50 micrometers
-cell membrane = 5 nm
-Giraffe nerve cell = 3 m
surface area to volume ratio
-cells must have methods of overcoming too great of an internal volume - "folds"
rate of material exchange
-larger volume w/less surface area = not room to escape or enter
starvation and poisoning
if you cant get needed nutrients in quickly or if you cant get waste to leave fact enough your cells will begin to die off
what does quadrupling the radius do to the SA
it increases the SA by 16x and the volume by 64x
Hooke
first person to use the term "cell"
Brown
-stained the nucleus of the cell
Schleiden
- said all plants were made of cells
Schwann
said all animals are made of cells
Virchow
figured out all cells come from other cells
organelle
a highly organized structure, internal to a cell, that serves some specialized function
Nucleus
-organelle that contains the DNA, Nucleolus, Chromatin, Chromosomes, Nuclear pores, and directs cell activities
-is a membrane-lined compartment that encloses the primary complement of DNA in eukaryotic cells
sight where DNA exists and where it is put together or synthesized for doubling
Nucleolus
- dense area of RNA, blueprints for protein synthesis
-where the synthesis of RNA takes place
-type of RNA part of ribosomes are called ribosomal RNA or rRNA
-so nucleolus is the area within the nucleus of a cell devoted to the production rRNA (one thing also in prokaryotic cell)
they are completely finished in the cytoplasm and then begin receiving mRNA
Endoplasmic Reticulum
-organelle Made of a lipid bilayer w/embedded proteins. Used for transport and reduces toxins (amphetamines/morphine)
rough ER
-used to produce and transport proteins
-a network of membranes that aids in the processing of proteins in eurkaryotic cells
-rough because it is studded with ribosomes endoplasmic because it it lies within(endo) the cytoplasm and reticulum because it is a network
smooth ER
used for lipid production
-a network of membranes that is the site of the synthesis for various lipids and a site at which potentially harmful substances are detoxified within the cell
-synthesis of fats are put together in the SER of fat and liver cells
-steroid lipids are put together in SER of ovaries and testes
-and detoxification is in SER of liver cells
vesicles
-pinching off of membranes w/proteins. Pinocytotic invaginations
phagocytosis
-takes in big objects to digest
pinocytosis
takes in small objects to digest
lysosomes
organelle packaged by the Golgi/contain digestive enzymes "feeling of sunburn"
mitochondria
organelle "powerhouse" 95 % of energy conversion for the cell
-organelles that are the primary sites of energy conversion in eukaryotic cells
-to turn the food into ATP mitochondria needs oxygen which is why we need oxygen to breathe and the products of it is water and carbon dioxide which is what we exhale
cell respiration
is the set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products.
Liver cell =
2,500 in each. ATP (energy carrying model) production
-folds of cristae for greater surface area
cristae
are folds of the inner mitochondrial membrane. The electron transport chain and chemiosmosis take place on this membrane as part of cellular respiration to create ATP.
DNA
-its own set to control independent functions
--contains information for putting proteins together from a starting set of amino acid building blocks
-whole DNA complement is like a cook book that contains individual protein recipes called genes
-in eukaryotic cell DNA is largely confined within a nucleus bound by a membrane
Golgi Apparatus
-organelle that packages proteins for transport in vesicles
-saliva carries digestive enzymes packaged in the Golgi
centrioles
organelle that helps with cellular reproductions and helps move DNA A centriole is a small set of microtubules arranged in a specific way. There are nine groups of microtubules. When two centrioles are found next to each other, they are usually at right angles. The centrioles are found in pairs and move towards the poles (opposite ends) of the nucleus when it is time for cell division.
microtubules
protein tubes... Flagella of Sperm (the tail)
-the largest of the cytoskeletal filaments, taking the form of tubes composed of the protein tubulin.
-play a structural role in the cell which seems to be the structural role to determining the shape of the cell
-serve as monorails of cells internal skeleton
flagella and cillia
help the cells move
vacuoles
storage container
cell walls
-ONLY FOR PLANTS AND SOME ALGAE
-primary = crunchy (thin and flexible like a carrot forms when cell is growing... "cellulose coating"
-secondary-rigid (wood) (thicker)
-middle lamella = pectin (glues adjacent cell walls together)
The cell wall is a very tough, flexible and sometimes fairly rigid layer that surrounds some types of cells. It surrounds the cell membrane and provides these cells with structural support and protection. In addition the cell wall is acting as a filtering mechanism
made of cellulose
plastids
ONLY FOR PLANTS AND SOME ALGAE
-chloroplasts, chromoplasts and leucoplasts(white-food storage)
chloroplasts
are organelles, specialized subunits, in plant and algal cells. Their main role is to conduct photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight, and stores it in the energy storage molecules ATP and NADPH while freeing oxygen from water.
-uses suns power membrane-laden organelles and water few minerals and end up with sugar and by product is oxygen
chromoplasts
are plastids, heterogeneous organelles responsible for pigment synthesis and storage in specific photosynthetic eukaryotes.... accessory pigments
water vacuoles (large)
ONLY FOR PLANTS AND SOME ALGAE
-storage in plants
-turgor pressure vs wilting
membrane
-most organelles are encased in their own membranes
-a flexible, chemically active outer lining of a cell or its compartments
typical animal cell
-roughly spherical surrounded by and linked to other cells of similar type and immersed in watery fluid and abt 25 micrometers in diameter
proteins
critical working molecules in living things
basic path of protein production in cells
1. Instructions from DNA are copied onto mRNA
2. mRNA moves to ribosome.
3. Ribosome moves to endoplasmic reticulum and "reads" mRNA instructions.
4. Amino acid chain growing from ribosome is dropped inside endoplasmic reticulum membrane. Chain folds into protein.
5. Protein moves to Golgi complex for additional processing and for sorting.
6. Protein moves to plasma membrane for export.
nuclear envelope
the double membrane that lines the nucleus in eukaryotic cells
RNA
-in order for DNA codes to be sent to the cytoplasm and put together they have to be copied onto a second long-chain model called RNA... RNA takes the info from the nucleus to the site of the protein synthesis... the ones that transfer DNA info are more specifically called messenger RNA (mRNA)
How does the mRNA leave the nucleus
-in order to go to the cytoplasm it must exit through thousands of channels that stud the surface of the nuclear envelope called nuclear pores (ways materials and proteins leave and enter nucleus)
Ribosome in RER
-the ribosome bound with its attached mRNA and polypeptide chains will migrate to the rough ER and dock on its outside face,. As the ribosome continues creating the polypeptide it drops inside the chamber of the RER
in the cisternal spaces of the RER
-inside the forms of periphery sacs made by the membrane of the RER are these ... here the polypeptide chains first fold up into their protein shapes then side chains add to the proteins like sugar side chains and then they go through a quality control test and if they pass they will move out of RER for more processing
free ribosomes
tend to produce proteins that will be used within the cell's cytoplasm or nucleus
transport vesicles
the membrane-lined spheres that move within a network (of membranes fusing and releasing protein cargo to eachother, )carrying proteins and other molecules
endomembrane system
-an interactive group of membrane-lined organelles and transport vesicles within eukaryotic cells
after transport vesicle bearing proteins bud off from RER and moves through cytosol to fuse with the membrane of another organelle they go to
the golgi complex which is a network of membranes that processes and distributes proteins that come to it from the rough ER
-some sugar chains might be cut off here or phossphate groups added but the golgi also "sorts" and "ships" the preoteins kinda like a distibution center reading the chemical "tags" that are part of the proteins
proteins drop off cargo at golgi
proteins arrive at the Golgi housed in the transport vesicles that fuse with the golgi "face" nearest the rough ER and here the vesicles release their protein cargo into the Golgi cisternal sacs for processing and once processed the proteins will bud off the outside face of the golgi now housed in their final transport vesicles
exocytosis
final step in the protein process
-once vesicle buds off from the golgi all that remains is for it to make its way through the cytosol to the plasma membrane at the outer reaches of the cell
-there the vesicle fuses with the plasma membrane and the protein is ejected into the extracellular world
lysosome
an organelle found in animal cells that digest worn-out cellular materials and foreign material that enters the cell
-kinda like seald off acid vats that take in large molecules break them down and then return the resulting smaller molecules to the cytosol and what they cannot not return they keep inside themselves or expel them outside the cell
how do lysosomes break down larger molecules
-use as many 40 different enzymes- an enzymatic array that allows each lysosome to break down most of what comes its way. A lysosome gets hold of its macromolecule prey through the endomembrane system. a lysosome will fuse with the membrane surrounding a work out organelle part and proceed ti engulf it then breaks it down the small molecules that result are passed freely out and reused elsewhere known as the recycling at the cellular level
cilia
underlying structure is microtubules
-these are microtubular extensions of cells that take the form of a large number of active, hair-like growths stemming fromthem.
-they move back and forth very rapidly and helps move the cell around ... grow in great profusions in eukaryotic cells
flagella
-microtubules are also underlying structure
-relatively long,tail-like extensions of some cells that function in cell movement
-sperm is only animal cell that is flagellated
difference between plant cell and animal cell
-plant has no lysosomes but has everything else
-but plants cells also have a thick cell wall, chloroplasts and central vacuole but animal cells dont
central vacuole
-really large
-composed mostly of water and holds a lot of nutrients and waste products
-defined as a large, watery plant organelle that has many functions, among them the storage of nutrients and the retention and degradation of waste products
-in last role the central vacuole uses digestive enzymes like lysosyme to degrade waste products
cell wall
-outer protective lining that makes their plasma membrane just inside the cell wall look rather thin and frail by comparison.
-provides structural strength and puts limit on the absorption of water and generally protects plants from harmul outside influences
-cell walls are rigid and inflexible which is why they rnt in animal cells cuz animals need to be flexible
-composed chiefly of cellulose (polysaccaride) which is sometimes joined by lignin
plasmodesmata (communication among plant cells)
-series of tiny channels in plant cell wall ready to communicate with other cells
-structure is one of these channels is such that the cytoplasm of one plant cell is continuous with another so it can look like one continuous whole
-basically a channel-linkage between two plant cells
-permanent channels between plant cells
gap junction (communication among animal cells)
-consists of clusters of protein structures that shoot through the plasma membrane of a cell from one side to the other forming a kind of tube
-when these tubes line up in adjacent cells the result is a channel for passage of small molecules and electrical signals
-defined as a protein assemblage tha forms communication channel between adjacent animal cells
-open only as necessary
chromosomes
Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique.
ribosomes made of
A ribosome is made from complexes of RNAs and proteins and is therefore a ribonucleoprotein. Each ribosome is divided into two subunits: a smaller subunit which binds to the mRNA pattern, and a larger subunit which binds to the tRNA and the amino acids.
chromatin
(the material of which the chromosomes of organisms other than bacteria (i.e., eukaryotes) are composed. It consists of protein, RNA, and DNA.)
Glycolipids
are lipids with a carbohydrate attached. Their role is to provide energy and also serve as markers for cellular recognition
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