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77 Cards in this Set

  • Front
  • Back
What is light microscope?
In LM, visible light is passed through specimen and then it is passed though glass lenses. Glass lenses will refract the light so that it will be magnified when it is projected into the eye, photographic film, digital sensor and video screen.
What is magnification?
The ratio of an object's image and its real size.
What is resolution?
The minimum distance that two points are separated and can still be distinguished as two points; it is to clarity the image.
How big can LM resolve?
Cannot resolve more than 0.2 micrometer or 200 nanometers.
What limits LM's resolution?
LM's resolution is limited by the shortest wavelength of light that is used to illuminate the microscope.
How much can LM magnify?
1,000 the actual size of specimen.
What is contrast?
Accentuates differences in parts of a sample. Staining or labeling cell's components can be carried out to stand out visually.
What cannot be resolved by the microscope?
Subcellular structures - organelles, the enclosed -membrane compartments of cell that are too small to be viewed by LM
What is electron microscope?
EM focuses beam of electron on the specimen or its surface.
Resolution of EM?
Resolution of EM is inversely related to the wavelengths of radiation that specimen uses for imaging, EM have much shorter wavelength than visible light.
Unaided eyes (Size range of cells)
human height > length of nerve and muscle cells > chicken egg > frog egg
LM (Size range of cells)
(frog egg) > most plants and animals cells > nucleus > most bacteria > mitochondrion
EM (Size range of cells)
(most plants and animals cells > nucleus > most bacteria > mitochondrion) > smallest bacteria > virsuses > ribosomes > proteins > lipids > small molecules > atoms
What is ultracellular structure?
Ultracellular structure is the specimen's anatomy revealed by electron microscope.
What is Scanning Electron Microsope?
An EM that is specially used to study the specimen's surface.
How does SEM work?
SEM scans samples of of specimen. These electrons get excited and they are then detected by an detected by a device that translate the patterns of electrons into electric signal to a video screen.
What is the result of SEM?
The result is specimen's topography and it is 3D.
What is Transmission Electron Microscope?
Is used to study the internal ultracellular of cells.
How does TEM work?
TEM aims an electron beams through a very thin section of specimen. The specimen is stained with heavy metal atoms, which makes some parts of cell denser than the others. TEM scatters in denser regions more than the rest => fewer electrons are transmitted. Lenses are electronmagnet to bend the paths of the electrons.
What are the advantages of EM?
Can be used to reveal subcellular structures and organelles
What are the disadvantages of EM?
Specialized in studying of living cells
What is Cytology?
The study of cell structure
What is Biochemistry?
The study of molecules and chemical (metabolism) processes of cells.
What is cell fractionation?
A useful technique for the study of cell structure and function which takes cells apart and separates organelles and other subcellulars from one another.
What is the instrument used for cell fractionation?
Centrifuge
How does centrifuge work?
Centrifuge spins test tubes holding mixture of disrupted cells. Cell components then fall to the bottom of the tube which creates pellet.
What is the most powerful machine for cell fractionation?
Ultracentrifuge
What does all cells have in common?
- Plasma membrane: a selective barrier.
- Cytosol: enclosed by plasma membrane which organelles and other cell components are found.
- Chromosomes: carry genes in form of DNA
- Ribosomes: tiny complexes that make proteins according to the instruction in genes.
What is the major difference of cells? Explain.
The location of their DNA. In eukaryotic cell, DNA is found in nucleus, bounded by double memebrane. In prokaryotic cell, DNA is found in nucloid that is not membrane enclosed.
What is the cytoplasm?
- Prokaryotic cell: it is the interior of the prokaryotic cell.
- Eukaryotic cell: it is the region between the cell membrane and the nucleus.
What is the smallest cell?
Mycoplasma - smallest packages with enough DNA to program metabolism and other cellular equipment.
Where are prokaryotic cells found?
Found in K. Monera, D. Bacteria + Archaea
Where are eukaryotic cells found?
All other kingdoms, plants and animals.
Ratio of SA:V
Smaller objects have greater SA:V. Larger organisms = more cells than smaller organisms, not larger cells.
What is high ratio of SA:V important for?
It is important for cells that exchange a lot of materials in their surroundings; i.e: intestinal cells.
What is a microvilli
Microvilli is a long, thin projection that increases the surface area without increasing the volume.
Why do plasma organelle membrances also participate in cell's metabolism?
Because many enzymes are built into the membranes.
What is a nucleus?
Contains most of the genes in eukaryotic cells (some genes are contained in mitochondrion and cytoplasm)
What is a nuclear envelope?
Encloses the nucleus, separating it from the cytoplasm. Nuclear envelope is double membrane. Each is lipid bilayer with associated proteins.
What is a nuclear pores?
Presents on the nuclear envelope for the entry and exit of RNAs, most protein and other macromolecules.
What is a nuclear lamina?
A netlike array of protein filaments that maintain the shape of the nucleus by supporting the nuclear envelope.
What is a nuclear matrix?
It is the framework of fibers extending throughout the nuclear interior.
What is a chromosome?
DNA is organized into chromosomes, structures that carry genetic information.
What is a chromatin?
Chromosomes are made up of chromatin. Chromatin is a complex of proteins and DNA. As cell is prepared for division, thin chromatin coils up and becomes thick enough to be distinguished as chromosomes.
How many chromosomes does a human cell have? How many chromosomes do sex cells have?
Human cells have 46 chromosomes and 23 are sex cells.
What is nucleolus?
A prominent structure that within the nondividing nucleus in which rRNA is formed based on information from the DNA. Proteins imported from the cytoplasm assembles with rRNA to form large and small ribosomal subunits. These subunits exit the nucleus via nuclear pore.
What is a ribosome?
Ribosomes are complexes made up of rRNA and proteins. Ribosomes carry out protein synthesis. Cells that have high rates of protein systhesis have large number of ribosomes.
What are the two cytoplasmic locales where ribosomes build proteins?
- Free ribosomes are suspended in the cytosol.
- Bound ribosomes are attracted the rough ER or nuclear envelope.
What are the functions of bound ribosomes?
- Make proteins that are destined for insertion into membrane.
- Packaging proteins in lysosomes.
- Exporting from the cell (secretion)
What is mitochodria?
The sites of cellular respiration, the metabolic process that generates ATP by extracting sugars, fats and other fuel with the help of oxygen.
What is chloropast?
Is found in plants and algae. It uses solar energy to covert into chemical enery by using sunlight to drive the synthesis of sugar from carbon dioxide and water.
How many membranes do mitochondria and chloropast?
- Mitochondria: 2 membranes
- Chloropast: 3 membranes (some algae have 4 membranes)
Which ribosomes are contained in the protein membrane of mitochondria and chloropast?
Ribosomes in the cytosol and ribosomes contained within the organelle itself.
What is an semiautonomous organelle?
Organelles that grow and reproduce within the cells.
What is the structure of mitochondria?
Some cells have one mitochondira, others have hundreds of them. Mitochondria has two membranes, each of them is phospholipid bilayer and embeded with a collection of proteins. Outer membrane is smooth, but the inner membrane is convoluted and infoldings called cristae. The are 2 compartments in the inner membrane: intermembrane and mitochondiral matrix. Intermembrane is the region between outermembrane and innermembrane. Mitochondial matrix is enclosed by the inner membrane, contains enzymes, ribosomes and mitochondiral DNA. Enzymes catalyze steps of cellular respiration. Cristae gives the mitochodria large SA => enhance the productivity of cellular respiration.
What is the structure of chloropast?
- Chloroplast is a member of plant organelle called plastids. In plastids, there are amyloplast and colorless platids which store starch; chromoplasts that makes fruits and flowers their orange and yellow hues; chloroplasts contain chlorophyll which have green pigments and supports photosynthetic production of sugar. This is found in leaves and other green algae.
Chloroplast is partitioned from the cytosol by an envelope consisting of two membranes separated by intermembrane. The inside of the chloropast contains flattened dics called thylakoids; thylakoids are stacked into granum and the space between granums in stroma. Stroma consists of mitochondrial DNA, ribosomes and enzymes. The membrane divides chloropast into 3 compartments: stroma, intermembrane space and thylakoid space.
What is peroxisome?
Peroxisome is a metabolic compartment that is bounded by a single membrane. Peroxisomes contain oxidases enzymes that transfer hydrogen from substrates into oxygen to create hydrogen peroxide.
What are the functions of peroxisomes?
- Break fatty acids into smaller molecules that can be used by mitochondria for cellular respiration.
- In liver, peroxisome can detoxify alcohol by transferring hydrogen from poisons to oxygen.
What does catalases enzyme in peroxisome do?
- Catalases enzymes can convert hydrgen peroxide into water.
What is the special peroxisome?
Special peroxisome is glyoxysomes which is in germinating seeds. This contains an enzyme that can transfer lipids into CHO.
How does peroxisome grow larger?
They do not bud from ER system. They grow larger by incorporating proteins from the cytosol, lipids made from ER and lipids synthesized from peroxisome itself.
General Information about cytoskeleton?
It gives mechanical support; it is important for animal cells since there's no cell wall; it is balanced by the opposing exertion of its elements; it provides anchorage for many cells, also includes cytosolic enzymes; it can be quickly dismanted in one part of the cell and reassembled in another part => changing shape of the cell.
How does cytoskeleton work in term of mobility and other functions?
- Cytoskeleton work with motor proteins to allow the whole cells to move along the fibers outside the cell. They slightly bend flagella and cilia by gripping mircrotobules and sliding them agaisnt each other. The contraction of muscle cells also carries out the same process, but it is with microfilaments.
- Cytoskeleton also helps the movement of neutron cells to move to the tip of axon by having the motor proten carrying the vesicles and travel along the microtubule.
- Vesicles from ER travel to Golgi via microtubule.
- Cytoskeleton manipulates plasma membrane to form food vacoules and phagocytic vesicles.
- Streaming of cytoplasm circulates materials with large plant cells.
- Cytoskeleton also regulates biochemical activities in respones to mechanical stimulation.
What is the general description about microtubule?
It is made of tublin proteins which consists of two slightly different types of polypeptides: alpha helix tubulin and beta helix tubulin
- Functions: suport and matin cell's shape; cell mobility; organelle movements; separation of chromosomes.
Centrosome and centrioles - mircrotubules
In animals cells, microtubules arise from centrosome. Each centrosome contains 2 centrioles. Each centrioles consists of 9 sets of triplet microtubules in a ring. Before a cell divides, centriole replicates. Yeast and plant cells lack centrosome with centrioles.
What are the functions of cilia and flagella?
- Flagella and cilia act as locomotor appendages which help cells to propell water (i.e: sperm).
- Extended from cell, flagella and cilia can also act as a part of tissues which helps fludi to move on the surface of the tissues.
What is the difference of flagella and cilia (motion, number of f and c)
- Flagella is limited to one or a few per cell, but cilia occur in large number on a cell's surface.
- Flagella usually undulates which means it moves in the same direction as the axis of the flagella.
- Cilia moves perpendicular direction to the flagellum. During its recovery stroke, it moves back close to the surface.
What is the general structure of flagella and cilia?
Both of them have the mircortubules sheath to plasma membrane. They follow the structure of '9+2' in which 9 doublets of mircotubules share a wall and create a ring around 2 microtubules in the center.
What is a nonmotile cilia?
It is the cilia that receives 'antenna. Membrane proteins receive cell signal from the cilia's envrionment, then send it to the cilia's interior, This triggers cilia's signaling pathways and thus leads to some changes. Nonmotile cilia is crucial to brain and embryotic function. It is the sturcture of 9+0 which lacks 2 mricrotubules.
What is a basal body?
Flagella and cilium are anchored in the cell by basal body. Basal body acts as centrioles.
What is the function of dynein?
It is the cross-linking protein that can link the outer doublets to each other and with the central mircrotubules. Each outer doublet also has pairs of dynein spaced along its length and reaching towards neighboring doublet. Each dynein composed of several polypeptides. It is responsible for bending movements of the oragnelles.
What is the structure of dynein?
Dyenin has two 'feet', one of them maintain the contact with the adjacent mircrotubule doublet while the other one releases and attaches to a step further than the other leg.
What is the effect of unstrained movements?
There is no cross-linking proteins which push the adjacent doubles to slide by side instead of bending.
What is the effect of restrained movements?
The dynein protein phiscally restrains 2 adjacent doublets so that they don't slide.
What is wavelike motion?
Cilia and flagella move outward to ward the tip.
What is microfilaments made of and what is its structure?
Microfilaments are made of actin proteins, globular proteins. It can form structural network as protein can bind to the actin filaments and allow new filaments to extent as a branch. Microfilament presents in all eukaryotic cells.
What is the structural role of microfilament?
It can bear tension. Microfilament inside the plasma membrane helps support the cell's shape. This network gives the cell the layer of cytoplasmic layer which is called cortex, the semisolid gel .- Animal cells which have specific function of transporting materials across cell membrane such as intestinal cells have mircofilaments to make up core of microvilli.