Explain the difference between magnification and resolution
Magnification is the degree to which the size of an image is larger
than the image itself.
Resolution is the degree to which it is
possible to distinguish between two objects that are very close together.
Explain the need for staining samples for use in light microscopy and electron microscopy
A lot of biological material inside a cell isn't coloured, so it
might be difficult to distinguish between different
features.
Coloured stains are used to stain specimens for use with the light
microscope. Chemicals which bind to
other chemicals on, or in,
the specimen, which allows the specimen be to seen. Some chemicals
bind to specific
structures, such as Acetic orcein staining DNA
red.
Electron micrographs start off black and white, with the
colour being added by a specialised computer program
afterwards.
Describe the major steps of cell fractionation and explain why it is a useful technique.
The major steps of cell fractionation are homogenization and differential centrifugation. It is a useful technique because it enables researchers to prepare specific cell components in bulk and identify their functions.
Distinguish between prokaryotic and eukaryotic cells.
In a prokaryotic cell, the DNA is concentrated in the nucleoid
without a membrane separating it from the rest of the cell.
In
eukaryotic cells, the chromosomes are contained within a membranous
nuclear envelope.
Explain why there are both upper and lower limits to cell size.
A cell can get too small to contain all the components necessary for
life.
As a cell gets larger, its surface area to volume ratio
gets much smaller, which means that it takes too long for substances
diffusing into the cell at the membrane (e.g., nutrients or oxygen) to
get to all parts of the cell
Explain the advantages of compartmentalization in eukaryotic cells.
Different cell organelles perform different functions, many of which require specialized components for specific targets. Compartmentalization creates appropriate microenvironments for these diverse processes, allows damage limitation, minimizes non-specific interactions and consequently increased cellular efficiency.
Briefly explain how the nucleus controls protein synthesis in the cytoplasm.
The nucleus directs protein synthesis by synthesizing messenger RNA (mRNA) according to instructions provided by the DNA. The mRNA is then transported to the cytoplasm via the nuclear pores. Once an mRNA molecule reaches the cytoplasm, ribosomes translate the mRNA's genetic message into the primary structure of a specific polypeptide
Explain how the nucleolus contributes to protein synthesis.
It creates ribsomal RNA which creates ribosomes in the cell and ribosomes create proteins.
Distinguish between free and bound ribosomes in terms of location and function.
Free ribosomes are in the cytosol and bound ribosomes are stuck to the outside of the ER or nuclear envelope
List the components of the endomembrane system, and describe the structure and functions of each component.
The ER, the Gogli apparatus, lysosomes and vacuoles.ER: consists of cisternae, functions as a seperator of the internal compartment of the ER lumen. Golgi apparatus: consists of flattened cisternae, functions by modifying ER and storing it then sending to different destinations. Lysosomes: membranous sac of hydrolytic enzymes, functions in animals to digest macromolecules. Vacuoles: membrane bound vesicles, functions as maintenance in cell compartments.
Describe three examples of intracellular digestion by lysosomes.
Phagocytosis is when smaller organisms or other food particles are eaten. Autophagy is when a damaged organelle or small amout of cytosol becomes surrounded by a double membrane and a lysosome fuses with the outer membrane of the visicle. Enzymes break down the material. Food vacuoles fuse with a lysosome, whose enzymes digest the food.
Name three different kinds of vacuoles, giving the function of each kind.
1. Contractile vacuole: pumps excess water out. 2. Central vacuole:helps maintain plants' shape and structure by storing water. 3. Food vacuole: storage for molecules that is a food source for the cell (phagocytosis).
Name the intercellular junctions found in plant (1) and animal (3) cells and list the function of each type of junction.
Plants: plasmodesmata- allow cells to share materials. Animals: (1) Tight Junctions:binds cells together. (2) Desmosomes: fasten cells together into strong sheets(anchoring junctions) (3) Gap Junctions: communicating junctions.
Explain how the extracellular matrix may act to integrate changes inside and outside the cell.
The ecm is made up of a network of proteoglycans.
they attach to
glycoproteins like fibronectin
which attaches to cell proteins
called integrins
which integrates information from both outside
and inside the cell
Explain how the ultrastructure of cilia and flagella relates to their functions.
THE ULTRASTRUCTURE IS MADE UP OF DYNEINS, WHICH ARE LIKE "FEET" AND ENABLE THE CILIA AND FLAGELLA TO "WALK", WHICH CONTRIBUTES TO THEIR SPECIALIZED MOVEMENT.
Describe the functions of the cytoskeleton.
A cytoskeleton acts as a framework that gives the cell it's shape and protects it to a certain degree. It also enables cellular motion.
Explain the roles of peroxisomes in eukaryotic cells.
PEROXISOMES =
Peroxisomes participate in the metabolism of
fatty acids and other metabolites. Peroxisomes have enzymes that rid
the cell of toxic peroxides. They have a single lipid bilayer membrane
that separates their contents from the cytosol (the internal fluid of
the cell) and contain membrane proteins critical for various
functions, such as importing proteins into the organelles and aiding
in proliferation. Like lysosomes, peroxisomes are part of the
secretory pathway of a cell, but they are much more dynamic and can
replicate by enlarging and then dividing.
Describe the structure of a mitochondrion.
a mitochondrion contains outer and inner membranes composed of phospholipid bilayers and proteins.[5] the two membranes, however, have different properties. because of this double-membraned organization, there are five distinct compartments within the mitochondrion. there is the outer mitochondrial membrane, the intermembrane space (the space between the outer and inner membranes), the inner mitochondrial membrane, the cristae space (formed by infoldings of the inner membrane), and the matrix (space within the inner membrane).
Describe the structure of a chloroplast
CHLOROPLASTS ARE THE SITES OF PHOTOSYNTHESIS. THESE DOUBLE-MEMBRANE BOUND ORGANELLES ENCLOSE ADDITIONAL MEMBRANES CALLED THYLAKOIDS. THE DISC-SHAPED THYLAKOIDS POSSESS AN INTERIOR SPACE. THE THYLAKOIDS ARE STACKED TO FORM GRANA, WHICH ARE SUSPENDED IN THE STROMA OF THE CHLOROPLASTS. DEMONSTRATE YOUR KNOWLEDGE OF CHLOROPLAST STRUCTURE BY PLACING THE LABELS IN THEIR CORRECT LOCATIONS.
Describe the structure and function of the nuclear envelope, including the role of the pore complex.
THE NUCLEAR ENVELOPE IS A DOUBLE MEMBRANE PERFORATED BY PORES.
THE PORE COMPLEX LINES EACH PORE, REGULATING THE PASSAGE OF CERTAIN LARGE MACROMOLECULES AND PARTICLES.
Compare the structure and functions of smooth and rough ER.
smooth er = smooth surface, synthesis of lipids, metabolism of carbohydrates, calcium storage, detoxification of drugs and poisons.
rough er = has ribosomes attached to its surface, and aids in synthesis of secretory and other proteins from bound ribosomes; adds carbohydrates to glycoproteins; produces new membrane.
Briefly describe the energy conversions carried out by mitochondria and chloroplasts.
MITOCHONDRIA = CELLULAR RESPIRATION = GENERATE ATP BY EXTRACTING ENERGY FROM SUGARS, FATS, AND OTHER FUELS WITH THE HELP OF OXYGEN.
CHLOROPLASTS = PHOTOSYNTHESIS = CONVERT SOLAR ENERGY TO CHEMICAL ENERGY AND SYNTHESIZE NEW ORGANIC COMPOUNDS SUCH AS SUGAR FROM CO2 AND H2O.
Describe the structure of a mitochondrion.
a mitochondrion contains outer and inner membranes composed of phospholipid bilayers and proteins.[5] the two membranes, however, have different properties. because of this double-membraned organization, there are five distinct compartments within the mitochondrion. there is the outer mitochondrial membrane, the intermembrane space (the space between the outer and inner membranes), the inner mitochondrial membrane, the cristae space (formed by infoldings of the inner membrane), and the matrix (space within the inner membrane).
Describe the structure of a chloroplast
CHLOROPLASTS ARE THE SITES OF PHOTOSYNTHESIS. THESE DOUBLE-MEMBRANE BOUND ORGANELLES ENCLOSE ADDITIONAL MEMBRANES CALLED THYLAKOIDS. THE DISC-SHAPED THYLAKOIDS POSSESS AN INTERIOR SPACE. THE THYLAKOIDS ARE STACKED TO FORM GRANA, WHICH ARE SUSPENDED IN THE STROMA OF THE CHLOROPLASTS. DEMONSTRATE YOUR KNOWLEDGE OF CHLOROPLAST STRUCTURE BY PLACING THE LABELS IN THEIR CORRECT LOCATIONS.