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56 Cards in this Set

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What is an ORGANELLE?
Subcellular structure find in the CYTOSOL of the the cell.
What are the two types of ELECTRON MICROSCOPE?
1. SCANNING ELECTRON MICROSCOPE (SEM) - used for the detailed study of the surface of a specimen.
2. TRANSMISSION ELECTRON MICROSCOPE (TEM) - used mainly for the study of the internal structure of the cell.
What is CYTOLOGY?
The study of a cell's structure
What is CELL FRACTIONATION?
To take a cell apart and seperate the major organelles from one another. (Usually done with a centrifuge.)
What are the basic features common to all cells?
- All bounded by a membrane (called a PLASMA MEMBRANE)
- CYTOSOL (semifluid substance within the membrane)
- All cells have CHROMOSOMES (carrying genes in the form of DNA)
- RIBOSOMES - tiny organelles that make proteins according to instructions from the genes.
What is the major difference between PROKARYOTIC and EUROKARYOTIC cells?
Chromosomes of a eukaryotic cell are located in a membrane-enclosed organelle called the NUCLEUS.
Where is DNA found in a PROKARYOTIC cell?
Concentrated in a region called the NUCLEOID (though it is not enclosed by a membrane.
What is the NUCLEAR LAMINA?
A netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope.
Where are CHROMOSOMES found?
In the nucleus.
- Chromosomes carry genetic information.
- Chromosomes are made up of material called CHROMATIN (a complex of proteins and DNA).
What is the NUCLEOLUS?
A prominent structure within the non-dividing nucleus.
- Here a special type of RNA called ribosomal RNA (rRNA) is synthesized from instructions in the DNA.
- Proteins imported from the cytoplasm are assembled with the rRNA into large nd small ribosomal subunits in the nucleolus.
What is a RIBOSOME?
The organelles that carry out protein synthesis.
- Free Ribosomes float free in the cytosol
- Bound Ribosomes are attached to the outside of the Endoplasmic Reticulum.
What is the difference between FREE and BOUND Ribosomes?
Free - Most proteins made on free ribosomes function within the cytosol (eg. enzymes that catalyse the first steps of sugar breakdown.)
- Bound: generally make proteins that are desined either for insertion into membranes, for packaging within certain organelles such as lysosomes or for export from the cell (secretion).
What is the ENDOMEMBRANE SYSTEM?
Different membranes that make up the Eukaryotic cell.
What components of a cell are included in the ENDOMEMBRANE SYSTEM?
Nuclear envelope; edoplasmic reticulum; Golgi apparatus; lysosomes, various kinds of vacuoles and the plasma membrane.
What is the ENDOPLASMIC RETICULUM?
An extensive network of membranes that seperates the internal compartment of the ER, caled the ER lumen or cisternal space, from the cytosol.
What composes the ENDOPLASMIC RETICULUM?
SMOOTH ER: so named because it's outer surface lacks ribosomes
ROUGH ER: has ribosomes that stud the outer surface of the membrane.
What is the role of the SMOOTH ER?
Important to the synthesis of lipids, including oils, phospholipids and steroids.
- Enzymes help detoxify drugs and poisons, especially in the liver cells.
- Stores calcium ions
What is the role of the ROUGH ER?
Protein secretion produced by ribsomes attached to the rough ER.
- Also the membrane factory for the cell
What is the GOLGI APPARATUS?
We can think of it as the center of manfacturing, warehousing, sorting and shipping.
- Products of the ER are odified and stored and then sent to other destinations.
- Especialy extensive in cells specialized for secretion.
What is a GLYCOPROTEIN?
A secretory proteins. (Have carbohydrates covalently bonded to them.)
- Found in the ER.
What composes the ENDOPLASMIC RETICULUM?
SMOOTH ER: so named because it's outer surface lacks ribosomes
ROUGH ER: has ribosomes that stud the outer surface of the membrane.
What is the role of the SMOOTH ER?
Important to the synthesis of lipids, including oils, phospholipids and steroids.
- Enzymes help detoxify drugs and poisons, especially in the liver cells.
- Stores calcium ions
What is the role of the ROUGH ER?
Protein secretion produced by ribsomes attached to the rough ER.
- Also the membrane factory for the cell
What is the GOLGI APPARATUS?
We can think of it as the center of manfacturing, warehousing, sorting and shipping.
- Products of the ER are odified and stored and then sent to other destinations.
- Especialy extensive in cells specialized for secretion.
What is a GLYCOPROTEIN?
A secretory proteins. (Have carbohydrates covalently bonded to them.)
- Found in the ER.
Describe the path of a product from the ER to the Golgi appartus.
Product protein:
- arrives on the CIS face (recieving end)
- usual modified as it travels to the TRANS end (shipping side)
- proteins are usually transported to the plasma membrane for secretion.
What is a LYSOSOME?
A membranous sac of hydrolytic enzymes that an animal cell uses to digest all kinds of macromolecules. (Carry out intracellular digestion.)
- lysomal enzymes work best in the acidic environment found in lysosomes.
What is PHAGOCYTOSIS?
The process of whereby amoebas and other protists eat by engulfing smaller organisms or other food particles.
What is AUTOPHAGY?
The process by which lysosomes use their hydrolytic enzymes to reyclce the cell's own organic material.
What is a VACUOLE?
Membrane sac that plays a role in intracellular disgestion and the release of cellular waste products.
- In the plant cell, the central vacuoleis usually the largest compartment.
What is a TONOPLAST?
The membrane that encloses the large, central vacuole in a plant cell.
How important is the VACUOLE to a plant cell?
Extremely. Plant cells enlarge as their vacuoles absorb water, enabling the cell to become larger with a minimal investment in the new cytoplasm.
What is a MITOCHONDRIA?
- Sites of cellular respiration
- Sites of the metabolic process that generates ATP by extracting energy from sugar, fats and other fuels with the help of oxygen.
What are CHLOROPLASTS?
Found only in plants and algae, are the sites of photosynthesis.
- contain the green pigment chlorophyll, along with enzymes and other molecules that function in the photosynthetic production of sugar.
Are MITOCHONDRIA and CHLOROPLASTS part of the endomembrane system?
In contrast to the organelles of the endomembrane system, these organelles have at least two membranes separating the innermost space from the cytosol.
- additionally, the contain DNA that prgorams the synthesis of the proteins made onthe organelle's own ribsomes
What is a PLASTID?
e.g. The Chloroplast is a specializd member of a family of closely related plant organelles.
What is a PEROXISOME?
A specialized metabolic compartment bounded by a single membrane.
- they contain enyzmes that transfer H from various substrates to O, producing Hydrogen peroxide.
What is the CYTOSKELETON?
Network of fibers extending throughout the cytoplasm.
- Gives mechanical support to the cell and helps maintain its shape
- Plays a major role in organizing the structures ad activities of the cell
- Composed of microtubules microfilaments and intermediate filaments.
- Can be disassembled and reassembled to change the shape of the cell
Is the CYTOSKELETON more important in plant or animal cells?
Animal cells b/c they lack walls.
What is CELL MOTILITY?
Encompasses bot changes in cell location and more limited movements of parts of the cell.
- Requires the interaction of the cytoskeleton with proteins called MOTOR PROTEINS
What is the function of the MICROTUBULES?
- Thickest component of the cytoskeleton
- They shape and support the cell
- Serve as tracks along which organelles equipped with motor proteins can move
- Responsible for the separation of chromosomes during cell division
- Act as compression-resisting girders of the cytoskeleton
- provide support to the motion of CILIA and FLAGELLA
What is the CENTROSOME?
A region often locatd near the nucleus that is considered to be a "microtubule-organizing center"
What are CENTRIOLES?
Found in the centrosome of the animal cell, each is composed of nine sets of triplet microtubules arranged in a ring
- Before a cell divides, centrioles replicate
Do plant cells have CENTROSOMES/CENTRIOLES?
- Both have centrosomes
- Plant cells do not have centrioles
What is a DYNEIN?
Dynein arms are responsible for he bending movements of cilia and flagella.
- Motor protein
- Performs a complex cycle of movements caused by changes in the conformation of the protein with ATP providing the energy for these changes. (Like a cat walking along along the branch of a tree.)
Provide info on a MICROFILAMENT.
- also called ACTIN filaments
- appear to be present in all eukaryotic cells
- role is to bear tension (pulling forces) between the microtubules
- form a 3-D network inside the plasma membrane that helps support the cells shape
- known for their role in cell molility
What is a PSEUDOPODIA?
Assist in the movement of amoeba
What is MYOSIN?
Motor protein that help with the movement of microfilaments
What are INTERMEDIATE FILAMENTS?
- Also specialized for bearing tension
- Larger than microfilament but smaller than microtubules
- more permanent fixtures in cells than microtubules or microfilaments
- they assist with the anchoring of the nucleus
What is PLASMODESMATA?
Perferations found in the walls of plant cells through which cytosol passes to connect to the chemical environment of adjacent cells.
What is SELECTIVE PERMEABILITY?
The plasma membrane allows some membranes to cross it more easily than others.
What are the staple ingredients of the plama membrane?
- Lipids and proteins
- To a lesser extent, carbohydrates
What is the most abundant lipid in the plasma membrane?
Phosopholipids
What is AMPHIPATHIC?
A phosopholipid is amphipatic in that it has both hydrophilic and hydrophobic regions.
What is an INTEGRAL PROTEIN?
A protein that pentrates th hydrophobic core of the lipid bilayer.
- Many can be transmembrane prtoein, which completely span the membane
What is a GLYCOLIPID?
A carbohydrate that is covalently bonded to lipids (e.g. to phospholipids in the plasma membrane layer)