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What is the size of an animal cell?
20 micrometers
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What is the size of a bacterium?
1 micrometer
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What is the main factor of resolution for microscopes?
wavelength
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Describe how green fluorescent protein can be used in fluorescence microscopy. (3 answers)
- All for live cells
- Insert gene into target cells, follow fate of cells (eg in embryo)
- - Attach gene to another gene (chimaera). Follow location
- - Attach gene to DNA regulatory sequence. Follow timing of expression
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What methods can be used to make cells fluorescent?
- 1. Use of fluorescent ion chelators
- 2. Use of antibodies
- 3. Use green fluorescent protein
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Describe how using antibodies can make a cell fluorescent.
- - Antigen with multiple epitopes (bumps)
- - primary antibody (rabbit vs antigen)
- - secondary antibody (goat vs rabbit) fluorescently tagged
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What is the function of ribosomes?
- "Protein synthesis machines"
- (Composed of ribosomal RNA and protein subunits)
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What are the characteristics and function of the nucleus?
- Diameter 5 - 10 microns
- Double membrane
- Carries most genomic information
- Site of RNA synthesis (transcription)
- Site of ribosome synthesis
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What is heterochromatin and what does it mean?
- - Densely stained areas
- - tightly packed
- - low transcriptional activity
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What is euchromatin and what does it mean?
- - light stained areas
- - loosely packed
- - high transcriptional activity
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Where does protein synthesis start?
in the cytoplasm
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What is the structure and function of the RER?
- - continuous with nuclear outer membrane
- - active ribosomes attached to membrane
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What is the function of the transport vesicles?
Bud off ER and travel through the cytoplasm to the golgi apparatus
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What are the different protein processing events that happen in the golgi?
- cis face: arrival of vesicles, protein phosphorylation
- medial golgi: addition of sugar residues
- trans face: proteolysis, sorting of lipids and proteins, vesicle release
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What is the function of lysosomes?
- - contains hydrolase enzymes that break down macromolecules
- - pH of the lysosome is maintained at 5.
- the destructive enzymes are active only in an acidic environment
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What are the types of filaments of the cytoskeletons?
- microfilaments (made of actin)
- intermediate filaments (variable protein composition depending on the tissue)
- microtubules (made of tubulin)
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What is the structure and function of the mitochondrion?
- 0.5-2 microns
- variable number per cell depending on energy requirements
- small cicular genome
- double membrane
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What are the kinds of covalent bonds?
- hydrogen bonds
- ionic bonds
- van der Waals attractions
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What is a hydrogen bond?
- electropositive hydrogen is shared between 2 electronegative atoms
- very weak
- can form between backbone or side chain groups
- very short range
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What is an ionic bond?
- electrostatic bonds or salt bridges
- formed between +ve and -ve charged amino acid side chains
- less strong on the surface of the molecule as water molecules cluster around the charged side chains
- very important in an environment protected from water
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What is a van der Waals interaction?
caused by fluctuating electric charges around molecules
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What is a hydrophobic effect?
hydrophobic amino acids are buried on the inside of the molecule, protected from interaction with polar water molecules
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What are disulfide bonds?
covalent bonds formed by the oxidation of two cysteine residues. They stabilize the tertiary and/or quaternary structure of proteins.
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What is the structure of a protein?
- primary structure - order of amino acids (covalent)
- secondary structure - alpha helices, beta pleated sheets (hydrogen bonds - weak bonds)
- tertiary structure - 3D structure (weak bonds)
- quaternary structure - multiple subunits (weak bonds)
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What are the most abundant types of collagen and where are they located?
- Type I (composed of two alpha 1 and one alpha 2 genes) - located in tendon, bone and dermis
- Type IV - located in the basement membranes
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What is the structure of collagen?
- Triple helix is formed by three alpha chains
- Repeating Gly-X-Y structure
- Essential that every 3rd residue is a Gly
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What are the characteristics and function of membranes?
- 2 molecules thick
- hydrophobic interior
- self-organizing and self-healing
- serve to partition aqueous compartments
- permeable to water by not ions
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What is a lipid bilayer composition?
- cholesterol
- phospholipid
- glycolipids
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What is entropy?
Degree of disorder
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What is an exergonic reaction?
- Energy releasing
- -ve deltaG(change in free energy level)
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What is an endergonic reaction?
- Energy requireming
- +ve deltaG (change in free energy level)
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What value does a spontaneous process have for free energy change? (delta G)
negative value
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What is the link in the body between energy yielding processes and energy requiring processes?
ADP/ATP
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What is considered a proton donor?
Acid
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What is considered a proton acceptor?
base
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When is buffering effective?
at pH values +1 or -1 from a weak acids pKa
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