MCB 104 Unit 3: Cell Biology Questions And Answers Well Illustrated.
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MCB 104 Unit 3: Cell Biology
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MCB 104 Unit 3: Cell Biology
MCB 104 Unit 3: Cell Biology Questions And Answers Well Illustrated.
What are the 3 domains? - correct answer. Bacteria, Archaea, Eukarya
What units do we measure cells in for radius and volume? - correct answer. micrometers, femtoliters
Minimum resolvable distance in: EM...
MCB 104 Unit 3: Cell Biology Questions
And Answers Well Illustrated.
What are the 3 domains? - correct answer. Bacteria, Archaea, Eukarya
What units do we measure cells in for radius and volume? - correct answer.
micrometers, femtoliters
Minimum resolvable distance in: EM, light microscopy, human eye - correct answer.
2 nm, 200 nm, 0.2 mm
resolution - correct answer. r = distance by which two closely spaced objects can be
distinguished
r and wavelength of illumination are proportional
What is empty magnification? - correct answer. increasing magnification in the
eyepiece only; the objective lens gives resolution
What is the max resolution of a light microscope? - correct answer. 200 nm
What does a light microscope use? - correct answer. phase contrast - phase shifts
due to light passing different media causes brightness changes
What is the max resolution of electron microscopy? - correct answer. ~2 nm
What is TEM and describe the procedure? - correct answer. transmission electron
microscopy;
1. fix cells
2. cut very thin sections
3. stain with heavy metals that scatter electrons to create contrast
prokaryote - correct answer. no organelles/nucleus; has compartments,
cytoskeleton, cell wall, nucleoid, inner and outer plasma membrane
fluorescence microscopy - correct answer. A fluorescent molecule (e.g. antibody -
which binds to target amino acids) is attached to a protein of interest. Use an excitation
light of known wavelength, which causes an emission light of longer wavelength (lower
energy).
,superresolution microscopy - correct answer. physical properties of fluorescent
samples are exploited using various optical and computational techniques to increase
resolution beyond the diffraction limit
What is GFP? - correct answer. green fluorescent protein; found in the jellyfish
Aequorea victoria
How crowded are cells? - correct answer. very, space between molecules = size of
molecules
What are advantages of compartmentalization of a cell? - correct answer. 1.
concentrate specific molecules
2. provide distinct microenvironments
3. sequester harmful molecules
4. enable regulation
Why do cellular lipid spontaneously form bilayers? - correct answer. entropy change
is positive when fatty acid tails pack against each other and exclude H2O molecules
Why is cholesterol important? - correct answer. membrane rigidity, precursor for
steroid hormones
What is unique about membrane composition? - correct answer. extracellular and
cytoplasmic sides each have different compositions of lipids
Where can exoplasmic faces face? - correct answer. outside the cell OR inside
vesicles/organelles
What protein structure spans membranes? - correct answer. alpha helix -
hydrophobic residues on membrane
What are the 4 types of membrane protein insertions? - correct answer. 1.
covalently attached lipid tail
2. electrostatic interaction - polar head of phospholipid (-) attracted to (+) charged
protein
3. partial insertion
4. bind to a different transmembrane protein
What are the functions of the membrane? - correct answer. 1. prevent
molecules/ions from leaking out
2. separation of charge -> membrane potential
, 3. platform for signaling complexes
pump transport protein - correct answer. absolute specificity, 100 ions/s, against
gradient -> needs energy input
carrier transport protein - correct answer. intermediate specificity, <1000 ions/s,
downhill, no energy needed
steps of signal transduction pathway - correct answer. 1. relay
2. amplify
3. integrate
4. execute
What are the fast and slow cellular responses to signals? - correct answer. slow =
altered protein synthesis (mins-hrs)
fast = altered protein function (sec-mins)
examples of ligands for cell-surface receptors - correct answer. insulin, interleukins,
ACh
examples of ligands for intracellular receptors - correct answer. testosterone,
cortisol
What is the structure of a GPCR? - correct answer. N-term outside, C-term inside, 7
transmembrane domains, large C3 loop between H5 and H6 where G-proteins interact
(also C4)
Describe the G-protein trimer. - correct answer. α and γ have lipid tails that insert in
membrane, α and βγ separate, α binds GTP/GDP
pathway involving βγ subunits - correct answer. 1. βγ subunits activate PLC
2. PLC cleaves inositol phospholipid (PIP3)
3. IP3 causes Ca2+ release from ER
4. BOTH DAG (membrane bound portion) AND Ca2+ bind and activate PKC
How is GPCR signaling terminated? - correct answer. α subunit can hydrolyze GTP;
cAMP hydrolyzed by cAMP phophodiesterase
coincidence detection - correct answer. Both DAG and Ca2+ needed to activate
PKC to prevent false signal
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