MCB 104 Unit 3: Cell Biology Exam Questions With Correct Answers
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Course
MCB 104
Institution
MCB 104
MCB 104 Unit 3: Cell Biology Exam
Questions With Correct Answers
What are the 3 domains? - answerBacteria, Archaea, Eukarya
What units do we measure cells in for radius and volume? - answermicrometers, femtoliters
Minimum resolvable distance in: EM, light microscopy, human eye - answer2 nm, 200...
MCB 104 Unit 3: Cell Biology Exam
Questions With Correct Answers
What are the 3 domains? - answer✔Bacteria, Archaea, Eukarya
What units do we measure cells in for radius and volume? - answer✔micrometers, femtoliters
Minimum resolvable distance in: EM, light microscopy, human eye - answer✔2 nm, 200 nm, 0.2 mm
resolution - answer✔r = distance by which two closely spaced objects can be distinguished
r and wavelength of illumination are proportional
What is empty magnification? - answer✔increasing magnification in the eyepiece only; the objective
lens gives resolution
What is the max resolution of a light microscope? - answer✔200 nm
What does a light microscope use? - answer✔phase contrast - phase shifts due to light passing different
media causes brightness changes
What is the max resolution of electron microscopy? - answer✔~2 nm
What is TEM and describe the procedure? - answer✔transmission electron microscopy;
1. fix cells
2. cut very thin sections
3. stain with heavy metals that scatter electrons to create contrast
prokaryote - answer✔no organelles/nucleus; has compartments, cytoskeleton, cell wall, nucleoid, inner
and outer plasma membrane
fluorescence microscopy - 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 - answer✔physical properties of fluorescent samples are exploited using
various optical and computational techniques to increase resolution beyond the diffraction limit
What is GFP? - answer✔green fluorescent protein; found in the jellyfish Aequorea victoria
How crowded are cells? - answer✔very, space between molecules = size of molecules
What are advantages of compartmentalization of a cell? - answer✔1. concentrate specific molecules
2. provide distinct microenvironments
3. sequester harmful molecules
4. enable regulation
Why do cellular lipid spontaneously form bilayers? - answer✔entropy change is positive when fatty acid
tails pack against each other and exclude H2O molecules
Why is cholesterol important? - answer✔membrane rigidity, precursor for steroid hormones
What is unique about membrane composition? - answer✔extracellular and cytoplasmic sides each have
different compositions of lipids
Where can exoplasmic faces face? - answer✔outside the cell OR inside vesicles/organelles
What protein structure spans membranes? - answer✔alpha helix - hydrophobic residues on membrane
What are the 4 types of membrane protein insertions? - 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? - answer✔1. prevent molecules/ions from leaking out
2. separation of charge -> membrane potential
3. platform for signaling complexes
pump transport protein - answer✔absolute specificity, 100 ions/s, against gradient -> needs energy
input
carrier transport protein - answer✔intermediate specificity, <1000 ions/s, downhill, no energy needed
steps of signal transduction pathway - answer✔1. relay
2. amplify
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