BIOL 3305 Study Guide - Spring 2018, Comprehensive Midterm Notes - Protein, Dna, Oxygen
BIOL 3305
MIDTERM EXAM
STUDY GUIDE
Fall 2018
o Cell Crawling.
Cell moving on its own, amoeboid movement is an example and
another example is phagocytosis.
Lamella podium, large plate-like projection.
Filapoida, small plate-like projection.
Basic process relies on actin polymerization.
Initial projection is achieved by actin polymerization.
Actin filaments grow, give protrusion, anchor and cell body gets
pulled in utilizing motor proteins. Initial part relies on
polymerization.
o Design an experiment to determine whether vesicle movement in a cell relies on
myosin or kinesin motor proteins. Briefly describe the experimental approach that
would be taken, the rationale for this experimental approach, and the expected
results.
o Myosin only walks on microfilaments, get rid of them, and movement
stops, it had to be on microfilaments, but if movement continues, then it
must by kinesin. To confirm this, break down microtubules, and if it stop
then you know for sure it was kinesin.
Intermediate Filaments
o Intermediate in diameter.
o Structurally, rather different, made up of proteins that are fibrous, long
string like proteins, instead of globe like proteins.
o To build in take to fibrous proteins, wind them together, gives us a dimer,
put two dimers side by side, a protofilament. Staggered arrangement is an
intermediate filament.
o Whole range of proteins that can be used to make them. Made up of 1 to
60 proteins, one of the most common is keratin.
o Strong rope like cytoskeletal elements, not as dynamic, more stable.
o Functions reflect stability, based on structural support.
o Only found in cytoplasm of animal cells, and found in nuclear membrane
of all eukaryotes.
o Role in cytoplasm is structural.
o Example of where they are found:
o Play a structural role outside the cell, like the slime in hagfish.
o Lacks jaws.
o Hagfish, when disturbed, produce large quantities of slime. Can drown
themselves in there own slime. Purpose of the slime, its though to be anti-
predator mechanism.
o What’s interesting about slime, it is a mix of proteins. Two different
components, glycoproteins and intermediate filaments.
o Slime glands all down length of fish, one cell produces glycoproteins, and
the other type of cell releases a wound up intermediate filament. When the
hagfish releases slime, intermediate bundle released with glycoproteins.
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Mix with seawater and smashing of fish, and intermediate filaments mix
with glycoproteins and produce slime.
AP.PNP is a non-hydrolysable analogue of ATP (modification of the phosphate groups
prevents ATP from being hydrolyzed to ADP). How would use of AP.PNO in a cell
affect…
a) Microfilaments?
a. Actin binds ATP, when ATP bound, polymerize to form
microfilaments, cannot hydrolyze, microfilaments will not break
down. Effect is to stabilize microfilaments in the cell.
b) Microtubules?
a. No effect, nucleotide is GTP.
c) Intermediate Filaments?
a. No effect, don’t bind any nucleotide.
d) Motor Proteins?
a. Motor proteins hydrolyze ATP for energy to move, everything
would grind to a halt.
Pop Quiz
1- Distinguish among actin, tubulin, and keratin.
a. Keratin found in intermediate filaments, and actin is found in microfilaments and
tubulin is found in microtubules. Globular actin molecules; two tubulin building
blocks form microtubules and is globular; and keratin is a fibrous protein.
2- What is the crossbridge cycle and why does it matter?
a. The cycle refers to myosin motor protein in muscle. Refers to the motor protein cycle
of myosin. Refers to myosin in muscle reaching out from thick filament to walk along
thing filament. It matters because without it muscles do not contract.
3- What is the sliding filament model and why does it matter?
a. Bigger scale, looking at level of sarcomere, instead of individual myosin molecule.
Refers to actin microfilaments sliding over myosin thick filaments. Because of sliding
filaments, sarcomere shrinks. Z lines pulled in towards into the middle.
4- What structural features of MFs and MTs contribute to their dynamic nature? Why is this
dynamic nature important to their function?
a. Made up of small units, and held together by non-covalent interactions. Proteins are
held together by non-covalent bonds, allowing them to be dynamic. What causes them
to break down, the hydrolysis of the nucleotide that is bounded to them. When it is
hydrolyzed, changes shape of building block so it can no longer stay attached.
Formation of mitotic spindle, must be built up and removed again, and also the actin
and myosin contraction that pinches off the two cells. Need to put highways where
you want things to go. Cell gliding/crawling.
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