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CBP bock1exam2
lecture 18-35
34
Biochemistry
Professional
09/15/2010

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Term
Name the cellular property which corresponds to the electrical component
Resister
Capacitor
Conductor
Battery
Definition
Closed channel
Cell membrane
Open membrane
Membrane voltage protential
Term
What is the driving force?
Definition
DF = Vm - Ex
desire for the ion (x) to flow into or out of the cell
Term
Nernst equation?
What does it mean?
Definition
Ex = -RT/(ZxF) ln([X]i/[X]o)
means the potential of the ion is dependent on ratio of concentrations of ion (x) in log scale
Term
Which way does an inward current flow? What is it's charge?
Which way does an outward current flow? What is it's charge?
Definition
Inward = (+) into cell, negative
Outward = (+) out of cell, positive
Term
What is the resting cell's membrane potential?
What is Nernst for most cells for the following ions...
Na+
K+
Ca+2
Definition
At rest = -90mV
+67 mV
-95 mV
+123 mV
Term
What ion is the outward rectifier in the cell? What one is the inward rectifier?
Definition
K+ current
Na+ current
Term
Describe the phases of an action potential and what ion channels open and close and inactivate during?
Definition
V-gated Na+ open first and causes sharp upshoot of Vm. They inactivate immediately. Vm gets more (-) again when K+ open. They are slower to open and to close--causes hyperpolarization undershoot before Vm returns to normal. Ca+2 channels can cause plateau in AP.
Term
Define absolute and relative refractory periods.
Definition
Absolute = can't trigger another AP no matter how much stimulus.
Relative = can have another AP at extra cost to cell
Term
Describe structure of V-gated K channels
Definition
> made of 4 identical units with 6 domains in each unit that come together to make one channel.
> S4 domain is voltage sensor and has (+) lys and arg residues
> S6 makes up part of channel, size of pore matches ion. Ion will bind alpha carbonyls
> also accessory units to regulate folding/function
Term
Low Ca+2 outside makes Na+ channel opening ______ likely
and the tissues __________
It ___________ the voltage threshold
Definition
more likely
hyperexcitable
reduces
Term
Along with voltage, increasing Ca+2 inside cells will _____ probability of K+ channel opening.
Definition
increase
Term
Describe what osteoblasts and osteoclasts do in bone remodeling.
Definition
Osteoblasts build bone
Osteoclasts break it down.
Term
What is intramembranous ossification and what bones do it
Definition
Bone forms from mesenchymal cells which migrate out and spread out. No template needed. Done in flat bones.
Term
What is endochondral ossification and what bones do it.
What is primary and secondary?
Definition
Method of making bone where hyaline cartilage forms the template first which is replaced with bone. Long bones are made this way.
Primary = middle of cartilage out
Secondary = at epiphyseal plates in ends of long bones.
Term
what is woven bone?
Definition
has type III collagen, found in fetal bone and damaged healing bone. should never be found in adults or else there's a problem
Term
what is an osteocyte?
Definition
when osteoblasts seal themselves inside bone and become osteocytes.
Term
what is osteon?
Definition
also called Haversian system. consists of type I collagen concentric ringed canal formed around a blood vessel. rings run in opposite directions to make bone stronger.
compact bone.
Term
what is trabecular bone?
Definition
no osteons, arranged in trabeulae
seen in short, flat, and irregular bones
lighter and has red bone marrow
Term
Type I osteoporosis
Definition
increased osteoclast activity in postmenopausal women as result of estrogen withdrawal
Term
what 2 control loops regulate bone remodeling?
Definition
hormonal to maintain Ca+ levels
mechanical/gravitational on skeleton
Term
what is osteomalacia
Definition
vitamin D deficiency characterized by inadequeate mineralization of bone
get Rickets in kids and Osteomalacia in adults
Term
what is scurvy?
Definition
inability of osteoblasts to make collagen due to low vitamin C
Term
what happens when there's too much PTH?
Definition
too much osteoclastic activity, too much Ca+2 resorption, brittle bones, muscles hypotonic.
Term
what happens when there is too much VitD?
Definition
too much inhibition of PTH, too little Ca+2 in the blood
Term
Name the purines and pyrimidines
Definition
Purine = adenine and guanine
double ring structure
Pyrimidine = cytosine and thymine
single ring structure
Term
what is a nucleoside? nucleotide?
Definition
nucleoside = base+sugar
Nucleotide = base+sugar+phosphates
Term
what base pairing is more stable?
Definition
C-G because they have 3 H bonds
Term
Centromere =
Telomere =
Definition
> constricted region to which mitotic spindle fibers bind during mitosis and meiosis
>at the ends of chromosomes, sequences which are repeated to limit DNA shortening during replication
Term
Heterochromatin
Euchromatin
Definition
>DNA tightly wrapped around histones, not mitotic
>DNA is loose, site of active DNA replication
Term
define mutation
somatic
germline
Definition
cellularly heritable alteration in DNA sequence.
> arise in tissues not involved in gamete production
> arise in cells whose genes are carried to gametes
Term
What causes Xeroderma Pigmentosum
Definition
mutation in ability to remove DNA pyrimidine dimers.
causes freckles which are linked to skin CA
Term
Name the 4 major mechanisms of DNA repair
Definition
Nucleotide excision
Base excision
Mismatch repair
Direct repair
Term
Define homologous recombination, translocation, and transposon
Definition
homologous recombination=similar strands of dsDNA interact and exchange
translocation=exachange of large chromosomal fragments usually caused by chemical or radiation
can be reciprocal or not
transposons=discrete DNA segments which move from one location on genome to another.
Term
Define Robertsonian Translocation
Definition
translocations between 2 acrocentric chromosomes which can give single metacentric chromosome and oos of the 2 short arms.
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