bio 2100 final exam with verified correct
answers
explain |how |it |was |discovered |that |secreted |proteins |move |from |ER |to |Golgi |to |outside |the |cell |- |
correct |answer |-Pulse |chase |experiment |
-to |track |proteins |and |they |movement
-treat |living |cells |in |cultures |with |radioactive |amino |acids
-in |the |presence |of |the |radioactive |amino |acids |the |proteins |would |incorporate |those |and |become |
radioactive
-the |time |is |referred |to |the |pulse |(often |kind |of |short=10-15 |mins)-the |chase |is |the |time |after |the |
pulse |when |the |cells |continue |to |do |their |thing |(synthesize |proteins) |in |the |absence |of |further |
labeling
-following |the |usle |the |radioactive |(amino |acid) |label |is |washed |out |and |flooded |with |nonradioactive |
amino |acids
-the |tine |of |the |chase |showed |where |the |radioactive |protein |was |(showed |the |movement |in |the |
secretory |route)
-longest |chase: |labeled |proteins |getting |to |the |plasma |membrane |and |leaving |the |cells
-ER |to |Golgi |to |plasma |membrane |to |out
explain |what |an |"autoradiogram" |is |- |correct |answer |-An |image |on |a |piece |of |X-ray |film |that |is |
produced |as |a |consequence |of |exposure |to |a |radioactive |substance. |For |example, |the |banding |pattern
|from |an |electrophoresis |gel |containing |fragments |of |radioactively |labelled |DNA
A |technique |using |X- |ray |film |to |visualize |molecules |or |fragments |of |molecules |that |have |been |
radioactively |labeled.
allosteric |regulation |- |correct |answer |-In |allosteric |regulation, |a |small |molecule |binds |to |a |large |
protein |and |causes |it |to |change |its |shape |and |activity.
explain |how |secretory |and |non-secretory |proteins |differ |as |well |as |what |they |have |in |common |- |
correct |answer |-non-secretory:
| -microsomes |do |not |protein |globin |from |the |protease
,-non |secretory |proteins |like |globin |are |not |cotranslationally |translated
-Globin/ |non |secretory
-microsomes |do |not |protein |globin |from |the |protease
-non |secretory |proteins |like |globin |are |not |cotranslationally |translocated
-not |moved |across |the |membrane |into |a |compartment
-protease |is |going |to |cut |it |up |(not |protected)
secretory:
-the |signal |peptidase |(the |pink |scissors)
-susceptible |to |protease |but |protected |by |microsomes
-secretory |proteins |do |undergo |cotranslational |translation
-light |chains |
-there |is |something |associated |with |the |microsomes |that |is |trimming |the |light |chain: |it |is |the |signal |
peptidase |(the |pink |scissors) |(a |natural |protease |that |existents |in |the |ER |lumen |and |therefore |also |
the |microsomes)
-susceptible |to |protease |but |protected |by |microsomes
-secretory |proteins |do |undergo |cotranslational |translocated
In |common: |
they |both |start |their |translation |on |free |polyribosomes |but |the |secretory |contain |a |signal |peptide |
that |targets |them |to |the |ER
cotranslational |translocation |- |correct |answer |-proteins |are |translocated |into |the |ER |during |their |
synthesis |on |membrane-bound |ribosomes
Cotranslational |translocation |occurs |when |membrane-bound |ribosomes |insert |growing |nascent |
polypeptide |chains |directly |into |an |ER |translocation |pore. |The |targeting |of |cytoplasmic |ribosomes |
translating |signal |sequence-containing |polypeptides |to |the |ER |is |mediated |by |the |signal |recognition |
particle |(SRP).
, SRP |(signal |recognition |particle) |- |correct |answer |-a |protein-RNA |complex |that |recognizes |a |signal |
peptide |as |it |emerges |from |a |ribosome |and |helps |direct |the |ribosome |to |the |endoplasmic |reticulum |
by |binding |to |a |receptor |protein |on |the |ER
-When |this |sequence |sticks |out |of |the |ribosome, |it's |recognized |by |a |protein |complex |called |the |
signal-recognition |particle |(SRP), |which |takes |the |ribosome |to |the |ER. |There, |the |ribosome |feeds |its |
amino |acid |chain |into |the |ER |lumen |(interior) |as |it's |made.
--how |we |can |separate |proteins |by |electrophoresis
-an |electrical |field |where |molecules |are |moving |towards |the |positive |control
-small |molecules |move |more |rapidly |than |larger |ones |and |that |means |things |are |separated |by |size
signal |peptides |- |correct |answer |--cuts |off |the |signal |
-how |we |know |that |secretory |proteins |(unlike |non |secretory) |have |at |their |amino |terminal |a |
hydrophobic |sequence |of |amino |acids |that |makes |sure |that |proteins |complete |their |synthesis |on |
rough |ER |rather |than |free |polyribosomes |and |that |the |polypeptide |is |cotranslationally |translocated |
into |the |ER |lumen |and |the |signal |is |cut |off |by |a |signal |called |signal |peptidase
-determines |the |secretory |from |the |non |secretory |proteins
-a |signal |which |is |a |stretch |of |hydrophobic |amino |acids |at |the |amino |terminal |end |of |the |polypeptide |
of |secretory |proteins |(only) |is |the |signal |that |makes |sure |that |these |proteins |complete |their |synthesis
|on |rough |ER |rather |than |completing |their |synthesis |on |a |free |polyribosome; |the |signal |is |recognized |
by |the |SRP |that |ensures |that |the |translation |continues |on |the |ER |membrane |and |that |the |polypeptide
|is |part |or |all |moved |across |the |ER |membrane |into |the |lumen |where |the |signal |is |cut |off |by |a |signal |
peptidase
-the |light |chain |has |the |amino |terminal |hydropic |signal |sequence |because |its |secretory
explain |the |synthesis |of |secretory |proteins |including |the |roles |of |the |signal |peptide |discovered |by |
Blobel, |the |SRP, |and |signal |peptidase |- |correct |answer |--Cotranslational |translocation: |the |movement |
of |polypeptides |across |a |membrane |into |the |ER |lumen |while |they |are |being |synthesized |(wanted |to |
do |this |in |a |cell |free |system
-he |used |microsomes |(ER) |(they |start |in |the |ER) |derived |from |broken |cells |are |essentially |equivalent |
to |ER
-of |crucial |important |to |Brobel's |discoveries |microsomes |contain |signal |peptidase
-we |are |looking |at |two |different |proteins:
answers
explain |how |it |was |discovered |that |secreted |proteins |move |from |ER |to |Golgi |to |outside |the |cell |- |
correct |answer |-Pulse |chase |experiment |
-to |track |proteins |and |they |movement
-treat |living |cells |in |cultures |with |radioactive |amino |acids
-in |the |presence |of |the |radioactive |amino |acids |the |proteins |would |incorporate |those |and |become |
radioactive
-the |time |is |referred |to |the |pulse |(often |kind |of |short=10-15 |mins)-the |chase |is |the |time |after |the |
pulse |when |the |cells |continue |to |do |their |thing |(synthesize |proteins) |in |the |absence |of |further |
labeling
-following |the |usle |the |radioactive |(amino |acid) |label |is |washed |out |and |flooded |with |nonradioactive |
amino |acids
-the |tine |of |the |chase |showed |where |the |radioactive |protein |was |(showed |the |movement |in |the |
secretory |route)
-longest |chase: |labeled |proteins |getting |to |the |plasma |membrane |and |leaving |the |cells
-ER |to |Golgi |to |plasma |membrane |to |out
explain |what |an |"autoradiogram" |is |- |correct |answer |-An |image |on |a |piece |of |X-ray |film |that |is |
produced |as |a |consequence |of |exposure |to |a |radioactive |substance. |For |example, |the |banding |pattern
|from |an |electrophoresis |gel |containing |fragments |of |radioactively |labelled |DNA
A |technique |using |X- |ray |film |to |visualize |molecules |or |fragments |of |molecules |that |have |been |
radioactively |labeled.
allosteric |regulation |- |correct |answer |-In |allosteric |regulation, |a |small |molecule |binds |to |a |large |
protein |and |causes |it |to |change |its |shape |and |activity.
explain |how |secretory |and |non-secretory |proteins |differ |as |well |as |what |they |have |in |common |- |
correct |answer |-non-secretory:
| -microsomes |do |not |protein |globin |from |the |protease
,-non |secretory |proteins |like |globin |are |not |cotranslationally |translated
-Globin/ |non |secretory
-microsomes |do |not |protein |globin |from |the |protease
-non |secretory |proteins |like |globin |are |not |cotranslationally |translocated
-not |moved |across |the |membrane |into |a |compartment
-protease |is |going |to |cut |it |up |(not |protected)
secretory:
-the |signal |peptidase |(the |pink |scissors)
-susceptible |to |protease |but |protected |by |microsomes
-secretory |proteins |do |undergo |cotranslational |translation
-light |chains |
-there |is |something |associated |with |the |microsomes |that |is |trimming |the |light |chain: |it |is |the |signal |
peptidase |(the |pink |scissors) |(a |natural |protease |that |existents |in |the |ER |lumen |and |therefore |also |
the |microsomes)
-susceptible |to |protease |but |protected |by |microsomes
-secretory |proteins |do |undergo |cotranslational |translocated
In |common: |
they |both |start |their |translation |on |free |polyribosomes |but |the |secretory |contain |a |signal |peptide |
that |targets |them |to |the |ER
cotranslational |translocation |- |correct |answer |-proteins |are |translocated |into |the |ER |during |their |
synthesis |on |membrane-bound |ribosomes
Cotranslational |translocation |occurs |when |membrane-bound |ribosomes |insert |growing |nascent |
polypeptide |chains |directly |into |an |ER |translocation |pore. |The |targeting |of |cytoplasmic |ribosomes |
translating |signal |sequence-containing |polypeptides |to |the |ER |is |mediated |by |the |signal |recognition |
particle |(SRP).
, SRP |(signal |recognition |particle) |- |correct |answer |-a |protein-RNA |complex |that |recognizes |a |signal |
peptide |as |it |emerges |from |a |ribosome |and |helps |direct |the |ribosome |to |the |endoplasmic |reticulum |
by |binding |to |a |receptor |protein |on |the |ER
-When |this |sequence |sticks |out |of |the |ribosome, |it's |recognized |by |a |protein |complex |called |the |
signal-recognition |particle |(SRP), |which |takes |the |ribosome |to |the |ER. |There, |the |ribosome |feeds |its |
amino |acid |chain |into |the |ER |lumen |(interior) |as |it's |made.
--how |we |can |separate |proteins |by |electrophoresis
-an |electrical |field |where |molecules |are |moving |towards |the |positive |control
-small |molecules |move |more |rapidly |than |larger |ones |and |that |means |things |are |separated |by |size
signal |peptides |- |correct |answer |--cuts |off |the |signal |
-how |we |know |that |secretory |proteins |(unlike |non |secretory) |have |at |their |amino |terminal |a |
hydrophobic |sequence |of |amino |acids |that |makes |sure |that |proteins |complete |their |synthesis |on |
rough |ER |rather |than |free |polyribosomes |and |that |the |polypeptide |is |cotranslationally |translocated |
into |the |ER |lumen |and |the |signal |is |cut |off |by |a |signal |called |signal |peptidase
-determines |the |secretory |from |the |non |secretory |proteins
-a |signal |which |is |a |stretch |of |hydrophobic |amino |acids |at |the |amino |terminal |end |of |the |polypeptide |
of |secretory |proteins |(only) |is |the |signal |that |makes |sure |that |these |proteins |complete |their |synthesis
|on |rough |ER |rather |than |completing |their |synthesis |on |a |free |polyribosome; |the |signal |is |recognized |
by |the |SRP |that |ensures |that |the |translation |continues |on |the |ER |membrane |and |that |the |polypeptide
|is |part |or |all |moved |across |the |ER |membrane |into |the |lumen |where |the |signal |is |cut |off |by |a |signal |
peptidase
-the |light |chain |has |the |amino |terminal |hydropic |signal |sequence |because |its |secretory
explain |the |synthesis |of |secretory |proteins |including |the |roles |of |the |signal |peptide |discovered |by |
Blobel, |the |SRP, |and |signal |peptidase |- |correct |answer |--Cotranslational |translocation: |the |movement |
of |polypeptides |across |a |membrane |into |the |ER |lumen |while |they |are |being |synthesized |(wanted |to |
do |this |in |a |cell |free |system
-he |used |microsomes |(ER) |(they |start |in |the |ER) |derived |from |broken |cells |are |essentially |equivalent |
to |ER
-of |crucial |important |to |Brobel's |discoveries |microsomes |contain |signal |peptidase
-we |are |looking |at |two |different |proteins:
