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69 Cards in this Set

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Proteins that have crossed a membrane are no longer topologically inside the cell and must ___ to get back inside
recross the membrane
____ move from compartment to compartment within a cell by ____ and _____
Vesicles
budding off
membrane fusion
Many proteins have ____ at their amino terminus that direct ____ to cross the membrane.
signal sequences

proteins
T/F

Many proteins have internal signal sequences
FALSE
Larger proteins pass through _____ by an ___ process
nucear pores

active
______ bind to _____ found on many nuclear bound proteins and facilitate transport into nucleus.
Nuclear import receptors

nuclear transport signals
It generally requires multiple signals to transport proteins from the cytosol into the ___ of the _____
lumen

mitochondria
There are multiple _____ in the mitochondrial membrane and each interacts with a specific set of proteins
protein translocators
T/F Protein transport into mitochondria requires energy
True
Proteins enter ____ using a mechanism similar to mitochondrial entry
peroxisomes
Proteins travel thru the ____ to many sites
ER
Translocation across the ER membrane requires a ____ that binds to the _____ on the nascent peptide chain
signal recognition protein (SRP)

signal sequence
The SRP signal sequence direct the ____ to the ER membrane
ribosome
The coupling of ___ and____ allows transport across th ER membrane without andy additional energy
translation and translocation
T/f
Most proteins are glycosylated in the mitochondria
False

they are glycosylated in the ER
Vesicles budding off the ____ are coated with molecules that direct them to specific locations in the cell
ER
Integral membrane proteins that facilitate membrane fusion
Snares
proteins that facilitate docking of transport vesicles to specific locations
Rab Proteins
___ proteins are recruited into specific transport vesicles by ___ receptors
cargo

cargo
Different areas of the ___ (compartments) have different processing proteins
Golgi
T/F

stacks within the golgi are connected
true
proteins destined for the _____ pass through the ____
lysosomes

golgi
Lysosomal proteins are glycosylated with ______-containing polysaccharide thats recognized by a ___ in golgi
mannose-6-phosphate

lysosomal specific receptor
2 pathways for transport of proteins through golgi to outside of cell?
1)constitutive secretory pathway

2)regulated secretory pathway
____ secretory pathway results in a constant level of secretion of the protein
constitutive
____ secretory pathway releases proteins to outside of cell in response to external stimuli
regulated
The ____ pathway to the outside of cell is the default pathway unless there are signals directing it to another pathway
constitutive
Lipid synthesis occurs on the ____ side of the ____
cytosolic

ER membrane
T/F

There are fewmechanisms that transport newly made lipids to their final destinations
False

there are many pathways
DNA and RNA are polymers of the monomeric unit ____
nucleotides
Each nucleotide is made of 3 components
Sugar
Base
Phosphate
DNA and RNA differ at __' carbon on the sugar how?
RNA has a hydroxyl group on the 2' carbon (ribose) and DNA (deoxyribose) does not
T/F
RNA cannot form double strands
False.
Although RNA can form double strands it is usually single stranded in cells
Each double stranded DNA molecule has ___ potential open reading frames
6
____ can catalyze its own modification (splicing)
RNA
6 functions of RNA
1)coding for proteins
2)ribosomes as structural
3)adaptor btwn mRNA and AA
4)signaling molecules
5) genetic info storage
6) gene expression modulator
2 processes that cells acquire nucleotides
de novo synthesis

salvage pathways
____ synthesis of ____ results in synthesis of ____ that can be converted into ___ and ____
De novo
purines
inosine
adenosine and guanosine
atoms in newly made purines come from:
aspartate
glutamine
glycine
methyl groups from folic acid
methyl groups from CO2
___ and ___ regulate de novo synthesis of purines at multiple points in the pathway
ADP

GDP
Hypoxanthine guanine phosphoribosyl transferase (HGPRT) does what?
recycles hypoanthine and guanine through the salvage pathway
___ catalyzes ahydroxylase reaction leading to __ formation that can be exreted
Xanthine oxidase
uric acid
Excess ___ is the cause of gout
uric acid
Gout is most often caused by low ____ secretion but can also be caused by excess productions
uric acid
Crystallization of _____ in the joints leads to a localized inflammatory response
Sodium urate
____ is a ___ analog used to treat gout. It inhibits ____ thus preventing uric acid formation
allopurinol
xanthine oxidase
HGPRT deficiency causes ____ that results in severe retardation, crippling gouty arthritis and self-mutilation
Lesch-Nyhan syndrome
The breakdown of ___ can replenish the TCA cycle intermediates through ___ production
purine

fumarate
The atoms in the pyrimidine ring are derived from ____ and ____
aspartate

carbamoyl phosphate
The first 3 enzymes for ____ synthesis are located on the same protein (CAD protein)
pyrimidine
dUMP is converted to TMP by ____, an enzyme requiring the transfer of a methyl group from____
thymidylate, synthase

tetrahydrofolate
Inhibitors of ____ are used as therapeutic agents for treating cancer and bacterial infections
tetrahydrofolate production
____ substituted pyrimidine analogs that inhibit ____ are used as anticancer agents
fluro

thymidylate synthase
____ converts ribonucleotides to deoxyribonucleotides at the ____ level (NDP to dNDPs)
ribonucleotide reductase

diphosphate
Cellular signal transduction cassettes detect, amplify and integrate external signals made of ____ (3)
-specific cell surface membrane receptors
-effector signaling elements
-regulatory proteins
Cellular signal transduction cassetes use these steps:
1-make signal molecule (ligand)
2-release signal mol.
3-move signal mol. to target cell
4-ligand bind to spec. receptor protein (conf change)
5-change in metab, func, devt of cell
6-ligand removal and degrade
____ are chem. messengers made by ___ cells that are secreted into blood and affect gene expression & protein synth
hormones

endocrine
auocrine vs paracrine?
autocrine act on same cell that secreted them

paracrine act on other cells
4 types of hormones?
steroids
amine (AA derived)
peptide
polypeptide
3 cholesterol precursors for steroid hormones?
corticosteroids
androgens
estrogens
Steroid hormones
1-immediately diffuse out of __ into __
2-__ soluble
3-__ receptors are_target cell
4-__acting/__half-life than peptide hormones
1-endocrine cells ; bloodstream
2-lipid (can cross cell-membran)
3-intracellular (cytoplasmic); in
4-slower ; longer
Amine hormones
1)__ or __ derived
2)stored in __ until secreted
3)receptor has 2 locations:__
1)tyrosine or tryptophan
2)endocrine cell
3)on cell surface or intracellular
Polypeptide Hormones
1) __ enter blood
2) __ soluble
3)called __ and bind to __
4)intracell. affects mediated by __ that have __MW (examples __ or __)
1) do not immediately
2)water-don't pass membrane
3)1st messengers;extern. receptors
4)2nd messengers;low;cAMp or Ca 2+
G-Protein Coupled Receptors
1)__ proteins (extracell. __ terminus)
2)__transmembrne a-helices
3)_extra&intracell. loops 3rd_
4)__cellular C-terminus
5)no intrinsic __
6)G-protein activates __
-activates __ in __(signal cascade)
-__ inactivates __(kills cell response
-specificity by ___ that contains __ and __
1)integral membrane; N-terminus
2) 7; (ligan binds to pocket)
3)3;3rd intracell. recruits g-prot.
4)intra
5)catalytic domains
6)adenylyl cyclase (ATP to cAMP)
-protein kinases; cytosol
-phosphodiesterase;cAMP
-a-subunit;GTP-bind site;GTPase activity
Adenylyl cyclase activated by_

Each molecule of bound hormone can stimulate many __ that amplify original signal
- a-subunit of G-protein

- a-subunits
2 bacterial toxins that target G-proteins by ADP ribosylating a-subunit of G-protein):
1- Cholera toxin-increase in cAMP within intesintal epith. causes phosphorylation of Cl- channels (diarrrheaa)

2-pertussis toxin- inc. cAMP and inhibits neutrophil function
Ion-Channel receptors
-__ changes receptor shape and allows __ to flow thru channel

-__ affects ion-channels by preventing acetylch. release & cleaves proteins involving neurotransmitt docking vesicls.
ligand binding; K+ and Na+

botulism toxin
Tyrosine kinase-linkd receptors
-no intrinsic __
-ligand binding forms __ that activates __ that __ downstream targets(signal cascade)
-enzyme activity

-dimer; tyrosine kinase; phosphorylate
Intrinsic Enzyme Activity Receptors

-__-triggered protein kinases
-similar to __ b/c __
-__complex directly acts as__by __
ligand
tyrosine-linked receptors; forms dimers upon ligand binding
-ligand/receptor;tyrosine kinase; phosphorylating other kinases