au13_-_biochemistry_final_exam_20141210194742 Flashcards
Proteins that have _______ a membrane are no longer topologically inside a cell. They must _______ the membrane to get back inside the cell.
crossedrecross
Vesicles move from compartment to compartment within a cell by _______ and _______
budding offmembrane fusion
Many proteins have signal sequences at their _______ that direct the proteins to _______. Fewer proteins have _______ signal sequences.
amino terminuscross the membraneinternal
The nucleus is surrounded by a _______, however _______ allow molecules, including proteins, to pass from the cytosol into the nucleus and back.
double lipid membrane bilayernuclear pores
Larger proteins pass through nuclear pores by _______.
an active process
_______ bind to _______ found on some nuclear bound proteins and facilitate transport into the nucleus.
nuclear import receptorsnuclear transport signals
It generally requires multiple signals to transport proteins from the _______ into the _______.
cytosollumen of the mitochondria
There are multiple _______ in the mitochondrial membrane. Each _______ interacts with a specific set of proteins.
protein translocatorstranslocator
Transport of protein into the mitochondria requires _______.
energy
Proteins enter _______ using a mechanism similar to _______.
peroxisomesmitochondrial entry
Proteins travel from the _______ through the _______ to many sites.
endoplasmic reticulum (ER)golgi
A _______ binds to the _______ during translation and directs the nascent peptide to _______.
signal recognition protein (SRP)signal sequenceER membrane
Proteins bound for the mitochondria are translated in _______ and then transported through the _______. This process requires _______.
cytosolmitochondrial membraneATP
Proteins that are headed into or through the ER are transported through _______ during _______. This process requires _______.
ER membranetranslationno additional energy
_______ modification of proteins in the _______ helps direct them to their ultimate location.
carbohydrateER
The “default pathway” if there are no other signals directing the protein to other locations is to send the protein to _______.
the cell surface
In _______ pathway, cells store proteins in _______ until they are signaled to release them from the cell by _______ of the vesicles with the cellular membrane.
regulated secretorysecretory vesiclesfusion
What are the major components of an animal cell?
- cytosol- mitochondria- rough and smooth ER- golgi cisternae- nucleus- peroxisomes- lysosomes- endosomes
Several factors contribute to the state of nutrition including: _______, _______, _______, _______, _______, _______, _______, and _______.
appetiteenergy expendituregenotypedigestionmetabolismavailability of foodcustomspresence of disease
_______, _______, and _______ are important regulators of food intake.
leptinghrelininsulin
_______ circulates in the body at levels proportional to _______.
leptinbody fat
_______ signals the brain that the body _______ or _______.
leptinhas had enough to eatsatiety
Adipose tissue produces _______ that regulate _______ to meet the body’s needs.
adipokinesmetabolic processes
_______ and _______ regulate _______ that senses cellular energy levels.
AMPAMP/ATPAMP-activated kinase (AMPK)
_______ regulates _______ in energy-producing and using pathways.
AMPKrate-limiting enzymes
High levels of _______ activity _______ energy-utilizing pathways and _______ energy-generating pathways.
AMPKinhibitstimulate
Increased _______ increases appetite.
ghrelin
_______ favors accumulation of _______ in the visceral fatty tissue.
ghrelinlipids
_______ for calories changes with _______ and _______. _______ requirements vary with _______ and _______.
estimated average requirements (EAR)agesexestimated daily proteinagesex
The ideal amount of calorie intake in a day is equal to _______.
the calorie utilization for that day
_______ for a nutrient is a value that is adequate for the great majority of individuals. The _______ reflects amount that is adequate for half of the population.
recommended daily allowance (RDA)estimated average requirement (EAR)
Different nutrients have different energy content. _______ has the highest energy content per weight. _______ has a high-energy content.
fatalcohol
Increases in obesity are correlated with an increase in _______.
the use of high fructose corn syrup
High fructose corn syrup is made by breaking down _______ into _______ using _______ followed by conversion to _______ with _______.
cornstarchglucoseamylasefructoseglucose isomerase
There are several potential health issues associated with consumption of high fructose corn syrup including: _______, _______, _______, _______, _______, and _______.
mercury exposurehypertensionelevated cholesterollong-term liver damageincreased risk of diabetesweight gain or obesity
Protein-calorie malnutrition causes a number of health problems including: _______, _______, _______, _______, _______, _______, _______, and _______.
decreased protein synthesis and glucose transportfatty liverliver necrosis and fibrosisdepressionhypothermiacompromised immune function and wound healingdecreased cardiac and renal functionloss of muscle
Obesity is associated with an increased risk for several conditions including: _______, _______, _______, _______, _______, _______, and several cancers including _______, _______, _______, _______, and _______.
type II diabeteshypertension and strokedyslipidemiagall stonesrespiratory disordersmusculoskeletal disordersbreastendometrialovariangall bladdercolon
_______ are not essential and provide no benefit to human health.
trans fatty acids
_______ increase levels of _______ (bad cholesterol).
saturated fatsLDL cholesterol
_______ increase levels of _______ and also lower levels of _______ (good cholesterol), thus increasing the risk of _______.
trans fatsLDLHDLcoronary heart disease
Measurements of vitamin levels in the blood relate more to _______ than to _______.
recent intakeoverall body status
_______ act as _______ in many metabolic pathways.
water-soluble vitaminscoenzymes
The body has no storage capacity for _______ except _______.
water-soluble vitaminsB12
Evidence is emerging that suggests an excess of some _______ can be toxic.
B vitamins
Most vitamins are _______ before they become _______.
modifiedactive
B vitamins are co-enzymes in different types of reactions:_______ - ______________ - ______________ - ______________ - ______________ - _______
B1 - carboxylationsB2/B3 - oxidoreductasesB6 - transaminasesbiotin - carboxylasesfolic acid/B12 - single carbon transfers
Lack of _______ causes _______.
riboflavinangular stomatitis
Eating _______ can cause a _______ deficiency.
raw egg whitesbiotin
_______ is needed, indirectly, for DNA synthesis.
folic acid
_______ are used as antibiotics (trimethoprim) and cancer therapy (methotrexate).
inhibitors of folate reduction
There is an increased demand for _______ during pregnancy.
folic acid
_______ deficiency is one of the most common vitamin deficiencies.
folic acid
The functions of _______ and _______ are interrelated.
B12folic acid
_______ is concentrated in the liver.
B12
_______ deficiency causes scurvy resulting in _______.
vitamin Cdefective collagen synthesis
Lack of _______ also impairs immune function.
vitamin C
_______ vitamins are not as readily absorbed as _______ vitamins, but can be stored in _______.
fat-solublewater-solubletissues
Some _______ vitamins (_______ and _______) can be toxic in excess.
fat-solubleAD
_______ is _______ and should be avoided during pregnancy.
vitamin Ateratogenic
_______ is a signaling molecule that interacts with _______.
retinoic acidligand-activated transcription factors
Deficiency of _______ causes night blindness.
vitamin A
_______ regulates calcium and phosphorous homeostasis.
vitamin D
The majority of _______ is produced by _______ of skin.
vitamin DUV exposure
People in northern climates have a difficult time getting sufficient _______ in the winter.
vitamin D
Deficiency of _______ causes _______ of bones with _______ susceptibility to fractures.
vitamin Ddemineralizationincreased
_______ deficiency is a link to childhood caries.
vitamin D
_______ is necessary for blood coagulation.
vitamin K
Which type of vitamin (water-soluble or fat-soluble) acts as coenzymes in many metabolic pathways?
water-soluble
Which type of vitamin (water-soluble or fat-soluble) is less readily absorbed through the diet?
fat-soluble
Which type of vitamin (water-soluble or fat-soluble) can be stored in tissues?
fat-soluble
What is the only water-soluble vitamin to be able to be stored?
vitamin B12
What is the only fat-soluble vitamin to act as a coenzyme?
vitamin K
There are close to _______ bases of the human genome, but only _______ protein-coding genes.
3 billion20,000-25,000
_______ and _______ result in 4-6 different _______ from a single gene.
alternative splicingalternative gene promotersmRNAs
The number of protein-coding mRNAs (_______) may be as large as _______.
transcriptome100,000
The original Human Genome Project used _______ and _______ approaches for sequencing.
“clone-by-clone”“shotgun”
There are _______ gaps remaining in the Human Genome (compared to _______ in draft).
250150,000
Since the completion of the human genome, sequence capacity has _______ dramatically while costs have _______.
increaseddeclined
_______ database has >10,000 entries that associate _______ with _______.
Online Mendelian Inheritance in Man (OMIM)human genesinherited diseases
_______ are mapped base positions in the genome where the _______ varies among people.
single nucleotide polymorphisms (SNPs)nucleotide
Companies (like 23 and Me) are offering _______ scans to individuals for less than $100. This analysis is based on _______.
full genomesingle nucelotide polymorphism analysis (SNP)
_______ is labeled DNA that is _______ to an array of several million _______ on chips. This can be used for _______ for early detection of _______.
chromosomal microarray analysis (CMA)hybridizedoligonucleotidesprenatal screeningchromosomal defects
_______ is the complement of mRNAs containing protein-coding sequences but there are also other RNAs produced that play _______ or _______ functions (miRNA, siRNA, etc.)
transcriptomestructuralregulatory
The _______ can be studied using _______, a collection of complementary DNA (cDNA) made from mRNA or synthetic oligonucleotides arranged on a solid phase slide in a defined order.
transcriptomemicroarrays
Generally, several _______ per gene are used.
oligonucleotide probes
Two samples can be compared by labeling each with _______ and hybridizing them to the same array (ex. two _______ arrays can compare normal and cancer cells)
a different fluorescent dyecolor
With advances in sequencing technology, _______ or sequencing the entire _______ in a sample, is rapidly replacing _______ approaches.
RNAseqcompliment of RNAmicroarray
Data analysis is _______ and requires _______.
bioinformatics intensivestringent statistical analysis
_______ is the study of the protein complement of a cell.
proteomics
_______ is the analysis of protein profiles from two or more samples (ex. diseased vs. healthy cells) to identify _______ that could be responsible for _______.
comparative proteomicsquantitative differencesobserved phenotypes
_______ can identify posttranslational modifications that cannot be detected by _______.
proteomicstranscriptome analysis
Proteins can be separated by _______ or by _______.
two dimensional polyacrylamide gel electrophoresis (PAGE)liquid chromatography (FPLC, HPLC)
Proteins are identified by _______.
mass spectrometry
_______ is the identification and quantification of steady-state levels of _______ (sugars, amino acids, lipids, nucleotides, etc.)
metabolomicsintracellular metabolites
Because the technology to identify every metabolite in a biological sample is not available, _______ is often carried out where a few specific metabolites are measured.
targeted metabolomics
Drug metabolism can take place anywhere in the body (_______, _______, _______, _______) but _______ is the prime site.
plasmakidneylunggut wallliver
There are three potential outcomes of drug metabolism:1. _______2. _______3. _______
- increase in drug hydrophilicity and ability to be excreted (hepatic)2. metabolic products are less pharmacologically active than the substrate drug3. inactive prodrugs converted to their active forms (hepatic)
There are several mechanisms of drug resistance including:1. _______2. _______3. _______4. _______5. _______
- decreased permeability2. alteration of the target site for the drug3. enzymatic inactivation of the drug4. active transport of the drug out of the cell5. amplification of the gene coding for the target of the drug
A _______ in DNA repair activity can _______ effectiveness of drugs that target DNA.
increasedecrease
_______ results from a increase in the amount of _______ that can pump many different drugs out of the cell.
mulitdrug resistancetransporter proteins
The 4 essential processes needed to develop from a single cell into a multicellular organism are: _______, _______, _______, and _______
cell proliferationcell specializationcell interactioncell movement
How is cell determination tested?
a portion from one section (ex. foot) of a donor organism is placed into a different section (ex. arm) of a host organism; if the host grows and exhibits the phenotype of the original section (ex. has a foot where a arm should be), then the portion of cells that were transplanted were fated (determined) to be a foot before the transplant
True or false: Very different organisms may have similarities in their developmental genes.
True. (ex. HOX genes)
_______ genes direct regions (segments) to differentiate into their final forms.
homeotic
Genes can have _______ expression patterns by having a series of _______ directing _______ in different regions of the organism.
complexcontrol regionstranscription
_______ genes are arrayed on the chromosome in the same spatial order as they are expressed in _______ and in the same order in _______ and _______.
homeoticdeveloping embryosfruit flieshumans
What is this compound?
cis unsaturated fatty acid
What is this compound?
trans unsaturated fatty acid
What is this compound?
What is the precursor of steroid hormones?
cholesterol
What are the three groups of steroid hormones?
- corticosteroids- androgens- estrogens
After steroid hormones are produced by gonads and adrenal cortex, they immediately diffuse out of _______ into _______.
- endocrine cells- bloodstream
Are steroid hormones lipid-soluble and why is this important?
- lipid-soluble- allows them to cross membranes
Where are steroid hormone receptors located?
inside the cell (cytosolic receptors)
Which hormones (steroid or peptide) are faster acting?
peptide
Which hormones (steroid or peptide) have a longer half-life?
steroid
Which hormones (steroid or peptide) are larger?
steroid
Do polypeptide hormones immediately enter the blood stream?
no
Where can polypeptide hormones be stored?
in endocrine cell vesicles
Are polypeptide hormones lipid-soluble or water-soluble?
water-soluble
Can polypeptide hormones pass readily through cell membranes?
no
What are polypeptide hormones sometimes called? Why did they get this nickname?
- “first messengers”- their receptors are located externally on the cell so they are usually the first to send the message and then a “second messenger” carries this message within the cell
What type of molecules are usually “second messengers”? Give examples.
- low molecular weight signaling molecules- cAMP or calcium
Describe the location and structure of a G-protein coupled receptor.
- integral membrane protein with an extracellular N-terminus- 7 transmembrane alpha helices- 3 extracellular and intracellular loops- intracellular C-terminal tail membrane- no intrinsic catalytic domain
Which part of the G-protein coupled receptor recruits the G-protein?
third intracellular loop
Where does the ligand bind to a G-protein coupled receptor?
in the pocket formed by the 7 alpha helices
What does the G-protein activate? What does that lead to?
- G-protein activates adenylyl cyclase which converts ATP to cAMP- activates protein kinases in the cytosol (signal cascade)
What inactivates cAMP, thus turning off the cell response of a signal cascade?
phophodiesterase
Which subunit of the G-protein contains the GTP-binding site and intrinsic GTPase activity?
alpha subunit
How is the signal amplified in a G-protein coupled receptor?
each bound hormone can stimulate many alpha subunits of G-protein
What toxins target G-proteins?
- cholera toxin- pertussis toxin
What does the cholera toxin do?
- ADP-ribosylates the G alpha subunit making it constitutively active- increases in cAMP within intestinal epithelial cells leads phosphorylation of Cl- channels and efflux of water and electrolytes
What does the pertussis toxin do?
- ADP-ribosylates the G alpha subunit making it constitutively active- enhances cAMP levels that inhibits neutrophil functions
What is the ratio of intracellular to extracellular calcium concentration? Why is this important?
- intracellular (100 nM) to extracellular (1 mM)- allows for rapid changes in calcium concentration via hormone ligation
What protein binds calcium? Describe the structure of that protein.
- calmodulin- has two globular domains (binds calcium) joined by a long alpha-helix
When calcium binds calmodulin, what happens?
conformational change that allows complex to bind to and modify target proteins (kinases) that initiate a signal cascade
What is the second messenger responsible for calcium mobilization?
phosphatidylinositol-4,5-bisphosphate (PIP2)
PIP2 is hydrolyzed by _______ to generate two second messengers: _______ and _______.
- PIP2-specific phospholipase C (PLC)- inositol trisphosphate (IP3)- diacylglycerol (DAG)
Which calcium second messenger is water-soluble and mobilizes calcium?
inositol trisphosphate (IP3)
Where is diacylglycerol (DAG) located and why? What is its function?
- anchored in plasma membrane due to hydrophobic fatty acid side chains- activates key protein kinase C (PKC) family
True or false: Receptor-mediated endocytosis is selective.
true
Where do the vesicles of receptor-mediated endocytosis form? What do they contain?
- form at the surface of the membrane- contain receptors and ligands
Describe the structure of the vesicles in receptor-mediated endocytosis.
- vesicles coated with three clathrin heavy chains and three light chains- forms a polyhedral lattice
What is an example of receptor-mediated endocytosis?
iron transport via transferrin receptor
