Deck 5: Genetics of Longevity

Question 1

Fill in the blank: After a transgenic or knockout gene has been developed,it is inserted into a(n)______ in order to make a transgenic or knockout organism.

Answer 1

embryo

Question 2

More than one codon can code for a single amino acid.

Answer 2

True

Question 3

Different gene expression in different cells,along with the universal mortality of somatic cells,has led many biogerontologists to suggest it is unlikely that longevity reflects alterations to a single gene.

Answer 3

True

Question 4

Short-answer question: Briefly describe (two or three sentences)the role of tRNA and aminoacyl-tRNA synthetase in building a protein from mRNA

Question 5

Chromosomes consist of DNA bound to proteins known as:
(a)histones.
(b)nucleosomes.
(c)primases.
(d)protostomes.

Question 6

Synthesis of mRNA occurs in the ______,whereas translation (protein synthesis)happens in the ______.
(a)nucleus;cytoplasm
(b)nucleus;Golgi complex
(c)cytoplasm;nucleus
(d)Golgi complex;nucleus

Question 7

Comparing a mutant strain with wild-type organisms in order to establish a suitable model system is called ______ screening.
(a)mutant
(b)genetic
(c)model
(d)test

Question 8

True or false: The knockout mouse has an extra copy of a single gene inserted into its genome.

Question 9

Knowledge about the genetic basis of longevity comes largely from studies of:
(a)yeast.
(b)worms.
(c)flies.
(d)all of the above.

Question 10

Alternative RNA splicing allows cells to make several variations of a common protein from one gene,______ the coding potential of the genome.
(a)maintaining
(b)controlling
(c)decreasing
(d)increasing
Analyzing Gene Expression in Biogerontology

Question 11

General transcription factors find the starting region of a gene by locating a sequence known as the:
(a)ATAT box.
(b)TATA box.
(c)CATA box.
(d)poly-A tail.

Question 12

Expression of genes can be turned on or off by the interaction of gene regulatory proteins with specific segments of noncoding DNA known as:
(a)promoter regions.
(b)enhancers.
(c)silencers.
(d)control elements.

Question 13

True or false: Research on the lac repressor demonstrated that DNA sequences in the binding sites of the genetic switches are highly conserved,from E.coli to humans.

Question 14

Nucleotides are read in groups of three known as ______,and each group of three corresponds to a specific amino acid.
(a)triplets
(b)promoters
(c)codons
(d)none of the above

Question 15

For gene expression to occur,histones must be modified so that they loosen their grip on the DNA.This is accomplished by:
(a)histone deacetylation.
(b)phosphorylation of histones.
(c)histone acetylation.
(d)dephosphorylation of histones.

Question 16

The RNA transcript is a single-stranded molecule.

Question 17

In the cloning of a gene by PCR,DNA is first made from mRNA by using which enzyme?
(a)DNA polymerase
(b)RNA polymerase
(c)reverse transcriptase
(d)aminoacyl-tRNA synthetase

Question 18

RNA polymerase II,general transcription factors,and the mediator protein form the:
(a)DNA polymerase complex.
(b)transcription initiation complex.
(c)translational initiation complex.
(d)enhancer complex.

Question 19

True or false: Knowing the base-pair sequence of a gene allows determination of the encoded protein's amino acid sequence and,thus,the protein's possible function.

Question 20

Only ______,the coding regions of a gene,are contained in mRNA.

Question 21

True or false: In general,diploid reproduction in S.cerevisiae occurs as a matter of chance and is regulated by environmental conditions.

Question 22

True or false: It takes relatively little time for a researcher to successfully develop a mutant that provides a suitable and reliable experimental system for testing a hypothesis about the impact of genes on longevity

Question 23

Which tough polymer of nitrogen-containing sugars forms between the bud and the parent cell of yeast after mitosis occurs?
(a)bud scar
(b)chitin
(c)glycosylated sugars
(d)connectin

Question 24

Determining a gene's function within the organism often starts by evaluating where and when the gene is expressed,utilizing:
(a)in situ hybridization.
(b)in vivo hybridization.
(c)in vivo electrophoresis.
(d)in situ electrophoresis.

Question 25

S)cerevisiae can exist in two chromosomal states: one containing two sets of each chromosome,known as the ______ state,and one containing one set of each chromosome,the ______ state.
(a)haploid;diploid
(b)duploid;singloid
(c)diploid;haploid
(d)singloid;duploid

Question 26

True or false: Weak mutations in critical genes that regulate dauer formation result in an extended adult life span.

Question 27

General recombination is an essential part of meiosis in S.cerevisiae,but it also gives rise to potentially damaging ______ rDNA circles.
(a)plasmid
(b)extrachromosomal
(c)chromosomal
(d)homologous

Question 28

Morphological and biochemical alterations in the C.elegans dauer increase its resistance to stress and thereby increase its chance of survival.These changes include all of the following except:
(a)increasing the thickness of the cuticle.
(b)decreasing the concentration of endogenous antioxidants.
(c)closing the buccal (mouth)cavity.
(d)increasing the concentration of endogenous antioxidants.

Question 29

Fill in the blank: After separation of the new yeast cell from the mother cell,a circular chitin residue known as the ______ remains permanently on the surface of the mother cell.

Question 30

True or false: Binding of NAD⁺ to the SIR2 protein causes activation of the histone deacetylase and compaction of the chromatin,silencing of the rDNA locus,reduction of the budding process,and an extended replicative life span for the yeast.
Genetic Regulation of Longevity in C.elegans

Question 31

When budding yeast cells enter a nondividing state,called the ______ phase,they remain metabolically active.
(a)stationary
(b)G₀
(c)resting
(d)asexual

Question 32

The method of applying an electrical current to a semi-solid material in order to separate molecules or compounds is known as:
(a)gel fluorescence.
(b)electro-separation.
(c)polymerase chain reaction.
(d)gel electrophoresis.

Question 33

True or false: A dauer is a worm in which development is halted at larval stage 3;the dauer is metabolically active but reproductively silent

Question 34

The hybridization technique that uses pieces of glass about the size of a postage stamp that are embedded with single-stranded DNA sequences from specific genes with known functions is called:
(a)DNA hybridization.
(b)DNA microarrays.
(c)in situ hybridization.
(d)PCR.
Genetic Regulation of Longevity in S.cerevisiae

Question 35

The amount of food in the yeast's environment seems to link reproduction to longevity.Food abundance results in ______ rates of reproduction and ______ longevity.
(a)high;increased
(b)high;decreased
(c)low;increased
(d)low;decreased

Question 36

True or false: The SIR2 protein is a histone acetylase that causes compaction of the chromatin and gene silencing.

Question 37

Cloning of the daf-2 gene revealed that it encodes a transmembrane receptor protein that has homology with a(n)_____ receptor found in other species.
(a)AGE-1/DAF-16 complex family
(b)forkhead box transcription factor family
(c)phosphatidylinositol-3-kinase
(d)insulin/insulin-like growth factor (IGF-1)

Question 38

Select the two sexual forms of C.elegans.
(a)hermaphrodite and male
(b)diploid and haploid
(c)hermaphrodite and female
(d)asexual and female

Question 39

The single-cell eukaryotic organism S.cerevisiae is a good model organism for aging research because of all the following characteristics except:
(a)it is short-lived.
(b)it is inexpensive to grow and maintain.
(c)it is well-characterized for its genetics and physiology.
(d)it has a well-defined neural system.

Question 40

Enzymes that cleave the DNA at specific sequences are called:

A)digestive enzymes.
B)proteases.
C)restriction nucleases.
D)polymerases.

Question 41

Extended longevity in S.cerevisiae and C.elegans appears to be tightly coupled to genes that regulate the response to:
(a)injury.
(b)predation threat.
(c)food availability and other environmental conditions.
(d)immunity.
Genetic Regulation of Longevity in D.melanogaster

Question 42

True or false: A mutation in a single gene can affect longevity in mammals.

Question 43

Cloning of the daf-16 gene has shown that the DAF-16 protein is a member of the ______ family of genes and that this particular transcription factor represses genes that govern growth and reproduction in C.elegans in response to low-food conditions.
(a)DAF-2
(b)AGE-1
(c)TOR
(d)FOXO

Question 44

The transgenic mth Drosophila was shown to live significantly longer than the wild-type fly and was more effective at:
(a)reproduction.
(b)resisting environmental stress.
(c)reducing food intake.
(d)reducing metabolic rate.

Question 45

True or false: The Drosophila life cycle consists of six stages: embryogenesis,three larval stages,a pupal stage,and an adult stage.

Question 46

A direct link between energy metabolism and life-span extension in C.elegans has been identified with a gene regulatory pathway found in mitochondria,involving the ______ genes.
(a)clock
(b)timing
(c)control
(d)regulator

Question 47

True or false: Increased survival of the chico knockout (Drosophila)was limited to mean life span.This suggests an alteration in the intrinsic rate of aging.

Question 48

Studies in Drosophila are consistent with results from C.elegans and suggest that life-span extension is associated with what type of physiological regulation?
(a)cellular
(b)neuroendocrine
(c)metabolic
(d)nutritional

Question 49

One challenge facing scientists in their efforts to determine the overall relevance of longevity results obtained from genetically manipulated organisms is:
(a)being able to vary rates of aging.
(b)establishing a suitable knockout mouse.
(c)establishing a suitable transgenic mouse.
(d)lack of replication of the findings.

Question 50

True or false: Studies using C.elegans and Drosophila have provided data that support the role of insulin-like/IGF-1 signaling pathways in linking reproduction and longevity.However,homologous genes for the insulin-like/IGF-1 receptor are not present in mice.

Question 51

True or false: Loss-of-function mutation in an insulin-like receptor (InR)in Drosophila reduces egg production and extends life,thereby linking the rate of reproduction to longevity.

Question 52

In Drosophila,the strategy of diapause seems to be heavily influenced by neurohormonal signals and is characterized by all of the following except:
(a)reproductive silence.
(b)reduced energy metabolism.
(c)increased reproduction.
(d)resistance to stress.
Genetic Regulation of Longevity in M.musculus

Question 53

The increased longevity of genetically manipulated mice with inhibited growth hormone/insulin-like signaling pathways is important because it demonstrates a ______ conserved mechanism for longevity.
(a)pleiotropically
(b)phylogenetically
(c)metabolically
(d)homeostatically

Question 54

Fill in the blank: Poor environmental conditions for C.elegans prevent the phosphorylation of DAF-16.DAF-16 enters the nucleus and represses genes that code for proteins involved in ______,which,in turn,results in dauer formation.

Question 55

True or false: In genetic experiments,limiting the mutation of C.elegans to neuroendocrine cells decreased longevity.

Question 56

Cloning of the daf-2 gene and identification of the DAF-2 protein as an insulin/IGF-1-like receptor indicate that gene regulation leading to increased life span of the adult worm is under ______ control.
(a)cellular
(b)metabolic
(c)neuroendocrine
(d)nutritional

Question 57

The Drosophila chico gene is homologous to the ______ gene described in C.elegans.
(a)InR
(b)age-1
(c)daf-16
(d)daf-2

Question 58

True or false: Extended longevity in mice caused by knocking out an insulin receptor substrate gene,Ins1,was observed only in female mice.