1The lack of bicoid mRNA in the anterior cytoplasm of a fertilized Drosophilia egg prevents development of an anterior head by allowing posterior parts to develop, demonstrates that bicoid gene products are which of the following?
- bicoid gene products are transcribed in the early embryo
- bicoid gene products normally leads to formation of tail structures
- bicoid gene products normally leads to formation of head structures
- bicoid gene products are proteins present in all head structures
- bicoid gene products are initiates programmed cell death
2Which molecules form gradients in the developing egg's cytoplasm?
- maternal Hox proteins
- maternal DNA genes
- maternal growth factors
- specific transcription factors to guide transcription of bicoid mRNA
- egg's growth factors
3Among the newly discovered small non coding RNAs, which type of RNA helps to reestablish methylation patterns during gamete formation and blocks expression of some transposons?
- miRNA
- piRNA
- lncRNA
- siRNA
- tRNA
4Which of the following statements correctly describes how RNA interference silences selected genes?
- double stranded RNA molecules stop transcription from occurring
- double stranded RNA molecules stop DNA replication from occurring
- double stranded RNA molecules block transcription of the gene's mRNA or active breakdown of the mRNA
- double stranded RNA molecules stop mitosis from occurring
- single stranded RNA molecules block transcription of selected DNA genes
5How does the transcription of bacterial structural genes in an inducible operon occur?
- it occurs continuously in the cell
- it starts when the pathway's substrate is present
- it starts when the pathway's product is present
- it stops when the pathway's product is present
6Gene expression is often assayed by measuring the level of mRNA produced from a gene. What level of the control of gene expression can be analyzed by this type of assay?
- replication control
- transcriptional control
- alternative splicing
- translational control
7Which of the following types of mutation would convert a proto-oncogene into an oncogene?
- a mutation that blocks transcription of the proto-oncogene
- a mutation that creates an unstable proto-oncogene mRNA
- a deletion of most of the proto-oncogene coding sequence
- a mutation that greatly increases the amount of the proto-oncogene protein
8Which of the following functions does the product of the p53 gene carry out?
- it inhibits the cell cycle
- it slows down the rate of DNA replication by interfering with the binding of DNA polymerase
- it causes cells to reduce expression of genes involved in DNA repair
- it allows cells to pass on mutations due to DNA damage
9In colorectal cancer, several genes must be mutated for a cell to develop into a cancer cell. Which of the following kinds of genes would you expect to be mutated to cause cancer?
- genes coding for enzymes that act in the colon
- genes involved in control of the cell cycle
- genes that are susceptible to mutation
- genes of the bacteria, which are abundant in the colon
- maternal effect genes
10Why are BRCA1 and BRCA2 considered to be tumor-suppressor genes?
- their normal products participate in repair of DNA damage
- their normal genes code for estrogens
- the mutant forms of either one of these prevent breast cancer
- the normal genes make estrogen receptors
- they block penetration of breast cells by chemical carinogens
11Mutants forms of the Ras protein found in tumors usually cause which of the following events to ocur?
- DNA replication stops
- nonfunctional cell-to-cell adhesion
- cytokinesis cell division cease
- excessive cell cycles and cytokinesis
- DNA repair damaged DNA is activated
12A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which types of cancer?
- colorectal cancer only
- lung and breast cancers
- lung cancer only
- lung and prostate cancers
- prostate cancer only
13The part of a G protein linked receptor that extends outside of the cell binds specifically to which of the following?
- the signaling molecule
- G protein
- the coupled enzyme
- ATP
- a second messenger ion
14Which event occurs as a G protein binds to a signal activated G protein coupled receptor?
- a signaling molecule then bonds to the receptor
- inactivated G protein activates an enzyme
- G protein is assembled
- GTP bound to the G protein is replaced by GDP
- GDP bound to the G protein is replaced by GTP
15The shape assumed by activated G proteins facilitates their binding to which of the following?
- the activated G protein receptor
- a nearby specific enzyme
- specific membrane phospholipids
- specific membrane cholesterols
- nearby ion channels
16Which receptors in the plasma membrane react to signal molecules by forming dimers that activate each other, and then activate relay proteins to start a signal transduction pathway?
- G protein-coupled receptors
- ligand-gated ion channels
- receptor tyrosine kinases
- steroid receptors
- extra cellular matrix
17Growth factor signaling molecules often bind to and activate which type of receptors to regulate cell growth and reproduction?
- ligand-gated ion channels
- G protein-coupled receptors
- cyclic AMP
- receptor tyrosine kinases
- neurotransmitters
18Which of the following statements about a G protein signaling pathway is true?
- A G protein-coupled receptor bound to GTP is in its active sate
- A G protein bound to GTP is in its active state
- A G protein bound to GDP is in its active state
- Hydrolysis of bound GTP by a G protein activates the G protein
19Which are the two components of MPF (maturation-promoting factor)?
- a growth factor and mitotic factor
- ATP synthetase and a protease
- cyclin and tubulin
- cyclin and a cyclin-dependent kinase
- GTP and G protein
20Which of the following is an inactive protein binds to cyclin to become an active catalysis?
- protein kinase
- MPE dependent kinase
- cyclin dependent kinase (Cdk)
- (Platelet Derived Growth Factor) PDGF
- MPF (maturation-promoting factor)
21Density-dependent inhibition is explained by which of the following?
- As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce control factors
- As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor
- As cells become more numerous, more and more of them enter the S phase of the cell cycle
- As tissue cell become more numerous and their surface receptors are signaled by contact with other tissue cells to stop cytokinesis
- As cells become more numerous, the level of waste products increases, eventually slowing down metabolism
22Starting with a fertilized egg (zygote), a series of five cell cycles division would produce an early embryo with how many cells?
23Which of the following statements about the DNA in one of your brain cells is true?
- Brain DNA has genes that code for intelligence
- Most of the DNA codes for proteins
- Most of its genes are likely to be transcribed
- It is the same as the DNA in one of your liver cells
- Each gene lies immediately adjacent to an enhancer
24Which is the function of eukaryotic nucleosomes?
- regulation of gene expression by selectively binding active transcription factors
- regulate gene expression by using its snRNA for alternative splicing of the mRNA
- alternative splicing of primary transcripts
- regulation of gene expression by inactivating genes wrapped around them
- all above answers are correct
25Which usually occurs to genes located in euchromatin regions in the nucleus?
- they are actively transcribed
- they are unregulated
- they are inhibited
- they are duplicated
- they are repressed
26Which of the following is a prophage?
- Phage DNA that is integrated into viral DNA
- Phage DNA that is integrated into bacterial DNA
- Phage DNA that replicates only when the eukaryotic cell it infects replicates its DNA
- An underdeveloped lytic virus
- A bacterial cell that is about to rupture
27The host range of cells that a virus can infect depends on which of the following?
- The enzymes carried by the virus
- whether is nucleic acid is DNA or RNA
- the proteins in the host’s cytoplasm
- the enzymes produced by the virus before it infects the cell
- proteins on the virus surface which can bind to protein receptors on the host cell’s surface
28Which of the following is characteristic of the phage lytic cycle?
- many bacterial cells containing viral DNA are produced by the lytic cycle
- Viral DNA becomes incorporated into the host genome
- The viral genome replicates without destroying the host
- Infected bacteria release large numbers of newly formed phages by cell rupture
- The virus-host relationship usually lasts for generations
29Which of the following statements describes the lysogenic cycle of the phage?
- After infection, phage genes are expressed to synthesize proteins that guide the bacterial host cell into a phage-producing factory that ruptures the cell
- Most of the prophage genes are expressed by the phage’s enzymes and products
- The phage genome is replicated along with the host genome
- Environmental changes can cause prophage DNA to exit the bacterial host genome to initate a lytic phase
- The virus DNA becomes incorporated in eukaryotic chromosomal DNA and is replicated during interphase S
30Which is a characteristic of virulent phages?
- They infect viruses
- They undergo a lytic cycle
- They undergo a lysogenic cycle
- They infect human cells
- They are produced by human cells
31Which is the protein coat of a virus?
- capsid
- capsule
- cell wall
- viral envelope
- a spike
32What is the main structural difference between enveloped viruses and non-enveloped viruses?
- Enveloped viruses enclose their genetic material with a single protein layer
- The genome of non-enveloped viruses is enclosed by a single phospholipid bilayer membrane, while eneveloped viruses have two membranes
- Enveloped viruses are surrounded by a phospholipid bilayer membrane which encloses their capsid and genome, whereas non-enveloped viruses do not have a phospholipid membrane
- Both types have a capsid and phospholipid membrane; but the genome is between two membranes is non-enveloped virus, while in the enveloped virus the genome is enclosed by both membranes
- Enveloped viruses secrete a slime capsule and non-enveloped viruses are mutants that cannot form a capsule
33Which process helps bacterial cells protect their own DNA from being attacked by restriction enzymes?
- adding methyl groups to adenines and cytosines nucleotides in DNA
- using DNA ligase to seal the bacterial DNA in a closed circle
- adding histones to protect the double-stranded DNA
- forming “sticky ends” of bacterial DNA to prevent enzymes ffrom attacking it
- secretion of slime capsules
34Which type of prokaryotic regulatory proteins of a specific operon are the products of expression of a specific regulatory gene and translation of its mRNA codes?
- inducer
- operator
- repressor
- co-repressor
- Cyclic AMP-CRP complex
35When are bacterial repressible operon genes, such as those of the trytophan operon blocked from being transcribed?
- When the supply of the end products formed by the enzymes encoded by the operon’s genes is low
- When the supply of the end products formed by the enzymes encoded by the operon bind to the promoter
- When co-repressors bind inactive repressors to activate them to bind to the operator of the operon
- When quantities of precursor molecules are high
- When distal DNA enhancers bind to the operon’s promoter
36Under what celll conditions does the trytophan repressor block transcription of the trytophan operon?
- when the repressor binds to the inducer
- when the repressor is not bound to trytophan
- when the repressor is not bound to the operator
- when the accumulation of excessive amounts of trytophan faciliates binding of repressor to trytophan
37Which of the following molecules binds with the bacterial lactose repressor to alter its shape to be released from the operator?
- promoter
- transcription factor
- cyclic AMP
- activator proteins
- inducer
38How does the transcription of structural genes in a bacterial inducible operon such as the lactose operon occur?
- the operon is always expressed in bacteria
- transcription starts when inducers such as lactose is the only sugar present in the cell’s environment
- it starts when the products of the catabolic breakdown of sugars like lactose to galactose and glucose increase in cells
- transcription of the inducible operon stops when the pathway’s products of galactose and glucose increase in cells
39Which of the following conditions must occur for a repressible operon to be transcribed?
- a corepressor must be present
- RNA polymerase and the active repressor must be present
- the repressor must be inactive, and the RNA polymerase must bind to the promoter
- RNA polymerase must not occupy the promoter, and the repressor must be inactive