exam 4 Flashcards
which of the following is a palidromic sequece?
A 5' CATTAG 3' B 5' CAATTG 3' C 5'CATTTG3' D 5'GATTTC3' E 5'CATCAT3'
B 5’CAATTG3’
DNA BECASUE IT HAS A _____ CHARGE MOVES TO THE_______ ELECTRODE DURING GEL ELECTROPHORESIS AND _____ DNA MOLECULES MIGRATE THE MOST QUICKY
NEGATIV, POSTITIVE, SMALLER
From the list below selec the sequence of steps for insreing a peice of foreign dna into a plasmid vector inroducing the plasmid into bacteria and verifying that the plasmid and the foreign gene are present
1, transform host cells
2 select for the the lack of plasmid reporter gene 1 function
3 select for the plasmid reporter gene 2 function
4 digest vector and foreign dna with a restriction enzyme which inactivates plasmid reporter gene 1
5 ligate the digested plasmid together with the foreign dna
4,5,1,3,2
our textbook describes a sheep named dolly whats special about dolly
she was the first cloned mammal
what percentage of the human genome codes for protein
less than 5%
the traditional way to study bacteria is to first grom them in the lab its now posile to isolat DNA from environmental samples and study bacteria without having to grow them in the lab what is this new field of study called
metagenomics
which of the following is a technques that can be used to clone mamals
a. mammals cant be cloned B, nuclear transer c. cDNA technology D x......... of eggs e. Microinjection of egg cytoplasm into somatic cells
c cDNA technology
restriction en- zymes
which cut dou- ble-stranded DNA molecules—such as those injected by bac- teriophage—into smaller, noninfectious fragments
These enzymes break the bonds of the DNA backbone between the 3′ hydroxyl group of one nucleotide and the 5′ phosphate group of the next nucleotide. This cutting process is called re- striction digestion.
Why doesn’t a restriction enzyme cut the DNA of the bacte- rial cell that makes it?
One way that the cell protects itself is by modifying the restriction sites on its own DNA. Specific modi- fying enzymes called methylases add methyl (—CH3) groups to certain bases at the restriction sites on the host’s DNA after it has been replicated.
Most virus particles, called viri- ons, are composed of?
only nucleic acid and a few proteins.
negative regulation
the gene is normally transcribed. Binding of a repressor protein prevents transcription.
positive regulation
the gene is normally not transcribed. An activator protein binds to stimulate transcription.
lytic cycle
the infected host cell lyses (bursts), releasing progeny viruses. Once a virus has injected its nucleic acid into a cell, that nucleic acid takes over the host’s synthetic machinery.
In a host cell infected with a virus, the viral genome uses its early genes to shut down host transcription while it replicates itself. Once the viral genome is replicated, its late genes produce capsid proteins that pack- age the genome and other proteins that lyse the host cell.
lysogenic cycle
Some viruses have evolved an ad- vantageous process called lysogeny that postpones the lytic cy- cle. In lysogeny, the viral DNA becomes integrated into the host DNA and becomes a prophage
In the lysogenic cycle, an inactive prophage is integrated into the host DNA where it is replicated during the bacterial life cycle.
The Reproductive Cycle of HIV
This retrovirus enters a host cell via fusion of its envelope with the host’s plasma mem- brane. Reverse transcription of retroviral RNA then produces a DNA provirus—a molecule of complementary DNA that inserts itself into the host’s genome.
inducers
Compounds that, like lactose, stimulate the synthesis of a protein are called inducers
An Inducer Stimulates the Expression of a Gene for an Enzyme It is most efficient for a cell to produce an enzyme only when it is needed. Some enzymes are induced by the presence of the substance they act upon (for example, β-galactosidase is induced by the presence of lactose).
inducible proteins
Proteins that ar made by inducers
constitutive proteins.
whereas proteins that are made all the time at a constant rate are called constitutive proteins. (Think of the constitution of a country, a document that does not change under normal circumstances.)
structural genes
The genes that encode the three enzymes for processing lactose in E. coli are structural genes; they specify the primary structure (the amino acid sequence) of a protein molecule. Structural genes are genes that can be transcribed into mRNA.
operon
A cluster of genes with a single promoter is called an operon, and the operon that encodes the three lactose-metabolizing enzymes in E. coli is called the lac operon.
the operon that encodes the three lactose-metabolizing enzymes in E. coli is called the lac operon.
the lac operon.
The lac operon of E. coli is a segment of DNA that includes a promoter, an operator, and the three structural genes that code for lactose-metabolizing enzymes.
What are Two Ways to Regulate a Metabolic Pathway
Feedback from the end product of a metabolic pathway can block enzyme activity (allosteric regulation), or it can stop the transcription of genes that code for the enzymes in the pathway (transcriptional regulation).
operator
The operator is a short stretch of DNA that lies between the pro- moter and the structural genes. It can bind very tightly with regulatory proteins that either acti- vate or repress transcription.
repressor
When the repressor is bound, transcription of the operon is blocked.
regulatory gene
the regulatory gene produces a protein whose sole function is to regulate expression of the other genes; and
• certain DNA sequences (operators and promoters) do not code for proteins, but are binding sites for regulatory or other proteins.
co-repressors
This binding causes the repressor to change shape and bind to the operator, thereby inhibiting transcription.
An example is the operon whose structural genes catalyze the synthesis of the amino acid tryptophan:
inducible system
the substrate of a
metabolic pathway (the inducer) interacts
with a regulatory protein (the repressor), rendering the repressor incapable of bind-
ing to the operator and thus allowing transcription.
repressible systems
the product of a metabolic pathway (the co-repressor) binds to a regulatory protein, which is then able to bind to the operator and block transcription.
catabolite repression,
a system of gene regulation in which the presence of the pre- ferred energy source represses other catabolic pathways
The promoter for the lac operon does not function efficiently in the absence of cAMP, as occurs when glucose levels are high. High glucose levels thus repress the enzymes that metabolize lactose.
the lactose-metabolizing enzymes—is transcribed.
What ways in which a prokaryotic cell can shut off the sup- ply of an unneeded protein.
The cell can:
• downregulate the transcription of mRNA for that protein;
• hydrolyze the mRNA after it is made, thereby preventing
translation;
• prevent translation of the mRNA at the ribosome;
• hydrolyze the protein after it is made; or
• inhibit the function of the protein.
you discover a new gene in the mouse and want to study its function which of the following techniques would you use to make a mouse with reporter gene inseted into the middle of the gene youre studying
A.DNA CHIP B. siRNA C.cDNA D.knockout E.PCR
knockout
which of the following techniques would be best for comparing the genes being expresed in normal cancer cells
A DNA sequencing B. Kockout Technology C. siRNA D. DNA chip Technology E. recumbanint DNA
D. DNA chip technology
Biotechnology is being used to do which of the following
a making insulin b making TPA C improving crops d. making vaccines E all of the above
all of the above
what are restriction enzymes
they cut DNA molecules at specific sequences
they protect bacteria from viral infections
which of the following would be used to join two differnt DNA molecules
DNA ligase
what does the c in cDNA stand for
complementary
which of the following is used to ihibit synthesis of a protein by destroying a specific mRNA molecule
a siRNA b. knockouts c alph protosome ambiones
siRNA
you have 2 clones of a human gene one was made from cDNA the other otained directly from a chromosome
how differnt are they
The cDNA lacks introns
red and white blood cells in adult humans are produces by stem cells in the
bone marrow
which of the following could not be used to regulate the activity of a gene in eukaryotes
A. chromatin structure B. transport to the cytoplasm C mRNA stability D post- transcriptional processing E all of the above could be used to regulate
all of the above can regulate
RNA interference (RNAi) inhibits ?
mRNA
why do eukaryotes usualy have many copies of the rRNA fenes
Eukaryotas need to make lots of rRNA
many eukaryotes have regions called enhancers what is an enhancer
a dna sequence far from the promoter whare a specific protein can bind to active transcription
a cell is found that contains two BARR bodies the cell has
Three X chromosmes
many organisms have DNA sequences that can move from place to place in their genome what are these DNA sequences called
transposons
Tropomyosin is a muscle protein that we studied in class the and is differnt in smooth muscle than skeletal muscle becasue
of alternative splicing
what sequence qacounts for over 10% do the human genome
Alu
which statement about gene transcription in eukaryotes is not ture
A. regulatory proteins can bind far from the promoter
b transcription factors are required
C genes are usually transcribed in groups called operons
genes are usualy transcribed in groups called operons
how many differnt kinds of RNA polymerase are found in prokaryotic cells
1
how many differnt kinds of RNA polymerase are found in eukaryotic cells
3
RNA polymerase that produces mRNA molecules in eukaryotic cells is
RNA polymerase II
Adenosine is binding to an Adenosine receptor on a nerve cell in the brain what is the result
reduction in brain activity
cell differentiation in mammals is usually not reversible
true
what is the result when homologous chromosomes brak at differnt positions and exchange segments
translocation
