Bio Exam 4

what is primary protein structure

a sequence of amino acids

Which direction does the template strand of DNA run

3-5

how many rna nucleotide bases specify an amino acid

3

a nonsense mutation is

a change in nucleotide sequence that results in an early stop codon

a missense mutation is

a change in nucleotide sequence that changes the amino acid specified by a codon

A cell with 4 chromosomes enters meiosis. How many chromosomes would bein its gametes if nondisjunction of one chromosomes occured in one daughter cell in meiosis 2?

1,2,3

rna polymerase is the enzyme that synthesizes rna. It catalyzes the formation of what type of bonds

phosphodiester

what determines the start site and direction of transcription

promoter

what would you predict to be the immediate outcome of adding a-amanitin to a cell

reduced production of one or more types of RNA

In eukaryotic cells, RNA processing coverts the RNA transcipt into

mRNA

eukaryotic genomes have gene sequences that can code for more than one polypeptide sequence because

different exons can be cut out of the premRNA

Doxycycline stops translation in bacteria. This means that the antibiotic directly affects the production of

polypeptides

what is the function of tRNA

Match the appropriate amino acid to its codon

Doxycycline binds the small ribosomal subunit in a manner that prevents tRNAs from entering the A site of the large subunit. Which of the following is directly affected by doxycycline

bringing in the next amino acid during elongation

the cells of individuals that recieved that COVID-19 vaccine make the viral protein because

the codons in the mRNA are universal

which of the following are parts of an a. operon b. rna polymerasec. promoterd. operatora and bb and c

b and c

a mutation occurs in the lacI gene resulting in no functional repressor protein being synthesized. Will expression of the lac operon be different when lactose is present and when it is not?

NO

your bone cells, muscle cells, and skin cells look different because

different genes are active in each kind of cell

the control of gene expression is more complex in multicellular eukaryotes than prokaryotes because

in a multicellular eukaryote, different cells are specialized for different functions

what is the epigenome

the chemical modifications on histones and DNA

Methyl groups on DNA are a type of epigenetic tag that

silence genes

histone deacetylases are enzymes that remove acetyl groups from histones. You treat cells with a drug that inhibit histone deacetylases. This drug treatment leads to

an increase in gene expresion

How does a microRNA recognize a specific target mRNA

A microRNA can recognize a specific target whenever it can form complementary base pairs with the target

what is an example of post-translational control

the removal of a phosphate group from a protein

Which level of gene regulation is most energy efficient

transcriptional control

TTX-sensitive and TTX-resistant sequences represent

different alleles

transcription is the creation of ______ from a _____ template

rna, dna

Which of the following best describes the relationship between a newly synthesized RNA molecule and the DNA template strand?

complementary

The genetic code is

unambiguousconservativeredundantuniversal

True or False? A missense mutation is one where a single nucleotide of DNA differs, leading to the change of a single amino acid.

true

mRNA

codes for protein

tRNA

is a carrier for amino acids Harbors an anticodon

rRNA

along with proteins make up a ribosome

which of the following describes a promoter

a site that recruits RNA polymerase

you want to engineer a bacterium to produce the gene product of a eukaryotic gene, What must you include in addition to the coding exons of the genes

a bacterial promoter sequence

Put the following events of bacterial transcription in chronological order.1. Sigma binds to the promoter region.2. The double helix of DNA is unwound, breaking hydrogen bonds between complementary strands.3. Sigma binds to RNA polymerase.4. Sigma is released.5. Transcription begins.

3.1.2.5.4

During translation, peptide chain elongation to produce a single protein continues until _________?

a stop codon in the A-site binds a release factor.

which types of cells does transcription occur in the nucleus

eukaryotic

which types of cells does translation occurs in the cytoplasm

both

which types of cells does the promoter for a gene contain a -0 and -35 box

prokaryotic

During RNA processing a(n) ___________ is added to the 3' end of the RNA.

long string of adenine nucleotides

True or False? Transcription and translation happen almost simultaneously in prokaryotes.

true

Choose the answer that places the following events of protein synthesis in the proper order.1. An amino-acyl tRNA binds to the A site.2. A peptide bond forms between the new amino acid and a methionine amino acid.3. The ribosome moves so that the "empty" tRNA moves from the P site to the E site and the amino-acyl tRNA moves from the A site to the P site.4. A small ribosomal subunit binds with mRNA, the tRNA for methionine (in the P site), and a large ribosomal subunit5. tRNA in the E site disassociates from the complex.

4,1,2,3,5

What happens to RNA polymerase in a eukyarotic cell after it has completed transcription of a gene?

It is free to bind to another promoter and begin transcription.

If the lac repressor were altered so it could not release lactose once lactose was bound to it, then you would predict that

The repressor could not bind to DNA.

True or False? The lac operon in E. coli utilizes both positive and negative control of gene expression.

true

True or False? If both glucose and lactose are found in the environment of a E. coli cell, lactose only will be used in the bacterium's metabolism.

false

How does the presence of glucose in an E. coli's environment affect the transcription of the lac operon?

Increased glucose levels decrease the level of cAMP, leading to less frequent transcription.

rna polymerase needs additional proteins to tightly bind a gene's promoter

transcriptional

mRNA is quickly degraded by an enzyme in the cell's cytoplasm before a protein can be made.

translational

A protein needs to have a phosphate group added to its structure before it can perform its function.

post-translational

translational control in what types of cells

both

mRNA processing in what types of cells

eukaryotes

post-translational modification in what types of cells

both

chromatin remodeling in what types of cells

eukaryotes

rnai in what types of cells

eukaryotes

transcriptional control in what types of cells

both

A(n) _____ is a stretch of DNA consisting of an operator, a promoter, and genes for a related set of proteins, usually making up an entire metabolic pathway.

operon

The ________ is/are arranged sequentially after the promoter.

genes of an operon

A(n) _______ is a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place.

promoter

Regulatory proteins often bind to the ______ to control expression of the operon.

operator

A(n) ________ is a protein that inhibits gene transcription. In bacteria, this protein binds to the DNA in or near the promoter.

repressor

A(n) _______ is a specific small molecule that binds to a bacterial repressor protein and changes its shape so that it cannot bind to an operator, thus switching an operon on.

inducer

How can one eukaryotic gene lead to the production of multiple different proteins?

Alternative Splicing

Imagine you discover a mutation in a eukaryotic gene that leads to loss of function of the protein that it encodes. You determine the mutant gene's nucleotide sequence from start site for transcription to the termination point of transcription and find no differences between the mutant gene and the normal gene. Where on the DNA could the mutation be?

an enhancera promoter-proximal element

Histone deacetylases are enzymes that remove acetyl groups from histones. You treat cells with a drug that inhibits histone deacetylases. This drug treatment leads to...

an increase in gene expression

Place the following steps in the correct order to explain how miRNA works in RNAi. Not all steps are shown.1. The RISC protein complex binds the miRNA.2. The newly transcribed RNA forms hairpins.3. The precursor miRNA is partially processed and exported to the cytoplasm.4. RNA polymerase transcribes the gene that encodes the precursor miRNA.5. The RISC/miRNA complex blocks transcription of its target mRNA.

4,2,3,1,5

Which of the following lead to chromatin condensation?An enzyme adds acetyl groups to histonesan enzyme adds methyl groups to DNAAn enzyme adds phosphate groups to DNAAn enzyme removes acetyl groups on histones

an enzyme adds methyl groups to DNA
An enzyme removes acetyl groups on histones

lactose absent

operon NOT trasncribed

lactose and glucose present

operon transcribed at a LOW rate

lactose present and glucose absent

operon transcribed at a HIGH rate

epigenome

all the chemical tags covering DNA and histones in a cell or organism

genome

all of the genetic information in the DNA of a cell or organism

proteome

all the proteins expressed in a cell or an organism

transcriptome

all the mRNA molecules expressed in a cell or organism

what level of control allows for a rapid response

post-transcriptional control

null alleles

alleles that do not function at all

one-gene, one-enzyme hypothesis

each gene is responsible for making one enzyme. This hypothesis has expanded to include genes that produce proteins other than enyzmes, RNA as final products, or two or more related products

genetic screen

any techinque for picking particular types of mutants out of many randomly generated

mutants

not unlike finding the proverbial needle in a haystack

genetic code hypothesis

Crick proposed that different combinations of bases could specify the 20 amino acids

RNA as the intermediary between genes and proteins

Jacobs and Monod suggest that RNA molecules link genes in nucleus and protein-manufactoring centers in cytoplasm

mRNA

single-stranded molecules of RNA carry info out of nucleus from DNA to site of protein synthesis in cytoplasm

messanger RNA hypothesis

dna is found in nucleus, mRNA connects DNA to protein, proteins sythesis takes place in the cytoplasm

rna polymerase

polymerizes ribonucleotides into strands of rna (uses DNA synthesize complimentary RNA molecule)

central dogma

summarizes the flow of info from DNA to protein

transcription

process of using a DNA template to make an RNA molecule that has a base sequence complementary t the DNA, DNA is transcribed to RNA by RNA polymerase

translation

process of using the information in the base sequence of mRNA to synthesize proteins. Information in the messenger RNA is translated into proteins by ribosomes

what is genotypes based on

sequence of dna

phenotype is basedon

proteins produced

genetic code

rules that specify the relationship between a sequence of nucleotides in DNA or RNA and the sequences of amino acids in proteins

triplet code

three-base code shortest genetic word to code for at least 20 amino acids

codon

group of 3 bases that specifies a particular amino acid

reading frame

series of adjacent, codons that specify a sequence of amino acids in a polypeptide

start codon

AUG signals that protein synthesis should begin at that pointAUG=methionine

stop codon

UAA, UAG, UGA, signal the end of the reading frame (end of polypeptide)

what are the 5 properties of code

it is redundantit is unambiguousit is non-overlappingit is nearly universalit is conservative

mutation

any permanent change in a gene or chromosome of a cell

point mutations

alters the sequence of one or a small number of base pairs

missense mutation

change the identity of an amino acid in a protein