Biology - Chapter 12
How many nucleotide bases are in one codon?
3
Translation proceeds toward the ______ end of the mRNA molecule being translated.
3'
How is an mRNA sequence used to produce a specific amino acid sequence?
A codon on mRNA base pairs with an anticodon on a tRNA that carries the appropriate amino acid.
What is a polypeptide?
A linear sequence of amino acids
In the process of protein synthesis, what recognizes the three stop codons?
A protein called release factor
Termination
A release factor binds to the A site of the ribosome.
What structural features are common to all tRNAs?
Acceptor stem for amino acid attachment Cloverleaf pattern with three stem-loops
What enzymes catalyze the addition of amino acids to tRNA molecules?
Aminoacyl-tRNA synthetases
What part of a tRNA binds to the codon of a messenger RNA molecule?
Anticodon
Which part of a tRNA molecule binds to a codon on mRNA to determine which amino acid will be added to a growing polypeptide?
Anticodon
In transcription, a sequence of ____ is copied into a sequence of ____.
Blank 1: DNA, deoxyribonucleicacid, or deoxyribonucleic acid Blank 2: RNA, mRNA, ribonucleicacid, or ribonucleic acid
At the molecular level, a gene is defined as an organized unit of DNA sequences that enables a segment of DNA to be transcribed into ____, resulting in the formation of a functional product.
Blank 1: RNA, mRNA, or ribonucleic acid
Ribosomes contain three discrete sites where tRNAs bind and the polypeptide is synthesized. These are called ____ site (A site), ____ site (P site), and ____ site (E site).
Blank 1: aminoacyl Blank 2: peptidyl Blank 3: exit
The structural features common to all transfer RNAs include a stem-loop containing a(n) ____ that is complementary to the codon on mRNA and an acceptor stem where a(n) ____ ____ can be attached.
Blank 1: anticodon or anti-codon Blank 2: amino Blank 3: acid
The ____ stage of translation involves the covalent bonding of amino acids to each other, one at a time.
Blank 1: elongation or second
One difference between RNA processing of bacteria versus eukaryotes is that mRNA transcripts undergo RNA processing or modification that is needed for proper translation in ____ cells.
Blank 1: eukaryotic, eukaryotes, or eukaryote
The end of translation is signaled by the ____ ____.
Blank 1: stop, termination, nonsense, or non-sense Blank 2: codon or codons
During the initiation stage of translation, an mRNA molecule, the first (initiator) ____ molecule, and the ribosomal subunits associate. During elongation, ____ bonds are formed between amino acids. Finally, translation ends when the ribosome reaches a(n) ____ codon.
Blank 1: tRNA or transferRNA Blank 2: peptide or covalent Blank 3: stop, termination, nonsense, or non-sense
Transcription factors are proteins that influence the ability of RNA polymerase to ____ genes.
Blank 1: transcribe, read, or express
In mature mRNAs of eukaryotes, identify the event where a modified guanosine covalently attaches at the 5' end.
Capping
Molecularly, a gene is an organized unit of ______ sequences that can be transcribed into RNA.
DNA
Identify the stage of translation in which polypeptide synthesis occurs.
Elongation
How does transcription differ in prokaryotes and eukaryotes?
Eukaryotic transcription requires more proteins.
True or false: Every gene controls the synthesis of a single enzyme.
False Reason: According to Beadle and Tatum's original hypothesis, each gene control the synthesis of a single enzyme. However, the hypothesis has been modified to account for proteins that are not enzymes, proteins that contain two or more polypeptides, alternative splicing of mRNA, and RNAs that do not encode polypeptides,
True or false: In eukaryotes, pre-mRNA molecules can be translated immediately without the need for modifications.
False Reason: In eukaryotes, pre-mRNA molecules are spliced, capped, and polyadenylated prior to translation.
Beginning at the start codon, in what direction is each triplet read during translation?
From the 5' to the 3' end
What term refers to gene function at the level of traits or at the molecular level?
Gene expression
Which tRNA recognizes and binds to the start codon in mRNA?
Initiator tRNA
What is the function of the anticodon of a tRNA molecule?
It binds to a codon on an mRNA molecule.
What is the purpose of the genetic code?
It specifies the relationship between mRNA and polypeptide sequences.
What occurs when genetic material, that can be inherited, is changed?
Mutations Reason: Genetically, duplications would be exact copies of the original gene. Reason: Stagnation is a period of inactivity. Mutations involve an active change in genetic material.
Elongation
Peptide bonds are formed between amino acids to synthesize a polypeptide.
Termination
RNA polymerase and the RNA transcript dissociate from the DNA.
Initiation
RNA polymerase binds to the promoter.
Elongation
RNA polymerase synthesizes the RNA transcript.
Where can the site for the binding of regulatory proteins be found?
Regulatory sequence
The one gene-one enzyme hypothesis has been modified in four ways. Identify them here.
Some proteins are composed of two or more different polypeptides. Many proteins do not function as enzymes. Some mRNAs are spliced in alternative ways so they produce two or more polypeptides. Some genes encode RNAs that are not used to make polypeptides.
What are the names of the three sites where tRNA molecules bind to the ribosome?
The aminoacyl site The exit site The peptidyl site
Initiation
The mRNA, tRNA, and ribosomal subunits are assembled.
Which RNA molecule involved in translation acts as an intermediary between an mRNA codon and an amino acid?
The tRNA
What type of RNA translates the language of mRNA into that of amino acids?
Transfer RNA
True or false: Bacteria and humans have the same genetic code, with rare exceptions.
True Reason: The genetic code is nearly universal. With only rare exceptions, bacteria, archaea, protists, fungi, plants, and animals all use the same genetic code.
Beadle and Tatum hypothesized that a mutation in a gene could cause ______.
a defect in an enzyme
A codon in an mRNA molecule can bind to a sequence in tRNA called the ____.
anticodon
In eukaryotes, a mature mRNA has a modified guanosine covalently attached at its 5' end. This is due to a process called ____.
capping
The portion of an mRNA sequence that specifies the amino acid sequence of a polypeptide is called the ____ sequence.
coding or exon
The genetic code is read in groups of three nucleotide bases known as ____.
codons
In bacteria, transcription and translation occur in the ______.
cytoplasm
The three stages of transcription are called initiation, ____, and termination.
elongation
Transcription is similar in prokaryotes and eukaryotes, except that ____ use more proteins.
eukaryotes
At the molecular level, coding sequences that are translated are found in:
exons
The coding sequences of genes are found in ______.
exons
Gene function either at the molecular level or at the level of traits is referred to as gene ____.
expression
The ______ that constitute the genetic material provide a blueprint for the characteristics of every organism.
genes
During the first stage of translation or ____, a complex is formed between an mRNA molecule, the first tRNA, and the ribosomal subunits.
initiation
To identify a mutant Neurospora strain that required arginine for growth, Beadle and Tatum plated the Neurospora cells on growth media that ______.
lacked arginine Reason: The lack of amino acids, not the presence of amino acids, allowed Beadle and Tatum to identify mutant strains that could not grow without added amino acids.
The genetic code specifies the relationship between the sequence of nucleotides in ______ and the sequence of amino acids in a polypeptide.
mRNA
Transfer RNA translates the language of ______ into that of amino acids.
mRNA
By plating the cells on growth media with or without arginine, Beadle and Tatum were able to identify ______.
mutant strains that required arginine for growth
Changes in genetic material that can be inherited are known as ____.
mutations
In eukaryotes, transcription occurs in the ____, whereas translation takes place in the ____.
nucleus cytosol or cytoplasm
In the middle ins the metabolic pathway on the left is the disorders when the enzyme is missing and on the right is the enzyme that catalyzes a specific step in this pathway. Phenylalanine is a carbon atom connected to H, NH2, COOH, CH2 hexagon rings. When acted by phenylamine hydroxylase it becomes tyrosine and mutation causes phenylketonuria. Tyrosine is a carbon atom attached to H, COOH, NH2, CH2 hexagon ring HO. This when acted by tyrosine aminotransferase gives p-hydroxyphenolypyruvic acid. This when acted by hydroxyphenylpyruvate oxidase gives homogentisic acid and its mutation can cause tyrosinosis. When homogentisic acid oxidase acts upon gives maleylacetoacetic acid and its mutation give alkaptonuria. If a person inherits two mutant genes that encode hydroxyphenylpyruvate oxidase, what metabolite will accumulate?
p-Hydroxyphenylpyruvic acid
In the middle ins the metabolic pathway on the left is the disorders when the enzyme is missing and on the right is the enzyme that catalyzes a specific step in this pathway. Phenylalanine is a carbon atom connected to H, NH2, COOH, CH2 hexagon rings. When acted by phenylamine hydroxylase it becomes tyrosine and mutation causes phenylketonuria. Tyrosine is a carbon atom attached to H, COOH, NH2, CH2 hexagon ring HO. This when acted by tyrosine aminotransferase gives p-hydroxyphenolypyruvic acid. This when acted by hydroxyphenylpyruvate oxidase gives homogentisic acid and its mutation can cause tyrosinosis. When homogentisic acid oxidase acts upon gives maleylacetoacetic acid and its mutation give alkaptonuria. The accumulation of high levels of phenylalanine in the blood would most likely be the result of mutations in the gene that encodes ______.
phenylalanine hydroxylase
A coding sequence specifies the amino acid sequence of a(n) ____.
polypeptide
A linear sequence of amino acids is denoted by the term ____.
polypeptide
The components mRNA, tRNA, ribosomes, and translation factors must be made by a cell so that ____ can be synthesized.
polypeptides, proteins, or protein
The characteristics of an organism are rooted in the activities of cellular ____ encoded by genes.
protein
During translation, the stop codons are recognized by a protein called a(n) ____ factor.
release
What molecules must assemble during the initiation stage of translation?
ribosomal subunits the first tRNA mRNA molecule
What is the site of translation?
ribosome
Antibiotics such as erythromycin and chloramphenicol inhibit bacterial translation by binding to bacterial:
ribosomes
Translation occurs on structures called ____.
ribosomes
The structural differences between bacterial and eukaryotic ____ allow for the treatment of bacterial infections in humans. This is possible because some antibiotics selectively inhibit translation in bacteria.
ribosomes or translation
During initiation of translation, the initiator tRNA recognizes the ____ codon in mRNA and binds to it.
start
The enzymes that catalyze the attachment of amino acids to tRNA molecules are known as aminoacyl-tRNA ____.
synthetases
The ____ molecule is attached to an amino acid and has an anticodon that can base pair with a codon.
tRNA
Which of the following components are necessary for translation?
tRNA mRNA translation factors ribosomes
The regulatory sequence of a gene can be bound by proteins that influence ______.
the rate of transcription
How many nucleotides are in an anticodon?
three
In a tRNA molecule, the anticodon is a ______-base sequence.
three
An RNA copy of a gene is produced via the process of ____.
transcription
The copying of DNA into RNA occurs in the process called ____.
transcription
The synthesis of an RNA copy of a gene is called ______.
transcription Reason: Translation is the synthesis of a polypeptide using the information in mRNA. The synthesis of RNA from a DNA template is called transcription.
Eukaryotic proteins that influence the ability of RNA polymerase to transcribe genes are called ______.
transcription factors
A messenger RNA sequence can be translated into a specific amino acid sequence because ____ RNA molecules base pair with mRNA codons and are attached to specific amino acids.
transfer, t, or tRNA
A stop codon specifies the end of
translation Reason: Codons are used during translation to convert an mRNA sequence into an amino acid sequence. Transcription is the synthesis of RNA from a DNA template, and the end of transcription is signaled by a terminator sequence on the DNA.
Because all organisms use the same code, with few exceptions, the genetic code is said to be nearly ____.
universal
Beadle and Tatum hypothesized that genes carry the information to make specific enzymes. They reasoned that a mutation might cause a defect in an enzyme required for the synthesis of an amino acid or another essential molecule such as a(n) ______.
vitamin