Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Micro Exam 3 > IV. Protein Synthesis: Translation > Flashcards

IV. Protein Synthesis: Translation Flashcards

(59 cards)

Start Studying
1
Q

What exactly is translation?

A

Translation is the process by which ribosomes synthesize proteins using messenger RNA (mRNA) as a template.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What exactly is a protein?

A

A protein is a large biomolecule composed of one or more long chains of amino acids, essential for various biological functions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is an amino acid? What are the major structural features of an amino acid?

A

An amino acid is a building block of proteins, characterized by a central carbon atom, an amino group, a carboxyl group, a hydrogen atom, and a variable side chain (R group).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a peptide bond? How do they form?

A

A peptide bond is a covalent bond that links two amino acids together, formed through a dehydration reaction between the amino group of one amino acid and the carboxyl group of another.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a polypeptide? How is a polypeptide different from a protein?

A

A polypeptide is a chain of amino acids linked by peptide bonds. A protein is a functional molecule that may consist of one or more polypeptides folded into a specific three-dimensional shape.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the four levels of protein structure? What types of chemical bonds or interactions are involved in forming and stabilizing each level of structure?

A

The four levels of protein structure are primary (amino acid sequence), secondary (alpha helices and beta sheets), tertiary (3D folding), and quaternary (multiple polypeptide chains). Bonds include peptide bonds, hydrogen bonds, ionic bonds, and hydrophobic interactions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are two examples of secondary structure?

A

Two examples of secondary structure are alpha helices and beta sheets.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are protein domains?

A

Protein domains are distinct functional and structural units within a protein, often associated with specific activities.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Do all proteins have quaternary structure?

A

No, not all proteins have quaternary structure; only those composed of multiple polypeptide chains exhibit this level.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What exactly is denaturation? What are some causes of this? Can this be reversed?

A

Denaturation is the process where a protein loses its native structure due to factors like heat, pH changes, or chemicals. It can sometimes be reversed if the denaturing agent is removed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the function of transfer RNA (tRNA)?

A

tRNA serves as an adaptor molecule that translates the codon sequence of mRNA into the corresponding amino acid sequence during protein synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a codon? On what type of RNA molecule are codons found?

A

A codon is a sequence of three nucleotides that corresponds to a specific amino acid, found on messenger RNA (mRNA).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is an anticodon? On what type of RNA molecule are anticodons found?

A

An anticodon is a sequence of three nucleotides complementary to a codon, found on transfer RNA (tRNA).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the precise relationship between codons and anticodons?

A

Codons on mRNA pair with complementary anticodons on tRNA during translation, ensuring the correct amino acid is added to the growing polypeptide chain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a cognate amino acid?

A

A cognate amino acid is the specific amino acid that corresponds to a particular tRNA molecule based on its anticodon.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the function of aminoacyl-tRNA synthetases?

A

Aminoacyl-tRNA synthetases are enzymes that attach the correct amino acid to its corresponding tRNA, a crucial step in protein synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the major structural features of a tRNA molecule?

A

tRNA molecules have a cloverleaf structure with an anticodon loop, a 3’ acceptor stem, and variable regions that contribute to their overall shape.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What unusual bases are found in tRNA molecules?

A

tRNA molecules contain unusual bases such as inosine, pseudouridine, and dihydrouridine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the function of the CCA-adding enzyme?

A

The CCA-adding enzyme adds a CCA sequence to the 3’ end of tRNA molecules, which is essential for amino acid attachment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

To what end of the tRNA molecule is its cognate amino acid added?

A

The cognate amino acid is added to the 3’ end of the tRNA molecule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why is the function of aminoacyl-tRNA synthetases so important?

A

Aminoacyl-tRNA synthetases ensure that the correct amino acid is matched with its corresponding tRNA, which is critical for accurate protein synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What parts of the tRNA molecule serve as contact points to the aminoacyl-tRNA synthetase?

A

The acceptor stem and the anticodon region of the tRNA molecule serve as contact points to the aminoacyl-tRNA synthetase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How are amino acids ‘activated’ by aminoacyl-tRNA synthetases?

A

Amino acids are activated by aminoacyl-tRNA synthetases through the formation of an aminoacyl-AMP intermediate, followed by the transfer of the amino acid to the tRNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is a charged tRNA molecule?

Study These Flashcards
A

A charged tRNA molecule is a tRNA that is covalently linked to its corresponding amino acid, ready for incorporation into a growing polypeptide chain.

25
How many ATP 'equivalents' are required to 'charge' a tRNA molecule?
Two ATP equivalents are required to charge a tRNA molecule.
26
What exactly is the genetic code?
The genetic code is the set of rules by which information encoded in mRNA is translated into proteins, specifying which amino acids correspond to each codon.
27
What exactly is a codon? What molecule contains codons? How many possible codons are there?
A codon is a sequence of three nucleotides in mRNA that specifies an amino acid. There are 64 possible codons.
28
How many naturally occurring amino acids are there?
There are 20 naturally occurring amino acids.
29
Why is the genetic code called degenerate (or redundant)?
The genetic code is called degenerate because multiple codons can specify the same amino acid, providing a buffer against mutations.
30
What exactly is an anticodon? What molecule contains an anticodon?
An anticodon is a sequence of three nucleotides that is complementary to a codon, found on transfer RNA (tRNA).
31
What is the wobble concept (wobble theory) and why is it important?
The wobble concept refers to the flexibility in base pairing between the third position of a codon and the first position of an anticodon, allowing for some codons to pair with multiple tRNAs.
32
What is a codon bias and how can this be used?
Codon bias is the preference for certain codons over others in the coding sequences of genes, which can be used to optimize gene expression in different organisms.
33
What is the sequence of the start codon?
The sequence of the start codon is AUG.
34
In Bacteria, what chemically modified amino acid begins every polypeptide chain?
In Bacteria, the chemically modified amino acid N-formylmethionine (fMet) begins every polypeptide chain.
35
Why is it important for translation to begin at the correct nucleotide?
Beginning translation at the correct nucleotide ensures that the ribosome reads the mRNA in the correct reading frame, producing the correct protein.
36
What are the -1, 0, and +1 reading frames?
-1, 0, and +1 reading frames refer to the different ways to read a nucleotide sequence in groups of three, with 0 being the correct frame, -1 being one nucleotide shifted left, and +1 being one nucleotide shifted right.
37
What is the Shine-Dalgarno sequence, where is it located, and why is it important?
The Shine-Dalgarno sequence is a ribosomal binding site in bacterial mRNA, located upstream of the start codon, important for initiating translation.
38
What are the sequences of the three stop (nonsense) codons?
The sequences of the three stop codons are UAA, UAG, and UGA.
39
What is unusual about some stop codons in Bacteria and Archaea? How does this process work?
In some Bacteria and Archaea, stop codons can be read as coding for amino acids due to specific tRNAs that recognize them, allowing for non-standard translation.
40
What exactly is an open reading frame (ORF)?
An open reading frame (ORF) is a continuous stretch of codons that begins with a start codon and ends with a stop codon, indicating potential protein-coding sequences.
41
In an unknown DNA sequence, what does the presence of an ORF indicate?
The presence of an ORF in a DNA sequence suggests that there may be a gene encoding a protein.
42
What are the three phases (steps) of protein synthesis?
The three phases of protein synthesis are initiation, elongation, and termination.
43
What energy source is used to synthesize proteins?
GTP (guanosine triphosphate) is the primary energy source used to synthesize proteins.
44
What molecules and organelles are required for synthesizing proteins?
Ribosomes, mRNA, tRNA, and various amino acids are required for synthesizing proteins.
45
In prokaryotes, what type or types of ribosomal RNA molecules are found in the small and large ribosomal subunits?
In prokaryotes, the small ribosomal subunit contains 16S rRNA, while the large subunit contains 23S and 5S rRNA.
46
What six components make up the protein synthesis initiation complex in Bacteria?
The six components are the small ribosomal subunit, mRNA, initiator tRNA, GTP, initiation factors, and the large ribosomal subunit.
47
What is the RBS (ribosome binding site) and where is it located? What is it complementary to?
The RBS is a sequence on mRNA that is located upstream of the start codon and is complementary to a region of the 16S rRNA in the small ribosomal subunit.
48
How are ribosomes able to translate polycistronic mRNA molecules?
Ribosomes can translate polycistronic mRNA molecules by recognizing multiple RBS sequences, allowing for the synthesis of multiple proteins from a single mRNA.
49
What is the purpose of the A, P, and E sites on a ribosome?
The A site (aminoacyl site) holds the incoming tRNA, the P site (peptidyl site) holds the tRNA with the growing polypeptide, and the E site (exit site) is where tRNA exits the ribosome.
50
What elongation factor is required to bind arriving tRNA molecules at the ribosome A site?
Elongation factor Tu (EF-Tu) is required to bind arriving tRNA molecules at the ribosome A site.
51
What, exactly, catalyzes the formation of the peptide bonds during translation?
The peptidyl transferase activity of the ribosomal RNA (rRNA) in the large subunit catalyzes the formation of peptide bonds during translation.
52
What happens during the translocation event in protein synthesis? What 3 elongation factors are required? How much 'energy' is needed for each translocation event?
During translocation, the ribosome moves along the mRNA, shifting the tRNA from the A site to the P site. Three elongation factors (EF-Tu, EF-Ts, and EF-G) are required, and one GTP is hydrolyzed for each translocation event.
53
What is a polysome?
A polysome is a complex of multiple ribosomes translating the same mRNA simultaneously, allowing for efficient protein synthesis.
54
What are release factors?
Release factors are proteins that recognize stop codons and promote the release of the newly synthesized polypeptide from the ribosome.
55
What is the general function of ribosomal proteins?
Ribosomal proteins help to stabilize the ribosomal RNA structure and facilitate the assembly and function of the ribosome.
56
What is/are the functions of 16S ribosomal RNA? of 23S ribosomal RNA?
16S rRNA is involved in the recognition of the mRNA and initiation of translation, while 23S rRNA has peptidyl transferase activity, catalyzing peptide bond formation.
57
What causes a ribosome to become 'trapped' or 'stalled' on a mRNA molecule?
A ribosome can become trapped or stalled due to the presence of a problematic codon, lack of a corresponding tRNA, or other translation errors.
58
What is tmRNA? How does it work to 'rescue' stalled ribosomes?
tmRNA is a molecule that acts as both tRNA and mRNA, allowing stalled ribosomes to add a short peptide tag to incomplete proteins, facilitating their degradation.
59
What happens to the protein that is made by a stalled ribosome?
The protein made by a stalled ribosome is often incomplete and may be tagged for degradation or misfolded, leading to potential cellular stress.

Micro Exam 3 (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions