Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology 108 Test #3 > Translation > Flashcards

Translation Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

How does the cell translate an mRNA message into a protein?

A

With the help of tRNA

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

How many nucleotides does a tRNA consist of? Is it a single strand?

A

80

YES

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

What is attached at the 3’ end of a tRNA?

A

an amino acid

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

What is the anticodon of the tRNA? How long is it? What is it complementary to?

A

This is a 3 nucleotide sequence that is located on the other end relative to the amino acid

This pairs complementary with a codon on mRNA

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

What is the function of aminoacyl-tRNA synthase?

A

This is an enzyme that matches and facilitates the binding of the amino acid to its appropriate tRNA molecule.

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

What are the two recognition steps that must occur in order for translation to be accurate?

A
  1. There must be a correct match between a tRNA and amino acid by the aminoacyl-tRNA synthase enzyme.
  2. There must be a correct match between the anticodon of the tRNA to the mRNA codon.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Look at this picture and have a basic understanding of how an amino acid is bound to tRNA.

A

Do it

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

How do ribosomes work with tRNA and mRNA in protein synthesis?

A

They facilitate the coupling of tRNA anticodons with their complementary mRNA codons.

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

What does a ribosome consist of?

A

Two ribosomal subunits: one large and one small

Ribosomal RNA (rRNA)

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

What are the three binding sites a robosome has for tRNA and their basic function?

A

P - holds the tRNA that carries the growing polypeptide chain

A - holds the tRNA that carries the next amino acid to be added to the chain

E - the exit site, tRNA leave the ribosome at this site.

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

Have an understanding of this picture of a ribosome with tRNA and mRNA attached.

A

DO IT

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

What are the three stages of translation? Which two steps may require energy? What is used as the source of energy?

A
  1. initiation (may use energy in form of GTP)
  2. elongation (may use energy in form of GTP)
  3. termination (use energy in form of GTP to dissociate ribosomal assembly)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Do all three stages of translation require cofactors to aid in the process?

A

YES

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

Describe the initiation stage of translation, this can be described in three steps.

A
  1. a small ribosomal subunit binds with mRNA and a special initiator tRNA (has methianine attached)
  2. the small subunit moves along the mRNA until it reached the start codon (AUG)
  3. Initiation factors (proteins) bring the large subunit and initiator tRNA takes up the P site of the large subunit.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the process of elongation in regards to translation. This is also described in a series of 3 steps.

A
  1. codon recognition - anticodon of incoming aminoacyl tRNA pairs with mRNA base sequence at the A site. (GTP hydrolysis makes this more efficient)
  2. Peptide bond formation - carboxyl end of elongated strand of amino acids in P site tRNA forms peptide bond with the amino group of new amino acid in A site on its tRNA. At this point the elongated strand is briefly at the A site.
  3. Translocation - robosome translocates the tRNA in the A site to the P site. At the same time the initial tRNA that was in the P site that is now empty of amino acids is moved to the E site where it is released. As the tRNAs are trnaslocated the mRNA moves alond with them because the tRNAs are bound to it. this exposes the next codon in the A site so the process can be repeated.

EACH ADDITION IS FACILITATED BY PROTEINS CALLED ELONGATION FACTORS.

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

Describe the process of termination in translocation. This is also described in a 3 step sequence.

A
  1. Ribosome reached stop codon on mRNA. The A site then accepts a release factor instead of a tRNA at this point.
  2. The release factor hydrolyzes the bond between the P site tRNA and the last amino acid of its polypeptide chain. Freeing the polypeptide and tRNA from the ribosome.
  3. The two ribosomal subunits and other components dissociate with the help of GTP hydrolysis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Can multiple ribosomes translate the same mRNA simultaneously? What does this form? Is there an advantage to this?

A

YES

This is called a polyribosome.

The advantage is many polypeptides can be made very quickly.

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

After translation, is a polypeptide chain ready to be considered a functional protein?

A

Most of the time, NO

They need to be modfied after translation

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

What happens after a polypeptide becomes a completed protein?

A

They are targeted to a specific site in the cell.

20
Q

Does a polypeptide chain coil and fold into a 3D molecule with secondary and tertiary structure during and after its synthesis?

A

YES

21
Q

What dictates the primary structure of the proteins (polypeptide chain)? What effect does this have on the conformation of the protein?

A

The gene

The determination of the primary structure indirectly determines the conformation of the polypeptide chain.

22
Q

What are some examples of posttranslational modifications that may be required before proteins can do their job?

A

attachment of sugars, lipids, phosphate groups, etc..

23
Q

What are the two types of ribosomes that may be found in a cells? What are they based on?

A

Based on their location:

Free ribosomes - found in cytosol and mainly produce proteins that function and stay in the cytosol

Bound ribosomes - Bound to the ER or nuclear envelope and produce proteins of the endomembrane system and proteins that are secreted from the cell (insulin, etc)

24
Q

Can free and bound ribosomes switch roles? Does this mean they are identical?

A

YES and YES

free can become bound and bound can become free

25
Q

Where does polypeptide synthesis ALWAYS start?

A

In the cytosol

26
Q

If polypeptide synthesis always started in the cytosol, how do polypeptides that are meant for the endomembrane system or for secretion make their way to the ER?

A

They are marked by a signal peptide.

27
Q

How does a signal peptide move a beginning polypeptide chain and its ribosome to the ER?

A

SRPs or signal recognition particles bind to the peptide and brings the signal peptide and its ribosome to the ER.

28
Q

Describe the function of mRNA, tRNA, and rRNA.

A

mRNA - carries information for amino acid sequences of proteins from DNA to ribosomes.

tRNA - serves as adapter molecule in protein synthesis and translated mRNA codons into amino acids

rRNA - Plays catalytic (ribozyme) roles and structural roles in ribosomes.

29
Q

What is a primary transcript?

A

This is a precursor to mRNA, rRNA, and tRNA before it is cleaved by splicing or cleavage.

30
Q

What is small nuclear RNA snRNA?

A

Plays a structural and catalytic role in spliceosomes.

31
Q

What is SRP RNA?

A

This is a component of the signal recognition particle (SRP).

32
Q

What is the role of small nucleolar RNA (snoRNA)?

A

Aids in processing pre-mRNA transcripts for ribosome subunit formation in the nucleolus.

33
Q

What is the function of small interfering RNA (siRNA) and microRNA (miRNA)?

A

These are involved in the regulation of gene expression.

34
Q

What enables RNA to have such diverse functions like structural, informational, and catalytic (3)?

A
  1. Can H-bond to other nucleic acids
  2. Can assume a 3D shape
  3. Has functional groups that allow it to act as a catalyst (ribozyme)
35
Q

What are two differences in the gene expression of prokaryotes vs. eukaryotes?

A
  1. The nuclear envelope separates transcription from translation in eukaryotes, these two can happen simultaneously in prokaryotes.
  2. Extensive RNA processing occurs in the nucleus before translation in eukaryotes. This does not occur in prokaryotes.
36
Q

What is the definition of a mutation?

A

Changes in the genetic material of a cell or virus.

37
Q

What is a point mutation?

A

This is a chemical change in just one base pair of a gene.

38
Q

What is it called when a mutation has an adverse effect on the phenotype of the organism?

A

Genetic disorder, or a hereditary disease

39
Q

Can even changing one base pair lead to an abnormal protein to be produced?

A

YES

40
Q

Understand this picture of a point mutation.

A

DO IT.

41
Q

A point mutation can be divided into two different categories, what are they?

A

Base-pair substitutions

Base pair insertions or deletions

42
Q

In the point mutation category that is base-pait substitutions, what does this refer to and what three sub-categories of mutation can occur?

A

This is the replacement of one nucleotide and its partner with another pair of nucleotide.

  1. Silent mutation - No effect on encoded protein due to redundancy of genetic code (multiple codons for same amino acid)
  2. Missense mutation - still codes for an amino acid, but not the right amino acid.
  3. Nonsense mutation - changing amino acid codon to a stop codon, nearly always lead to a nonfunctional protein.
43
Q

In regards to base-pair insertions or deletions point mutations, what are they are what do they cause?

A

The addition or loss of nucleotide pairs in a gene.

These often have a much more disasterous effect on the resulting protein than base pair substitution mutations do.

They cause a shift in the READING FRAME, which leads to a FRAMESHIFT MUTATION

44
Q

While some mutations are spontaneous, others are caused by physical or chemical agents. What are these agents called?

A

Mutagens.

45
Q

What is a gene?

A

A region of DNA whose final product is either a polypeptide or an RNA molecule.

Biology 108 Test #3 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions