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Molecular Genetics > Protein Synthesis > Flashcards

Protein Synthesis Flashcards

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1
Q

What is meant by “the genetic code is universal” and why is this significant?

A

It is used by all known organisms as the code for the DNA, mRNA, and tRNA. It is like a universal language.

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2
Q

What is transcription?

A

The copying of the info. in DNA to mRNA.

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3
Q

What is translation?

A

The ribosomes using the mRNA as a blueprint to synthesize a protein.

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4
Q

What does mRNA stand for and what does it do?

A

Messenger RNA. It copies DNA’s code & carries genetic info. to ribosomes.

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5
Q

What does rRNA stand for and what does it do?

A

Ribosomal RNA. Along with protein, makes up ribosomes.

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6
Q

What does tRNA stand for and what does it do?

A

Transfer RNA. Transfers amino acids to ribosomes where no proteins are synthesized.

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7
Q

RNA polymerase

A

An enzyme that transcribes DNA into complementary mRNA.

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8
Q

Describe tRNA.

A
  • clover leaf shape
  • single stranded with attachment site at one end for amino acid
  • opposite end has 3 nucleotide bases called anticodon
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9
Q

What is the codon and what is its function?

A

A sequence of 3 bases in DNA or complementary mRNA that serves as a code for a certain amino acid. It designates amino acids.

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10
Q

What is a start codon and stop codon?

A

A start codon signals the ribosome that the translation starts here and a stop codon does the opposite.

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11
Q

Describe mRNA

A
  • long straight chain
  • made in nucleus
  • sequence of 3 bases (codon)
  • AUG (methionine) is start codon
  • UAA,UAG or UGA are stop condons
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12
Q

Describe rRNA

A
  • made in nucleus

- site of protein synthesis

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13
Q

How many amino acids are there and how many possible combinations of codons are there?

A

20 amino acids and 64 possible codons

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14
Q

Can an amino acid have more than 1 codon?

A

Yes

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15
Q

List the codons for these amino acids:

Gly-Phe-Lys

A

Glycine
Phenylalanine
Lysine

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16
Q

What are the possible sequences for:

Gly-Phe-Lys

A

GGG, GGC, GGA, GGU
UUU, UUC
AAA, AAG

17
Q

What is the first major step of protein synthesis? Briefly describe it.

A

Initiation. The enzyme RNA polymerase binds to the DNA double helix and unwinds the strand exposing the template strand.

18
Q

What is the central dogma?

A

It states that DNA -> RNA -> protein.

19
Q

Why does RNA polymerase bind “upstream” of the DNA.

A

The upstream region consists of mainly A and T base pairs with 2 H bonds. It takes less energy to break them apart so less energy is expended opening the helix.

20
Q

What is the second step of protein synthesis?

A

Elogation. mRNA is synthesized in the direction of 5’ to 3’ using one strand as a template. RNA polymerase synthesizes mRNA. Termination sequence is reached.

21
Q

Is it in DNA replication or protein synthesis that RNA polymerase does not require a primer?

A

Protein synthesis.

22
Q

What is the third step of protein synthesis?

A

Termination. RNA synthesis ceases. The mRNA and RNA polymerase are released.

23
Q

Differences of DNA replication and transcription.

A
  • Rep. occurs in preparation for cell division
  • Tran. in preparation for protein translation
  • Rep. for regulating growth/division of cells
  • Rep will not occur is certain growth factors are missing
  • Tran. Regulate gene expression
  • Tran. only occurs when gene is activated
24
Q

Similarities between DNA replication and transcription

A
  • involve binding complementary nucleic acids
  • yield a new strand of info.
  • can both lead to errors that cause change in gene
25
Q

Role of template strand?

A

The strand of DNA that the RNA polymerase uses as a guide to build the mRNA.

26
Q

Role of a ribosome?

A

Synthesizes the assembly of proteins.

27
Q

What is a DNA triplet?

A

A group of 3 bases that code for an amino acid.

28
Q

How does a DNA triplet differ from a codon?

A

3 bases on mRNA and complementary to DNA triplet.

29
Q

How does a DNA triplet differ from a anticodon?

A

3 bases on tRNA and complementary to a codon.

30
Q

What are nucleotides?

A

Form the basic structure of DNA. They are composed of a phosphate group, a sugar and a nitrogenous base.

Molecular Genetics (2 decks)

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