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Biology > Protein Synthesis > Flashcards

Protein Synthesis Flashcards

1
Q

What is the molecular definition of genes?

A

Sequences of nucleotides inside DNA that perform specific functions

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2
Q

What does the Garrod Hypothesis state?

A

One gene directs the production of one protein or enzyme

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3
Q

What does the Central Dogma Hypothesis state?

A

The genome is located inside the nucleus however proteins are synthesized outside the nucleus on the ribosomes

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4
Q

Why is one copy of DNA likely not sufficient?

A

Protein is required in large amounts. Thus one copy of DNA is likely, not sufficient because of the Garrod Hypothesis which states that one gene makes one protein

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5
Q

How is messenger RNA created in protein synthesis? how many copies of mRNA can be created?

A

DNA from the nucleus is copied into a single-stranded messenger RNA that is capable of encoding genetic information

-numerous copies of mRNA can be manufactured in the nucleus

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6
Q

What is transcription?

A

Copy of DNA information into mRNA

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7
Q

What is translation?

A

when Ribosomes read mRNA to make amino acid sequences into proteins

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8
Q

What are the three key characteristics of messenger RNA?
lit

A
  1. varies in length depending on the gene
  2. act as an intermediary between DNA and ribosomes
  3. translated into proteins by ribosomes
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9
Q

What are the two key characteristics of transfer RNA?
dc

A
  1. delivery of amino acids to ribosomes as they make proteins
  2. short and clover-shaped
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10
Q

What are the two key characteristics of ribosomal RNA?
ab

A
  1. help with the assembly and synthesis of ribosomes
  2. bind with proteins to form ribosomes
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11
Q

What codes for one amino acid? What is the start codon?

A

-three nucleotides are used to codes for one amino acid

-one codon codes for the start codon (AUG) while several others serve as stop codons

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12
Q

How many possible combinations of codons are there? What is the significance of this?

A

64 (because DNA consists of four different bases, and because there are three bases in a codon, and because 4 * 4 * 4 = 64) thus more than one codon can code for each amino acid

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13
Q

What is the codon chart used for?

A

Gives detailed information on which codon codes for which amino acid and the start and stop codons

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14
Q

What is the function of RNA polymerase?

A

Bonds to DNA segment meant to be transcribed. More specifically, it binds to the upstream region of the gene at the promoter and opens the helix

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15
Q

What is the function of the promoter?

A

Serve as the initial starting point for rna polymerase

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16
Q

Give a brief description of the structure of the promoter?

A

Consists of a region high of adenine and thymine (TATA Box) . Adenine and Thymine are held together by two hydrogen meaning they’re easier to separate than Cytosine and Guanine

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17
Q

Which direction does rna polymerase begin elongating?

A

In the 5’ to 3’ direction

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18
Q

When does rna polymerase begin elongating?

A

As soon as rna polymerase binds to the promoter

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19
Q

Does rna polymerase require a primer?

A

No

20
Q

Is the promoter transcribed?

A

No

21
Q

How many strands are transcribed?

A

Only one strand is transcribed

22
Q

What is the template strand?

A

The strand chosen for transcription

23
Q

What is the coding strand?

A

The strand that is not used for transcription (it will be identical to the newly formed rna except it has thymine instead of uracil)

24
Q

What happens to rna polymerase once it reaches the terminator sequence? What is the significance of this?

A

the newly synthesized mRNA dissociates from the template

Rna polymerase is now free to transcribe another gene

25
Q

What is the 5’ cap made of and why is it added to the gene?

A

made of 7 methyl guanosine

added to protect mRNA from digestion from other nucleases and phosphates in the cytoplasm

plays a role in initiating translation to create mature and stable messenger rna

26
Q

Why is the 3’ Cap called the poly-A-Tail and why is it added to the gene?

A

-consist of approximately 200 adenine ribonucleotides by enzyme poly-A-polymerase

-further protects against degradation

27
Q

What are spliceosomes?

A

Proteins that cut out non coding regions called introns and join together coding regions called exons

28
Q

How are quantity and speed favoured over quality in the transcription phase of protein synthesis?

A

-there is no quality control to ensure mRNA transcript is correct. Hence many more errors are made

-a single gene may be transcribed 100 times because there are not enough correcting proteins to make sure enough proteins are being formed

29
Q

What happens after transcription is complete?

A

The mRNA exits the nucleus and enters the cytoplasm to be translated by ribosomes

30
Q

What does ribosome structure look like?

A

Ribosomes is composed of two subunits; a large and small set

31
Q

Which direction do ribosomes add amino acids? How does it do this?

A

5’ to 3’ direction, adding a new amino acid for every codon it reads

32
Q

What is the reading frame?

A

The section of mRNA that is read for polypeptide formation

33
Q

What is the function of specific sites on the ribosome?

A

help guide the process of translation and the entry and exit of transfer RNA molecules with their amino acids

34
Q

What is the structure of tRNA

A

-a single stranded nucleic acid whose structure resembles a clover leaf

-at one arm exist the anticodon which recognizes the mRNA codon

-the opposite arm carries the corresponding amino acid

35
Q

What is the wobble hypothesis?

A

Every tRNA carries only one specific amino acid. Therefore, at least 20 distinct tRNA molecules must exist

-suggest that tRNA can recognize more than one codon by unusual pairing between the codon and the anticodon. It corrects for possible gene errors in mRNA

36
Q

What are Aminoactyl- tRNA? How many of these enzymes are there?

A

-Enzymes responsible for adding appropriate amino acids to its corresponding tRNA

-there are 20 of these amino acids. One specific to each amino acid and tRNA

37
Q

where is the P site located in the ribosome and what is its function?

A

the second binding site in transfer RNA in the ribosome

it holds the transfer RNA linked to the growing polypeptide chain

38
Q

where is the E site located in the ribosome and what is its function?

A

it is the third and final binding site for transfer RNA

a site where tRNA molecules bind before they dissociate from the ribosome

39
Q

where is the A site located in the ribosome and what is its function?

A

it is the first binding site in transfer RNA in the ribosomes

the a site binds incoming transfer RNA with the complementary codon on the mRNA

40
Q

what is the release factor?

A

a protein that allows the termination of translation by recognizing that stop codon in the mRNA sequence

41
Q

what is a transfer RNA

A

a molecule that makes sure the right amino acid is delievered to the mRNA

42
Q

what is a polypeptide?

A

a chain of amino acids linked together by peptide bond.

43
Q

What are ribosomes?

A

macromolecule machines that perform protein synthesis

44
Q

what is an anti-codon?

A

a sequence of nucleotides that form three complementary base pairs to one or more codons

45
Q

what are amino acids?

A

molecules that bind to form proteins

46
Q

what is a peptide bond?

A

a bond that holds two amino acids in a polypeptide chain

Biology (35 decks)

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