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College Biology > Lecture 11 - test 3 > Flashcards

Lecture 11 - test 3 Flashcards

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1
Q

What is a gene?

A

A sequence of bases in a DNA molecule that carries information for making proteins.

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2
Q

What is a genome?

A

An organisms complete set of DNA.

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3
Q

Does all DNA contain instructions for making proteins?

A

No.

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4
Q

How big is human’s genome compared to an amoeba?

A

Small.

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5
Q

What are introns?

A

Non-coding DNA within genes.

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6
Q

How does DNA turn into a protein?

A

DNA is transcribed to RNA and RNA is translated into a protein.

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7
Q

What is transcription?

A

When the gene’s sequence is copied from DNA to a middleman molecule called RNA. (DNA -> RNA)

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8
Q

What is translation?

A

When the gene’s sequence is encoded in mRNA, which directs the production of a protein. (RNA -> protein)

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9
Q

What violates the order of central dogma?

A

Viruses.

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10
Q

What are the steps of transcription?

A
  1. Recognize and bind
  2. Transcribe
  3. Terminate
  4. Cap and process
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11
Q

What happens during the first stage of transcription?

A

The RNA polymerase recognizes a promoter site and binds to one strand of the DNA.

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12
Q

What happens during the second stage of transcription?

A

The DNA strand goes through the RNA polymerase and it builds a single strand RNA copy of the gene, called mRNA transcript.

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13
Q

What happens during the third stage of transcription?

A

The RNA polymerase encounters a code that tells it to stop transcribing and releases the mRNA.

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14
Q

What happens during the fourth stage of transcription?

A

A cap and tail is put on the mRNA for protection and to promote recognition and the non-coding sections are removed.

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15
Q

What are the steps of translation?

A
  1. Recognition and initiating protein building
  2. Elongate
  3. Terminate
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16
Q

What happens during the first stage of translation?

A

The start sequence of the mRNA is recognized and the tRNA attaches, with the ribosomal subunits assemble.

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17
Q

What happens during the second stage of translation?

A

The tRNA molecule binds to the mRNA and then floats away.

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18
Q

What happens during the third stage of translation?

A

The ribosome encounters the stop sequence and the mRNA is released.

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19
Q

What nitrogen base in DNA is replaced in RNA?

A

T (thymine) is replaced by U (uracil).

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20
Q

What does RNA polymerase creat?

A

RNA.

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21
Q

What is RNA made of?

A

RNA nucleotides.

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22
Q

What are 3 requirements for transcription?

A
  1. A promoter
  2. A start site
  3. A termination site
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23
Q

Wha is a promoter?

A

It forms a recognition and binding site for the RNA polymerase and is found in front of the start site. It is not transcribed.

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24
Q

What are 2 forms of RNA polymerase?

A
  1. Core polymerase
  2. Holoenzyme
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25
Q

What is the holoenzyme for?

A

It is needed to accurately initiate synthesis.

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26
Q

What direction does transcription elongation occur?

A

5’-3’

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27
Q

What is a transcription bubble?

A

It contains an RNA polymerase, DNA template, and growing RNA transcript.

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28
Q

What happens after the DNA is transcribed and leaves the transcription bubble?

A

It rewinds into the double helix.

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29
Q

What nucleotides pair together?

A

C to G
A to T (or U in RNA)

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30
Q

What happens when transcription is terminated?

A

A hairpin is formed when the RNA joins with itself and pokes the polymerase to release the RNA.

31
Q

What is an operon?

A

A single mRNA that contains multiple genes in prokaryotes.

32
Q

What is different about transcription and translation in prokaryotes?

A

They occur at the same time.

33
Q

What does RNA polymerase I transcribe?

A

rRNA.

34
Q

Wat does RNA polymerase II transcribe?

A

mRNA and some snRNA.

35
Q

What does RNA polymerase III transcrib?

A

tRNA and some other small RNAs.

36
Q

What is the initiation complex?

A

When the RNA polymerase II associates with the transcription factors.

37
Q

What are mRNA modifications that occur in eukaryotes?

A
  1. A 5’ cap is added
  2. A 3’ poly-A tail is added
  3. Introns are removed
38
Q

What are introns?

A

non-coding sequences.

39
Q

What are exons?

A

Sequences that will be translated.

40
Q

What are snRNPs?

A

small ribonucleoprotein particles that form spliceosome and removes introns.

41
Q

What is pre-mRNA splicing?

A

When the introns are removed.

42
Q

What is alternative splicing?

A

When a single primary transcript is spliced intro different mRNAs by exluding different sets of exons.

43
Q

What does alternative splicing explain?

A

How humans have only 20,000 genes, but can encode 93,000 proteins.

44
Q

How is the order of amino acids determined?

A

By the order of nucleotides in DNA and RNA.

45
Q

What is a codon?

A

A block of 3 DNA nucleotides corresponding to an amino acid.

46
Q

Are amino acids only specified by one codon?

A

No there are 64 possible codons and only 20 amino acids, so more than one codon specify only one amino acid.

47
Q

Can one codon code for more than 1 amino acid?

A

No.

48
Q

What are 2 types of special codons?

A

Stop codons and start codons.

49
Q

How is tRNA used in the process?

A

It brings amino acids to be added to a protein.

50
Q

What do aminoacyl-tRNA synthetases do?

A

Add amino acids to the acceptor stem of RNA.

51
Q

How many subunits do ribosomes have?

A

Large and small.

52
Q

What are the tRNA-binding sites on ribosomes?

A
  1. E site
  2. P site
  3. A site
53
Q

What is the E site on a ribosome?

A

It binds the tRNA that carries the previous amino acid added.

54
Q

What is the P site on a ribosome?

A

It binds the tRNA attached to the growing peptide chain.

55
Q

What is the A site on a ribosome?

A

It binds the tRNA carrying the next amino acid site.

56
Q

What are two primary functions of ribosomes?

A
  1. Decode the mRNA
  2. Form peptide bonds
57
Q

What is peptidyl transferase?

A

It forms peptide bonds between amino acids.

58
Q

What is translation?

A

The creation of proteins.

59
Q

What are requirements of translation?

A
  1. Ribosomes
  2. mRNA
  3. tRNA
  4. Amino acids
60
Q

What do ribosomes do in translation?

A

They decode the mRNA and create the protein.

61
Q

What do mRNA do in translation?

A

They code for the amino acid order.

62
Q

What do tRNA do in translation?

A

They bring the correct amino acid to be added.

63
Q

What do amino acids do in translation?

A

They are the building blocks of proteins.

64
Q

In prokaryotes, what makes up the initiation complex?

A
  1. Initiator tRNA charged with N-formylmethionine
  2. Small ribosomal subunit
  3. mRNA strand
65
Q

What happens in prokaryotic translation?

A

The ribosome binding sequence of mRNA positions small subunit, the large subunit is added, and the initiator tRNA binds to the P site.

66
Q

How is eukaryotic translation different from prokaryotic translation?

A
  1. The initiating amino acid is methionine
  2. It is a more complicated process
  3. Lack of an RBS (ribosome binding sequence)
67
Q

What is elongation in translation?

A

When amino acids are added.

68
Q

What happens in elongation?

A

The second tRNA binds to the empty A site, EF-Tu bind to tRNA and GTP and a peptide bond is formed. Amino acids are added as the cycle continues.

68
Q

What is the elongation cycle?

A
  1. The tRNA anticodon is matched with the mRNA codon
  2. The peptide bond is formed
  3. Ribosomes are translocated
69
Q

What is wobble pairing?

A

When there are fewer tRNA’s than codons.

70
Q

What does wobble pairing accomplish?

A

It allows less stringent pairing between the 3’ base of the codon and the 5’ base of the anticodon, which allows fewer tRNAs to accommodate all codons.

71
Q

What is the translation termination?

A

When the ribosome encounters a stop codon, which releases the polypeptide chain.

72
Q
A

College Biology (24 decks)

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