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Biology 120 > Chapter 13 > Flashcards

Chapter 13 Flashcards

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1
Q

What is the central dogma of molecular biology?

A

All organisms use the same basic processes to generate proteins from the hereditary information stored in the DNA molecule; the seven rules that govern the production of proteins.

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2
Q

What is the bacterial gene made up of?

A

A promoter (binds RNA polymerase and signals the start of the gene), a TATA box (a sequence found in the promoter that signals where transcription will start), a transcription unit (contains the information required to directly translate the amino acid sequence), a transcription stop point (marks the end of the gene and signals the end of transcription).

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3
Q

Where does transcription and translation occur in bacteria?

A

In the cytoplasm.

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4
Q

Where does transcription and translation occur in eukaryotes?

A

In the nucleus and in the cytoplasm.

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5
Q

What are the stages of transcription?

A

Initiation, Elongation, Termination

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6
Q

What is Initiation? (Transcription)

A

The molecular machinery that carriers out transcription assembles at the promoter and begins synthesizing a RNA copy of the gene. The promoter marks the beginning and tells the RNA polymerase where to start.

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7
Q

What is Elongation?(Transcription)

A

Polymerization of the RNA transcript. The sigma factor releases the RNA polymerase which opens the DNA double helix and begins to move along the DNA strand, making a mobile copy of the gene called mRNA.

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8
Q

What is Termination?(Transcription)

A

As the RNA polymerase moves along the DNA, it rewinds the double helix behind it. When the RNA polymerase reaches the termination signal, it and the new mRNA molecule will dissociate from the DNA strand - ending the transcript.

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9
Q

What is mRNA?

A

Messenger RNSs, transcribe genes that code for proteins; the most common type. Encoded by genes and made by RNA polymerases.

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10
Q

What is tRNA?

A

Transfer RNAs, translation interpreters. Important because they allow the translation to actually occur; reads the code and brings in the amino acid language - allowing them to work together. Encoded by genes and made by RNA polymerases.

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11
Q

What is rRNA?

A

Ribosomal RNAs, structural part of the ribosome - doesn’t get translated. Encoded by genes and made by RNA polymerases.

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12
Q

What is the Eukaryotic Gene?

A

Contains promoters and terminators and Introns. The exons are the pieces of DNA information we want, the introns must be removed.

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13
Q

What are Introns?

A

Sequences of DNA that are transcribed but are removed before translation.

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14
Q

What is the process for maturing pre-mRNA?

A

A cap is added to the 5’ end of the RNA, then the introns are removed, and then a poly-A tail is added to the 3’ end, and then it is exported.

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15
Q

Why is the poly-A tail needed?

A

To stabalize the mRNAs. As the mRNA ages the tail will get shorter, RNA is a lot more unstable than DNA.

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16
Q

What is a Silent Mutation?

A

Causes no change.

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17
Q

What is a Missense Mutation?

A

Changes one amino acid.

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18
Q

What is a Nonsense Mutation?

A

Changes to a stop codon.

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19
Q

What is a Frameshift Mutation?

A

Produces a different amino acid sequence.

20
Q

How can mutations alter phenotypes?

A

By generating a non-functional protein, changing how a protein works, altering when a gene is expressed, or changing where a gene is expressed.

21
Q

True or False: Mutations are random occurrences.

A

True. They can range from simple base pair changes to loss of chromosome fragments.

22
Q

What can cause a mutation?

A

Any agent that can damage DNA - UV light, chemicals, viruses, mistakes in the DNA replication process.

23
Q

What is the One Gene-One Polypeptide Hypothesis?

A

Restatement of the one gene-one enzyme hypothesis, taking into account some proteins consist of more than one polypeptide and not all proteins are enzymes.

24
Q

What is Translation?

A

The use of information encoded in the RNA to assemble amino acids into a polypeptide.

25
Q

What is the Genetic Code?

A

The nucleotide information that specifies the amino acid sequence of a polypeptide.

26
Q

What is a Codon?

A

A three-letter word of the genetic code.

27
Q

What is Methionine? (AUG)

A

The start codon, initiator codon.

28
Q

What are UAA, UAG, and UGA?

A

Termination or nonsense codons.

29
Q

Define Degeneracy

A

The feature of the genetic code in which (except for methionine and tryptophan) more than one codon represents each amino acid.

30
Q

Define Commaless

A

The sequential nature of the words of the nucleic acid code, with no indicators such as commas or spaces to mark the end of one codon and the beginning of the next

31
Q

Define Reading Frame

A

The particular grouping of triplet bases read by transfer RNA during translation

32
Q

Define Promoter

A

The site to which RNA polymerase binds for initiating transcription

33
Q

What is mRNA splicing?

A

The process where introns are removed from pre-mRNAS and exons are joined together - occurs in the nucleus.

34
Q

What are Spliceosomes?

A

A complex formed between the pre-mRNAs and snRNAs where mRNA splicing takes place. Cleaves the pre-mRNA to release the intron and join the exons.

35
Q

What are snRNAs?

A

Particles that are a complex of RNA and proteins. They bind in a particular order to an intron in the pre-mRNA to release the intron and form the active spliceosome.

36
Q

What is Alternate Splicing?

A

A mechanism that joins exons in different combinations to produce different mRNAS from a single gene. Increases the number and variety of proteins encoded in the nucleus.

37
Q

What direction is translation done in?

A

5’ to 3’.

38
Q

What are Anticodons?

A

The three-nucleotide segment in tRNAs that pair with a codon in mRNAs

39
Q

What is Aminocylation?

A

The process of adding an amino acid to a tRNA (charging).

40
Q

What is the A site of the rRNA?

A

The site where incoming aminoacyl-tRNA (tRNA linked to the amino acid) binds to the mRNA

41
Q

What is the P site of the rRNA?

A

The site in the ribosome where the tRNA is bound.

42
Q

What is the E site of the rRNA?

A

The site where an exiting tRNA binds before being released from the ribosome.

43
Q

What is Initiation? (Translation)

A

Translation components assemble on the start codon.

44
Q

What is Elongation? (Translation)

A

Assembled complex reads the string of codons in the mRNA one at a time while joining the amino acids into the polypeptide.

45
Q

What is Termination?(Translation)

A

Completes the translation process when the complex disassembles after the last amino acid specified has been added. Release factor protein recognizes stop codons.

Biology 120 (13 decks)

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