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4U BIO > 6.1/6.2/6.3 > Flashcards

6.1/6.2/6.3 Flashcards

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1
Q

One-Gene/One-Polypeptide Hypothesis

A

A proposal that one gene codes for one polypeptide (or protein)

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2
Q

Messenger RNA (mRNA)

A

RNA that contains the genetic information of a gene and carries it to the protein synthesis machinery; provides the information that determines the amino acid sequence of a protein.

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3
Q

How is mRNA synthesized?

A

It is synthesized from the DNA of genes.

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4
Q

The mRNA base sequence would be ____________ to the gene DNA sequence.

A

Complementary

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5
Q

Genetic Code

A

A set of rules for determining how genetic information in the form of a nucleotide sequence is converted to an amino acid sequence of a protein; a code specifying the relationship between a nucleotide codon and an amino acid.

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6
Q

Triplet Hypothesis

A

A proposal that the genetic code is read three nucleotide bases at a time.

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7
Q

Codon

A

A combination of three nucleotides.

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8
Q

How is the genetic code always interpreted?

A

In terms of the mRNA codon rather than nucleotide sequence of the DNA.

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9
Q

Three Important Characteristics of the Genetic Code

A

1) It is redundant.
2) It is continuous.
3) It is nearly universal.

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10
Q

The Genetic Code is Redundant

A
  • More than one codon can code for the same amino acid.

- Three codons don’t code for any amino acid. (Serve as ‘stop’ signals that end protein synthesis)

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11
Q

The Genetic Code is Continuous

A

-reads as a series of three-letter codes without spaces, punctuation of overlap

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12
Q

The Genetic Code is Nearly Universal

A

-almost all organisms build proteins with the same genetic code

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13
Q

Gene Expression

A

The transfer of genetic information from DNA to RNA to protein.

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14
Q

Central Dogma

A

The theory that genetic information flows from DNA to RNA to protein.

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15
Q

Two Steps in Gene Expression

A
  • Transcription

- Translation

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16
Q

Transcription

A

The synthesis of RNA from a DNA template.

-mRNA is synthesized

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17
Q

Translation

A

The synthesis of protein from an mRNA template.

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18
Q

What is DNA often described as?

A

The blueprint of a cell, which stores information needed for survival and reproduction.

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19
Q

Where is RNA synthesized?

A

Nucleus

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20
Q

Messenger RNA (mRNA)

A
  • the RNA strand that is synthesized in the nucleus and carries the template for translation to the cytoplasm
  • nucleus –> cytoplasm
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21
Q

Transfer RNA (tRNA)

A
  • transport amino acids to ribosomes
  • positions each amino acid at correct place on polypeptide chain
  • cytoplasm
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22
Q

Ribosomal RNA (rRNA)

A
  • site of polypeptide synthesis (not involved in coding)

- ribosomes

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23
Q

What is the main objective of transcription?

A

To accurately produce a copy of a small section of genomic DNA.

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24
Q

Three Stages of Transcription

A

Initiation, Elongation, Termination

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25
Q

For each gene, how many strands of double-stranded DNA molecules are transcribed?

A

Only One

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26
Q

Antisense Strand

A
  • the strand of DNA that is transcribed

- ‘non-coding strand’

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27
Q

Sense Strand

A
  • the strand of DNA that is not transcribed

- ‘coding’ strand

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28
Q

RNA Polymerase

A

The main enzyme that catalyzes the formation of RNA from a DNA template.

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29
Q

At what point does transcription begin?

A
  • When RNA polymerase binds tightly to a promoter region on the DNA
  • DNA is unwound and opens a section of the double helix
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30
Q

Promoter Region

A

A sequence of nucleotides in DNA that indicates where the RNA polymerase complex should bind to initiate transcription.

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31
Q

Initiation in Transcription

A

-the correct position for transcription to start is selected and the transcription machinery , composed of large-protein DNA complex is assembled

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32
Q

Elongation During Transcription

A

-the RNA polymerase complex works its way along the DNA molecule, synthesizing a strand of mRNA that is complementary to the anti-sense or template strand of DNA

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33
Q

In what direction does RNA polymerase work?

A

5’ to 3’

new nucleotides are added to the 3’ end with hydroxyl

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34
Q

As soon as the RNA polymerase complex starts to move along the DNA..what can happen?

A

A second RNA polymerase complex can bind to the promoter region and start to synthesize another RNA molecule.

35
Q

Termination During Transcription

A
  • specific nucleotide sequences in the DNA template serve as the signal to stop transcription
  • RNA polymerase detaches from DNA strand
  • new mRNA strand is released and DNA double helix reforms
36
Q

What must mRNA undergo before it is transported across the nuclear membrane into the cytoplasm?

A

It must undergo modification.

37
Q

Precursor mRNA (pre-mRNA)

A

-mRNA that has not undergone processing

38
Q

Mature mRNA

A

-mRNA that has undergone processing

39
Q

What are the two ways that mRNA is modified?

A
  • addition of 5’ cap
  • addition of 3’ poly-A tail
  • removal of introns
40
Q

5’ Cap

A

-modified form of a G nucleotide; added to the 5’ end of an mRNA

41
Q

3’ Poly-A Tail

A

A series of A nucleotides added to the 3’ end of mRNA

42
Q

Introns

A

Non-coding regions of genes.

43
Q

Exons

A

Coding regions of genes

44
Q

Splicing

A

In mRNA, a process of excising out the introns and combining in the exons.

45
Q

What is responsible for splicing?

A

-snRNPs (snurps)

46
Q

Alternative Splicing

A

-when only certain exons are used to form a mature RNA transcript

47
Q

Transfer RNA (tRNA)

A

An RNA molecule that links the codons on mRNA to the corresponding amino acid for protein synthesis.
cloverleaf shape with anticodon on bottom and amino acid on top

48
Q

Anticodon Loop

A

A triplet of bases positioned at one end of a tRNA that recognizes and base-pairs with a codon on mRNA during protein synthesis.

49
Q

Acceptor Stem

A

The 3’ end of a tRNA molecule that is the site of attachment for a particular amino acid, based on the anticodon

50
Q

What direction are anticodon written in?

A

3’ to 5’

51
Q

Aminoacyl-tRNA Synthetase

A

The enzyme responsible for attaching an amino acid to a tRNA

52
Q

Ribosome

A

A cell structure composed of proteins and rRNA that provides the site where protein synthesis occurs.

53
Q

Ribosomal RNA (rRNA)

A

The RNA that is associated with proteins in the ribosome.

54
Q

Two Sub-Units of Ribosome

A

Large Sub-Units: 60S

Small Sub-Unit: 40S

55
Q

What are the binding sites on the ribosomes called?

A

A Site: Acceptor Site, where new tRNA’s enter the ribosome

P Site: Peptide Site, where tRNA moves to allow next tRNA to enter, forms the peptide bond

56
Q

Polyribosome

A

A structure composed of multiple ribosomes along a strand of mRNA.

57
Q

Initiation During Translation

A
  • initiation factors assemble the small ribosomal sub-unit, mRNA, initiator tRNA, and large ribosomal sub-unit
  • small RSU attaches to mRNA at start codon (AUG)
  • initiator tRNA binds to AUG codon
  • large RSU joins to form active ribosome
58
Q

Start Codon

A

A triple of three bases that specifies the first amino acid of a protein.

59
Q

Reading Frame

A

Collectively, the codons of mRNA that are read to produce an amino acid sequence; it is set by the start codon.

60
Q

Elongation During Translation

A
  • as tRNA leave through the exit site, new tRNA bind to the A site
  • as tRNA move to the P site a peptide bond is formed between the first and second amino acids
61
Q

Peptide Bond

A

A covalent bond formed between two amino acids during protein synthesis.

62
Q

Termination During Translation

A
  • occurs when stop codon is reached on mRNA (UGA,UAG,UAA)
  • polypeptide and components of machinery are separated
  • release factor cuts the polypeptide from the last tRNA
63
Q

Mutation

A

A permanent change in the nucleotide sequence of a cell’s DNA that is inherited

64
Q

Single-Gene Mutation

A

A mutation that involves changes in the nucleotide sequence of one gene.

65
Q

Chromosomal Mutation

A

A mutation that involves changes in chromosomes, and may involve many genes.

66
Q

Point Mutation

A

A mutation involving a single base pair substitution, insertion of deletion.

67
Q

Substitution Mutation

A

A mutation that exchanges one base for another.

68
Q

Deletion Mutation

A
  • one or more base pairs on the DNA is removed or eliminated
  • changes the properties of the protein and can result in the production of a defective protein
69
Q

Insertion Mutation

A
  • one or more base pairs is added to the DNA sequence
  • results in an extra amino acid being coded for in the polypeptide sequence
  • can alter how the protein behaves
70
Q

Frameshift Mutation

A

A mutation caused by the addition or deletion of a number of nucleotides not divisible by three, resulting in a change in the reading frame.

71
Q

Three Types of Substitution Mutations

A
  • Silent Mutation
  • Missense Mutation
  • Nonsense Mutation
72
Q

Silent Mutation

A

A mutation that does not change the amino acid sequence of a protein.

73
Q

Missense Mutation

A

A mutation that changes the amino acid sequence of a protein.
A different amino acid is coded, so sequence changes.

74
Q

Nonsense Mutation

A
  • a mutation that shortens a protein by introducing a stop codon
  • causes polypeptide chain to be terminated prematurely
75
Q

Types of Chromosomal Mutations

A
  • deletion
  • duplication
  • inversions
  • translocations
76
Q

Deletion in Chromosomal Mutations

A

-a section of the chromosome is deleted

77
Q

Duplication in Chromosomal Mutations

A

-a section of the chromosome is repeated

78
Q

Inversion in Chromosomal Mutations

A

-a section of the chromosome is broken and then re-inserted in the opposite direction

79
Q

Translocations in Chromosomal Mutations

A

A fragment of DNA breaks off and joins at another place on the chromosome or on another chromosome.

80
Q

Transposon

A

A short segment of DNA capable of moving within the genome of an organism; also called a jumping gene.

81
Q

Spontaneous Mutations

A

-take place naturally in the cell as a result of normal molecule interactions

82
Q

Mutagen

A

An event or substance that increases the rate of changes to the DNA sequence of an organism’s genome.

83
Q

Chemical Mutagen

A

A molecule that can enter the nucleus of a cell and induce mutations by reacting chemically with the DNA.
eg. Nitrites, gasoline fumes, cigarette smoke

84
Q

Physical Mutagen

A

A mutagen that physically changes the structure of DNA.

eg. X-rays, UV Radiation

4U BIO (11 decks)

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