Exam 2 - Chapter 7 Flashcards

1
Q

Genome

A

Complete set of genetic information

- chromosome plus plasmids

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2
Q

mRNA

A

Messenger RNA

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3
Q

rRNA

A

Ribosomal RNA

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4
Q

tRNA

A

Transfer RNA

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5
Q

Replisomes

A

Assembly line of DNA replication

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6
Q

Leading Strands

A

Synthesized continuously in the 5’ to 3’ direction

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7
Q

Lagging Strands

A

Synthesized discontinuously in the 5’ to 3’ direction

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8
Q

DNA Gyrase

A

Enzyme that temporarily breaks the strands of DNA, relieving the tension caused by unwinding the two strands of the DNA helix

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9
Q

DNA Ligase

A

Enzyme that joins two DNA fragments together by forming a covalent bond between the sugar and phosphate residues of adjacent nucleotides

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10
Q

DNA Polymerases

A

Enzymes that synthesize DNA; they use one strand of DNA to make the other complementary strand. Nucleotides can only be added to the 3’ end of an existing fragment-therefore, synthesis always occurs in the 5’ to 3’ direction

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11
Q

Helicases

A

Enzymes that unwind the DNA helix at the replication fork

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12
Q

Origin of Replication

A

Distinct region of a DNA molecule at which replication is initiated

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13
Q

Primase

A

Enzyme that synthesizes small fragments of RNA to serve as primers for DNA synthesis

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14
Q

Primer

A

Fragment of nucleic acid to which DNA polymerase can add nucleotides (the enzyme can add nucleotides only to existing fragments)

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15
Q

Replisome

A

The complex of enzymes and other proteins that synthesize DNA

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16
Q

Okazaki Fragments

A

Nucleic acid fragment produced during discontinuous synthesis of the lagging strand of DNA

17
Q

1st Step of DNA Replication

A

Helicases unzip the DNA helix at the replication forks, revealing two strands that will act as templates

18
Q

2nd Step of DNA Replication

A

Synthesis happens continuously at the leading strand, nice and easy

19
Q

3rd Step of DNA Replication

A

Synthesis happens discontinuously at the lagging strand, because it can’t add nucleotides to the 5’ end. So it basically has to redo itself with a new RNA primer every time, making okazaki fragments

20
Q

4th Step of DNA Replication

A

DNA polymerase adds nucleotides to the 3’ end of okazaki fragments, eventually running into the 5’ end. So it has to replace the RNA primers with deoxynucleotides (no oxygen)

21
Q

5th Step of DNA Replication

A

DNA ligase fills the gaps between okazaki fragments with covalent bonds

22
Q

(-) Strand

A

Strand of DNA that serves as the template for RNA synthesis; the resulting RNA molecule is complementary to this strand

23
Q

(+) Strand

A

Strand of DNA complementary to the (-) strand that serves as the template for RNA synthesis; the nucleotide sequence of the RNA molecule is the same as this strand, except it has Uracil instead of Thymine

24
Q

Promoter

A

Nucelotide sequence to which RNA polymerase binds to initiate transcription

25
RNA Polymerase
Synthesizes RNA in 5' to 3' direction
26
Sigma Factor
Component of RNA polymerase that recognizes the promoter regions. A cell can have different types of sigma factors that recognize different promoters, allowing the cell to transcribe specialized sets of genes as needed
27
Terminator
Nucleotide sequence at which RNA synthesis stops; the RNA polymerase falls off the DNA template and releases the newly synthesized RNA
28
1st Step of Transcription
RNA polymerase binds to the promoter with the use of the sigma factor, and denatures a short stretch of DNA
29
2nd Step of Transcription
RNA polymerase synthesizes RNA in the 5' to 3' direction, denaturing DNA furthermore and renaturing the used portions
30
3rd Step of Transcription
RNA polymerase encounters the terminator, falling off and allowing the new RNA to be released
31
Anticodon
Sequence of 3 nucleotides in a tRNA molecule that is complimentary to a particular codon in mRNA
32
Polyribosome (Polysome)
Multiple ribosomes attached to a single mRNA molecule
33
Reading Frame
Grouping of a stretch of nucleotides into sequential triplets that code for amino acids; an mRNA molecule has 3 potential reading frames, but only 1 is typically used in translation
34
Ribosome
Structure that facilitates the joining of amino acids during the process of translation; composed of protein and ribosomal RNA. The prokaryotic ribosome (70S) consists of a 30S and 50S subunit
35
Ribosome Binding Site
Sequence of nucleotides in mRNA to which a ribosome binds; the first time the codon for methionine (AUG) appears after that site, translation generally begins
36
rRNA
Type of RNA molecule present in ribosomes
37
Start Codon
Codon at which translation is initiated; it is typically the first AUG after a ribosome-binding site
38
Stop Codon
Codon that terminates translation, signaling the end of the protein; there are 3 stop codons
39
tRNA
Type of RNA molecule involved in interpreting the genetic code; each tRNA molecule carries a specific amino acid dictated by its anticodon