Exam 2 - Chapter 7 Flashcards

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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
Q

RNA Polymerase

A

Synthesizes RNA in 5’ to 3’ direction

26
Q

Sigma Factor

A

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
Q

Terminator

A

Nucleotide sequence at which RNA synthesis stops; the RNA polymerase falls off the DNA template and releases the newly synthesized RNA

28
Q

1st Step of Transcription

A

RNA polymerase binds to the promoter with the use of the sigma factor, and denatures a short stretch of DNA

29
Q

2nd Step of Transcription

A

RNA polymerase synthesizes RNA in the 5’ to 3’ direction, denaturing DNA furthermore and renaturing the used portions

30
Q

3rd Step of Transcription

A

RNA polymerase encounters the terminator, falling off and allowing the new RNA to be released

31
Q

Anticodon

A

Sequence of 3 nucleotides in a tRNA molecule that is complimentary to a particular codon in mRNA

32
Q

Polyribosome (Polysome)

A

Multiple ribosomes attached to a single mRNA molecule

33
Q

Reading Frame

A

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
Q

Ribosome

A

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
Q

Ribosome Binding Site

A

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
Q

rRNA

A

Type of RNA molecule present in ribosomes

37
Q

Start Codon

A

Codon at which translation is initiated; it is typically the first AUG after a ribosome-binding site

38
Q

Stop Codon

A

Codon that terminates translation, signaling the end of the protein; there are 3 stop codons

39
Q

tRNA

A

Type of RNA molecule involved in interpreting the genetic code; each tRNA molecule carries a specific amino acid dictated by its anticodon