Exam 2 - Chapter 7

Question 1

Genome

Answer 1

Complete set of genetic information

- chromosome plus plasmids

Question 2

mRNA

Answer 2

Messenger RNA

Question 3

rRNA

Answer 3

Ribosomal RNA

Question 4

tRNA

Answer 4

Transfer RNA

Question 5

Replisomes

Answer 5

Assembly line of DNA replication

Question 6

Leading Strands

Answer 6

Synthesized continuously in the 5’ to 3’ direction

Question 7

Lagging Strands

Answer 7

Synthesized discontinuously in the 5’ to 3’ direction

Question 8

DNA Gyrase

Answer 8

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

Question 9

DNA Ligase

Answer 9

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

Question 10

DNA Polymerases

Answer 10

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

Question 11

Helicases

Answer 11

Enzymes that unwind the DNA helix at the replication fork

Question 12

Origin of Replication

Answer 12

Distinct region of a DNA molecule at which replication is initiated

Question 13

Primase

Answer 13

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

Question 14

Primer

Answer 14

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

Question 15

Replisome

Answer 15

The complex of enzymes and other proteins that synthesize DNA

Question 16

Okazaki Fragments

Answer 16

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

Question 17

1st Step of DNA Replication

Answer 17

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

Question 18

2nd Step of DNA Replication

Answer 18

Synthesis happens continuously at the leading strand, nice and easy

Question 19

3rd Step of DNA Replication

Answer 19

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

Question 20

4th Step of DNA Replication

Answer 20

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)

Question 21

5th Step of DNA Replication

Answer 21

DNA ligase fills the gaps between okazaki fragments with covalent bonds

Question 22

(-) Strand

Answer 22

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

Question 23

(+) Strand

Answer 23

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

Question 24

Promoter

Answer 24

Nucelotide sequence to which RNA polymerase binds to initiate transcription

Question 25

RNA Polymerase

Answer 25

Synthesizes RNA in 5’ to 3’ direction

Question 26

Sigma Factor

Answer 26

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

Question 27

Terminator

Answer 27

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

Question 28

1st Step of Transcription

Answer 28

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

Question 29

2nd Step of Transcription

Answer 29

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

Question 30

3rd Step of Transcription

Answer 30

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

Question 31

Anticodon

Answer 31

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

Question 32

Polyribosome (Polysome)

Answer 32

Multiple ribosomes attached to a single mRNA molecule

Question 33

Reading Frame

Answer 33

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

Question 34

Ribosome

Answer 34

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

Question 35

Ribosome Binding Site

Answer 35

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

Question 36

rRNA

Answer 36

Type of RNA molecule present in ribosomes

Question 37

Start Codon

Answer 37

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

Question 38

Stop Codon

Answer 38

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

Question 39

tRNA

Answer 39

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