Chapter 17 Terms

Question 1

genes

Answer 1

The information found in DNA is stored in specific regions of chromosomes called genes

Question 2

gene expression

Answer 2

the process by which DNA is converted into RNA and proteins, involves two stages:

• transcription
• translation

Question 3

transcription

Answer 3

The conversion of DNA into RNA

Question 4

translation

Answer 4

the process by which mRNA is converted into polypeptides

Question 5

messenger RNA

Answer 5

Required for protein synthesis

- contains the code for proteins

Question 6

transfer RNA

Answer 6

carries amino acids to ribosomes during protein synthesis

Question 7

ribosomal RNA

Answer 7

Required for protein synthesis

- major component of ribosomes

Question 8

primary transcript (pre-mRNA)

Answer 8

The initial mRNA (primary transcript) produced in eukaryotes undergoes processing inside the nucleus prior to being translated

Question 9

mature mRNA

Answer 9

pre-RNA is processed into mature mRNA prior to translation

Question 10

RNA polymerase

Answer 10

The main enzyme that carries out transcription
-Eukaryotes have three different RNA polymerases (one for mRNA, one for tRNA, and one for rRNA) while bacteria only have one RNA polymerase that make all three forms of RNA

Question 11

template strand

Answer 11

Only one of the two DNA strands is used for transcription. This is called the template strand

Question 12

codon

Answer 12

The nucleotide sequence of mRNA is read as three nucleotides units called codons

Question 13

anti-codon

Answer 13

At one end of the tRNA is an anticodon on the other end (the anticodon base-pairs with a complementary codon on mRNA)

Question 14

reading frame

Answer 14

a result of mutated genes

-Codons must be read in the correct reading frame

Question 15

frame shift

Answer 15

A shift in the reading frame lead to mutated proteins (frame shift mutation)

Question 16

promoter

Answer 16

RNA attaches and initiates transcription at a special DNA sequences called promoters that are found “upstream” of the gene that will be transcribed

Question 17

transcription: initiation, elongation, termination

Answer 17

RNA polymerase carries out transcription in three main steps:
–Initiation - RNA polymerase recognizes and binds to a special DNA sequence located upstream of a gene called a promoter
RNA polymerase then separates double stranded DNA forming a transcription bubble
–Elongation - RNA polymerase adds RNA nucleotides that are complementary to the DNA template strand in the 5’ to 3’ direction
–Termination - RNA transcript is released from DNA template and RNA polymerase detaches from DNA

Question 18

TATA box

Answer 18

In eukaryotes: transcription factors must first bind to a specific sequence in the promoter called the TATA box

Question 19

transcription initiation complex

Answer 19

The completed assembly of transcription factors and RNA polymerase II bound to a promote

Question 20

terminator sequence

Answer 20

In bacteria, the polymerase stops transcription at the end of the terminator sequence and the mRNA can be translated without further modification

Question 21

polyadenylation

Answer 21

In eukaryotes, RNA polymerase II transcribes the polyadenylation signal sequence (AAUAAA); the pre-RNA transcript is released 10–35 nucleotides past this polyadenylation sequence

Question 22

RNA processing

Answer 22

The pre-mRNA made during eukaryotic transcription is modified by enzymes prior to leaving the nucleus and being translated

Question 23

5’ cap

Answer 23

The 5’ end receives a 5’ cap made of a modified guanine nucleotides

Question 24

poly A tail

Answer 24

The 3’ end receives a poly A tail made of 50-250 adenine nucleotides

Question 25

introns

Answer 25

Pre-mRNA transcripts contain non-coding sections called introns that are found in between coding sections called exons
Introns are removed through RNA splicing

Question 26

exons

Answer 26

Pre-mRNA transcripts contain non-coding sections called introns that are found in between coding sections called exons

Question 27

RNA splicing

Answer 27

a process that removes introns and joins exons to create an mRNA molecule with a continuous coding sequence

Question 28

spliceosome

Answer 28

Protein and RNA enzyme complex that carries out RNA splicing

Question 29

ribozymes

Answer 29

The RNA molecules in the spliceosome

Question 30

aminoacyl-tRNA synthase

Answer 30

Enzyme that correctly matches tRNA and an amino acid for accurate translation of a mRNA molecule

Question 31

ribosome P site, A site, E site

Answer 31

A ribosome has three binding sites for tRNA:

• -The P site holds the tRNA that carries the growing polypeptide chain
• -The A site holds the tRNA that carries the next amino acid to be added to the chain
• -The E site is the exit site, where discharged tRNAs leave the ribosome

Question 32

translation: initiation, elongation, termination

Answer 32

• -Initiation brings together mRNA, an initiator tRNA , and the two ribosomal subunits to form an initiation complex
• -During elongation, amino acids are added one by one to the growing polypeptide chain
• -Translation proceeds along the mRNA in a 5′ → 3′ direction and Termination occurs when a stop codon in the mRNA reaches the A site of the ribosome

Question 33

translation initiation complex

Answer 33

Initiation brings together mRNA, an initiator tRNA , and the two ribosomal subunits to form an initiation complex

Question 34

initiator tRNA

Answer 34

In Translation: First, a small ribosomal subunit binds with mRNA and a special initiator tRNA (met-tRNA)

Question 35

start codon

Answer 35

In translation: the small subunit moves along the mRNA until it reaches the start codon (AUG)

Question 36

translation: initiation factors

Answer 36

Proteins called initiation factors bring in the large subunit that completes the translation initiation complex

Question 37

codon recognition

Answer 37

In Elongation: the anticodon of incoming amino acid-tRNA binds to codon of mRNA

Question 38

translocation

Answer 38

In Elongation: the P site tRNA moves to E site and is then released; A site tRNA moves to P site which makes A site available for new tRNA to bind

Question 39

stop codon

Answer 39

Termination of translation occurs when a stop codon in the mRNA reaches the A site of the ribosome

Question 40

release factor

Answer 40

In translation: a protein called a release factor binds to the stop codon A site

Question 41

post translational modification

Answer 41

addition of other molecules or functional groups to polypeptide
(Polypeptide chains undergo this before becoming a fully functional protein)