Exam 4 - Chapter 17

Question 1

gene expression

Answer 1

process by which DNA directs proteins synthesis as described by the central dogma

Question 2

transcription

Answer 2

DNA in genes encode for mRNA

Question 3

translation

Answer 3

mRNA is converted into amino acids that make up a protein

Question 4

one gene-one polypeptide hypothesis

Answer 4

• one gene codes for one polypeptide.

- many proteins are composed of multiple polypeptides, each coded for by their own gene

Question 5

mRNA

Answer 5

messenger RNA- intermediate between DNA and protein, codes for amino acid sequence

Question 6

rRNA

Answer 6

ribosomal RNA-makes up ribosomes along with proteins

Question 7

tRNA

Answer 7

transfer RNA-folded RNA that carries amino acids and transfers them to the ribosome during translation

Question 8

codon

Answer 8

mRNA nucleotide triplet which codes for a specific amino acid

Question 9

start codon

Answer 9

codes for an amino acid and begins translation-AUG

Question 10

stop codon

Answer 10

don’t code for an amino acid and ends translation- UAA, UAG, UGA

Question 11

reading frame

Answer 11

once the start codon is reached, mRNA is read in groups of 3 nucleotides until a stop codon is reached

Question 12

redundant

Answer 12

more than one codon codes for a specific amino acid

Question 13

unambiguous

Answer 13

each codon only codes for one amino acid

Question 14

nearly universal

Answer 14

shared by nearly all organisms

Question 15

eukaryotic transcription

Answer 15

occurs in the nucleus

Question 16

prokaryotic transcription

Answer 16

occurs in the cytoplasm

Question 17

Transcription DNA->RNA

Answer 17

synthesis of mRNA

Question 18

Template strand direction read

Answer 18

3’-5’

Question 19

mRNA synthesized direction

Answer 19

5’-3’

Question 20

Template strand

Answer 20

only one DNA strand is transcribed

Question 21

other template strand

Answer 21

non-template or coding strand

Question 22

RNA polymerase

Answer 22

primary enzyme which functions during transcription

Question 23

initiation

Answer 23

RNA polymerase binds to a promoter and pries the DNA strands apart forming a transcription bubble

Question 24

Initiation in prokaryotes

Answer 24

RNA polymerase binds to a promoter and pries the DNA strands apart forming a transcription bubble

Question 25

initiation in eukaryotes

Answer 25

transcription factors bind to promoter, allowing RNA polymerase to bind to TATA box, forming transcription initiation complex, DNA strands are separated forming transcription bubble

Question 26

Enlogation

Answer 26

RNA polymerase unwinds and reads template strand, builds up mRNA transcript in the 5’ to 3’ direction

Question 27

Termination in prokaryotes

Answer 27

RNA polymerase stops transcription at termination sequence

Question 28

Termination in Eukaryotes

Answer 28

RNA polymerase transcribes polyadenylation sequence which signals transcription complex to stop

Question 29

Termination in both

Answer 29

mRNA and proteins disassociate and DNA helix reanneals

Question 30

Translation

Answer 30

RNA->protein

Question 31

Translation-mRNA

Answer 31

codons are read by the ribosomes in the 5'-3' direction and polypeptide is synthesized

Question 32

Ribosomes

Answer 32

composed of a large and small subunit made of protein and rRNA

Question 33

E site

Answer 33

the exit site, where dischared tRNAs leave the ribosome

Question 34

P site

Answer 34

holds the most current tRNA attached to the growing polypeptide

Question 35

A site

Answer 35

holds the tRNA that carries the next amino acid to be added to the polypeptide chain

Question 36

tRNA

Answer 36

delivers specific amino acid to the ribosome

Question 37

wobble

Answer 37

- flexible pairing at the third base of an mRNA codon | - allows some tRNA to bind to more than one mRNA codon

Question 38

Translation-initiation

Answer 38

– small ribosomal subunit binds with mRNA and initiator tRNA in P site - ribosomal subunit moves along mRNA until it reaches the start codon (AUG) where tRNA binds to mRNA - initiation factors bring in large subunit building translation initiation complex

Question 39

Translation-Elongation

Answer 39

- amino acids are added to preceding amino acid | - requires elongation factors (4 steps: codon recognition, peptide bond forms, translocation)

Question 40

translation-termination

Answer 40

-occurs when stop codon on mRNA reaches A site causing A site to accept release factor adding water molecule

Question 41

post-translation modifications

Answer 41

- during and after protein synthesis, a polypeptide may be chemically modified or appended - the final polypeptide will fold into its 3d functional form resulting in a protein

Question 42

mutations

Answer 42

a random and permanent change in the genetic material of a cell or virus

Question 43

point mutation

Answer 43

changes in just one nucleotide base pair

Question 44

substitution mutation

Answer 44

point mutation where one base pair is replaced by another

Question 45

insertions mutation

Answer 45

one ore more base pairs are inserted into a gene

Question 46

deletions mutation

Answer 46

one or more base pairs are deleted from a gene

Question 47

Base pair substitution - silent

Answer 47

doesn't change amino acid, same protein results

Question 48

base pair substitution - missense

Answer 48

changes amino acid, different protein results

Question 49

base pair substitution - nonsense

Answer 49

premature stop codon, abbreviated protein results

Question 50

frameshift mutation

Answer 50

alter of the codon reading frame, produces a non-functional protein

Question 51

causes of mutation

Answer 51

- spontaneous mutations during dna replication, recombination or repair - exposure to mutagens, carcinogens