Ch 10 From DNA to Proteins

Question 1

ribosomal RNA (rRNA)

Answer 1

along with ribosomal protein subunits, makes up the ribosome

Question 2

messenger RNA (mRNA)

Answer 2

carries the coding instructions for polypeptide chains from DNA to the ribosome

Question 3

pre-messenger RNAs (pre-mRNAs)

Answer 3

large precursor molecules; are the immediate products of transcription in eukaryotic cells
not found in bacterial cells

Question 4

transfer RNA (tRNA)

Answer 4

serves as the link between the coding sequence of nucleotides in an mRNA molecule and the amino acid sequence of a polypeptide chain

Question 5

small nuclear RNAs (snRNAs)

Answer 5

combine with small protein subunits to form small nuclear ribonucleoproteins (snRNPs)

Question 6

small nucleolar RNAs (snoRNAs)

Answer 6

takes part in the processing of rRNA

Question 7

microRNAs (miRNAs) and small interfering RNAs (siRNAs)

Answer 7

two types of very small and abundant RNA molecules found in the cytoplasm of eukaryotic cells

Question 8

RNA interference (RNAi)

Answer 8

a process in which these small RNA molecules help trigger the degradation of mRNA or inhibit its translation into protein

Question 9

three major components of transcription

Answer 9

1) A DNA template
2) The raw materials (ribonucleotide triphosphates) needed to build a new RNA molecule
3) The transcription apparatus, consisting of the proteins necessary for catalyzing the synthesis of RNA

Question 10

template strand

Answer 10

the nucleotide strand used for transcription

Question 11

nontemplate strand

Answer 11

not ordinarily transcribed

Question 12

transcription unit

Answer 12

a stretch of DNA that encodes an RNA molecule and the sequences necessary for its transcription

Question 13

promoter

Answer 13

a DNA sequence that the transcription apparatus recognizes and binds
indicates which of the two DNA strands is to be read as the template and the direction of transcription

Question 14

RNA-coding region

Answer 14

a sequence of DNA nucleotides that is copied into an RNA molecule

Question 15

three critical regions within a transcription unit

Answer 15

a promoter, an RNA-coding sequence, and a terminator

Question 16

terminator

Answer 16

a sequence of nucleotides that signals where transcription is to end

Question 17

ribonucleoside triphosphates

Answer 17

RNA is synthesized from this

Question 18

RNA polymerase

Answer 18

carries out all the required steps of transcription

Question 19

core enzyme

Answer 19

five subunits (individual polypeptide chains) make up this
enzyme catalyzes the elongation of the RNA molecule by the addition of RNA nucleotides

Question 20

sigma factor

Answer 20

controls the binding of RNA polymerase to the promoter

Question 21

holoenzyme

Answer 21

sigma factor associates with the core enzyme

Question 22

consensus sequences

Answer 22

short stretches of common nucleotides; they possess considerable similarity, or consensus

Question 23

10 consensus sequence

Answer 23

sometimes called the Pribnow box

written simply as TATAAT

Question 24

35 consensus sequence

Answer 24

sequence common to most bacterial promoters is TTGACA, which lies approximately 35 nucleotides upstream of the start site

Question 25

Rho-dependent terminators

Answer 25

able to cause the termination of transcription only in the presence of an ancillary protein called the rho factor

Question 26

Rho-independent terminators

Answer 26

also known as intrinsic terminators | able to cause the end of transcription in the absence of rho

Question 27

rho utilization site (rut)

Answer 27

serves as a binding site for the rho protein, which binds the RNA and moves toward its 3' end, following the RNA polymerase

Question 28

hairpin

Answer 28

inverted repeats (sequences of nucleotides on the same strand that are inverted and complementary) are transcribed into RNA and bind to each other, forms this secondary structure

Question 29

polycistronic RNA

Answer 29

produced when a single terminator is present at the end of a group of several genes that are transcribed together, instead of each gene having its owen terminator

Question 30

exons

Answer 30

- many eukaryotic genes contain these coding regions | - are joined to yield the mature RNA

Question 31

introns

Answer 31

noncoding regions called intervening sequences common in eukaryotic genes but are rare in bacterial genes tend to be longer than exons do not encode proteins

Question 32

codon

Answer 32

in mRNA, each amino acid in a protein is specified by a set of three nucleotides

Question 33

three primary regions of prokaryotic and eukaryotic mRNAs

Answer 33

5' untranslated region, the protein-coding region, and the 3' untranslated region

Question 34

5' untranslated region

Answer 34

5' UTR, sometimes called the leader | a sequence of nucleotides at the 5' end of the mRNA, does not encode any of the amino acids of a protein

Question 35

Shine-Dalgarno sequence

Answer 35

a consensus sequence (UAAGGAGGU) which serves as the ribosome-binding site during translation found approximately seven nucleotides upstream of the first codon translated into an amino acid (the start codon)

Question 36

protein-coding region

Answer 36

comprises the codons that specify the amino acid sequence of the protein begins with a start codon and ends with a stop codon

Question 37

5' untranslated region

Answer 37

3' UTR, sometimes called a trailer | a sequence of nucleotides that is at the 3' end of the mRNA and is not translated into protein

Question 38

5' cap

Answer 38

cap consists of an extra modified nucleotide at the 5' end of the mRNA as well as methyl groups (CH3) on the 2'-OH group of the sugar of one or more nucleotides at the 5' end

Question 39

poly(A) tail

Answer 39

addition of 50-250 or more adenine nucleotides at the 3' end; these nucleotides are not encoded in the DNA, but are added after transcription in a process termed polyadenylation

Question 40

RNA splicing

Answer 40

removal of introns | takes places in the nucleus, before the RNA moves to the cytoplasm

Question 41

5' splice site and 3' splice site

Answer 41

these splice sites possess short consensus sequences

Question 42

branch point

Answer 42

an adenine nucleotide that lies from 18 to 40 nucleotides upstream of the 3' splice site

Question 43

spliceosome

Answer 43

splicing takes place within a large structure which is one of the largest and most complex of all molecular structures

Question 44

lariat

Answer 44

pre-mRNA is cut at the 5' splice site which frees exon 1 from the intron, and the 5' end of the intron attaches to the branch point; that is, the intron folds back on itself

Question 45

alternative processing

Answer 45

many eukaryotic mRNAs undergo this which is a single pre-mRNA is processed in different ways to produce alternative types of mRNA, resulting in the production of different proteins from the same DNA sequence

Question 46

alternative splicing

Answer 46

the same pre-mRNA can be spliced in more than one way to yield multiple mRNAs that are translated into different amino acid sequences and thus different proteins

Question 47

cloverleaf structure

Answer 47

some of the nucleotides in a tRNA are complementary to each other and form intramolecular hydrogen bonds which results in this

Question 48

anticodon

Answer 48

a set of three nucleotides which pairs with the corresponding codon on the mRNA during protein synthesis to ensure that the amino acids link in the correct order

Question 49

trimming

Answer 49

additional nucleotides may then be removed one at a time from the 5' and 3' ends of the tRNA in a process known as this

Question 50

two subunits of a functional ribosome

Answer 50

large ribosomal subunit and small ribosomal subunit

Question 51

RNA interference (RNAi)

Answer 51

a powerful and precise mechanism used by eukaryotic cells to limit the invasion of foreign genes (from viruses and transposons) and to censor the expression of their own genes triggered by double-stranded RNA molecules, which may arise in several ways: by the transcription of inverted repeats into an RNA molecule that then base pairs with itself to form double-stranded RNA; by the simultaneous transcription of two different RNA molecules that are complementary to one another and that pair, forming double-stranded RNA; or by infection by viruses that make double-stranded RNA

Question 52

two abundant classes of RNA molecules that function in RNA

Answer 52

small interfering RNA and microRNAs

Question 53

RNA-induced silencing complex (RISC)

Answer 53

both siRNA and miRNA molecules combine with proteins to form this the key to functioning of RISCs is a protein called Argonaute

Question 54

CRISPR RNAs

Answer 54

Assist in the destruction of foreign DNA molecules