Case 4 DNA expression (M1B1)

Question 1

Eukaryotic transcription involves separate polymerases for the synthesis of?

Answer 1

mRNA, rRNA, tRNA

Question 2

what do mRNA, rRNA, tRNA do?

Answer 2

• mRNA: type of rna that carries instructions from the DNA in the nucleus to the ribosome
• tRNA: type of rna that carries amino acids to the ribosome (used in translation)
• rRNA: reads dna sequence, makes polypeptides that go to make up PROTEINS

Question 3

a molecules that regulate gene expression by binding onto promoters of DNA and create transcription complex?

Answer 3

transcription factors

Question 4

types of RNA polymerase?

Answer 4

rna polymerase 1, 2 and 3

their non-coding

Question 5

functions of RNA polymerase 1, 2 and 3?

Answer 5

• RNA P 1: synthesizes 28S, 18S, and 5.8S rRNA in the nucleus
• RNA P 2: synthesizes mRNA that are subsequently translated to produce proteins
• RNA P 3: transcribes tRNA, one rRNA, and one snRNA.

Question 6

Polymerase 2 also synthesizes certain small ncRNAs, such as?

Answer 6

snRNA
snoRNA
miRNA

Question 7

A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex.Thymine and adenine rich consensus sequence region

Answer 7

TATA/Hogness box

Question 8

A consensus sequence that occur upstream by 70-80 bases to the initial transcription site?

Answer 8

CAAT box

The CAAT box signals the binding site for the RNA transcription factor

Question 9

the initial, linear, RNA copy of a transcription unit the segment of DNA between specific initiation and termination sequences is called?

Answer 9

primary transcript

Question 10

The primary transcripts of both prokaryotic and eukaryotic tRNA and rRNA are posttranscriptionally modified by cleavage of the original transcripts by?

Answer 10

ribonucleases

Question 11

eukaryotic and prokaryotic tRNA are also made from longer precursor molecules that must be modified. Sequences at both ends of the molecule are removed and, if pre- sent, an intron is removed from the anticodon loop by

Answer 11

nucleases

Question 12

collection of all the primary transcripts synthesized in the nucleus by RNA polymerase II is known as?

Answer 12

heterogeneous nuclear RNA (hnRNA)

Question 13

The pre-mRNA components of hnRNA undergo extensive co- and posttranscriptional modification in the nucleus. These modifications usually include?

Answer 13

1) 5’ “Capping”
2) Addition of a poly-A tail
3) Removal of introns

Question 14

which modification is this:

In eukaryotic pre-mRNA processing, the additoin of 7-methylgluanosine to the nucleotide at the 5’ end of pre-mRNA by a triphosphate bridge. Methylation of adjacent nucleotides may also occur.

Answer 14

5’ capping

Question 15

3) Addition of a poly-A tail: Most eukaryotic mRNA have a chain of 40–200 adenine nucleotides attached to the 3’-end. This poly-A tail is not transcribed from the DNA, but rather is added after transcription by the nuclear enzyme, polyadenylate polymerase, using ATP as the substrate.

Answer 15

…

Question 16

3) Removal of introns: Maturation of eukaryotic mRNA usually involves the removal of RNA sequences (introns, or intervening sequences), which do not code for protein from the primary tran- script. The remaining coding sequences, the exons, are joined together to form the mature mRNA.

Answer 16

…

Question 17

The process of removing introns and joining exons is called?

Answer 17

splicing

Question 18

The molecular complex that accomplishes splicing is known as the?

Answer 18

spliceosome

Question 19

Upstream consensus sequence of eukaryotic promoters that is rich in guanine and cytosine?

Answer 19

GC rich box

GGGCGG located -90 or more upstream

Question 20

The pathway of protein synthesis is called………….. because the “language” of the nucleotide sequence on the mRNA is translated into the “language” of an amino acid sequence.

Answer 20

translation

Question 21

Any alteration in the nucleic acid sequence may result in an incorrect amino acid being inserted into the polypeptide chain, potentially causing?

Answer 21

disease or even death of the organism

Question 22

three-base sequence on messenger RNA that codes for a single amino acid?

Answer 22

codon

Question 23

group of three bases on a tRNA molecule that are complementary to an mRNA codon?

Answer 23

anticodon

Question 24

codon sequences are written from what to what?

Answer 24

5’-end to the 3’-end

Question 25

Three of the codons that do not code for amino acids, but rather are termination codons are?

Answer 25

UAG, UGA, UAA

Question 26

Characteristics of the genetic code include?

Answer 26

1. Specificity: genetic code is specific a specific codon always codes for the same amino acid
2. Universality: genetic code is virtually universal
3. Degeneracy: The genetic code is degenerate. Although each codon corresponds to a single amino acid, a given amino acid may have more than one triplet coding for it.
4. Nonoverlapping and commaless: the code is read from a fixed starting point as a continuous sequence of bases, taken three at a time

Question 27

if one amino acid is missing during protein synthesis what happens?

Answer 27

translation stops

Question 28

At least one specific type of tRNA is required for each amino acid.

Answer 28

…

Question 29

a two-step reaction that results in the covalent attachment of the carboxyl group of an amino acid to the 3’-end of its corresponding (cognate) tRNA is the?

Answer 29

Aminoacyl-tRNA synthetases

Question 30

ribosome has three bind- ing sites for tRNA molecules the which are?

Answer 30

A, P, and E sites

Question 31

Initiation, elongation, and termination (or release) factors are required for?

Answer 31

peptide synthesis

Question 32

Binding of the tRNA anticodon to the mRNA codon follows the rules of complementary and antiparallel binding, that is, the mRNA codon is “read” 5’→3’ by an anticodon pairing in the “flipped” (3’→5’) orientation

Answer 32

…

Question 33

The process of trans- lation is divided into three separate steps which are?

Answer 33

initiation, elongation, termination.