2.6 dna/rna structure

Question 1

draw a labeled diagram of 4 nucleotides of dna

Answer 1

see notebook

Question 2

what are the 3 principal components of a nucleotide?

Answer 2

5-carbon pentose sugar (pentagon)
Phosphate group (circle)
Nitrogenous base (rectangle)

Question 3

what does dna stand for?

Answer 3

deoxyribonucleic acid

Question 4

what does rna stand for?

Answer 4

ribonucleic acid

Question 5

Differences between DNA and RNA: pentose sugar

Answer 5

dna is deoxyribose, rna is ribose

Question 6

Differences between DNA and RNA: base composition

Answer 6

dna: a, g, c, t
rna: a, g, c, u

Question 7

Differences between DNA and RNA: number of strands

Answer 7

dna: double-stranded, forms a double helix
rna: single-stranded

Question 8

explain dna structure

Answer 8

DNA is a double helix molecule made of two antiparallel strands of nucleotides linked by hydrogen bonding between complementary base pairs

Question 9

what type of bond connects complementary nitrogenous bases?

Answer 9

hydrogen bonds

Question 10

how many h-bonds b/w adenine and thymine/uracil?

Answer 10

2

Question 11

how many h-bonds b/w guanine and cytosine?

Answer 11

3

Question 12

who created the first correct dna model?

Answer 12

James Watson and Francis Crick

Question 13

name 3 faults in early dna models

Answer 13

• The first model generated was a triple helix
• Early models had bases on the outside and sugar-phosphate residues in the centre
• Nitrogenous bases were not initially configured correctly and hence did not demonstrate complementarity

Question 14

which nitrogenous bases are purines?

Answer 14

guanine and adenine

Question 15

which nitrogenous bases are pyrimidines?

Answer 15

cytosine, thymine, and uracil

Question 16

3 types of rna

Answer 16

messenger rna, transfer rna, ribosomal rna

Question 17

messenger rna (mRNA)

Answer 17

a transcript copy of a gene which encodes a specific polypeptide

Question 18

transfer rna (tRNA)

Answer 18

carries the polypeptide subunits (amino acids) to the organelle responsible for synthesis (ribosome)

Question 19

ribosomal rna (rRNA)

Answer 19

a primary component of the ribosome and is responsible for its catalytic activity