Polymers of Life 8: DNA & RNA

Question 1

Does DNA stand for

Answer 1

Deoxyribose Nucleic Acid

Question 2

Definition of ribose

Answer 2

Sugar like glucose but with only five carbon atoms and it’s molecule

Question 3

Definition of deoxyribose

Answer 3

Almost the same as ribose but lacks 1 alcohol group

Question 4

Describe the basic building blocks of DNA

Answer 4

• Deoxyribose for DNA or ribose
  for RNA
• phosphate groups ( H3 PO4 )
• 4 different bases ( A, G, C, T )

Question 5

How do you join a deoxyribose molecule and a phosphate group together

-be able to draw

Answer 5

• condensation reaction ( water formed)
• 2 alcohol groups from the deoxyribose drawing to the phosphate group
• 2 Alcohol groups from the phosphate group join to the deoxyribose molecule

Look at sheet on how to draw

Question 6

What does the joining of many phosphate groups and deoxyribose

Answer 6

• Starting polymer structure for different kinds of DNA nucleotide formation
• exposed OH on deoxyribose will bond to the bases
• non exposed chain = phosphate backbone = remain the same ( where as different bases will be attached to exposed OHs)

Question 7

What is a DNA nucleotide

Answer 7

deoxyribose + phosphate + one of the bases

3 things have to be present for it to be a DNA nucleotide

Question 8

Name the 4 most common organic bases

Answer 8

1. Adenine, A
2. Thymine, T
3. Cytosine, C
4. Guanine, G

Question 9

Which part of the bases joins with the alcohol on the deoxyribose

Answer 9

Amine group = hydrogen bonding

Question 10

Be able to draw a full DNA nucleotide

Answer 10

Look at sheet

Question 11

How is the DNA molecule formed

Answer 11

• By millions of nucleotides joined together in a long chain
• alternating sugar-phosphate groups ( backbone ) + bases

Question 12

Why is DNA double stranded

Answer 12

Each of the nucleotides has 2 base & the complimentary base has to pair with it

Question 13

Give the bearings of the bases

baes always pair up in the same way

Answer 13

• Adenine & Thymine = A-T

- Cytosine & Guanine = C-G

Question 14

What kind of bonding is there between the base pairing

Answer 14

Hydrogen bonding between the base pairs holds DNA strands together

Question 15

Describe the difference in hydrogen bonding between GC & AT

Answer 15

• GC contains 3 hydrogen bonds

- AT contains 2 hydrogen bonds

Question 16

Describe the structure of DNA

Answer 16

• double helix

- Base paired strands = coiled into a spiral = double helix

Question 17

Describe the steps of protein synthesis ( 3 )

Answer 17

1. Transcription = copy DNA into mRNA
2. mRNA leaves the neucleus & goes to the ribosomes ( protein synthesis takes place in ribosomes )
3. Ribosomes read mRNA & hook on the correct amino acid = Translation

Question 18

What happens in transcription ( 2 )

Answer 18

1. Part of the DNA double helix unwinds & unzips

2. One strand acts as a template for the synthesis of a single-stranded mRNA copy of the gene

Question 19

What are the key differences between DNA and RNA

Answer 19

1. DNA = deoxyribose
   RNA = ribose
2. DNA = A T C G
   RNA = A U C G ( uracil not Thymine )
3. DNA = double stranded
   RNA = single stranded

Question 20

How does mRNA carry the code

Answer 20

• In a sequence of bases that - corresponds to a particular amino acid
• Code = triplet code = 3 bars coding for each amino acid = codon

Question 21

What is the rule for each triplet code or codon

Answer 21

• Each triplet codes for a specific amino acid

- amino acids = joined together in the correct sequence to make part of a protein

Question 22

What happens once the DNA strand is transcripted into mRNA

Answer 22

• Code carried by mRNA is translated with the aid of a transfer RNA (tRNA ) and particles in the cell called ribosomes

Question 23

What does mRNA and tRNA stand for

Answer 23

• Messenger RNA and transfer RNA

Question 24

What does tRNA have

Answer 24

Contains anti codon for binding to a codon on mRNA from the nucleus

Question 25

How does tRNA work

Answer 25

• tRNA molecules bind to the mRNA molecule in the ribosome and a bond forms between the two amino acids that they carry away
• having delivered it’s amino acid the tRNA molecule separates from the mRNA and leaves the ribosome
• The ribosome moves further along the mRNA chain & continues to put different amino acids together

Question 26

What happens when a complete proteins is synthesised

Answer 26

Certain mRNA codons ( UAA, UGA, UAG ) code for a stop, signalling the release of the completed protein

Question 27

How does an amino acid link to a tRNA molecule

Answer 27

Forms an ester bonds with the carboxylic acid present on the amino acid