nucleotides and nucleic acids

Question 1

2 types of ribose? What’s the difference? What are they in?

Answer 1

Deoxyribose (DNA)
Ribose (RNA)
Deoxy- oxygen removed (in this case from C2)

Question 2

What is a 1,4 glycosidic bond? In what reaction?

Answer 2

The bond between C1’ and C4’ in a disaccharide
Condensation reaction

Question 3

Lactose

Answer 3

Galactose + glucose

Question 4

Maltose

Answer 4

Glucose + glucose

Question 5

Sucrose

Answer 5

Fructose + glucose

Question 6

2 types of nucleic acids? Difference?

Answer 6

Deoxyribonucleic acid (one less oxygen on C2’)
Ribonucleic acid (one more oxygen on C2’)

Question 7

3 types of RNA?

Answer 7

tRNA, mRNA, rRNA

Question 8

Nucleotide structure (3)

Answer 8

PO4 ^2- phosphate group
Pentose sugar monosaccharide (ribose or deoxyribose)
Nitrogenous base (A,T,G,C)

Question 9

What reaction makes a polynucleotide? Bonds? Between what?

Answer 9

-Condensation
-Phosphate group on C5’ forms a phosphodiester bond with hydroxyl group on C’3

Question 10

What is a polynucleotide?

Answer 10

One DNA strand

Question 11

Bonds between bases? What is the rule that bonds these bases?

Answer 11

Hydrogen bonds
Complementary base pairing

Question 12

Purine structure? Egs?

Answer 12

Double ring
A,G

Question 13

Pyrimidine structure? Egs?

Answer 13

Single ring
T,C,U

Question 14

Anti parallel strands means?

Answer 14

2 strands run in opposite directions

Question 15

Why is complementary base pairing important? (2)

Answer 15

-allows DNA to be copied and transcribed during protein synthesis
-maintains 2nm width of DNA

Question 16

True or false- RNA is single stranded, unlike DNA

Answer 16

True

Question 17

Alternating sugar and phosphate groups called?

Answer 17

Sugar phosphate backbone

Question 18

What is DNA replication? why must it be accurate?

Answer 18

making identical copies of DNA molecules
so daughter cells have exact copy of parental DNA

Question 19

4 steps of DNA replication
(1st enzyme, pairing from nucleus, 2nd enzyme, result)

Answer 19

• helicase unwinds + unzips hydrogen bonds
• Bases (from nucleus-abundant nucleotides) bind to bases on the strands
• polymerase joins phosphodiester bonds, forming backbone
• 2 identical DNA molecules

Question 20

Why is DNA replication called semi conservative?

Answer 20

1 strand og
1 strand new

Question 21

Where does the water molecule come from during the condensation reaction to make polynucleotides?

Answer 21

The OH- in the phosphate group on C5’ and the H from the hydroxyl group on C3’

Question 22

Genetic code- 4 adjectives + their meanings

Answer 22

• triplet code
• universal: genetic code applies to all organisms
• degenerate: 1 amino acid can be made from lots of combos of diff codons
• nonoverlapping: codons read ‘in frame’ (nucleotides don’t share codons)

Question 23

Transcription vs translation (process + location)

Answer 23

Transcription- copy gene into mRNA (nucleus)
Translation- decode mRNA into protein (cytoplasm)

Question 24

What is the ‘reading frame’? What is usually the start codon?

Answer 24

The arrangement of nucleotides into codons
ATG/AUG

Question 25

What are the 2 strands of DNA in transcription called? What are their functions?

Answer 25

Sense strand- coding strand Antisense strand- template strand

Question 26

mRNA has the same codon sequence as which DNA strand?

Answer 26

sense

Question 27

tRNA has the same codon sequence as which DNA strand?

Answer 27

antisense

Question 28

What enzyme is used in TRANSCRIPTION to unwind DNA into sense and antisense strands? Which enzyme is this similar to?

Answer 28

RNA polymerase (similar to DNA helicase)

Question 29

List 3 similarities between transcription and replication HINT (bonds, enzyme, nucleotide)

Answer 29

- both form hydrogen bonds - both use polymerase to form phosphodiester bonds between nucleotides - both require free nucleotides to pair bases

Question 30

List 3 differences between transcription and replication HINT (product, enzyme, nucleotide)

Answer 30

- transcription makes a single mRNA strand whereas replication makes 2 DNA molecules - transcription uses RNA polymerase whereas replication uses DNA polymerase - transcription uses A,U,G,C (ribonucleotides) whereas replication uses A,T,G,C (deoxyribonucleotides)

Question 31

Is mRNA single or double stranded?

Answer 31

Single

Question 32

What did the semi-conservative experiment prove and how?

Answer 32

- that one DNA strand in replicated molecules was old and one was new - using heavy and light nitrogen to form the bases (before division: all heavy, 1st division: half heavy, 2nd division: all light, some a little bit heavy)

Question 33

Explain the process of translation in protein synthesis (6)

Answer 33

- mRNA start codon binds to **rRNA** in ribosomes (in the rough ER) - a **tRNA** with a complementary anticodon and an amino acid binds to mRNA start codon - repeat with more tRNA so the first amino acid is transferred to the second amino acid via a **peptide bond** - catalysed by **peptidyl transferase** (in ribosome) - ribosome moves along mRNA, releasing tRNA, until a **polypeptide** is formed

Question 34

What does ATP stand for?

Answer 34

Adenosine triphosphate

Question 35

Adenosine Triphosphate structure vs Adenosine Diphosphate structure

Answer 35

TRI: 3 phosphate groups, ribose sugar, adenine DI: 2 phosphate groups, ribose sugar, adenine

Question 36

How much energy does ATP release per hydrolysis? Endo or exo? Why?

Answer 36

30.6 KJmol-1 Exo bc energy change is pos so more energy is taken in breaking bonds

Question 37

What is the equation for ATP hydrolysis?

Answer 37

ATP + water--> P (inorganic) + ADP

Question 38

Properties and functions of ATP? (5)

Answer 38

- Small- moves easily - Releases small amounts of energy- reduces waste - Unstable- phosphate easily removed, immediate energy source - Regenerated easily from ADP- constant energy supply - Water soluble- can dissolve in cytoplasm where chemical reactions occur

Question 39

5 steps to DNA extraction HINT: each step involves one thing removing one part of the cell

Answer 39

1. Grind sample= cell wall 2. Mix detergent= cell surface membrane 3. Salt= hydrogen bonds (so DNA does not dissolve in water) 4. Protease= histones 5. Alcohol= makes DNA a precipitate

Question 40

Names of strands in DNA replication vs transcription

Answer 40

Replication: leading and lagging Transcription: sense and antisense