Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A Level Biology: 2.1.2 Biological Molecules > 2.1.2i Nucleic Acids > Flashcards

2.1.2i Nucleic Acids Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards Organic Chemistry 101 flashcards
1
Q

What are nucleotides

A

Monomers which are the building blocks of DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How many different nucleotides are there

A

5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the basic common structure of all 5 different nucleotides

A
  • a ribose sugar joined to a phosphate group & a nitrogen-containing base
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 5 different nucleotides

A
  • Guanine
  • Thymine (DNA only) or Uracil (RNA only)
  • Adenine
  • Cytosine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 2 groups of nitrogenous bases

A

Purines & Pyrimidines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What bases are part of the Purine group

A
  • Adenine
  • Guanine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What bases are part of the Pyrimidine group

A

pYrimidine:
- thYmine
- uracil
- cYtosine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Ring structure of purine bases

A

Double ring structure of C and N

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Ring structure of pyrimidine bases

A

Single ring structure of C and N

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

See slide 3 for structure of all 5 different nucleotides

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does DNA stand for

A

Deoxyribonucleic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does RNA stand for

A

Ribonucleic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are DNA & RNA an eg of

A

DNA & RNA are both types of nucleic acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Similarities between DNA & RNA

A
  • Both are types of nucleic acids
  • Both are long chain polymers made up of many units called nucleotides joined tg by phosphodiester bonds in a condensation reaction
  • They are attached between the sugar of one nucleotide & the phosphate of the next nucleotide. The bond that forms between the 2 nucleotides is a phosphodiester bond
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Difference between DNA & RNA

A
  • DNA is a double stranded molecule, whilst RNA is a single stranded molecule
  • Have diff types of pentose sugar: DNA has deoxyribose, RNA has ribose
  • Composition of nitrogenous bases: DNA has (A, G, C, T) whilst RNA has (A, G, C, U)
  • DNA has hydrogen bonding, RNA does not
  • Base pairing: DNA has complementary base pairing, RNA has no base pairing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Structure of a nucleotide

A

see slide 5
(pentose sugar attached to phosphate group and nitrogenous base)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Structure of DNA nucleotides

A

see slide 6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Structure of RNA molecules

A

see slide 6

18
Q

Type of pentose sugar in DNA

A

Deoxyribose

19
Q

Type of pentose sugar in RNA

A

Ribose

20
Q

Base composition of DNA

A

(A, C, G, T)
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Thymine (T)

21
Q

Base composition of RNA

A

(A, C, G, U)
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Uracil (U)

22
Q

see slide 8 to see physical difference between DNA & RNA side by side

A
23
Q

Joining of nucleotides

A

Nucleotides are monomers. They need to bond to other nucleotides to form polynucleotide molecules (eg. mRNA)

24
Q

How do nucleotides join together

A
  1. The nucleotides bond between the phosphate group of one nucleotide & the sugar of another nucleotide. This is via a condensation reaction & the formation of a phosphodiester bond (consisting of the phosphate group & 2 ester bonds)
  2. The chain of sugars & phosphates is known as the sugar-phosphate backbone
  3. Polynucleotides can be broken down into nucleotides again by breaking the phosphodiester bonds (hydrolysis reaction)
    (see slide 9-11 for diagram)
25
Q

How are 2 polynucleotide chains of DNA held together

A

2 polynucleotide chains of DNA are held tg via hydrogen bonding between complementary nitrogenous bases.

  • Adenine (A) can only pair with Thymine (T) via TWO hydrogen bonds
  • Guanine (G) can only pair with Cytosine (C) via THREE hydrogen bonds

(see slide 12 for dia)

26
Q

What does it mean by the 2 strands of DNA being called antiparallel in the joining of base pairs

A

In order for the bases to be facing each other & thus able to pair, the strands must be running in opposite directions.
- The two strands of DNA are described as being antiparallel

(see slide 13 for dia)

27
Q

Structure + Function of DNA

A
  • Sugar phosphate back bone –> DNA is strong & stable
  • Many hydrogen bonds –> Provides strength & stability
  • Hydrogen bonds are weak –> Strands can be separated during DNA replication
  • Double stranded –> Bases are protected & replication can be semi-conservative
  • Long polymer –> Can store lots of genetic info
  • Double helix –> compact
  • Bases are in sequence (specific order) –> Info can be stored (base sequence code for amino acid/protein)
28
Q

EXAM Q: A sample of DNA was tested & 17% of the total bases present were found to be Adenine.
Calculate the percentages of each of the other 3 bases present in this sample.

A

Adenine always base Paris w Thymine, so same amount of Thymine (17%).

Adenine & Thymine tg is 34%, so Cytosine & Guanine must be (100 - 34 = 66%).

Cytosine always base pairs w Guanine, sp equals same amount, 66/2=33.

Therefore, cytosine 33% % guanine 33%

29
Q

ATP is…

A

…a nucleotide

30
Q

What is ATP energy required for

A
  • All organisms require a constant supply of energy to maintain their cells & stay alive
  • In all organisms this energy is required for:
    • ANABOLIC REACTIONS (building larger molecules from smaller ones)
    • MOVING SUBSTANCES across the cell membrane or moving substances within the cell
31
Q

What else is ATP required for (specific to animals only)

A
  • MUSCLE CONTRACTION: to coordinate movement at the whole-organism level
  • The conduction of nerve impulses
32
Q

Why is ATP known as the universal energy currency

A

In all known forms of life, ATP from respiration is used to transfer energy in all energy-requiring processes in cells

33
Q

What does ATP stand for

A

Adenosine Triphosphate

34
Q

Structure of ATP

A
  • ATP is another type of nucleic acid & hence it is structurally very similar to the nucleotides that make up DNA & RNA.
  • It is a phosphorylated nucleotide
  • Adenosine (a nucleoside) can be combined with 1, 2 or 3 phosphate groups:
    • 1 phosphate group = adenosine monophosphate (AMP)
    • 2 phosphate groups = adenosine diphosphate (ADP)
    • 3 phosphate groups = adenosine triphosphate (ATP)
      (see slide 18 for dia)
35
Q

What is the process used for purifying DNA

A

We can purify (isolate) DNA via the process of precipitation

36
Q

What is the process of precipitation (purifying DNA)

A

The process of converting a chemical substance into a solid form from a solution by changing the substance into an insoluble form.
When the reaction occurs in a liquid solution, the solid formed is called the precipitate

37
Q

Why might we want to isolate DNA (purification)/why is it important

A

Isolating DNA from cells is an essential starting point for a huge range of other investigations

38
Q

What is the name of the common method used to isolate DNA

A

The ‘Marmur preparation’
- This method is derived from the work of Julius Marmur (1926-96), an American molecular biologist who made significance contributions to DNA research

39
Q

3 basic steps of the ‘Marmur preparation’

A
  1. Breaking (lysing) the cells & disrupting the nuclear membranes to release the DNA
  2. Using enzymes to denature & remove the proteins (histones) associated with the DNA
  3. Precipitating the DNA using an organic solvent (eg. ethanol)
40
Q

Good eg for purification of DNA practical

A

Onions are good to use for this investigation as their cells contain a relatively large amount of DNA
- Fruits that also have large amounts of DNA in their cells sa strawberries, bananas, kiwis can also be used

41
Q

Equipment needed for purification of DNA practical

A
  • ice-cold ethanol (10 cm^3)
  • protease enzyme (2-3 drops)
  • ice water bath
  • plastic funnel
  • plastic syringe
    etc
42
Q

Full method of purification of DNA (onion)

A
  1. Place the ethanol in freezer 24hrs before starting (must be ice cold)
  2. Cut up onion into small pieces (5mm x 5mm)
  3. Add washing up liquid to 90cm^3 of tap water in beaker & add onion pieces into beaker
  4. Place beaker in water bath at 60dc for 15mins
    • the detergent (washing up liquid) & the heat disrupt the phospholipid bilayer of the onion cell membranes & nuclear membranes, releasing the DNA
    • the heat also denatures enzymes released from the cell that would otherwise begin to digest the DNA
  5. Cool mixture in ice-water bath for 5mins, stirring
    • lowering temp prevent DNA itself from breaking down, which would occur if the high temp form previous step was maintained
  6. Pour mixture into blender for 5secs
    • blending breaks down the cell walls & membranes of the onion cells even further, releasing more DNA
    • only blended for very short to ensure DNA strands are not broken apart
  7. Using filter paper, filter mixture into beaker (filtrate now contains DNA & its associated histones)
  8. Pour 10cm^3 of filtrate into test tube & add 2-3 drops of protease enzyme (to denature & remove the proteins, leaving just DNA)
  9. Add ice-cold ethanol to test tube. Nucleic acids are insoluble in ice-cld ethanol so DNA forms a white precipitate at top of test tube

A Level Biology: 2.1.2 Biological Molecules (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions