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Biology > Nucleic Acids Section 1 Topic 2 > Flashcards

Nucleic Acids Section 1 Topic 2 Flashcards

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1
Q

What are the two most known nucleic acids

A

Ribonnucleic acid (RNA) and deoxyribonucleic acid (DNA)

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2
Q

What are the basic facts of DNA

A

Double helix shape, made up of nucleotides, carries genetic information, passes on features of organisms from one generation to the next

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3
Q

What are the 3 components of nucleotides

A

Pentose sugar (deoxyribose in DNA, ribose in RNA)
Phosphate group
Nitrogen containing organic base

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4
Q

What type of reactions form single nucleotides (mononucleotide)

A

Condensation reactions join the phosphate base, pentose sugar and base

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5
Q

What is the bond between the deoxyribose sugar of a mononucleotide and phosphate group of another called forming a dinucleotide

A

Phosphodiester bond

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6
Q

What does the continuous joining of nucleotides form

A

Polynucleotide

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7
Q

What is RNA

A

A polymer made up of nucleotides, it’s a single relatively short polynucleotide chain in which the pentose sugar is always ribose. It’s bases are A G C U, and it transfers genetic info from the DNA to the ribosomes

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8
Q

What is DNA

A

It’s a polymer made up of 2 strands of nucleotides, each extremely long and joined together by hydrogen bonds. It’s pentose sugar is always deoxyribose and it’s based are A T G C

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9
Q

What are the two base parings

A

AT and GC, adenine is said to be completely to thymine and guanine is said to be complimentary to cytosine

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10
Q

What part of the DNA ‘ladder’ are the different components

A

The phosphate group and the pentose sugar form the structural phosphodiester backbone, and the base pairings hold the two strands together with hydrogen bonds

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11
Q

Why is DNA a stable molecule

A

The phosphodiester backbone protects the more chemically reactive bases in the double helix. There are hydrogen bonds between the bases; a triple bond between G and C, and a double bond between A and T. Therefore the more GC bonds the more stable the molecule

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12
Q

What is the function of DNA

A

DNA is responding for passing genetic information from cell to cell and generation to generation, in total there is about 3.2 billion base pairs in the DNA of a typical cell

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13
Q

What are the two groups of base pairs

A

Purines are A and G
Pyrimidines are T and C

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14
Q

How is DNA adapted to carry out its function

A

Very stable and passes on without change.
The strands can separate because the are joined by hydrogen bonds.
Very large and carry’s lots of genetic info.
Base pairs inside the backbone protects genetic info from being corrupted.
Base parings leads to DNA being able to replicate and transfer info as RNA. It’s also very compact and the phosphate is negative protecting from attack

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15
Q

What is the bond between the base and sugar called

A

Glycocydic bond

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16
Q

What is the length of one nucleotide

A

0.34 nm

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17
Q

What is the width of dna

A

2 nm

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18
Q

How long is one full DNA rotation

A

3.4 nm (10 nucleotides)

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19
Q

How many rings do purines and pyrimidines have

A

Purines have 2
Pyrimidines have 1

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20
Q

What are the 3 different kinds of RNA

A

Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)

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21
Q

What does mRNA do

A

Carries the code of a nucleotide in codon form from the DNA to the ribosomes

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22
Q

What does tRNA do and what does it look like

A

It’s folded into a clover leaf shape, and carry’s a specific amino acid on one end and an anticodon on another end, which pairs with a a complimentary codon on the mRNA in the cytoplasm of the cell

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23
Q

What does rRNA do

A

Helps to bond mRNA to proteins of the ribosome

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24
Q

Where and when does semi conservative replication take place

A

Takes place in the nucleus of an eukaryote and the cytoplasm of a prokaryote. It takes place during interphase before cell division

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25
Q

Explain the process of semi conservative replication

A

1)The enzyme DNA helicase breaks the hydrogen bonds between the complimentary base pairs
2) the double helix separates
3)each exposed strand now acts as a template
4)complementary, free nucleotides in the cytoplasm are attracted to the exposed bases on the strands
5)energy (ATP) is required to activate the free nucleotides
6)once these nucleotides are in place their deoxyribose phosphate backbone is joined together by DNA polymerase
7)two new strands are produced

26
Q

What are two cases that DNA replication would not be good

A

Cancerous cells or a pathogen

27
Q

How could we prevent DNA replication

A

Prevent enzyme action and limit energy

28
Q

What did Stahl believe

A

DNA replicates semi conservatively

29
Q

What is Meselson believe

A

DNA replicates conservatively

30
Q

How did Meselson and Stahl conduct their experiment

A

1) E. Coli bacteria were grown in ‘known’ forms of nitrogen (these were the control tests)
2) the cells were killed and DNA extracted
3) these DNA samples are then spun in a high speed centrifuge- the samples were made visible under UV light

31
Q

What does bacteria do with the nitrogen isotopes in the Meselson and Stahl experiment

A

Takes in the nitrogen isotopes to make new DNA nucleotides

32
Q

DNA only grown in a medium with only N14 will…

A

Have DNA which only contains this isotope and will be lighter

33
Q

How can we confirm DNA density

A

DNA samples can be spun in a centrifuge

34
Q

Phosphate groups bonds in ATP are…

A

Unstable so have low activation energy

35
Q

Why do the phosphate groups in ATP have unstable bonds

A

Repelling action between the phosphates and single bonds

36
Q

What 2 things are needed to break phosphate group bonds in ATP

A

Water and ATP hydrolase

37
Q

An ATP molecule that has lost a phosphate is now called

A

ADP

38
Q

What is an inorganic phosphate written as

A

Pi

39
Q

What is energy released in ATP used for

A

Metabolism
Movement (muscle contraction)
Secretion

40
Q

What is ATP comprised of

A

Adenine
Ribose
3 phosphate groups

41
Q

what does the Pi released do

A

lowers activation energy

42
Q

what type of reaction releases ATP as energy

A

hydrolysis and exergonic

43
Q

why does the body prefer ATP to glucose

A

-ATP is a more immediate source of energy because only one bond needs to be broken vs glucose which is broken down in a series of steps
-ATP releases energy in small manageable amounts whereas glucose releases a lot more
(However ATP cannot be stored so must be continuously made in the matrix of the mitochondria)

44
Q

explain the dipolar nature of water

A

oxygen is more electronegative than hydrogen so is delta negative, while hydrogen is delta positive

45
Q

describe how water easily dissolves other substances

A

the delta positive hydrogen attracts the negative ion solute in solution, as the delta negative oxygen attracts the positive ion in the solute

46
Q

what does hydrophillic mean

A

attracted to water

47
Q

what does hydrophobic mean

A

repels water

48
Q

explain water as a metabolite

A

Many metabolic processes occur faster in water, and its used to break down many complex molecules

49
Q

explain waters properties around freezing and density

A

water molecules move further apart when frozen due to the formation of hydrogen bonds, so is less dense as a solid

50
Q

why is water being less dense as a solid a good thing

A

it can float which creates habitats for animals like polar bears

51
Q

explain waters high heat capacity

A

a lot of energy is needed to raise the temp of water because some of the energy is needed to break hydrogen bonds

52
Q

What can water act as due to it only fluctuating in temp

A

Buffer against temp variations which keep aquatic environments stable

53
Q

What effect does water provide through evaporation

A

Cooling effect e.g sweating

54
Q

What causes cohesion and tension in water

A

Hydrogen bonds as they cause the molecules to be strongly attracted to other molecules

55
Q

What does cohesion and tension in water molecules help

A

Columns of water to be linked together to be pulled up through the xylem

56
Q

Why is water adhesive

A

Because it’s polar

57
Q

What is a cation

A

A positive ion

58
Q

What is an anion

A

A negative ion

59
Q

What is the use of an iron ion (Fe2+ and Fe3+) in the body

A

Haemoglobin is a protein made up of 4 polypeptide chains with Fe2+ in the middle that binds to oxygen forming Fe3+

60
Q

What are the use of hydrogen ions

A

Determine pH so acidic environments have lots of free hydrogen ions

61
Q

What are the use of phosphate ions (PO4^3-) in the body

A

Major components of DNA and ATP when attached to another molecule it becomes a phosphate group

62
Q

What are the use of sodium ions (Na+)

A

Are involved in the co transport of glucose and amino acids across membranes

Biology (5 decks)

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