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a level biology > 3.1.5 - 3.1.8 DNA (structure and replication), ATP, water, inorganic molecules i’m > Flashcards

3.1.5 - 3.1.8 DNA (structure and replication), ATP, water, inorganic molecules i’m Flashcards

1
Q

what is our genetic code?

A

universal, same in all living organisms and cells (prokaryotes and eukaryotes), composed of DNA (deoxyribonucleic acid)

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2
Q

where is DNA found?

A

our nucleus contains the genetic material/our DNA, contained in large molecules called chromosomes, associated with proteins called histones in eukaryotes

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3
Q

what are chromosomes?

A

23 pairs of chromosomes in every body cell but not gametes (sex cells), chromosomes are made of genes, short sections of DNA that code for one polypeptide or functional RNA

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4
Q

what is the structure of chromosomes?

A

DNA molecule, combined with histones (proteins), DNA histone complex is coiled, coils fold to form loops, loops coil and pack together to form the chromosomes

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5
Q

what makes up the nucleus?

A

DNA, combined with histones (proteins), linear chromosomes, nucleus

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6
Q

what are genes?

A

lengths of DNA that code for a certain protein

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7
Q

how many chromosomes are in eukaryotes?

A

46 (except gametes)

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8
Q

what is the polymer DNA made up of?

A

monomers linked together called nucleotides via phosphodiester bonds in condensation reactions

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9
Q

what does each nucleotide consist of?

A

phosphate group, pentose sugar (deoxyribose), nitrogenous base

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10
Q

what is the A base?

A

Adenine

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11
Q

What is the T base?

A

Thymine

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12
Q

what is the G base?

A

Guanine

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13
Q

what is the C base?

A

Cytosine

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14
Q

what are the two rules that Chargaff discovered?

A

the number of cytosine always equals the number of guanine, the number of A,T,G and C present differs in species

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15
Q

what did Crick and Watson discover?

A

using UV images deduced the double helix structured G is base bared with C by 3 hydrogen bonds, A is paired with T by 2 hydrogen bonds

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16
Q

describe the structure of DNA including that of nucleotides (6 marks)

A

DNA is a double helix structure made up from two polynucleotide chains of monomers. These monomers are called nucleotides, nucleotides have three main components: a sugar phosphate backbone, and nitrogenous base, and a deoxyribose sugar.The four bases are adenine, thymine, guanine and cytosine which have complimentary base pairings of G+C and A+T. These bases are joined by hydrogen bonds whereas nucleotides are joined by phosphodiester bonds

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17
Q

compare and contrast the structure of DNA in eukaryotes and prokaryotes (5 marks)

A

in eukaryotic cells DNA is combined with proteins called histones but not in prokaryotic cells, the DNA in eukaryotes makes up linear chromosomes inside the nucleus where as in prokaryotes DNA is free floating and has a circular shape rather than being inside nucleus this is because prokaryotes are a lot smaller and have shorter DNA molecules, DNA in prokaryotes is also a lot simpler and contains a lot less junk DNA (introns) than eukaryotes , all eukaryote except gametes contain 46 chromosomes but prokaryotes do not

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18
Q

what is RNA?

A

ribonucleic acid, polymer of nucleotides, made up of phosphate, nitrogenous based (U,A,C,G), pentose sugar (ribose), and is a shorter molecule/single stranded

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19
Q

what is the sugar present in RNA?

A

ribose

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20
Q

what is the structure of rna?

A

single stranded

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21
Q

what are the bases in RNA?

A

AUCG

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22
Q

what is the length of RNA?

A

short

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23
Q

what is the base pairing in RNA?

A

no base pairing, cannot predict percentage of other bases for percentage of one base

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24
Q

what does mRNA stand for?

A

messenger RNA

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25
Q

what does rRNA stand for?

A

ribosomal RNA

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26
Q

what does tRNA stand for?

A

transfer RNA

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27
Q

what is the function of mRNA?

A

copies of the DNA sequence which leaves the nucleus through membrane pores and give instructions to the ribosomes e.g. to make protein

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28
Q

what is the function of rRNA?

A

combines with protein to make up the ribosome structure

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29
Q

what is the function of tRNA?

A

carries specific amino acids during the process of protein synthesis (called translation)

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30
Q

what is DNA replication vital for?

A

growth, development/specialisation, reproduction

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31
Q

what is conservative replication?

A

one dna molecule contains both parental DNA strands, the other molecule only contains newly synthesised DNA

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32
Q

what is dispersive replication?

A

parental DNA is interspersed between the two molecules, both strands have some new and some original DNA

33
Q

what is semi conservative replication?

A

both DNA double helices, consist of one parental and one new strand of DNA

34
Q

what are the key requirements for semi conservative replication?

A

DNA template, free nucleotides, DNA helicase, DNA polymerase

35
Q

describe the semi conservative method of DNA replication (6 marks)

A

The enzyme DNA helicase breaks the hydrogen bonds between the nitrogenous bases of the parent strand, leaving a template strand, free nucleotides in the cytoplasm move towards the template strand mamd form week hydrogen bonds with their complimentary bases, the enzyme DNA polymerase resynthesises the phosphodiester bonds between the pentose sugars, two new DNA molecules are formed each with half of the original parental DNA

36
Q

what does ATP stand for?

A

adenosine triphosphate

37
Q

what is one molecule of ATP?

A

a nucleotide derivative made up of a molecule of ribose, a molecule of adenine, three phosphate groups

38
Q

where does the energy come from in ATP?

A

result of ATP hydrolysis, broken down into ADP and Pi (phosphate), using the enzyme ATP hyrdolase, phosphate is a useful reactant used in many reactions e.g. active transport

39
Q

what is hydrolysis?

A

the breakdown of a molecule using water

40
Q

what does the breakdown of ATP release?

A

hydrolysis is adenosine triphosphate produces adenosine diphosphate, phosphate ion, energy

41
Q

why is the phosphate ion released in the breakdown of ATP useful?

A

phosphorylate compounds, more reactive so reacts with water

42
Q

what does the re synthesis of ATP need?

A

condensation reaction using ATP synthase, requires energy and ADP and a phosphate ion

43
Q

what are the products of ATP re-synthesis?

A

ATP and water

44
Q

where do we find water?

A

oceans, atmosphere (keeps the planet warm), 80% of our bodies

45
Q

what is waters structure?

A

covalent compound, chemical symbol H2O, consists of two hydrogen atoms covalently bonded to one oxygen

46
Q

what is a covalent bond?

A

covalent bonds form when two atoms share electrons to fill their outer shell

47
Q

what is a polar molecule?

A

a molecule that has an unequal distribution of of electron charges, polar bonds are arranged asymmetrically

48
Q

what is cohesion?

A

the negative end of the oxygen atom is attracted to the positive end of the hydrogen atom in the adjacent molecule, a hydrogen bond forms, this cohesive force gives water its unique properties

49
Q

what properties do it’s polarity give water?

A

high heat capacity,large latent heat of vaporisation, forms strong cohesion between water molecules, important solvent

50
Q

how is water an important solvent?

A

positive and negative charges attract other molecules to dissolve it, metabolic reactions can occur, enabled waste and essential molecules transport

51
Q

what is meant by solvent?

A

liquid that other substances dissolve in

52
Q

what is meant by solute?

A

the substance that dissolves in a liquid

53
Q

what is meant by solution?

A

mixture formed of solute and solvent

54
Q

how is water a metabolite?

A

metabolic reactions set of chemical transformations in cells, hydrolysis required water to digest larger molecules, condensation reactions synthesis of molecules such as protein synthesis give off water, ATP synthesis, digestion, protein synthesis

55
Q

how does water have a high heat capacity?

A

absorbs a large amount of energy before it gets hot, keeps beaches cooler in the day and warmer at night, moderated climate/body temperature (thermoregulation)

56
Q

what is heat capacity?

A

the amount of energy required to change 1g of a substance by 1*C

57
Q

how does water have strong cohesion bonds between water molecules?

A

can form tube like columns, hydrogen bonds cause continuous stream, creates surface tension with air (elastic tendency, low surface area) allows animals to live on the surface, for support, transpiration and forming water droplets

58
Q

how does water have a large latent heat of vaporisation?

A

the energy taken in or given out by a substance when o changes state from a liquid to vapour, the average energy of water decreases, cools down, provides a cooling effect, little water lost through evaporation, water evaporating in sweat cools you down

59
Q

why is waters high heat capacity important?

A

keeps the body at the optimum temperature for protein and enzyme action and the optimum rate for metabolic reactions in the body as they won’t become denatured

60
Q

why is waters large latent heat of vaporisation important?

A

keeps the body at the optimum temperature for enzymes and protein, don’t become denatured

61
Q

why are strong cohesion bonds between water molecules important?

A

transpiration in plants, the water can move up the plant from the roots to the leaves where it is needed for photosynthesis, allows animals to live on the surface of water

62
Q

why is water being a solvent important?

A

minerals to grow, glucose to respite, dispose of toxic CO2 and urea

63
Q

why is water being a metabolite in many metabolic reactions important?

A

important in essential processes such as ATP synthesis, digestion, protein synthesis. energy for movement, minerals, enzymes

64
Q

what are ions?

A

an atom or molecule that carries charge

65
Q

why do ions have charge?

A

the total number of protons and electrons is not equal, the atom/molecule has a net + or - electrical charge

66
Q

what are inorganic ions?

A

an ion that does not contain carbon (with exceptions), found in solution, cytoplasm’s of cells and in body fluids of organisms

67
Q

where are inorganic ions found?

A

in cytoplasm and body fluids

68
Q

what concentration are inorganic ions found in?

A

some in high concentrations some in low concentrations

69
Q

how is concentration of inorganic ions controlled?

A

through diet and membrane permeability

70
Q

how do inorganic ions move?

A

via diffusion through protein channels and active transport

71
Q

what are the four main ions?

A

hydrogen, iron, sodium, phosphate

72
Q

why is sodium important?

A

move amino acids and glucose in and out of cells to stop it reaching equilibrium, glucose for respiration, amino acids to make DNA, establishing a nervous response, transport of molecules through sodium potassium pump, co-transporter proteins

73
Q

why is iron important?

A

makes your blood red, too little you need to take medication, high if eat too much red meat or broccoli, major component of haemoglobin to carry oxygen for aerobic respiration, electron transport chain

74
Q

why is hydrogen important?

A

buffering the blood and maintaining pH, number per litre in moles is what pH is, too many can result in death, too few makes blood acidic/death, enzymes active site change shape if pH is wrong for metabolic reactions

75
Q

why is phosphate important?

A

make lots of different biological molecules e.g. nucleus acid, ATP, phospholipids, NAD and NADP (photosynthesis), DNA and RNA strong sugar backbone, ATP respiration/energy, phospholipids important in cell membranes

76
Q

what base is different in RNA?

A

Uricil

77
Q

how does elephants spraying themselves with water act as a cooling mechanism? (3 marks)

A

Water evaporates from the surface of the elephants body, heat energy breaks hydrogen bonds in water, cools surfaces of elephants body

78
Q

why does water form droplets when elephant sprays it from it’s trunk? (2 marks)

A

Strong cohesion between water molecules, water has high surface tension in contact with air so forms droplets

a level biology (21 decks)

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