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Biological molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a monomer?

A

A small sub-unit that can join with others to make a larger molecule.

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2
Q

What is a polymer?

A

A larger molecule made from two or more monomers.

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3
Q

What is a condensation reaction?

A

Monomers are joined to form a larger molecule, a bond, and a molecule of water.

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4
Q

What is a hydrolysis reaction?

A

A larger molecule is broken down into monomers by adding a molecule of water.

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5
Q

What are carbohydrates made up of?

A

Carbon, hydrogen, oxygen.

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6
Q

What bonds do carbohydrates form?

A

Glycosidic bonds.

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7
Q

What is an isomer?

A

Compounds with a single chemical formula but in different forms that impact its properties.

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7
Q

What are monosaccharides?

A

Single sugars named after their number of carbon atoms.

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7
Q

What is the formula of a monosaccharide?

A

(CH2O)n

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8
Q

What isomers does glucose exist as and what is the difference between them?

A

Alpha glucose, OH group below.
Beta glucose, OH group above.

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9
Q

What are disaccharides?

A

Two monosaccharides.

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10
Q

What are polysaccharides? Three examples?

A

Chains of molecules that are not classed as sugars.
Starch, glycogen, cellulose.

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11
Q

Describe the role and structure of starch.

A

A glucose storage molecule in plants.
alpha glucose monomers, 1-4 glycosidic bonds, 10-30% helical amylose, 70-90% branched amylopectin with additional 1-6 glycosidic bonds.

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12
Q

How is starch adapted for its function?

A

Insoluble so doesnt affect cells water potential.
Branched so easily accessible for respiration.

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13
Q

Describe the role and structure of glycogen.

A

Glucose storage molecule in animals.
alpha glucose molecules.
1-4 glycosidic bonds with additional 1-6 glycosidic bonds.

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14
Q

How is glycogen adapted for its function?

A

Highly branched so accessible for respiration.

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15
Q

Describe the role and structure of cellulose.

A

Forms microfibrils in cell walls that are embedded in a framework of substances to give the cell strength and support.
beta glucose molecules.
1-4 glycosidic bonds.
alternating molecules flipped 180° to allow for bonding of hydroxyl groups.

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16
Q

What elements do lipids contain?

A

Carbon, hydrogen, oxygen.

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17
Q

What bonds do lipids form?

A

Ester bonds.

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18
Q

What are the two types of lipids?

A

Triglycerides and phospholipids

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19
Q

What is the structure of a triglyceride?

A

One glycerol molecule and three fatty acid molecules by condensation reactions.

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20
Q

What is the structure of a fatty acid?

A

An acid group and a long chain of hydrophobic hydrocarbons. They can either be saturated or unsaturated, causing the chain to kink.

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21
Q

What is the function of a triglyceride?

A

Used as energy storage molecules.

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22
Q

How are triglycerides adapted for their function?

A

Bundle together in droplets so hydrophobic tails face away from water as to not alter water potential.

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23
Q

What is the structure of a phospholipid?

A

One glycerol molecule and two fatty acids by condensation reaction, and one phosphate group covalently bonded.

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24
Q

What is the function of a phospholipid?

A

Make up cell membranes and control what enters/leaves the cell.

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25
Q

How are phospholipids adapted for their function?

A

Centre of bilayer is hydrophobic fatty acids so that soluble substances cannot easily pass through. Phosphate heads on outside of bilayer as hydrophilic so can interact with water.

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26
Q

How are proteins made?

A

Food in diet broken down into amino acids OR some amino acids made from other materials in the body?

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27
Q

What is the function of proteins?

A

Enzymes, hormones, keratin.

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28
Q

What are proteins made up of?

A

Many different amino acid monomers with 20 different R groups, forming protein or polypeptide.

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29
Q

What is the purpose of the different R groups?

A

Determines properties of molecule.

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30
Q

Why are amino acid monomers not stored in the body?

A

Toxic in high quantities so undergoes deamination in the liver to be converted into urea.

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31
Q

What the the primary structure of a protein?

A

The sequence of amino acids.

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32
Q

What is the secondary structure of a protein?

A

Primary either folds into beta plated sheet with irregularly hydrogen bonds between NH of one and CO further down, or twists into alpha helix with regular hydrogen bonds between NH of one and CO four down.

33
Q

What is the tertiary structure of a protein?

A

Secondary continues to fold and forms 3D structure that is a functioning protein. Contain hydrogen bonds, ionic bonds between NH3+ and COO- of R groups as + and - are strongly attracted, disulphide bridges (strong covalent) between R groups of two cysteines, bonding between R groups.

34
Q

What is a cysteine?

A

Amino acid containing sulfur.

35
Q

What is a quaternary structure of a protein?

A

Only forms when protein has more than one polypeptide chain. Each chain held in precise structure and may have a prosthetic group.

36
Q

What is a prosthetic group of a protein?

A

A non-protein that helps the polypeptide perform its function.

37
Q

What is a fibrous protein and an example?

A

Repetitive order of amino acids that is insoluble and structural. Collagen used in artery walls.

38
Q

What is a globular protein and an example?

A

Almost spherical and insoluble, formed when hydrophobic R groups move to centre of structure and twist amino acid chains. Haemoglobin, binds to oxygen in red blood cells.

39
Q

What is an enzyme?

A

A tertiary structure protein which catalyses reactions.

40
Q

What do enzymes do?

A

Lower the activation energy required for the reaction to occur.

41
Q

What are the two theories to explain enzyme action?

A

Lock and key-> active site is fixed shape and substrate is complementary.
Induced fit-> active site induced to mould around the substrate by straining bonds.

42
Q

What happens when an enzyme denatures?

A

The bonds holding the tertiary structure begin to break which causes active site to change shape so that it is no longer complementary to the substrate.

43
Q

What is an enzyme optimum?

A

The condition at which an enzyme will cause a reaction to occur at its quickest rate.

44
Q

How does temperature affect enzyme activity?

A

Increase causes enzymes to move with more kinetic energy so more successful collisions occur. Too hot and enzymes vibrate with too much kinetic energy so that hydrogen and ionic bonds break so it denatures.

45
Q

How does pH affect enzyme activity?

A

Active site is only the correct shape at a specific hydrogen concentration so changes in pH changes shape of active site and causes it to denature. The hydrogen ions interact with polar and charged groups in the tertiary structure to change their interaction.

46
Q

How does substrate concentration affect enzyme action?

A

The more molecules there are, the more collisions will occur in the right orientation until Vmax is reached where there is no free enzymes left to bind.

47
Q

What are enzyme cofactors?

A

Non-proteins that attach to the enzymes to activate them.

48
Q

What do inhibitors do?

A

Prevent or slow down enzyme activity by binding to enzymes that they inhibit.

49
Q

What are competitive inhibitors?

A

Have a similar shape to a substrate and binds to complimentary active site to block it so enzyme-substrate complex cannot form. Can be overcome by adding more substrate.

50
Q

What are non-competitive inhibitors?

A

Bind to enzymes allosteric site and changes the tertiary structure so that substrate is no longer complementary and fewer enzyme-substrate complexes can form.

51
Q

Two examples of nucleic acids?

A

DNA & RNA.

52
Q

What is the monomer of a nucleic acid?

A

Nucleotide.

53
Q

What is the polymer of a nucleic acid?

A

Polynucleotide.

54
Q

What elements do nucleic acids contain?

A

Carbon. hydrogen, oxygen, nitrogen, phosphorus.

55
Q

What is DNAs function?

A

The storage of genetic information that codes for polypeptides.

56
Q

What is RNAs function?

A

The translation of genetic information that codes for polypeptides.

57
Q

What is a nucleotide made up of?

A

Slightly negatively charged phosphate group.
Pentose sugar.
Organic base containing nitrogen.

58
Q

What bonds do the bases form with each other in nucleotides?

A

Hydrogen bonds.
3 for G-C.
2 for T-A.

59
Q

What bonds do nucleotides form between one another?

A

Phosphodiester bonds between adjacent nucleotides.

60
Q

What are the five possible bases in a nucleotide?

A

Adenine, thymine, uracil.
Cytosine, guanine.

61
Q

What are the main features of DNA?

A

Contains thymine, longer molecule, double-stranded, pentose sugar is deoxyribose.

62
Q

What are the main features of RNA?

A

Contains uracil, shorter molecule, single-stranded, pentose sugar is ribose.

63
Q

Who discovered DNA structure and what?

A

In 1953 by Crick and Watson, found double-helix and two polynucleotide strands running antiparallel that are made of many single nucleotides joined together.

64
Q

What is the conservative theory of DNA replication?

A

A new polynucleotide is made out of completely new nucleotides.

65
Q

What is the semi-conservative theory of DNA replication?

A

The DNA acts as a template to form new polynucleotides made up of one strand original nucleotides and one strand new nucleotides.

66
Q

Describe the process of semi-conservative replication of DNA.

A

Two strands unzip due to H bonds between complementary bases broken by DNA helicase enzymes.
Strands act as templates for free complementary nucleotides in nucleoplasm.
Adjacent nucleotides joined by DNA polymerase, forming phosphodiester bonds.

67
Q

What are the enzymes involved in replication of DNA and their roles?

A

DNA helicase-> breaks H bonds between complementary bases.
DNA polymerase-> forms phosphodiester bonds between adjacent nucleotides.

68
Q

The semi-conservative was proved to be the correct theory for DNA replication; who, when, what did they replicate and why?

A

Meselsohn and Stahl.
1958.
Bacteria because fast replication and take in nitrogen from surroundings for any new nitrogenous bases in DNA.

69
Q

How was the semi-conservative theory of DNA replication proved?

A

Grew bacteria in 15N, centrifuge to get pellet of 15N DNA as denser.
Let cells replicate in 14N, centrifuge to get hybrid pellet of 15N and 14N.
Let cells replicate again in 14N, centrifuge to get 14N pellet and hybrid pellet.

70
Q

Where is water found in organisms?

A

Bodily fluids, cytoplasm.

71
Q

What type of molecule is water and why?

A

Dipolar molecule because it has two charged regions.

72
Q

How does water have five main properties?

A

Due to the molecules sticking together due to hydrogen bonds forming between molecules due to opposite charges attracting one another.

73
Q

What are the five main properties of water?

A

Metabolite in hydrolysis and condensation reactions.
Universal solvent.
High specific heat capacity.
High latent heat of vaporisation.
Cohesive.

74
Q

Why is water a universal solvent? Why is this useful?

A

Due to polarity as a charged solvent that causes ions to surround solute.
Used as a transport medium and to dilute toxic substances.

75
Q

Why does water have a high specific heat capacity? Why is this useful?

A

A large amount of energy required to raise temp.
Remains thermally stable as it buffers changes so is good living environment.

76
Q

Why does water have a high latent heat of vaporisation? Why is this useful?

A

Takes a large amount of energy to go from liquid to gas.
When a person sweats they cool as it evaporates and energy is lost.

77
Q

Why is it useful that water is cohesive?

A

Produces surface tension so some invertebrate can live on surface and molecules can move constantly up during transpiration.

78
Q

What is the symbol of the iron ion and its role?

A

Fe2+
Haemoglobin, oxygen transport.

79
Q

What is the symbol of the hydrogen ion and its role?

A

H+
Chemiosmosis, maintaining pH, oxidative phosphorylation.

80
Q

What is the symbol of the sodium ion and its role?

A

Na+
Co-transport, depolarisation, sodium potassium pump in action potentials.

81
Q

What is the symbol of the phosphate ion and its role?

A

PO4 3-
Phospholipid bilayer, DNA, RNA, ATP.

Biology (6 decks)

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