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Biological Molecules Flashcards

1
Q

Define monomer

A

Smaller units that join together to form larger molecules

Monosaccharides
Amino acids
Nucleotides

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2
Q

Define polymer

A

Molecules formed when many monomers join together

Polysaccharides
Proteins
DNA/RNA

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3
Q

What happens in a condensation reaction

A

A chemical bond forms between 2 molecules and a molecule if water is removed/produced

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4
Q

What happens in a hydrolysis reaction

A

A water molecules is used to break a chemical bind between 2 molecules

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5
Q

Name the three hexose monosaccharides

A

Glucoses
Galactose
Fructose

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6
Q

Name the type of bond formed when monosaccharides react

A

Glycosidic bond

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7
Q

Name three disaccharides

Describe how they form

A

Maltose
Sucrose
Lactose

Condensation reactions forms a glycosidic bond between 2 monosaccharides

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8
Q

Whats different between alpha and beta glucose

A

Alpha has OH at bottom on right side
Beta has OH at top on right side

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9
Q

Describe structure and function of starch

A

Storage polymer of alpha glucose in plant cells
Insoluble- no osmotic effect in cell
Large- does not diffuse out of cell

Made from amylose:
1,4 glycosidic bonds
Helix with intermolecular H-bonds (compact)

And amylopectin:
1,4 and 1,6 glycosidic bonds
Branched- many terminal ends for hydrolysis into glucose

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10
Q

Describe structure and function of glycogen

A

Main storage of alpha glucose in animal cells
1,4 and 1,6 glycosidic bonds
Branched- many terminal ends for hydrolysis
Insoluble- no osmotic effect and does not diffuse out of cells
Compact

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11
Q

Describe the structure and function of cellulose

A

Polymer of beta glucose gives rigidity to plant cell walls

1,4 glycosidic bonds
Straight-chain, unbranched molecule
Alternate glucose molecules are rotated 180
H-bonds crosslinks between parallel strands form microfibrils= high tensile strength

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12
Q

Describe Benedict’s test for reducing sugars

A
  1. Add an equal volume of Benedict’s reagent to a sample
    2.Heat the mixture in an electric water bath at 100•c for 5 minutes
    3.positive result- colour change from blue to brick red
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13
Q

Describe benedicts test for non reducing sugars

A

1.Negative results: Benedicts reagent remains blue
2.Hydrolyse non-reducing sugars by adding 1cm^3 of HCL. Heat in water bath for 5 minutes
3.Neutralise the micture usinh sodium carbonate solution
4.Add an equal volume of Benedict’s reagent to a sample
5.Heat the mixture in an electric water bath at 100•c for 5 minutes
6.positive result- colour change from blue to brick red

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14
Q

Describe test for starch

A

1.Add iodine solution
2.Positive result: colour change from orange to blue/black

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15
Q

Describe how to test for lipids

A

1.dissolve solid samples into ethanol
2.add an equal volume of water and shake
3.positive result: milky white emulsion forms

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16
Q

How do triglycerides form

A

Condensation reaction between 1 molecule of glycerol and 3 fatty acids form an ester bond

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17
Q

Contrast saturated and unsaturated fatty acids

A

Saturated:
Contain only single bonds
Straight chained molecules
Higher melting point

Unsaturated:
Contain C=C bonds
Have kinks within the molecule
Lower melting point

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18
Q

Relate the structure of triglycerides to their functions

A

Insoluble hydrocarbon chain- no effect on water potential of cells
Less dense then water- buoyancy of aquatic animals

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19
Q

Describe the structure and function of phospholipids

A

Glycerol attached to 2 hydrophobic fatty acids trails and 1 hydrophilic polar phosphate head

Forms phospholipid bilayer in water- component of membraine

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20
Q

Compare phospholipids to triglycerides

A

Both have glycerol backbones
Both may be attached to a mixture of saturated and unsaturated fatty acids
Both contain elements C, H, and O
Both formed by condensation reactions

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21
Q

Contrast phospholipids and triglycerides

A

Phospholipid:
2fatty acids and 1 phosphate group attached
Hydrophilic head and hydrophobic tail
Used in membrane formation

Triglycerides:
3 fatty acids attached
Entire molecule is hydrophobic
Used as a storage molecule

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22
Q

Are phospholipids and triglycerides polymers

A

No
They are not made of small repeating units

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23
Q

Why is water a polar molecule

A

O is more electronegative than H so attracts the electron density in the covalent bond more strongly

Forms O delta neg (slight neg charge)
And H delta pos (slight pos charge)

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24
Q

State 4 biologically important properties of water

A

.Metabolite- solvent for chemical reactions in the body
.High specific heat capacity
.High lateny heat of vapourisation
.Cohesion between molecules

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25
Explain why water is significant to living organisms
Solvent for polar molecules during metabolite reactions Enables organisms to avoid fluctatiobs in core temperatures Cohesion-tension of water molecules in transpiration stream
26
What are inorganic ions and where are they found in the body
Ions that do not contain carbon atoms Found in cytoplasm and extracellular fluid May be high or very low concentrations
27
Explain the role of hydrogen ions in the body
High concentrations of H+ = loe (acidic) pH H+ ions interact with H-bonds and ionic bonds in tertiary structure of proteins which cab cause them to denature
28
Explain the role of ions in the body
Fe2+ bonds to porphyrin ring to form haem group in haemoglobin Haem group has binding site to transport 1 O2 molecule around the body in bloodstream 4 haem groups per haemoglobin molecule
29
Explosion the role of sodium ions in the body
Involved in co transport for absorption of glucose and amino acids in lumen of gut Involved in propagation of action potentials in neurons
30
Explain the role of phosphate ions in the body
Component of: DNA ATP NADP cAMP
31
What is the general structure of an amino acid
COOH-carboxyl group R- variable group NH2- amino group
32
Describe the test for proteins
1.add equal volume of sodium hydroxide to sample at room temperature 2.Add drops of dilute copper sulfate solution then swirl to mix 3. POS results: blue to purple color change NEG results: remains blue
33
How many amino acids there and how do they differ from one another
20 and they only change by their R group
34
How do dipeptides and polypeptides form
Condensation reaction forms peptide bonds between amino acids and removes a molecule of water
35
How many levels of protein structure are there
4
36
Define the primary structure of a protein
Sequence number and type of amino acid in the polypeptide Determined by the sequence of codons on mRNA
37
Define secondary structure of a protein
Hydrogen bonds form between O delta neg attached to -C=O and H delta pos attached to -NH
38
Describe the 2 types of secondary structures
Alpha helix: All N-H bonds on same side of protein chain Spiral shape H-bonds parallel to helical axis Beta-pleated sheets: N-H and C=O groups alternate from one side to the other
39
Define tertiary structure of a protein and name all the bonds present
3D structure formed by further folding of polypeptide Disulphide bridges Ionic bonds Hydrogen bonds
40
Describe each bond in the tertiary structure of proteins
Disulphide bridges- strong covalent S-S bibs between molecules of the amino acid cysteine Ionic bonds- relatively strong bonds between charged R groups Hydrogen bonds- numerous and easily broken
41
Define quaternary structure of a protein
Functional proteins may consist of more than one polypeptide Precise 3D structure held together by the same toes of bonds as tertiary structure May involve addition of prosthetic groups e.g. metal ions or phosphate groups
42
Describe structure and function of globular proteins
Spherical and compact Hydrophilic R groups face outwards and hydrophobic R groups face inwards= usually water soluble Involved in metabolic processes e.g. enzymes and haemoglobin
43
Describe the structure and function of fibrous proteins
Can form long chains or fibres Insoluble in water Useful for support and structure
44
Outline how chromatography could be used to identify the animo acids in a mixture
1.Use capillary tube to spot mixture onto pencil origin line and place chromatography paper in solvent 2. Allow solvent to run until it almost touches the other end of paper. Amino acids move different distances based on relative attraction to paper and solubility in solvent 3. Use revealing agent or UV light to see spots 4. Calculate R value and match to database
45
What are enzymes
Biological catalysts for intra and extracellular reactions Specific tertiary structure determines shape of active site, complimentary to a specific substrate Formation of enzyme-substrate complex lowers activation energy of metabolic reactions
46
Explain the induced fit model of enzyme action
Share of active site is not directly complementary to substrate and is flexible Conformational change enabled enzyme-substrate complexes to form This puts strain on substrate bonds, lowering activation energy
47
How have models of enzyme action changed
Initially lock and key model: rigid shape of active site complementary to only 1 substrate Currently induced fit model: also explains why binding at allosteric sites can change shape of active site
48
Name 5 factors that affect the tastes of enzyme controlled reactions
.Enzyme concentration . Substrate concentration . Concentration of inhibitors .pH . Temperature
49
How does substrate concentration affect rate of reaction
Rate increases proportionally to substrate concentraction
50
How does enzyme concentration affect the rate of reaction
Rate increases proportionally to enzyme concentration
51
How does temperature affect rate of reaction
Rate increases as kinetic energy increases and peaks at optimum temperature
52
How does pH affect rate of reaction
Enzymes have a narrow optimum pH range Outside range enzymes denature
53
Constant competitive and non competitive inhibitors
Competitive inhibitors: .Similar shape to substrate- bind to active site .Do not stop reaction ES complex forms when inhibitor is released .increasing substrate concentration decreases their effect Non-competitive inhibitors: .bind at allosteric binding site .may permanently stop reaction-triggers active site to change shape . Increasing substrate concentration has no impact on their effect
54
Outline how to calculate rate of reaction from a graph
Calculate gradient of line or gradient of tangent to a point Initial rate: draw tangent at t= 0
55
Outline how to calculate rate of reaction from raw data
Change in concentration of product or reactant/time
56
Why is it advantageous to calculate initial rate
Represents maximum rate of reaction before concentration of reactants decreases and ‘end product inhibition’
57
Name the pentose sugar in DNA and RNA
DNA-deoxyribose RNA-oxyribose
58
State the role of DNA in living cells
Base sequence of genes codes for functional RNA and amino acid sequence of polypeptides Genetic information determines inherited characteristics = influences structure and function of organisms
59
State the role of RNA in living cells
mRNA-complementary sequence to 1 gene from DNA with introns spliced out. Codons can be translated into a polypeptide by ribosomes. rRNA-component of ribosomes tRNA-supplies complimentary amino acid to mRNA codons during translation
60
How do polypeptides form
Condensation reactions between nucleotides form strong phosphodiester bonds
61
Describe the structure of DNA
double helix of 2 polynucleotide strands H-bonds between complementary base pairs on opposite strands
62
Name the complementary base pairs in DNA
Adenine + thymine Guanine + cytosine
63
Name the complimentary base pairs in RNA
Adeline + Uracil Cytosine + Guanine
64
Name the complimentary base pairs in RNA
Adeline + Uracil Cytosine + Guanine
65
Relate the structure of DNA to its functions
.Sugar phosphate backbone and many H-binds provide stability . Long molecules stores lot of information . Helix is contact for storage in nucleus . Base sequence of triplets code die amino acids . Double stranded for semi conservative replication . Complimentary base pairing for accurate replication . Weak H-bonds break so strands separate for replication
66
Describe the structure of mRNA
.Long ribose polynucleotide(shorter then DNA) . Contains uracil not thymine . Single stranded and linear . Codon sequence is complimentary to exons of 1 gene from 1 DNA strand
67
Relate the structure of mRNA to its function
. Breaks does quickly so no excess polypeptide forms .ribosome can move along stand and tRNA can bind to exposed bases . Can be translated into a specific polypeptide by ribosomes
68
Describe the structure of tRNA
.Single stranded of about 80 nucleotides .Filed into clover shape .Anticodon on one end, amino acid binding site on the other Anticodon binds to complementary mRNA codon Amino acid corresponds to anticodon
69
Why is DNA replication described as semi conservative
Sienna from original DNA molecule act as a temple New DNA molecule contains 1 old strand and 1 new strand
70
Outline the process of semi conservative DNA replication
1.DNA delicate breaks H-bonds between base pairs 2. Each streams acts as a template 3.Free nucleotides from nuclear attach to exposed bases by complimentary base pairing 4.DNA polymerase catalyses condensation reactions that join adjacent nucleotides on new strand 5.H-bonds reform
71
Describe the structure of adenosine triphosphate (ATP)
Nucleotide derivate of adenine with 3 phosphate groups
72
Explain the role of ATP in cells
ATP hydrolase catalyses ATP —> ADP + Pi Energy released is coupled to metabolic reactions Phosphate group phosphorylates compounds to make them more reactive
73
How is ATP re synthesised in cells
ATP synthase catalyses condensation reaction between ADP + Pi During photosynthesis and respiration
74
Explain why ATP is suitable as the ‘energy currency’ of cells
. High energy bonds between phosphate groups . Small amounts of energy released at a time =less energy wasted as heat . Single step hydrolysis = energy available quickly . Readily resynthesised

Biology (8 decks)

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