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A Level Biology > Unit 1 > Flashcards

Unit 1 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Monomer

A

Single units that are joined together to create a chain.

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2
Q

Polymer

A

Large molecules made up of repeating smaller molecules.

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3
Q

Condensation Reaction

A

A chemical process in which two molecules combine to form complex structures like polysaccharides and polypeptides. Usually eliminates water.

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4
Q

Hydrolysis Reaction

A

The breaking down of large molecules into smaller molecules by the addition of water.

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5
Q

3 types of carbohydrates:

A

Monosaccharides, disaccharides, polysaccharides.

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6
Q

Bond between monosaccharides:

A

Glycosidic!!!

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7
Q

Bond between amino acids:

A

Peptide

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8
Q

Bond between glycerol and fatty acid within a lipid:

A

Ester bond

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9
Q

Bond between DNA/RNA bases:

A

Phosphodiester.

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10
Q

Monosaccharide examples:

A

-Glucose
-Fructose
-Galactose

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11
Q

Two isomers of glucose:

A

-Alpha-glucose (draw it!)
-Beta-glucose (draw it!!)

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12
Q

How is a glycosidic bond formed?

A

Two hydroxl (-OH) groups react together forming a covalent bond (-O-) and water comes away. Condensation reaction.

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13
Q

Disaccharide examples:

A

-Maltose
-Sucrose
-Lactose

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14
Q

Glucose + Glucose –>

A

Maltose

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15
Q

Glucose + Fructose –>

A

Sucrose

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16
Q

Glucose + Galactose –>

A

Lactose

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17
Q

Starch contains:

A

-Amylose
-Amylopectin

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18
Q

Amylose

A

-1-4 glycosidic bonds, straight chains.
-Helix structure enables it to be more compact and resistant to digestion.

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19
Q

Amylopectin

A

-1-4 glycosidic bonds but ALSO 1-6 glycosidic bonds creating branched molecules.
-Branches mean more terminals which can be hydrolysed to use for respiration or to be added to for storage.

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20
Q

Glycogen

A

-Highly branched
-More compacts so animals can store more energy.
-The branching means more free ends to which glucose molecules can either be added or removed.
-The storage or release of glucose can suit the demands of the cell.

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21
Q

Cellulose chains can be:

A

-Branched and unbranched
-Folded (can be made compact)
-Straight or coiled
-Insoluble

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22
Q

Cellulose Structure

A

-Long chain of beta glucose joined by 1-4 glycosidic bonds.
-Rotated 180 degrees and each monomer is inverted.
-Bc of inversion, hydrogen bonds form between the chains.

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23
Q

Cellulose Function

A

-Cell walls because hydrogen bonds between parallel chains creating microfibrils.
-High tensile strength allows it to be stretched.
-Cellulose fibres are permeable.

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24
Q

Test for reducing sugars:

A

-Add Benedict’s Reagent to the sample.
-Heat in water bath at 80 degrees
-Will turn brick red if reducing sugars are present.
(Benedict’s Reagent has Copper Sulfate ions making it a pale blue colour. When reducing sugars are present, the CuSO4 is reduced to CuO.)

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25
Q

Test for non-reducing sugars:

A

-Add dilute HCl.
-Heat in water bath.
-Neutralise using Sodium Hydrogencarbonate (use indicator to check).
-Carry out Benedicts test as normal.

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26
Q

Test for starch:

A

-Add iodine to potassium iodide solution.
-Add that to the sample of food.
-Colour change from orange/yellow to blue/black.

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27
Q

Saturated fatty acid

A

Single covalent bonds between carbon atoms.

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28
Q

Unsaturated fatty acid

A

Double covalent bonds between carbon atoms.

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29
Q

Triglyceride

A

Contains 1 glycerol molecule and 3 fatty acids.
Ester link between hydroxyl on glycerol and carboxylic group on fatty acid. O-C=O
Condensation reaction.
Water molecule comes away.

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30
Q

Triglyceride functions:

A

-Energy store
-Insulation
-Buoyancy
-Protection

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31
Q

Phospholipid

A

1 glycerol, 1 phosphate group, 2 fatty acids
‘Heads’ and ‘tails’

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32
Q

Role of phospholipids

A

-Cell membrane
-Barrier to water-soluble molecules
-Saturated fatty acid tails- less fluid.
-Unsaturated fatty aid tails- more fluid.

33
Q

Test for lipids:

A

-Qualititive test
-Add ethanol to food sample.
-Add water
-Cloudy/milky emulsion- lipids present.

34
Q

Amino acid general formula

A

NH2-CHR-COOH
Draw

35
Q

Condensation reaction of amino acids

A

-Peptide bond between H fron NH2 and OH from COOH.
-H2O formed.

36
Q

Primary structure of protein

A

-Sequence of amino acids bonded together by peptide bonds forming a polypeptide chain.
-DNA affects sequence and therefore protein.

37
Q

Secondary structure of a protein

A

-Weak hydrogen bonds between partially negative N and O and partially positive H.
-Forms alpha-helix or beta-pleated sheet.
-Fibrous proteins typically have secondary structure.
-Secondary structure refers to the hydrogen bond between the amino acid and carboxyl group.

38
Q

Alpha-helix bonding

A

Hydrogen bond between every fourth peptide bond.

39
Q

Beta-pleated sheet bonding

A

Protein folds and polypeptide chains are parallel enabling hydrogen bonds to form between parallel peptide bonds.

40
Q

Tertiary structure of protein

A

-Bonds form between R groups (side chain).
-Hydrogen bonding
-Ionic bonding
-Disulphide bridges
-Weak hydrophobic interactions
-Often in globular proteins

41
Q

Disulphide Bonds

A

-Form between 2 cysteine R groups
-Stabilise the protein
-Broken by reduction
-Common in proteins secreted by cells.

42
Q

Ionic Bonds

A

-Form between + charged (amine group) and - charged (carboxylic acid) R groups.
-Broken by pH changes

43
Q

Hydrogen Bonds

A

-Between strongly polar R groups.
-Most common.

44
Q

Hydrophobic Interaction

A

Forms between hydrophobic, non-polar R groups in the interior of proteins.

45
Q

Quaternary structure of proteins:

A

Multiple polypeptide chains joined together by peptide bonds.

46
Q

Globular vs fibrous proteins

A

Globular proteins (e.g. enzymes) are compact.
Fibrous proteins (e.g. keratin) are long forming fibres.

47
Q

Test for proteins

A

-Add NaOH or KOH to make sample alkaline.
-Add Copper(II) Sulfate to the solution
-(Biuret’s Reagent contains both these.)
-Colour change from blue to purple indicates the presence of proteins.

48
Q

Enzymes

A

-Act as a catalyst by lowering activation energy needed to start a reaction.
-Globular protein that has a specific region called an active site.
-Substrates bind to the active site forming an enzyme-substrate complex.

49
Q

Induced fit model

A

-Proposes the idea that the active site changes shape slightly to accommodate the substrate.
-As it changes shape, the enzyme puts a strain on the substrate molecule.
-The strain distorts bonds in the substrate and consequently lowers the activation energy needed to break the bond.

50
Q

Lock and key model

A

-Each key fits and operates only a single lock (one substrate only fits one specific enzyme).
-A limitation of this is that enzymes are considered a rigid structure.
-Enzymes are actually flexible so therefore the induced fit model was developed.

51
Q

Factors affecting the rate of enzyme reactions

A

-Temperature
-pH
-Enzyme concentration
-Substrate concentration

52
Q

Temperature

A

-As temperature increases so does the rate of reaction.
-This is because there is more kinetic energy so therefore molecules move more and there are more collisions and more successful enzyme substrate complexes.
-After the optimum temperature is reached, the rate of reaction decreases.
-At high temps, the enzymes vibrate too much and the bonds that maintain tertiary structure are broken.
-Active site changes shape and no more ES complexes so enzyme is denatured.

53
Q

pH

A

-All enzymes have optimum pH.
-Above and below the optimum, the H+ and OH- ions disrupt the ionic and hydrogen bonds in the tertiary structure of the enzyme.
-Active site changes shape, no more ES complexes so enzyme is denatured.

54
Q

Enzyme Concentration

A

-Increases number of active sites for collisions.
-More ES complexes form.
-Rate of reaction increases until amount of substrate becomes the limiting factor then the graph plateaus.
-Increasing the enzyme concentration after this will not have an effect.

55
Q

Substrate Concentration

A

-Increases rate of reaction as there is more chance of successful collisions so more ES complexes form.
-Rate of reaction will slow as enzyme conc becomes a limiting factor. All active sites are occupied.
-Increasing the substrate concentration will no longer have an effect on the rate.

56
Q

Competitive inhibitors

A

-Have a molecular shape similar to that of the substrate.
-Occupies the active site of an enzyme.
-Prevents substrates from binding and forming enzyme-substrate complexes.
-Reduces rate of reaction.
-Can overcome this by increasing the concentration of the substrate so it increases the likelihood of enzyme-substrate complexes forming.

57
Q

Non-competitive inhibitors

A

-They attach at the allosteric site.
-When they attach they alter the shape of the active site.
-This decreases the rate of reaction as the enzyme can therefore not be used so no enzyme-substrate complexes will form.

58
Q

RNA

A

-Transfers genetic material from nucleus to ribosomes.
-Nucleotides contain: ribose sugar, phosphate group and a nitrogenous base.
-Uses uracil instead of thymine.

59
Q

DNA

A

-Holds genetic information.
-Nucleotides contains: deoxyribose sugar, phosphate group and a nitrogenous base (A=T, C3-G).

60
Q

Stability of DNA

A

-Phosphodiester backbone protects the more chemically reactive organic bases inside the double helix.
-Hydrogen bonds link the organic base pairs forming bridges between the phosphodiester uprights.
-There are 3 hydrogen bonds between C and G so therefore a higher proportion of C-G bonds, the more stable.

61
Q

Prime location

A

-3’ is the hydroxyl group
-5’ is the phosphate group
-In double helix, one strand runs 5’ to 3’ and the other runs 3’ to 5’. Referred to as ‘antiparallel’.

62
Q

4 differences of DNA and RNA

A

-Double strand vs single strand.
-Hydrogen bonds vs no hydrogen bonds.
-Uses thymine vs uses uracil.
-Long vs short.
-Deoxyribose sugar vs ribose sugar.

63
Q

DNA is stable because:

A

-Phosphodiester backbone protects the highly reactive nitrogen base in the helix.
-Hydrogen bonds form bridges between phosphodiester uprights.
-More C-G bonding= more stable due to 3 hydrogen bonds.

64
Q

Semi-conservative replication needs:

A

-Each types of bases (A, T, C, G).
-Enzyme of DNA Polymerase.
-Chemical energy source.
-Both strands of DNA act as a template for attachment of nucleotides.

65
Q

Semi-conservative replication

A

-DNA helicase breaks the hydrogen bonds between the bases causing the helix to unwind.
-Free nucleotides enter and use one strand as a template and complementary bases pairing occurs.
-DNA Polymerase joins the nucleotides forming phosphodiester bonds.
-Two strands of DNA are formed.

66
Q

Meselson-Stahl Experiment of Semi-conservative replication

A

Draw it!!!!!!

67
Q

Transcription

A

-DNA helix unwinds to expose bases to act as a template.
-Only one chain of the DNA acts as a template.
-Catalysed by DNA helicase.
- DNA helicase breaks hydrogen bonds between bases.
-Free mRNA nucleotides in the nucleus align with opposite exposed complementary bases.
- Enzyme RNA polymerase bonds together the RNA nucleotides creating RNA polymer chain. one gene is copied (pre-mRNA).
-Splicing- introns are ‘spliced out’ (by protein- splicesome) as they don’t code for proteins.

68
Q

Translation

A

-Once the modified mRNA leaves the nucleus, attaches to ribosomes.
- Ribosomes attach to start codon.
-tRNA with complementary anticodon to codon aligns opposite mRNA.
-Ribosome will move along the mRNA reading it in triplets.
-Amino acids brought by tRNA form peptide bond (catalysed by enzymes and requires ATP).
-Continues to stop codon (doesn’t code for amino acid) so ribosome detaches and ends.

69
Q

ATP

A

-Consists of ribose, adenine, and three phosphate groups.
-ATP—> ADP + Pi (condensation catalysed by ATP hydrolase)
-ADP + Pi —> ATP (hydrolysis catalysed by ATP synthase)
-Pi can phosphorylate other molecules making them more reactive.

70
Q

3 ways that ATP is synthesised:

A

-In chlorophyll-containing plant cells during photosynthesis (photophosphorylation).
-In plant and animal cells during respiration (oxidative phosphorylation).
-In plant and animal cells when phosphate groups are transferred from donor molecules to ADP (substrate-level phosphorylation).

71
Q

Roles of ATP:

A

-Metabolic processes- provides energy to build up macromolecules from basic units.
-Movement- energy for muscle contraction, filaments of muscle slide past one another to shorten overall length of muscle fibre.
-Active transport- change shape of carrier proteins in membrane, allows molecules to be moved against a conc gradient.
-Secretion- form lysosomes needed for secretion of cell products.
-Activation of molecules- Pi can make molecules more reactive, lowering the activation in enzyme-catalysed reactions. E.g. Pi+glucose at start of glycolysis.

72
Q

Water structure

A

-Dipolar
-2 hydrogen atoms and 1 oxygen.
-Oxygen is partially negative and hydrogen is partially positive.

73
Q

Specific heat capacity of water

A

-Hydrogen bonding means that molecules stick together and therefore more energy is needed to separate them.
-Acts as a buffer against sudden temperature variations.
-Makes aquatic environments more temperature-stable.
-Buffers organisms against sudden temperature changes in terrestrial environments.

74
Q

Latent heat of vaporisation of water

A

-Hydrogen bonding between water molecules means that it required a lot of energy to evaporate 1 gram of water.
-Sweating in thermoregulation provides a cooling effect through evaporation.

75
Q

Cohesion and surface tension of water

A

-Tendency for molecules to stick together is cohesion.
-Due to hydrogen bonding, water has high cohesion forces which allows it to be pulled through a tube.
-ST is a force that means that when water molecules meet air, they tend to be pulled back into the body of water rather than escaping from it.

76
Q

Water in metabolism

A

-Break down and build up molecules (condensation and hydrolysis).
-Chemical reactions take place in an aqueous medium.
-Raw material in photosynthesis.

77
Q

Water as a solvent

A

Readily dissolve:
-Gases such as O2 and CO2.
-Wastes such as ammonia and urea.
-Inorganic ions and small hydrophilic molecules such as amino acids, monosaccharides and ATP.
-Enzymes whose reactions take place in solution.

78
Q

Other properties of water

A

-Evaporation cools organisms and allows them to control temperature.
-Not easily compressed and therefore provides support.
-Transparent so photosynthesis can occur and also light rays penetrate jelly fluid in eye so light rays reach retina.

79
Q

Inorganic ions

A

-Fe+ ions- found in haemoglobin and play a role in transport of oxygen.
-Phosphate ions- structural role in DNA and storing energy in ATP molecules.
-H+ ions- determining pH of solutions and functioning of enzymes.
-Na+ ions- important in transport of glucose and amino acids across plasma membrane.

A Level Biology (9 decks)

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