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biology paper 1 > carbs and lipids > Flashcards

carbs and lipids Flashcards

biological molecules

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AP® Biology flashcards Biology 101 flashcards
1
Q

what are the 5 biological molecules?

A
  1. carbohydrates
  2. lipids
  3. proteins
  4. DNA/RNA
  5. water
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2
Q

what are monomers?

A

individual units that makes up a polymer

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3
Q

what are polymers?

A

many repeating units of monomers

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4
Q

what are some examples of monomers?

A
  • nucleotide
  • monosaccharide e.g. glucose
  • amino acids
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5
Q

what is the definition of a condensation reaction?

A

when 2 molecules join together to form a chemical bond which releases a water molecule

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6
Q

what is the definition of a hydrolysis reaction?

A

2 molecules separated to break a chemical bond using a water molecule

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7
Q

what are some examples of a polymer?

A
  • polynucleotide (DNA/RNA)
  • polysaccharide e.g. starch
  • polypeptide (protein)
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8
Q

why are lipids not polymers?

A

because its not made from many repeating units of monomers, therefore it cant be a polymer

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9
Q

what is the chemical formula of the molecule that is produced by a condensation reaction?

A

C12H22O11
-not C12H24O12, it is initially when the 2 molecules joins together
but releasing one H2O
molecule (2 hydrogens and 1 oxygen) reduces the number of hydrogen and oxygen atoms.

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10
Q

what are monosaccharides? include examples

A

monomers from which larger carbohydrates are made.
e.g. glucose (alpha + beta), galactose, fructose

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11
Q

What is the name of this structure ?

A

alpha glucose

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12
Q

What is the name of this structure ?

A

Beta glucose

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13
Q

What structure is this ?

A

Galactose

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14
Q

describe the difference between the structure of alpha and beta glucose.

A
  • they are isomers : same molecular formula but differently arranged atoms.
  • OH group is below carbon 1 in alpha glucose but above carbon 1 in beta glucose
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15
Q

how are disaccharides formed ?

A

when two monosaccharides joins together via condensation reaction to form a glycosidic bond

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16
Q

what does 2 alpha glucose form?

A

maltose

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17
Q

what does glucose and fructose form?

A

sucrose

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18
Q

what does glucose and galactose make?

A

lactose

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19
Q

what is the structure of maltose?

A
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20
Q

What are polysaccharides and include some examples

A

Many monosaccharides joined together via condensation reaction to form glycosidic bonds.
E.g. starch, glycogen + cellulose

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21
Q

describe the function and structure of starch

A
  • energy store in plant cells in the formation of grains
  • polysaccharide of a-glucose
  • some has 1,4-glycosidic bonds so is unbranched (amylose)
    -some has 1,4 and 1,6- glycosidic bonds so is branched (amylopectin)
22
Q

describe the function and structure of glycogen

A
  • energy store in animal cells (cytoplasm) in the form on granules
    -polysaccharides of many a-glucose joined via condensation reaction in the form of glycosidic bonds
    -1,4 and many more 1,6 glycosidic bonds compared to starch - branched
23
Q

describe the function and structure of cellulose

A
  • provides strength and structural support to plant/algal cell walls
  • polysaccharide of many b-glucose molecules joined via condensation reaction to form b-1,4 glycosidic bonds
  • 1,4 bonds are straight and unbranched chains
    -chains linked in parallel by hydrogen bonds, forming microfibrils
24
Q

explain how the structures of starch relate to their functions

A
  • large: cant diffuse out of cell
  • insoluble: osmotically inactive
    -helical : compact energy store ( helix shape due to the force of attraction between the positive and negative)
    -branched: rapidly release a-glucose when needed
25
Q

explain how the structures of glycogen relate to their functions

A
  • large: cant diffuse out of cell
  • insoluble: osmotically inactive
    -helical : compact energy store
    -branched: rapidly release a-glucose when needed
  • branched : compact/ fit more molecules in small area + more ends for faster hydrolysis which releases glucose for respiration to make ATP for energy release
26
Q

explain how the structure of cellulose relates to its function

A

-every other b-glucose is inverted in a long, straight, unbranched chain
-parallel bonds can form hydrogen bonds (crosslinks) to form microfibrils (adds strength) which joins to form strong fibres - provides strength to plant cells

27
Q

what are the reducing sugars?

A
  • the monosaccharides : a/b glucose, galactose + fructose.
  • the disaccharides: maltose + lactose.
    (sucrose is the only non reducing sugar)
28
Q

how does reduction happen?

A

-reduction is the gain of electrons (OIL RIG).
- oxidation is the loss of electrons
- a reducing sugar is able to lose an electron (oxidation) and give it to another compound
- we test reducing sugars by giving them something to reduce - benedict reagent

29
Q

how does the solution of benedict turn from blue to red in the form of a chemical reaction?

A

simple term: the benedict solution is blue but when it gains an electron it turns red

30
Q

what is the test for reducing sugars?

A
  1. add benedict solution (blue) to sample
  2. heat in a boiling water bath
  3. positive results : green/yellow/orange/red precipitate - increasing quantity of sugar
    - results are SEMI- QUANTITATIVE
31
Q

what is the test for non reducing sugars?

A
  1. get a negative benedict’s test - stays blue
  2. boil with HCL to hydrolyse into reducing sugars in a water bath. (normally with water but will require a lot more energy)
  3. cool and neutralise HCL with alkali using NaOH ( sodium hydroxide)
  4. add benedict reagent
  5. heat in a boiling water bath
  6. positive results: green/yellow/orange/red precipitate
32
Q

describe the biochemical test for starch

A
  1. add iodine dissolved in potassium iodine (orange/brown) and shake/stir
  2. positive results: blue-black
33
Q

suggest some methods to measure the quantity of sugar in a solution

A
  • carry out Benedict’s test as above, then filter and dry precipitate
  • find mass/weight
  • colorimeter
34
Q

diagram of how a colorimeter works

A
35
Q

how to identify unknown glucose concentration?

A
  1. make sugar solutions of known concentrations ( e.g. dilution series)
  2. heat a set volume of each sample with a set volume of Benedict’s solution for the same time
  3. use a colorimeter to measure absorbance of light of each known concentration.
  4. plot calibration curve - concentration on X-axis and absorbance on y-axis then draw a line of best fit
  5. repeat Benedict’s test with unknown sample and measure absorbance
  6. read off graph to identify concentration of unknown solution
    NOTE: using “amounts” is too vague to get the mark. must use “volume” instead
36
Q

how does starch and glycogen act as energy stores?

A

they are made of a-glucose which is the substrate for respiration in cells. this produce ATP for energy release

37
Q

TRUE OR FALSE
cellulose is strong because of hydrogen bonds

A

FALSE - hydrogen bonds are weak individually but strong in high numbers. (you need to specify there are many hydrogen bonds)

38
Q

what are lipids used for?

A
  • energy store
  • insulation ( thermal, electrical - myelin sheaths cover nerves)
  • water proofing ( waxy cuticle)
  • protection (lipids covers heart + kidneys)
39
Q

what are the 2 types of lipds?

A
  • triglycerides
  • phospholipids
40
Q

describe the structure of a fatty acid (RCOOH)

A
  • variable R-group - hydrocarbon chain ( could be saturated or unsaturated)
  • COOH = carboxyl group
41
Q

What structure is this?

A

Glycerol

42
Q

Describe the difference between saturated and unsaturated fatty acids

A
  • saturated - no C=C double bonds in hydrocarbon chain- all carbons fully saturated with hydrogen
  • unsaturated - one or more C=C double bond in hydrocarbon chain (creating a bend/ kink)
43
Q

Describe how triglycerides form

A
  • 1glycerol molecule and 3 fatty acids
  • 3 condensation reactions removing 3 water molecules
  • forming 3 ester bonds
44
Q

What is the general structure of triglycerides?

A
  • consists of fats (solid at room temp) and oils (liquid at room temp)
  • never bonds together
45
Q

explain how the properties of triglycerides are related to their structure

A
  • hydrophobic/ non-polar fatty acids- insoluble in water (clump together as droplets, tails inwards) : osmotically inactive so no effect on water potential of cell - waterproofing
    -low mass to energy ratio : don’t have to carry heavy energy store
  • high ratio of H atoms to O atoms : water can be released during breakdown
  • high ratio of energy storing of C-H bonds to carbon atoms in hydrocarbon chain: energy dense molecule - used in respiration to release more energy than the same mass of carbohydrates
46
Q

what is the general structure of a phospholipid?

A
  • the fatty acid tails are non-polar: electrons are evenly spread. the tails are hydrophobic
  • the phosphate head is polar: delta positive and delta negative regions. This is an uneven distribution of electrons. The head is hydrophilic
47
Q

What is the chemical structure of a phospholipid?

A
48
Q

Diagram of what a phospholipid look like in water

A
  • two layers : phospholipid bilayer
  • a molecule with polar and non polar regions is called “AMPHIDATHIC”. This property is essential to form a phospholipid bilayer
49
Q

describe the difference between the structure of triglycerides and phospholipids

A

one fatty acids of a triglyceride is substituted by a phosphate- containing group
NOTE: phosphate groups NOT phosphorus

50
Q

describe how the properties of phospholipids relate to their structure

A

form a bilayer in cell membrane, allowing diffusion of lipid- soluble (non-polar) or very small substances and restricting movement of water-soluble (polar) or larger substances

51
Q

explain how the structures of phospholipids relate to its function

A
  • phosphate head are hydrophilic : attracted to water so point to water (aqueous environment) either side of membrane
  • fatty acid tails are hydrophobic: repelled by water so point away from water/ to interior of membrane
  • glycolipids can form: allows for cell recognition - protein/ carbs
52
Q

Describe the test for lipids

A
  1. Add ethanol, shake (to dissolve lipids), then add water
  2. Positive result = milky white emulsion

biology paper 1 (7 decks)

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