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Biology > Biological Molecules - Carbs And Lipids > Flashcards

Biological Molecules - Carbs And Lipids Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a monomer?

A

small identical/similar molecules condensed to make larger molecules called polymers
eg: alpha glucose, aa, nucleotides

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2
Q

What is a polymer?

A

Large molecules made by joining 3 or more identical or similar monomers together
eg: proteins, polysaccharides, polynucleotides

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3
Q

define condensation reactions

A
  • joins two monomers together to form a - chemical bond
  • removal of one water molecule
    eg: alpha glucose -> starch
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4
Q

define hydrolysis reaction

A
  • breaks a chemical bond between two monomers
  • via addition of water molecule
    eg: cellulose -> beta glucose
    DNA -> DNA nucleotides
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5
Q

disaccharide/dimer equation

A

C6H12O6 + C6H12O6 -> C12H22O11 + H2O

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6
Q

Where do condensation reactions occur in monomers?

A

0H group of C4 and C1 H of other group

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7
Q

maltose

A

alpha glucose + alpha glucose
maltase enzyme

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8
Q

lactose

A

galactose + glucose
lactase enzyme

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9
Q

sucrose

A

glucose + fructose
sucrase enzyme

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10
Q

differences between monosaccharides

A

a-glucose: both OH (hydroxyl groups) down
galactose: both OH up
B-glucose: one OH down, one OH up
fructose: pointy top

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11
Q

starch

A
  • insoluble, doesn’t affect water potential
  • helical, so compact
  • large so doesnt diffuse out of cells
  • branched so high surface area for rapid hydrolysis to release glucose for respiration
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12
Q

amylose

A

a (1-4) glycosidic bonds
- linear chains of a glucose
- compact and helical, so good for storage
- insoluble, doesnt affect water potential

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13
Q

amylopectin

A

branched
a(1-4) and a(1-6) glycosidic bonds
large SA for rapid hydrolysis
isnoluble doesnt affect water potential
large so doesnt diffuse out of cells

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14
Q

glycogen

A
  • shorter chains
  • more branched
    -larger SA
    -humans/animal cells
    -short chains so more rapidly hydrolysed into glucose for RP
    -insoluble, doesnt affect water potential
  • large, so doesnt diffuse out of cells
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15
Q

a strach molecule has a spiral shape. explain why this shape is important to its function in cells.

A

helical so compact
insoluble, no effect in WP
large molecule so cant leave out of cell

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16
Q

structure of cellulose is related to its role in plant cell walls. explain how.

A
  • long straight unbranched chains of beta glucose
  • joined by many weak hydrogen bonds
  • form microfibrils
  • provides strength
17
Q

cellulose structure

A
  • long straight unbranched chains
  • every other b glucose inverted 180 degrees
  • b (1-4) glycosidic bonds
  • weak Hydrogen bonds form cross links between chains
  • forms microfibrils (that form cellulose fibres, stregnth and support in plant cell walls)
18
Q

hydrogen bonds are important in cellulose molecules. explain why.

A

hydrogen bonds forms cross links between chains
-form microfibrils
- provides strength and rigidity
-weak hydrogen bonds provide strength in large numbers

19
Q

reducing sugars

A

galactose
glucose
lactose
maltose
fructose

20
Q

non reducing sugars

A

sucrose

21
Q

describe how the student would show that a reducing sugar was present in a solution

A
  • add equal volumes of benedicts solution
  • and heat to 95 degrees celsius
  • red/orange PPT is a positive result
22
Q

2 different reducing sugar solutions (A+B) of same concentration have an enzyme added before benedicts. They both produced red PPT.
After 20 minutes, B had twice as much PPT as A. Suggest why.

A

A is a monosaccharide and B is a disaccharide
- enzyme hydrolysed glycosidic bonds in disaccharide, releasing 2 monosaccharides
- both monosaccharides are reducing sugar, PPT doubled in B

23
Q

describe how the student would show a non-reducing sugar was present in a solution

A
  • complete benedicts test and observe a negative result (blue solution)
  • add acid (HCl) and heat to 95 degrees
  • then neutralise with alkali
  • add benedicts solution again and then heat to 95
  • red/orange PPT is positive result
24
Q

describe how you would produce a calibration curve for a reducing sugar of unknown concentration and use it to obtain results

A
  • make up several known concentrations of [R sugar]
  • carry out benedicts test
  • use a colourimeter to measure the colour absorbance of each solution
  • and plot a calibration curve:
    X: known conc
    Y: absorbance/transmission
  • find conc of unknown sample using calibration curve
25
Q

standardising colourimeter method

A
  • samples shaken before testing
  • zero colourimeter before use with a control
  • use same filter
  • use same volume for each reading
26
Q

describe how you would test a sample of food for the presence of starch

A
  • add potassium iodide (KI) solution
  • blue/black indicates starch is present
27
Q

The structure of cellulose is related to its role in a plant cell wall. Explain how.

A
  • Long, straight unbranched chains of beta glucose
  • joined by many weak hydrogen bonds
  • form microfibrils
  • provide strength/rigidity
28
Q

Give one feature of starch and explain how it enables it to act as a storage substance

A
  • helical so compact
  • insoluble so doesnt affect water potential
  • large molecule so doesnt leave cell
  • branched chains so rapid hydrolysis to remove glucose for respiration
29
Q

Hydrogen bonds are important in cellulose. Explain why.

A

Holds chain together/form microfibrils
Providing strength and rigidity
Weak Hydrogen bonds provide strength in large numbers

30
Q

Describe how lactose is formed and where in the cell it would be attached to a polypeptide to form a glycoprotein

A

Glucose and galactose
Joined by condensation reaction
Jojned by glycosidic bond
Added to polypeptide in golgi

31
Q

Describe how you would test a liquid sample for the presence of a lipid vox and how you would recognise a positive result

A

Mix with ethanol then water
And shake
Cloudy white emulsion

32
Q

Omega 3 fatty acids are unsaturated. What is an unsaturated fatty acid?

A

Double bond
Between carbon atoms within the hydrocarbon chain

33
Q

Describe how a ester bond is formed in a phospholipid molecule

A

Condensation
Between a glycerol and fatty acid

34
Q

What are the differences between a triglyceride and a phospholipid

A

Fatty acid removed
Replaced with a phosphate group

35
Q

Compare and contrast the structure and properties of triglycerides and phospholipids

A
  • both contain ester bonds
  • both contain glycerol
    -fatty acids on both may be saturated or unsaturated
  • both are insoluble in water
  • both contain C, H and O but phospholipids also contain P
  • triglycerides have 3 fatty acids and phospholipids have 2 fatty acids plus a phosphate group
  • triglycerides are hydrophobic and phospholipids have a hydrophilic and hydrophobic region
  • phospholipids form bilayer but triglycerides do not
36
Q

Desctibe the biochemical tests you would use to confirm the presence of lipid, non reducing sugar and amylase in a sample

A

Lipid
- add ethanol then water and shake
- white milky emulsion

Non reducing sugar
- Do benedicts and get a negative result
- boil with acid and immedicately neutralise with an alkali
- heat with benedicts and red/orange precipitate

Amylase
- add bieuret reagenr and purple
- add starch
- test for reducing sugar

37
Q

A student carried out the benedicts test. Suggest a method, other than usinf a colorimeter, that this student could use to measure the quantity of reducing sugar in a solution

A
  • filter and dry the precipitate
  • find mass/weight

Biology (29 decks)

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