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Biology 🧬 > bio molecules > Flashcards

bio molecules Flashcards

1
Q

Carbohydrates

A
  • Polysaccharides of monosaccharides
  • contain C, H, O
  • monosaccharides joined by condensation reactions
    = disaccharides, then poly
  • form glycosidic bonds
  • broken by hydrolysis
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2
Q

Disaccharides

A

Glucose + fructose = sucrose
Glucose + glucose = maltose
Glucose + galactose = lactose

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3
Q

Reducing sugars test

A

Monosaccharides and some disaccharides

  • add Benedict’s reagent to sample (in excess)
  • heat in water bath

+ coloured precipitate
(Blue to brick red)
- blue

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4
Q

Non-reducing sugars test

A

Eg sucrose
If reducing sugars test negative

Break into monosaccharides:
- add dilute HCl
- heat in water bath
- neutralise with sodium hydrogencarbonate

Do reducing sugars test

+ coloured precipitate
(Blue to brick red)
- blue

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5
Q

Starch

A

Plants store excess glucose as starch
2 polysaccharides of alpha glucose

Amylose
- long, unbranded chain of alpha glucose
- angle of glycosidic bonds = coiled
- compact for storage
- 1,4 glycosidic bonds

Amylopectin
- long, branched chain of alpha glucose
- branches allow enzymes to hydrolyse glycosidic bonds easier, released quick
- 1,4 and 1,6 glycosidic bonds

Insoluble in water
- doesn’t affect water potential or osmotic activity
- good for storage

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6
Q

How to test for starch

A
  • Add iodine dissolved in potassium iodide solution
    + blue-black
  • brown/orange
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7
Q

Glycogen

A

Animals store glucose as glycogen
Polysaccharides of alpha glucose

Long, branched chain
Enzymes can hydrolyse glycosidic bonds easier, broken down and released quick

Compact for storage
(Angle of glycosidic = coiled)
- 1,4 and 1,6 bonds

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8
Q

Cellulose

A

In plant cell walls

Long, unbranched chains of beta glucose
= straight cellulose chains
1,4 glycosidic bonds

Linked by hydrogen bonds = microfibrils
Strong fibres to provide structural support

Due to positive of OH and H in beta, to form glycosidic bonds:
- every other molecule of b inverts
- allows hydrogen bonds between chains

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9
Q

Triglycerides

A

Glycerol + 3 fatty acids

  • lipid
  • joined by condensation reactions
  • hydrophobic tails - insoluble in water

Fatty acid tails - contain chemical energy
- lots of energy released when hydrolysed

Insoluble - don’t affect water potential
- no osmotic activity
- arrange in droplets with hydrophobic tails facing in

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10
Q

function of triglycerides

A

energy storage
- long hydrocarbon tails store lots of energy in bonds, released when broken down

insoluble as hydrophobic - doesn’t affect water potential
act as insulator eg myelin sheath

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11
Q

Saturated fatty acids

A

Saturated
- no double binds between carbon

Unsaturated
- at least one double bind between carbons

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12
Q

Phospholipids

A

Glycerol + 2 fatty acids + phosphate

  • phosphate group hydrophilic
  • fatty acids hydrophobic
    = arrange in belayer

Centre hydrophobic
- water soluble substances can’t pass through, barrier

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13
Q

Test for lipids

A

Emulsion test

  • shake substance with ethanol (until dissolves)
  • poor solution in water

+ milky solution

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14
Q

Proteins

A

Polymers of amino acids

  • formed by condensation reactions = dipeptides, then poly
  • form peptide bonds

Have same general structure
- carboxylate group, amine group
And variable group

  • 4 structural levels
    Quaternary, tertiary, secondary and primary
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15
Q

Structural levels of proteins

A

Primary
- sequence of amino acids in a polypeptide

Secondary
- folding of primary using hydrogen bonds
- alpha helix or beta pleated sheet

Tertiary
- folded and coiled further
- hydrogen, ionic and disulphide bridges
- for 1 chain = final 3D structure

Quaternary
- multiple polypeptide chains joined by bonds
- final 3D structure

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16
Q

4 functions of proteins

A

Enzymes
Antibodies
Transport proteins
Structural proteins

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17
Q

Test for proteins

A

Biuret test

  • add sodium hydroxide (=alkaline)
  • add copper II sulphate solution

+ purple
- blue

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18
Q

What are enzymes?

A

Catalyse metabolic reactions
- lower activation energy for a reaction
- less energy (heat) needed for reaction to start, speeds up rate

Can hold molecules together to join them
- bonds form more easily
Or binds to active site and puts pressure on bonds (bends them)
- substrate breaks up more easily

Proteins with specific tertiary structure = specific shape active site

If denatured, tertiary structure (shape) changes
= doesn’t fit so can’t catalyse

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19
Q

Lock and key model

A

Substrate is a complementary shape to enzymes active site so fits together
= enzyme substrate complex

20
Q

Induced fit model

A

Active site and substrate not originally complementary
Substrate binds and change shape of active site slightly (tertiary structure)
= enzyme substrate complex

21
Q

Factors affecting enzyme activity

A

Temperature
pH
Enzyme concentration
Substrate concentration

22
Q

Temperature

A

More heat = molecules have more kinetic energy, more faster
= enzymes more likely to collide with substrates
- collisions also have more energy, so reaction more likely

At too high temperatures = enzyme denatures
- hydrogen bonds broken
- tertiary structure changes
= active site no specific shape - not complementary
(No longer catalyses)

23
Q

pH

A

All have optimum pH

Too many H+ or OH- ions break ionic and hydrogen bonds
- change tertiary structure
= active site changes shape, denatured

24
Q

Enzyme concentration

A

More enzyme molecules = more likely substrate will collide
= enzyme substrate complex
So rate increased

But substrate is limited
- adding more enzyme has no further effect on rate

25
Q

Substrate concentration

A

Higher substrate concentration = collisions between enzyme and substrate more likely
- more active sites used

Up to saturation point
- active sites all full, adding substrate has no effect

Rate decreases overtime as substrates used (unless replaced)

26
Q

Inhibition of enzyme activity

A

Competitive
- similar shape to substrate
- bind to active site, block it
- no substrate can fit = no reaction

Inhibition depends on concentration of either, more of one will increase its chance of colliding

Non-competitive
- not same shape as substrate
- bind to site away from active site
- causes active site to change shape, substrate can’t bind

Increasing concentration of substrate has no effect, still inhibited

27
Q

Importance of water

A

Metabolite in metabolic reactions
- condensation and hydrolysis

Solvent
- can dissolve substances, eg cytoplasm

Temperature control

28
Q

Structure of water

A

1 oxygen and 2 hydrogen
- joined by shared electrons

Polar molecule
- partial + and - charge on each side

  • oxygen attracts + hydrogen
    Creates hydrogen bonds
29
Q

Useful properties of water

A

Metabolite
High latent heat
High specific heat capacity
Good solvent
Cohesion

30
Q

Metabolite

A

Used in metabolic reactions
- condensation produce water
- hydrolysis use water

31
Q

High latent heat of vaporisation

A

Takes a lot of energy to break hydrogen bonds between water molecules
So a lot of energy used when evaporated

Cools organisms down through evaporation, takes heat energy (eg sweating)

32
Q

High specific heat capacity

A

Hydrogen bonds between molecule absorb a lot of energy
= high SHC, takes allot of energy to heat it

Means water doesn’t change temperature easily
- buffer to temperature change

Good habitat
Maintain stable internal temperature

33
Q

Solvent

A

Water is polar
+ end attracted to - ion and - end attracted to + ion

= ions surrounded by water molecules, dissolve
Important solvent

34
Q

Cohesion

A

Attraction between water molecules
Due to polarity, hydrogen binding between molecules

Useful for transporting substances eg in xylem
Creates high surface tension, creates droplet and some insects can walk on it

35
Q

ATP

A

Adenine, ribose, 3 phosphates

Energy released from glucose in respiration used to make ATP
- energy stored between phosphate groups

When used:
- energy released
- ATP hydrolysed into ADP and Pi
- catalysed by ATP hydrolyse

When made:
- energy used
- ADP and Pi synthesised into ATP (condensation reaction)
- catalysed by ATP synthase

36
Q

Iron ions

A

Used in haemoglobin
To transport oxygen
- 4 polypeptide chains and an iron ion

Iron ion that binds to oxygen = oxyhaemoglobin

37
Q

Hydrogen ions

A

Determines pH
- high concentration of H+ = acidic

Affects enzyme reactions

38
Q

Sodium ions

A

Transport of glucose and amino acids in co-transport
- absorption in digestion

sodium ions active transported from ileum epithelial cells into blood
by sodium potassium pump
makes concentration of sodium ions
higher in lumen then epithelial cells
sodium ions diffuse down concentration gradient into epithelial cells
through co-transporter proteins
takes glucose with it

39
Q

Phosphate ions

A

Added as phosphate groups
DNA, RNA, ATP

Important:
bonds between phosphate group that store energy in ATP
allow nucleotides to join into polynucleotides

40
Q

How is glucose stored? (In animals)

A

Alpha glucose join by condensation reactions
Produces water
1,4 glycosidic bonds = chains of alpha glucose
1,6 glycosidic bonds = branches
= glycogen

41
Q

DNA

A

Nucleotide - deoxyribose, phosphate group and a base
- adenine, guanine, cytosine, thymine

Holds genetic information

Double helix
2 polynucleotide chains
Hydrogen bonds between specific complementary bases
Phosphodiester bonds between nucleotides (sugar and base)

42
Q

RNA

A

Nucleotide - ribose, phosphate group, base
- adenine, cytosine, guanine, uracil

Transfers genetic matieral from DNA to ribosomes

Short polynucleotide chain
Single stranded

43
Q

Semi conservative replication

A

In each new DNA molecule, one DNA strands if from the original DNA molecule

Importance:
- ensures genetic continuity

44
Q

Meselson and Stahl

A

Confirmed semi conservative replication

Sample of DNA containing heavy nitrogen
Sample of DNA containing light nitrogen

If conservative, would contain only heavy or light
- sink in centrifuge

Eventually contained both heavy and light
- had conserved
- settled in middle of centrifuge

45
Q

How do enzymes increase rate of reaction?

A

binds to active site and puts pressure on bonds (bends them)
- substrate breaks up more easily

Or? Can hold molecules together to join them
- bonds form more easily

46
Q

Structure of amino acid

A

R
H2N - C - COOH
H

Biology 🧬 (23 decks)

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