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Biology AQA Alevel > 3.1 Biological Molecules > Flashcards

3.1 Biological Molecules Flashcards

1
Q

What is an isomer?

A

Same chemical formulae, different arrangement

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2
Q

Monomers making Maltese?

A

2 glucose

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3
Q

Monomers making Sucrose?

A

Glucose + Fructose

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4
Q

Monomers making Lactose?

A

Glucose + Galactose

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5
Q

Bonds between sugars

A

Glycosidic

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6
Q

Isomers of glucose

A

Alpha glucose

Beta glucose- flip on carbon 1, alternating directions when in chain

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7
Q

Starch

A

Alpha glucose (stored on plants)

  • mostly unbrancged and tight helix shape
  • insoluble, compact, easily hydrolized, large molecule
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8
Q

Glycogen

A

Alpha glucose (stored in animals)

  • short and branched, tight helix shape
  • insoluble, compact, lots of ends for hydrolysis, large molecule
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9
Q

Cellulose

A

Beta glucose (cel walls)

  • straight and unvranched, parrelel chains connected by hydrogen bonds
  • Cross links so collectively strong, microfibrels and fiberals for more stregnth
  • stops cell from wilting
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10
Q

Test for reducing sugar

A

2cm³ of food sample +Benedicts solution+ heat

Colour change blue to red (shows concentration by colour)

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11
Q

Testing for non reducing sugars

A

2cm³ of food sample + 2cm³ of HCl (hydrolize into monomers)
+ NaHCO3 (neutralize)
Then perform reducing sugars test

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12
Q

Test for Starch

A

Drops of iodine on 2cm³ of food sample

Colour change brown to blue/black

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13
Q

Colorimeter in test for sugars

A

tests solutions absorbance of light

  • more intence the colour more absorbant it is
  • need to caliberate device with water and known concentrations glucose (Quantative Data)
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14
Q

7 Functions of protiens with examples

A
  • contractile (actin+myosin, cilia+flagellum)
  • storage (ovalbumin (egg white) and in seeds)
  • receptor and hormonal (nerve membrane and insulin)
  • transport (haemoglobin)
  • enzymatic (digestive enzymes)
  • structural (silk fibers for webs, collagen and elastin, keratin for hair/feathers/horns)
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15
Q

Amino acid structure and properties of R groups

A

NH2-CHR-COOH (amine and carboxly group)
-20 natural occurring amino acids

R groups can be:
hydrophilic (charged) or hydrophobic
-acidic, basic or amphoteric (acid and base so used as buffers)

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16
Q

Simple protien

A

Made if only amino acids

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17
Q

Conjuncted protiens

A

Contain amino acids and a non-Amino acid part called “prosthetic group”

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18
Q

Primary structure of protiens

A

The sequence of amino acids joined by peptide bonds

-change to primary structure due to mutations in DNA

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19
Q

Secondary structure of protien

A

The way the polypeptide chain is folded into ALPHA HELIX or BETA PLEATED SHEETS
-joined by weak Hydrogen bonds

-chain can have some regions coiled and others folded

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20
Q

Tertiary structure of protiens

A

Protien folds further to give molecule a globular shape

  • forms specific 3D shapes
  • important for enzymes and antibodies
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21
Q

Types of bonds in tertiary structure of protien

A

Ionic- NH2 • • •COOH, broken by pH change
Hydrogen- strong in number, broke by temp or pH change
Disulphide- strongest bond in structure (S‐S)

Hydrophobic interactions- hydrophobic R group cluster together in presence of water (not a bond)

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22
Q

Structure of DNA

A
  • nucleotide (phosphate group, deoxyribose pentosugar, nitrogeonous base)
  • joined by PHOSPHODIESTER BONDS
  • double helix
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23
Q

Bases and Base interactions

A 
Adenine Guanine (purine)
Thymine Cytosine (pyrimidines)
A--T
C---G 
Hydrogen Bonds
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24
Q

Structure of DNA to its functions

A

double stranded- template for semi conservative replication
weak h-bonds- can be broken for easy replication
many h bonds- overall strong
complementary base pair- accurate replication
sugar phosphate backbone- protects from corruption
large molecule- store lots of info
double helix- compact

25
Q

importance of DNA

A 
genetic code (for all protiens)
mitosis
variation
26
Q

difference between DNA and RNA

A

RNA- ribose sugar, smaller, single helix, Uracil instead of Thymine

27
Q

Process of DNA replication

A
  • DNA helicase breaks H bonds, DNA unravel
  • strands act as templates
  • free floating activated nucleotides attract to specific complementary base
  • DNA polymerase joins nucleotides (phosphodiester)
  • Semi conservative, ensures genetic continuity
28
Q

uses of ATP

A
  • movement
  • metabolism
  • maintaining temperature
  • active transport
  • PHOSPHORYLATION to change protein shape
  • cell division
  • production/secretion of other products (e.g. from lysosomes)
29
Q

Structure of ATP

A

-adenine
-ribose pentose sugar
-3 phosphate group (last bond unstable and easily broken)
KNOWN AS A NUCLEIC ACID

30
Q

How does ATP release energy?
How does it return to ATP?
How much energy released?

A
  • last phosphate covalent bond broken by ATP hydrolase
  • reversible, joined back by ATP synthase
  • immediate release of energy, in manageable amount (33kJ)
31
Q

What is triglyceride made of?

A

1 glycerol molecule( 3 hydroxyl groups)
and 3 fatty acid molecules (each has 1 carboxyl group)

Connected by ester bond

32
Q

Saturated lipid

A

No carbon-carbon double bonds
Straight and closely packed (dense)
-so solid at room temp
E.g. fats/butter

33
Q

Unsaturated lipids

A

Has carbon-carbon double bond
Causes chain to bend, less dense
- liquid at room temp
E.g. oil

34
Q

Properties of triglycerides

A

-good energy store
(high proportion of H so provides 2× more energy than respiration and provides water so reduces mass needed to be carried by animals)
-non polar (doesn’t affect water potential, provides waterproof layer)
-thermal and electrical insulation
-protect internal organs (as cushioning)
- less dense than water (aids in buoyancy)

35
Q

Phospholipid structure

A

1 phosphate group (PO⁴R) negative ion
1 glycerol (3 hydroxyl groups)
2 fatty acid chains (each has 1 carboxyl group)

Head is charged so polar so hydrophilic
Tails are unchanged so hydrophobic

36
Q

Shapes formed by phospholipids

A
  • monolayer ontop of water
  • MICELLES- monolayer ball
  • BILAYER- fluid membrane but stable shape
  • barrier and electrical insulation
  • ions dissolved in water so cant go through membrane (surrounds nerve cells)
37
Q

Test for lipids

A

EMULSION TEST
If sample solid it must be crushed

2cm³ of sample and add 5cm³ of ethanol
Shake tube and add 5cm³ of water, reshake
WHITE EMULSION

38
Q

Light Microscope

pros and cons

A

uses light and lenses
low mag and resolution
for bacteria/tissue
simple and cheap

39
Q

Electron Microscope

pros and cons

A

uses electron and electromagnets
high mag and resolution
for organelles/organisms
complex and expensive

40
Q

Setting sample for Electron microscope

A

Killed, Dehydrated, stained with heavy metals (which can cause artifact/debris to damage sample), fixed in a vacuum

41
Q

TEM (pros and cons)

A
  • to see organelles inside (stains absorb electron)
  • has slightly better resolution that SEM
  • used for cells, cant use it for organisms
42
Q

SEM (pros and cons)

A
  • to see surface of specimen (stain reflects electron)
  • 3D
  • can be used to see specimens
43
Q

steps in Differential Centrifugation

A
  • chop and place in ICE COLD ISOTONIC BUFFER
  • homogenize
  • spin in centrifuge, remove supernatant
  • repeat at faster speeds

-first pellet: nucleus, 2nd pellet: chloroplast/mitochondria

44
Q

creating temporary mount

A

-cut thin enough for light to pass through
-flatten then stain with Iodine SOLUTION
(unless looking at something pigmented)
-use mounting needle to lower cover slip at an angle

45
Q

Why is cells placed in ice cold, isotonic, buffer solution? (for centrifugion)

A

cold-reduce hydrolytic enzyme activity
isotonic- so doesn’t affect water content of cells
buffer- constant pH so structural proteins not changed

46
Q

difference in 2 strands of DNA

A

-antiparallel strands
-phosphate end (5 prime/leading), sugar (3 prime/lagging)
DNA POLYMERASE WORKS FROM 5 TO 3 PRIME

47
Q

Experiment for Semi Conservative Replication

A

bacteria grown in heavy nitrogen, next replications done in light nitrogen for 3 generations
-spun in DENCITY GRADIENT CENTRIFUGION

48
Q

what is density gradient centrifugation?

A

DNA centrifuging in a solution of caesium chloride, DNA separates at its densities
compare bands to normal light nitrogen bands

49
Q

Results of Experiment of Semi Conservative Proof

A
  1. all heavy so at bottom
  2. half heavy have hybrid
  3. half hybrid half light
    4 quarter hybrid, rest light
50
Q

structure of ATP

A

adenine, ribose pentosugar, 3 phosphate groups

51
Q

properties of water

A 
cohesion
water tension
high heat capacity
high latent heat of vaporization
used in metabolism
universal solvent
amphoteric
low density as solid
52
Q

Properties of water- cohesion

A

attraction between molecules

h20 sticks together so can FLOW (needed in phloem)

53
Q

Properties of water- metabolism

A

used in HYDROLOSIS and produced in CONDENSATION

  • many reactions happen in aqueous conditions
  • needed in photosynthesis
54
Q

Properties of water- as a solvent

A

H2O has dipole so can dissociate ions in ionic compounds

-gasses waste products, inorganic molecules DISSOLVE in water to be TRANSPORTED

55
Q

Properties of water- Latent heat of vaporization

A

needs lot of energy to turn water to vapor (COOLANT)

-use as a way for organism to get rid of excess heat SWEATING

56
Q

Properties of water- surface tension

A

-hydrogen bonds strong at surface molecules, allows insets to walk on water

57
Q

Properties of water- amphoteric

A

is an acid (H+) and base (OH-)

BUFFER for chemical reactions, keeps constant pH

58
Q

Properties of water- high heat capacity

A

needs lot of energy for an increase in temperature, allows organisms to MAINTAIN TEMPRATURE, NO SUDDEN CHANGE in temp

59
Q

Properties of water- low density as solid

A

h-bonds keep molecules further in solid than liquid

  • ice FLOATS on water
  • acts as insulator to water and organisms below

Biology AQA Alevel (6 decks)

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