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Biology A level > Unit 1 - Biological Molecules > Flashcards

Unit 1 - Biological Molecules Flashcards

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1
Q

Examples of of monomers

A

Monosaccarides
Amino acids
Nucleotides

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2
Q

Condensation reaction points

A

Molecules joining together
Water is formed as a byproduct
Reaction between OH’s and H

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3
Q

Hydrolysis

A

Large to small molecules
Water is required
Forms H+ and OH- ions

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4
Q

What are amino acids joined together by?

A

Peptide bonds

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5
Q

Examples of proteins

A

Insulin
Enzymes
Structural proteins (Keratin and Collagen)

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6
Q

Non polar amino acid points

A

Hydrophobic

On the inside of proteins

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7
Q

Polar amino acid points

A

Hydrophilic

Found on the outside of proteins

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8
Q

Electrically charged

A

Have a whole charge

Want to form ionic bonds

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9
Q

What is the primary structure

A

Sequential chain of amino acids joined by peptide bonds

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10
Q

What are the bonds found in secondary structures?

A

Hydrogen bonds

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11
Q

What are the bonds in Tertiary structure? (In order of strength)

A

(Covalent) Disulphide bridges
Ionic bonds
Hydrogen bonds

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12
Q

What are the bonds in Tertiary structure? (In order of strength)

A

(Covalent) Disulphide bridges
Ionic bonds
Hydrogen bonds

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13
Q

Bonds found in globular proteins

A

Ionic and hydrogen bonds

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14
Q

Bond found in fibrous proteins

A

Disulphide bonds

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15
Q

Fibrous protein properties

A

Insoluble in water
Alpha helicies or beta pleated sheets
Disulphide bonds
Structural proteins

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16
Q

Globular protein properties

A

Soluble in water
Alpha helicies and beta pleated sheets
Ionic and hydrogen bonds
Metabolic proteins

Shape: Roughly circular
Function: Physiological
Examples: Hemoglobin, enzymes, insulin

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17
Q

Why do substances move at different rates in chromatography?

A

Affinity to the stationary phase

Solubility in the solvent

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17
Q

Why do substances move at different rates in chromatography?

A

Affinity to the stationary phase

Solubility in the solvent

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18
Q

Enzyme definition

A

Biological catalysts which provide an alternative reaction pathway with a different activation energy.

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19
Q

Describe the structure of enzymes?

A

Globular proteins with a 3D tertiary structure
Hydrophilic side chains
Have an active site

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20
Q

Described the induced fit model

A

1) Enzymes and substrates have specific tertiary structures that are roughly complementary
2) Substrate goes into active site
3) Bonds form and active site bends around substrate forming and induced fit and putting strain on the bonds
4) Activation energy is therefore lowered- substrate breaks
5) Products are released

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21
Q

Equation for temperature coefficient

A

Temperature coefficient= Rare of reaction at (x+10)/ Rate of reaction at x

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22
Q

Describe enzyme and decreasing PH

A
  • In a higher PH, there are (less) H+ ions
  • This causes the hydrogen and ionic bonds to break in the tertiary structure
  • The enzymes denature
  • Substrate and active site are no longer a complementary fit
  • The enzyme substrate complex can no longer be made
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23
Q

Describe enzyme activity and increasing temp

A
  • Increase in the kinetic energy of substrate and enzyme
  • The enzyme and substrate move faster
  • Substrate and enzyme more likely to collide
  • An optimym temp is reached where are there are many random collisions but the shape of the active site hasn’t changed
  • Enzymes absorb so much energy that the ionic and hydrogen bonds within them break- changing the 3D tertiary structure
  • The enzymes become denatured
  • There is no longer a complementary fit between the substrate and active site
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24
Q

Describing the effect of change of substrate conc

A
  • Initially the substrate is the limiting factor as the enzyme (active site) is in abundance
  • As substrate conc increases- more substrates can bind with active sites- forming and induced fit and giving an alternative reaction pathway with a lower activation energy.
  • Eventually, the substrate is no longer the limiting factor- it is enzyme conc
  • Increasing substrate conc no longer increases the rate of reaction
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25
Q

What are carbs made out of and in what ratio are they found?

A

Carbon, Oxygen and Hydrogen in the ratio CH2O

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26
Q

General properties of sugars

A 
Sweet
Soluble in water 
White 
Crystaline
All have the suffix of OSE
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27
Q

What are disaccarides?

A

Two monosaccarides joined together by a gylcosidic bond- they are insoluble in water

28
Q

Examples of Disaccarides

A

Sucrose- Glucose and Fructose
Lactose-Glucose and Galactose
Maltose- Glucose and Glucose

29
Q

How are polysaccharides formed?

A

Multiple monosaccarides joined together by glycosydic bonds

30
Q

Methods of breaking down polysaccarides into monosaccarides

A

Enxyme hydrolysis- Mix enzyme with polysaccaride at room temp
Acid hydrolysis- Boil HCl with the polysaccaride

31
Q

What are Reducing sugars

A

A sugar that is able to donate an electron to something else

32
Q

Which ones are the reducing sugars?

A

Glucose
Fructose
Maltose

33
Q

How to test for a reducing sugar

A
  • Heat with benedicts solution at 70 degrees in a thermostatically controlled water bath
  • If a reducing sugar is present- Will go from blue- green-yellow-orange-brick red
34
Q

To find out if a solution has reducing sugars but no non-reducing sugars

A
  • Heat with benedicts solution, should go blue to brick red
  • Another sample, heat with HCL and neutralise- should go the same colour
35
Q

To find out a solution has non reducing but no reducing sugars

A
  • Heat a sample with benedicts-should stay blue

- Heat another sample with HCL and neutralise with sodium hydrogencarbonate- when benedicts is added- should go brick red

36
Q

To find if a solution has both reducing and none reducing sugars

A
  • Add Benedicts reagent - if negative result (stays blue negative result)
  • Add dilute HCl then neutralise with sodium hydrogencarbonate
  • Then carry out the benedicts test again
37
Q

Starch adaptations

A
  • Insoluble so it doesn’t affect water potential or diffuse
  • Compact- Doesn’t take up too much space
  • Forms glucose when hydrolysed- can easily be transported and used in respiration
  • Branched form can be very efficient
38
Q

Cellulose adaptations

A
  • Makes cell walls strong due to parallel chains held together by hydrogen bonds
  • Can resist tugor pressure- this means it stops the cell from swelling too much
  • Resists digestion from enzymes and microorganisms
  • Glycosydic- Bonds alternate due to the fact that it uses beta glucose- postition of H and OH- causing the cellulose to form fibres
39
Q

Glycogen adaptations

A

Insoluble- Doesn’t affect water potential- doesn’t diffuse out of cells
Compact- A lot can be stored in a small volume
Efficient to break down- Easily accessible for enzymes to break it down as it has lots of branches which can be acted on simultaneously.

40
Q

Types of RNA

A

tRNA
mRNA
rRNA

41
Q

DNA structure

A

Double helix
The two polynucleotide chains are antiparallel- they run upside down from each other
Made up of monomers of nucleotides
The two strands of nucleotides are held together by hydrogen bonds between complementary base pairs

42
Q

Structure of RNA

A

Short polynucleotide chain joined together by covalent bonds `
Uses uracil instead of thymine

43
Q

Properties of DNA vs RNA

A 
Stable- Unstable 
ATGC- AUGC
Bigger- Smaller 
Double helix-Single strand 
Hydrogen bonds- No hydrogen bonds
44
Q

What is the type of bond between nucleotides

A

Phosphodiester bonds

45
Q

Reasons why bases always pair with complementary pairs

A
  • Bases are too big to fit- causing DNA to bulge
46
Q

Characteristics of lipids

A
  • They contain carbon, hydrogen and oxygen
  • There are more hydrogens and carbons for every oxygen then that of carbohydrates
  • They are insoluble in water
  • They are soluble in organic solvents
47
Q

The effects of having unsaturated fats

A

The double bonds formed from unsaturated hydrocarbons cause a kink in the molecule
meaning they can’t form a tight side by side structure.
Thus they are more likely do be liquid at room temp

48
Q

The functions of triglycerides relating to structure

A
  • High ratio of energy storing carbon-hydrogen bonds relative to other atoms
  • Low mass to energy ratio- good storage molecules- reduces mass that animals carry around
  • Being large non-polar molecules, triglycerides are insoluble in water- water potential and osmosis isn’t affected
  • Source of water due to high ratio of hydrogen oxygen atoms
49
Q

Structure of phospholipids relating to properties

A
  • Hydrophilic head and hydrophobic body- In an aqueous environment it forms a bilayer within the cell surface membrane- forming a hydrophobic bilayer.
  • Hydrophilic phosphate heads help hold the molecules at the surface of the cells
  • Phosphates allow them to form glycolipids by joining with carbs- glycolipids are used for cell recognition
  • Contribute to the flexibility of membranes and the transfer of substances.
50
Q

General functions of lipids

A
  • Source of energy- High ratio
  • Waterproofing- Lipids are insoluble- can be used for waxy cuticles
  • Insulation- Poor conductors of heat- retain body heat
  • Poor conductors of electricity- used for things like myelin sheath
51
Q

Emulsion test for lipids

A
  • Take a dry test tube
  • Add a sample to ethanol in the ratio 2:5
  • Shake thoroughly (dissolves lipids)
  • Add 5cm cubed of water and shake gently
  • If there is a milky white emulsion- lipids are present
  • As a control- do the test with water
52
Q

Semi-conservative replication requirements

A
  • The 4 types of nucleotide and their bases
  • The strands of DNA act as a template for the attatchment of the nucleotides
  • The Enzyme DNA polymerase
  • A source of chemical energy is required to drive the process
53
Q

The process of DNA replication

A
  • The enzyme DNA helicase, causes the two strands of the DNA to separate by breaking hydrogen bonds between the bases- resulting in the double helix separating into two separate strands.
  • Each exposed polynucleotide acts as a template to which complementary bases bind by base pairing
  • Free nucleotides that have been activated bind specifically to the complementary bases
  • The nucleotides are joined together by DNA polymerase which makes phosphodiester bonds, forming the sugar-phosphate backbone
  • Each of the new DNA molecules contains one of the original DNA strands- half of the original DNA has been saved and built into the new DNA molecules.
54
Q

Constituent parts of ATP

A
  • Nitrogenous base
  • Ribose
  • Phosphate
55
Q

What are the three ways that synthesis of ATP occurs

A
  • In chlorophyll- containing plant cells during photosynthesis (Phosphorylation)
  • In plant and animal cells during respiration (Oxidative phosphorylation )
  • In plants and animals when phosphate groups are transfered from donor molecules to ADP
56
Q

ATP properties

A
  • Each ATP molecule releases less energy than each glucose molecule- the energy of each reaction is lower- less waste of energy and more heat control.
  • The hydrolysis of ATP to ADP is a single reaction that releases immediate energy. The breakdown of glucose is longer
  • ATP cannot be stored- needs to be continuously made in the cells that need it.
57
Q

Roles of ATP

A
  • Metabolic processes (building up molecules)
  • Movement- Contraction of muscles
  • Active transport- Used to change the shape of carrier proteins to allow molecules to go through
  • Secretion- used for forming lysosomes
  • Activation of molecules- Phosphorylation of other molecules
58
Q

Describe Specific heat capacity of water

A
  • A lot of energy input is required to increase heat by a small amount
  • Due to bond enthalpies between water molecules
  • Large volumes of water change temp slowly
59
Q

High latent heat of vaporisation

A
  • Hydrogen bonds require a lot of energy to break and thus cause water to evaporate
  • Lots of energy is used to evaporate a small amount of water
  • High heat to water loss ratio
60
Q

Cohesion

A
  • Hydrogen bonds between water molecules means that they are attracted
  • This keeps them attracted to each other so they stick together
61
Q

Adhesion

A
  • Water is attracted to other molecules and other water molecules
  • This causes it to stick to surfaces
62
Q

Surface tension

A
  • There is a higher density of hydrogen bonds on the surface of water
  • To break these bonds requires a lot of energy as they are collectively strong
63
Q

Water as a Solvent

A
  • Allows water to transport dissolved molecules over large distances
  • Creates a place for reactions to happen
64
Q

Water as a substrate/ metabolite

A

Water is needed for hydrolysis as it is needed to create OH groups

65
Q

Water properties in real life

A

Surface tension- Creates habitats for creatures above water
Cohesion- Water moves up xylem
Water is less dense when solid- Creates habitats, insulating water beneath
High specific heat capacity-Water maintains a relatively constant temp- high heat loss to water loss ratio
Water is a solvent- Transports molecules in blood around the body- dissolves minerals which can be taken up by plants
Its immiscible with fat- Membranes separate cells from environment, creating different conditions

66
Q

Roles of organic ions
Sodium
Potassium
Phosphate
Iron
H+

A

Na+- Cotransport in illeum
Fe2+- Component of haemoglobin
Phosphate ions PO4 3- - Component of DNA
H+ role in pH

67
Q

Why are lipids not considered polymers

A

Consist of two different molecules
Polymers must be repeated monomers

Biology A level (13 decks)

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