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AA biology a level - pippa > Section 1: Biological molecules > Flashcards

Section 1: Biological molecules Flashcards

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1
Q

what is a condensation reaction

A

joining 2 molecules together
monomer to polymer
larger molecule is formed
covalent bond
water is released

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2
Q

what is a hydrolysis reaction

A

polymer to monomer
breaking down larger molecule into a smaller one
water molecule is used

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3
Q

how many carbons are in a alpha glucose

A

six

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4
Q

what is the ratio of carbon : hydrogen : oxygen in glucose

A

c : 2h : o
1 : 2 : 1

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5
Q

what is the name of two monosaccharides joined together

A

disaccharide

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6
Q

glucose x 2 is what disaccharide?

A

maltose

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7
Q

glucose + galactose is what disaccharide?

A

lactose

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8
Q

glucose + fructose is what disaccharide?

A

sucrose

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9
Q

what bond forms between 2 monosaccharides

A

glycosidic bond when it forms a disaccharide

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10
Q

what does the prefix glyco mean

A

sugar (carbohydrates)

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11
Q

name function, location and structure of starch (in plants)

A

polysaccharide storage molecule
long straight chain amylose molecules and branched amylopectin
stored in chloroplasts in membrane bound starch grains
can be broken down into glucose for respiration to release energy

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12
Q

describe function, location and structure of glycogen (in animals)

A

polysaccharide storage molecules
more branched amylopectin
shorted 1-4 amylose chains
can be broken down into glucose for respiration to release energy
more compact , forms glycogen granules in places like liver and muscle cells

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13
Q

Describe the function, location and structure of cellulose

A

B-glucose , straight un-branched, parallel Hydrogen bonds with cross linkage makes it strong micro-fibrils form fibres , plant cell walls prevents from bursting

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14
Q

What are lipids made up of? and describe there solubility in water and organic solutions?

A

Made up of carbon oxygen hydrogen
Insoluble in water
Soluble in organic solutions

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15
Q

What are the roles of lipids

A

energy source : more energy released than carbs + releases water when oxidised
Waterproofing: waxy lipid cuticle, oily skin secretion
Insulation: slow conductors of heat so retain body temperature well
Protection: around delicate organs

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16
Q

What are the adaptations of lipids that make it good for their roles

A

High ratio of bonds to carbon atoms make it excellent energy source
Low mass to energy ration excellent storage molecule
Large, non polar and insoluble doesnt effect water potential so wont diffuse or osmosis out of cells
Important water source due to high H:O ratio

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17
Q

What is the reaction forming a triglyceride? state equation and bond

A

Glycerol + 3 fatty acids —> triglyceride + 3 water
condensation reaction
ester bond formed

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18
Q

What does a phosphate and 2 fatty acids make

A

Phospholipid

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19
Q

Describe features of phospholipid and their uses

A

Polar molecule : forms bilayer and barrier due to hydrophilic head and hydrophobic tail
Structure allows them to form glycolipids

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20
Q

How would cellulose give something strength

A

Straight un branched chain
Many hydrogen bonds and cross linkage
Chains lie side by side (micro) fibrils

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21
Q

Give two feature and explain why starch is a good storage substance

A

Insoluble : water isnt drawn out or into cells by osmosis/ doesnt effect water potential
Coiled : Very compact lots can be stored
Large : wont diffuse out cells
Branched : multiple ends acted on by enzymes rapidly

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22
Q

What is the difference between a globular and fibrous protein

A

Globular are spherical and soluble
Fibrous are elongates and not water soluble

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23
Q

What proteins are globular

A

Enzymes
Hormones
transport
Antibodies

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24
Q

What proteins are fibrous

A

Keratin
Collagen
Myosin, actin

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25
What are four factors effecting enzyme action
Temperature PH Substrate concentration Enzyme concentration
26
What are buzz words to use in an enzyme question
Acts as catalyst Lowers activation energy Enzymes substrate complex Induced fit
27
Describe structure of an amino acid
Amino group (-NH2) Carboxylate group (-COOH R group Hydrogen (-H)
28
Primary structure description
Polymerisation Peptide bonds -OH and -H Long polypeptide chain Specific order
29
Secondary structure description
3-D shape Hydrogen bonds -NH and -COOH A helix or b pleated sheets
30
Tertiary structure
Disulphide bridges Ionic bonds Hydrogen bonds
31
Quaternary structure description
Multiple polypeptide chains together for example haemoglobin has 4
32
What is a prosthetic group and give example
Prosthetic groups are non-peptide (non-protein) compounds that mostly attach to proteins and assist them in different ways. Such as Haemgroup (Fe containing) in Haemglobin
33
What are nucleotides made up of
Phosphate group, pentose sugar and nitrogen base
34
How would heat effect the tertiary structure
Will damage the ionic H or disulphide bonds and break the shape
35
How may a change in the primary structure of a globular protein result in a change of three-dimensional structure
Sequence of amino acid changes Different places where bonds are different folding into tertiary
36
How does temperature effect enzyme action
temp falls = less kinetic energy = less frequent collisions = rate of reaction decreased
37
How does ph effect enzyme action
Alters shape Bonds break Active site deformed cant form e-s complex Rate of reaction decrease
38
Describe 5 features of DNA
Double helix provides strength Phosphodiester backbone protects from chemicals THe Higher the C-G pairings more stable the DNA because C-G has 3 hydrogen bonds Very stable and can be passed on generation to generation Base pairings ensure this Large and carry’s lots of information
39
When does DNA replication happen?
Interphase
40
Describe DNA replication briefly
Semi-conservative DNA helicase break H bonds linking bases Double helix separates Both strands act as templates Free nucleotides attach to bases DNA polymerase join agacent nucleotides together
41
What bonds do DNA helicase and polymerase break and form
DNA helicase hydrolyse hydrogen bonds DNA polymerase form phosphodiester bonds
42
What is ATP made up of
Nitrogen base (Adenine) Ribose 3 phosphates
43
What are the uses of ATP
Metabolic processes - making starch from glucose Movement - muscle contraction Active transport - changes shape of carrier proteins Secretion - needed to form lysosomes Activation of molecules - addition of phosphate to glucose at start of glycolysis
44
Why is ATP a good energy source
Manageable quantities: releases less energy than glucose Immediate energy source: only requires one reaction ( hydrolysis of ATP) unlike glucose Regenerate/Reversible reaction
45
What are the 5 features of water and the mnemonic
Metabolite (hydrolysis) Solvent (dissolves gasses, enzymes, wastes) High heat capacity (due to hydrogen bonds) Large latent heat of vaporisation (evaporation of sweat very effective) Cohesion (tendency of molecules sticking together ex. xylem tube) My sofa has large cushions
46
Does water have a charge
No however is dipolar as Oxygen has slight negative change and hydrogen has a slight positive charge so 2 water molecules are often attracted to each other hydrogen bonds between water molecules and covalent bonds betweeen 2 hydrogen atoms and one oxygen atom.
47
What is a monomer (1mark)
small repeating unit molecule from which larger molecules/polymers are made
48
49
Describe a biochemical test to show that a solution contains non-reducing sugar (3marks)
Heat with acid and neutralise Heeat with Benedict’s solution Red precipitate colour
50
51
Glycogen and cellulose are both carbohydrates. Describe two differences between the structure of a cellulose molecule and a glycogen molecule.
Cellulose is made up of β-glucose (monomers) and glycogen is made up of α-glucose (monomers); Cellulose molecule has straight chain and glycogen is branched; Cellulose molecule has straight chain and glycogen is coiled; glycogen has 1,4- and 1,6- glycosidic bonds and cellulose has only 1,4- glycosidic bonds; Ignore ref. to H bonds / microfibrils 2 max
52
Describe the structure of glycogen (2marks)
Polysaccharide of alpha glucose Joint by glycosidic bonds or branched structure
53
Suggest how glycogen acts as a source of energy
Hydrolysed to glucose Glucose used in respiration
54
Describe how you would test for the presence of a lipid in a liquid sample of food
Add ethanol then add water and shake and mix white milky emulsion if positive
55
Describe how a triglyceride molecule is formed (3 marks)
One glycerol and three fatty acids Condensation reactions and removal of three molecules of water Ester bond is formed
56
Describe how an ester bond is formed in a phospholipid molecule. 2 marks
Condensation reaction loss of water between glycerol and fatty acids
57
58
Explain five properties that make water important for organisms
A metabolite in condensation/hydrolysis/ photosynthesis/respiration; A solvent so allowing transport of substances; High (specific) heat capacity so buffers changes in temperature; Large latent heat of vaporisation so provides a cooling effect (through evaporation); Cohesion (between water molecules) so supports columns of water (in plants); Cohesion (between water molecules) so produces surface tension supporting (small) organisms;
59
State and explain the property of water that helps to prevent temperature increase in a cell.
High heat capacity Acts as a buffer for temperature change / needs a large amount of energy to heat water up
60
State and explain the property of water that can help to buffer changes in temperature.
1. water has a relatively) high (specific) heat capacity; Ignore numbers relating to heat capacity 2. Can gain / lose a lot of heat / energy without changing temperature; OR Takes a lot of heat / energy to change temperature; Accept due to H bonding between water molecules
61
Give two properties of water that are important in the cytoplasm of cells. For each property of water, explain its importance in the cytoplasm.
1. Polar molecule; 2. Acts as a (universal) solvent; OR 3. (Universal) solvent; 4. (Metabolic) reactions occur faster in solution; OR 5. Reactive; 6. Takes place in hydrolysis / condensation / named reaction;
62
63
How can i test wether a sample contains reducing or non-reducing sugars?
First add benedict’s reagent to the sample and heat in a water bath If it turns brick-red reducing sugar is present If it stays blue no reducing sugar is present and you can test further Boil the sample with dilute HCL then neutralise and add Benedict’s reagent again and heat If it now turns brick-red a non reducing sugar was originally present
64
Why Don’t Non-Reducing Sugars React with Benedict’s Reagent?
They can’t donate electrons to Benedict’s reagent, so the solution stays blue instead of turning brick-red. While reducing sugars do have free electron to donate so do turn solution brick-red.
65
Why Does Breaking Down a Non-Reducing Sugar Give a Positive Result to Benedict’s reagent?
The acid breaks it into smaller sugars that can donate electrons to Benedict’s. These sugars are reducing sugars, so the solution turns brick-red after heating.
66
Describe structure and function of the nucleus. 4 marks
Nuclear envelope, double membrane and nuclear pores Chromosomes or DNA with hi stones Nucleolus Holds genetic information for polypeptides DNA replication occurs Production of mRNA/tRNA or transcription occurs Production of rRNA/ribosomes
67
Give two types of molecules that make up a ribosome.
RNA/nucleotides Protein/ amino acids
68
Describe the role of the ribosome in the formation of a polypeptide. 3 marks
mRNA binds to ribosome; Idea of two codons/binding sites; (Allows) tRNA with anticodons to bind/associate; (Catalyses) formation of peptide bond between amino acids (held by tRNA molecules); Moves along (mRNA to the next codon)/translocation described;
69
Suggest and explain two ways the cell-surface membranes of the cell lining the uterus may be adapted to allow rapid transport of nutrients. 2 marks
Membrane folded so increased/large surface area; OR Membrane has increased/large surface area for (fast) diffusion/facilitated diffusion/active transport/co-transport; Large number of protein channels/carriers (in membrane) for facilitated diffusion; Large number of protein carriers (in membrane) for active transport; Large number of protein (channels/carriers in membrane) for co-transport
70
In a eukaryotic cell, the base sequence of the mRNA might be different from the sequence of the pre-mRNA. Explain why. 2 marks
1. Introns (in pre-mRNA); 2. Removal of sections of (pre-mRNA)/splicing
71
How many binding sites/ codons do the ribosomes act on during translation?
Two codons/ binding sites
72
Describe how bacteria divide.
1. Binary fission; 2. Replication of (circular) DNA; 3. Division of cytoplasm to produce 2 daughter cells; 4. Each with single copy of (circular)
73
High absorption of salt from the diet can result in a higher than normal concentration for salt in the blood plasma entering capillaries. This can lead to a build-up of tissue fluid. Explain how.
(Higher salt) results in lower water potential of tissue fluid; (So) less water returns to capillary by osmosis (at venule end); OR (Higher salt) results in higher blood pressure/volume; (So) more fluid pushed/forced out (at arteriole end) of capillar

AA biology a level - pippa (10 decks)

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