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Biology Unit 1 (Biological Molecules) > Biological Molecules > Flashcards

Biological Molecules Flashcards

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1
Q

Define MONOMERS with examples

A

Monomers are smaller units from which larger molecules are made. Examples of monomers include:
Monosaccharides
Nucleic acids
Amino acids

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2
Q

Define POLYMERS

A

Polymers are chemical molecules, made from monomers, joined together in a, specific/repeating pattern

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3
Q

What is the reaction involved to make monomers into polymers?
(One word answer)

A

Condensation reaction

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4
Q

What is the name of the reaction involved to make polymers into monomers?

A

Hydrolysis

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5
Q

Define condensation reaction [3 marks]

A

A condensation reaction joins two molecules together(monomers)[1]with the formation of a chemical bond [1] and removal of water[1]

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6
Q

Define hydrolysis [2 marks]

A

A hydrolysis reaction breaks the chemical bond between two molecules [1] with the use of water[1]

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7
Q

Molecule with the same structure BUT with different atoms connected is known as _______

A

Isomers

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8
Q

Carbohydrates are _________ whose monomers are called _________.
Carbohydrates contain__,__,__
Monosaccharides are joined together by a ________ _______
What kind of bond is made when two monomers are joined together by a condensation reaction releasing water?
What is it made when two monosaccharides are joined together!

A

Polymers
Monosaccharide
C,H,O
Condensation Reaction
Glycosidic bond
Disaccharide

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9
Q

Glucose is a monosaccharide with six carbon atoms in each molecule. This is called__________
Define the two types of glucose!
You need to know the structures of both the α-glucose and β-glucose. Draw the structures of both isomers.

A

Hexose sugar
Alpha glucose and Beta glucose

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10
Q

Write the three equations that you must remember for your exam: [two alpha glucose make______]

A

Glucose + glucose make Maltose
Glucose + Fructose make Sucrose
Glucose + galactose make Lactose

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11
Q

Sugar is the general term for ___________ and __________.
All sugars can be classified as _______ or _________
What test is used to test for sugars?
Reducing sugars include all ______

A

Monosaccharides and disaccharides
Reducing or non-reducing sugars!
The test is known as Benedict’s Test
All monosaccharide and LACTOSE+FRUCTOSE

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12
Q

Describe the test for reducing sugars. What will happened if the results are positive. And state ALL the colours for a positive result.

A

Add the benedict’s reagent solution to a sample
HEAT it in a water bath that’s been brought to the BOIL
If the test is positive a solid precipitate would be formed
The colour of the precipitate changes from;
Blue
Green
Yellow
Orange
Red brick

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13
Q

Describe the test for a NON-REDUCING sugar. State the steps and the colours for a positive result.

A

First, carry out the test with the Benedict reagent as normal to see the negative result.
BREAK them down into MONOSACCHARIDES(HOW DO YOU DO THIS?)
DO THIS BY GETTING A SAMPLE AND ADDING dilute hydrochloric acid
Then carefully boil the sample
Then neutralise it with sodium hydrogen carbonate
Then just carry the benedict’s test as usual with the reducing sugars and heat!
If it’s negative, the solution would stay blue, meaning there is no type of sugar present

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14
Q

What is a more ACCURATE way to do this experiment?

A

A more accurate way of doing this is to filter the solution and then weigh the precipitate

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15
Q

Describe the test for the presence of starch

A

To test the presence of starch, add iodine solution
to the sample. If the result is positive, then the colour would change from orange/brown to blues/black

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16
Q

Glycogen and starch are made by a __________ reaction of _ glucose
________ is made by a _ glucose

A

Condensation reaction, alpha glucose
Cellulose, beta glucose

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17
Q

What is the main energy store in plants and animals.
What is cellulose?

A

Starch in plants and glycogen in animals.
Cellulose is the major component
of cell walls in plants

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18
Q

Define amylose in detail

A

It is a long, unbranched chain of alpha glucose molecules joined together by a condensation reaction. The angles of the glycosidic bonds give it a coiled structure. This makes it compact so you can store a lot of glucose.
It’s also insoluble therefore it will not affect the water potential of the cells through osmosis and cannot leave the cell MEMBRANE as it is relatively large

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19
Q

Define amylopectin in detail

A

Long, branched chain of alpha glucose molecules joined together by a condensation reaction with (1,4) and (1,6) glycosidic bonds. The side branches allow the enzymes to break down the molecules and get to the glycosidic bonds quickly to release glucose. It’s also insoluble and large, so it doesn’t affect the water potential of the cell and can’t leave the cell membrane.

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20
Q

Define starch in detail

A

Starch is insoluble therefore it does not affect the water potential of the cell through osmosis. It’s large and cannot leave the cell membrane.

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21
Q

GLYCOGEN is…

A

Excess glucose is stored as glycogen in the liver and other muscle cells of the body. Its structure is very similar to amylopectinso it has (1,4) and (1,6) glycosidic bonds, except that it has LOADS more SIDE BRANCHES. Loads of side branches will allowstored glucose to be releasedquickly, which is important. It’s also very COMPACT molecule so really good for storage. It is insoluble so it does not affect the water potential of the cell by osmosis.

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22
Q

Define cellulose in detail.

A

Cellulose is made of LONG, UNBRANCHED chains of BETA glucose. When beta glucose molecules bond, they form STRAIGHT cellulose chains. Those cellulose chains are linked together by HYDROGEN BONDS to form strong fibres called MICROFIBRILS. Microfibrils provide STRUCTURAL SUPPORT for cells in plants

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23
Q

Define the two types of lipids that you are required to know for the AQA exam

A

Triglycerides and phospholipids

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24
Q

Define triglyceride and how their structure is related to their function

A

Triglyceride is a group of phospholipids. They are made from one molecule of glycerol and three fatty acid which are either satured or unsatured. The condensation reaction between a glycerol molecule and a fatty acid creates an ESTER bond.
The fatty acids are made from hydrocarbons and have very long tails which are HYDROPHOBIC, meaning that they repel from water. This makes them insoluble, and unable to dissolve energy meaning that it would not affect the water potential of the cells all by osmosis. The tails of the fatty acids are full of chemical energy, which when broken, releases a lot of energy! They are also very light, so it’s easy to carry it around. The triglycerides also have a lot of H to O ratio, meaning that they can be oxidised to release water, this is extremely important for organisms living in deserted areas

25
Q

Define phospholipids and explain their structure related to their function

A

Phospholipids are like triglycerides but one of the fatty acids is replaced by a phosphate containing group!
The phosphate containing group is hydrophilic (attract water)
and the fatty acids’ tails are hydrophobic. This is important in cell membranes.
They make up the bilayer of the cell membranes.
The centre of the bilayer is hydrophobic therefore it stops other liquid substances to pass through!

26
Q

Describe the test for the presence of lipids

A

Shake the test substances with ethanol for about a minute so that it dissolves, then pour the solution into water. Shake throughout. The presence of lipids would be a positive result that would go from clear white to milky white emulsion

27
Q

Define saturated and unsaturated

A

Saturated fatty acids don’t have any double bonds between their carbon atoms

Unsaturated fatty acids at least have a double bond between their carbon atoms

28
Q

Draw the basic structure of a fatty acid

A

https://www.google.com/imgres?imgurl=https%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2Fb%2Fb5%2FCarboxylic-acid.svg%2F800px-Carboxylic-acid.svg.png&tbnid=c9xdB5vZMg2GDM&vet=12ahUKEwj2yK_Gz6KCAxVunScCHYzaBPwQMygIegQIARBX..i&imgrefurl=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FCarboxylic_acid&docid=pF5ao4DH-tKF6M&w=800&h=641&q=basic%20structure%20of%20fatty%20acid&ved=2ahUKEwj2yK_Gz6KCAxVunScCHYzaBPwQMygIegQIARBX

29
Q

Name the formula of glycerol

A

C3H8O3

30
Q

Protein - Protein Structure (7)

A

Polymer of amino acids;
2. Joined by peptide bonds;
3. Formed by condensation;
4. Primary structure is order of amino acids;
5. Secondary structure is folding of polypeptide chain due to hydrogen bonding; (into alpha helix or beta pleated sheet)
6. Tertiary structure is 3-D folding due to hydrogen bonding and ionic/disulphide bonds between R groups;
7. Quaternary structure is more than one polypeptide chains;

31
Q

Test for a protein

A
  1. Add Biuret reagent to the sample (1);
  2. colour change to lilac (1) (or lilac band
    appears
32
Q

Enzymes – “Induced Fit” Model (3

A
  1. (before reaction) active site not
    complementary to/does not fit substrate;
  2. Shape of active site changes as substrate
    binds/as enzyme-substrate complex forms;
  3. Stressing/distorting/bending bonds (in
    substrate leading to reaction);
33
Q

Enzymes – Increased temperature
and reaction rate (4)
Link between the temperature and the rate of reaction

A
  1. particles have more kinetic energy
  2. therefore they move more
  3. so there are more collisions between
    substrates and active sites
  4. so more ES complexes form
34
Q

Enzymes – Denaturation (5)

A
  1. Heat above the optimum breaks hydrogen
    bonds
  2. this causes the tertiary structure to unfold
  3. so the active site changes shape
  4. substrate can no longer bind to the active
    site, as it’s no longer complementary
  5. so fewer ES complexes form
35
Q

Enzymes – Effect of Changes in pH
(4

A
  1. Ionic bonds holding tertiary structure break
  2. active site distorts and substrate no longer
    binds to active site
  3. charges on amino acids in active site affected
  4. fewer ES complexes form
36
Q

Enzymes – Concentration of
Substrate (2)

A
  1. (Rate of) increase in concentration of
    product slows as substrate is used up OR High
    initial rate as plenty of
    substrate/more E-S complexes;
  2. No increase after 25 minutes/at end/levels
    off because no substrate left;
    Reject ref. to enzyme being used up
37
Q

Enzymes – Comparison of
Competitive and Non Competitive
Inhibition (4)

A
  1. Competitive inhibitor binds to active sites of
    enzyme but non-competitive inhibitor binds at
    allosteric site/away
    from active site;
  2. (Binding of) competitive inhibitor does not
    cause change in shape of active site but
    (binding of) non-competitive
    does (cause change in size of active site);
  3. So with competitive inhibitor, at high
    substrate concentrations (active) enzyme still
    available but with noncompetitive inhibitor
    (active) enzymes no longer available;
  4. At higher substrate concentrations likelihood
    of enzyme-substrate collisions increases with
    competitive inhibitor
    but this is not possible with non-competitive
    inhibitor
38
Q

Describe DNA replication (6)

A
  1. DNA helicase unwinds DNA/double
    helix
    OR
    DNA helicase breaks hydrogen bonds;
  2. Both strands act as templates;
  3. (Free DNA) nucleotides line up in
    complementary pairs/Adenine-Thymine
    and Guanine-Cytosine;
  4. DNA polymerase joins nucleotides
    (of new strand);
    Reject forms hydrogen bonds/joins bases
  5. Forming phosphodiester bonds;
  6. Each new DNA molecule consists of
    one old/original/template strand and one
    new strand;
39
Q

Describe the structure of DNA (5)

A

1.Polymer of nucleotides;
Accept ‘Polynucleotide’
Accept for ‘phosphate’.
phosphoric acid
2. Each nucleotide formed from
deoxyribose, a phosphate (group) and an
organic/nitrogenous base;
3. Phosphodiester bonds (between
nucleotides);
4. Double helix/2 strands held by
hydrogen bonds;
5. (Hydrogen
bonds/pairing) between
adenine,
thymine and cytosine,
guanine

40
Q

Describe and explain how the structure of
DNA allows accurate replication (4)

A

1 two strands therefore semi-conservative replication (possible);
2 base pairing / hydrogen bonds holds
strands together
3 hydrogen bonds weak / easily
broken, allow strands to separate;
4 bases (sequence) (exposed so) act
as template / can be copied;
5 A with T, C with G / complementary
copy;
6 DNA one parent and one new
strand;

41
Q

Describe how a phosphodiester bond is
formed between two nucleotides in a DNA
molecule. (3)

A
  1. condensation reaction/loss of water
  2. (between) phosphate and deoxyribose
  3. (catalysed by) DNA Polymerase
42
Q

ATP – Uses and properties as an energy
source (5)

A
  1. Releases relatively small amount of energy / little
    energy lost as heat;
  2. Releases energy instantaneously;
  3. Phosphorylates other compounds, making them
    more reactive;
  4. Can be rapidly re-synthesised;
  5. Does not leave cells;
43
Q

ATP – Structure compared with DNA
nucleotide (3)

A
  1. ATP has ribose and DNA has deoxyribose;
  2. ATP has 3 phosphates and DNA nucleotide has
    one phosphate;
  3. Base is always adenine in ATP and bases vary in
    DNA nucleotide (A,C,G or T)
44
Q

Water – Properties that make water
important for organisms (6)

A
  1. A metabolite in
    condensation/hydrolysis/photosynthesis/respiration;
  2. A solvent so (metabolic) reactions can occur;
  3. High heat capacity so buffers changes in
    temperature;
  4. Large latent heat of vaporisation so provides a
    cooling effect (through evaporation);
  5. Cohesion (between water molecules) so supports
    columns of water (in plants);
  6. Cohesion (between water molecules) so produces
    surface tension supporting organisms
45
Q

DNA and RNA are both polymers of nucleotides.
describe the structure of both of their nucleotides

A

DNA nucleotides consist of:
deoxyribose,
a phosphate group
nitrogenous bases (adenine, thymine, cytosine, guanine)
RNA nucleotides consist of:
ribose sugar,
phosphate,
and only one nitrogenous base which is Uracil

46
Q

Compare the nucleotides of DNA and MRNA. Start with similarities first.

A

Both have a pentose sugar and a phosphate containing group.
DNA has all four bases whereas RNA only had Uracil base.
DNA has deoxyribose while RNA has only ribose.

47
Q

Compare DNA and RNA (not the nucleotides, but in general)

Hint: 3 points

A

DNA holds the genetic information while RNA carries the genetic information

DNA is longer and RNA is shorter

DNA is double stranded while RNA is single stranded

48
Q

Name the 2 enzymes needed for DNA replication

A

DNA helicase and DNA polymerase.

49
Q

Describe the role of DNA polymerase

A

Joins adjacent nucleotides together and makes a phosphodiester bond via condensation reaction

50
Q

Describe the role of DNA helicase

A

Unwind the DNA and and release free nucleotides by breaking the hydrogen bonds

51
Q

In what way do the DNA strands move?

A

Antiparallel

52
Q

Explain why, using enzymes knowledge, the DNA strands run antiparallel

A

DNA polymerase is an enzyme with specific 3D structure and function. Its active site is ONLY complementary to the 3’ end. So new strands are made from 5’ to 3’ end

53
Q

Evidence for semiconservative replication.

A

1-Two samples of bacteria grown, one in light nitrogen (N14) and one in heavy nitrogen(15).
2-A sample of DNA taken from each batch and and SPUN in a centrifuge. The DNA with the heavy nitrogen settled lower than the DNA containing light nitrogen (all due to the densities)
3- The bacteria grown in the heavy nitrogen broth were taken out and put in a broth containing light nitrogen. And then left the DNA for one round of replication.
4-The DNA turned out to have a mixture of both nitrogen, so it was proved to be a SEMI-CONSERVATIVE replication

54
Q

Draw the nucleotide of an ATP
DNA
RNA

A

ATP: https://www.google.com/imgres?imgurl=https%3A%2F%2Fstatic.aqa.org.uk%2Fassets%2Fimage%2F0020%2F235442%2F00055366-DA00045784-DB.png&tbnid=3Nl_R4UTHJU7GM&vet=12ahUKEwjrr9CJ16KCAxXOnycCHVz-DEgQMygRegQIARBs..i&imgrefurl=https%3A%2F%2Fwww.aqa.org.uk%2Fsubjects%2Fscience%2Fas-and-a-level%2Fbiology-7401-7402%2Fsubject-content%2Fbiological-molecules%2Fatp&docid=VkZ6IzAfvLyhxM&w=960&h=401&q=nucleotide%20of%20atp&ved=2ahUKEwjrr9CJ16KCAxXOnycCHVz-DEgQMygRegQIARBs
DNA: https://www.google.com/imgres?imgurl=https%3A%2F%2Fstatic.aqa.org.uk%2Fassets%2Fimage%2F0003%2F235443%2F00055366-DA00045783-DB.png&tbnid=iRKRKai6-SJIoM&vet=12ahUKEwiPkeuc16KCAxUfnCcCHdbSBjoQMygFegQIARBS..i&imgrefurl=https%3A%2F%2Fwww.aqa.org.uk%2Fsubjects%2Fscience%2Fas-and-a-level%2Fbiology-7401-7402%2Fsubject-content%2Fbiological-molecules%2Fnucleic-acids-are-important-information-carrying-molecules%2Fstructure-of-dna-and-rna&docid=UPrE_rhe_WXQPM&w=960&h=460&q=nucleotide%20of%20DNA%20AQA&ved=2ahUKEwiPkeuc16KCAxUfnCcCHdbSBjoQMygFegQIARBS
RNA: https://www.google.com/imgres?imgurl=https%3A%2F%2Fstatic.aqa.org.uk%2Fassets%2Fimage%2F0003%2F235443%2F00055366-DA00045783-DB.png&tbnid=iRKRKai6-SJIoM&vet=12ahUKEwinqOKl16KCAxWhpicCHZmGDmsQMygAegQIARBI..i&imgrefurl=https%3A%2F%2Fwww.aqa.org.uk%2Fsubjects%2Fscience%2Fas-and-a-level%2Fbiology-7401-7402%2Fsubject-content%2Fbiological-molecules%2Fnucleic-acids-are-important-information-carrying-molecules%2Fstructure-of-dna-and-rna&docid=UPrE_rhe_WXQPM&w=960&h=460&q=nucleotide%20of%20RNA%20AQA&ved=2ahUKEwinqOKl16KCAxWhpicCHZmGDmsQMygAegQIARBI

55
Q

Name the enzymes for breaking and making ATP

A

ATP hydrolase and ATP synthase

56
Q

Uses of ATP

A

1-Releases energy in small amounts
2- Can phosphorylate other compounds making them more reactive
3-can be quickly resynthesized
4- needed for respiration and muscle contraction.

57
Q

Equation for the hydrolysis of ATP

A

ATP+ water ——–> ADP+Pi

58
Q

Describe the roles of iron ions, sodium ions, and phosphate ions in cells.

A

Iron ions
1. Haemoglobin binds/associates with oxygen
OR
Haemoglobin transports/loads oxygen;
Sodium ions
2. Co-transport of glucose/amino acids (into cells);
3. (Because) sodium moved out by active transport/Na – K pump;
4. Creates a sodium concentration/diffusion gradient;
5. Affects osmosis/water potential;
Phosphate ions
6. Affects osmosis/water potential;
7. Joins nucleotides/in phosphodiester bond/in backbone of
DNA/RNA/in nucleotides;
8. Used in/to produce ATP;
Reject ‘energy produced’
9. Phosphorylates other compounds (usually) making them more
reactive;
10. Hydrophilic/water soluble part of phospholipid bilayer/membrane;

Biology Unit 1 (Biological Molecules) (2 decks)

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