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B1- BIOLOGICAL MOLECULES Flashcards

3.1.1 Monomers and polymers 3.1.2 Carbohydrates 3.1.3 Lipids (46 cards)

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1
Q

3.1.1 Monomers and polymers

What are Monomers? Include examples

A

Monomers are small units which are the components of larger molecules.
Examples:
- monosaccharides (glucose, fructose and galactose)
- amino acids
- nucleotides

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2
Q

3.1.1 Monomers and polymers

What are Polymers? Include examples

A 
Polymers are molecules made from a large number of monomers joined together.
Examples:
- DNA
- RNA
- Proteins
- Polysaccharides
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3
Q

3.1.1 Monomers and polymers

What is a Condensation Reaction?

A

A condensation reaction joins two monomers together whereby a water molecule
is eliminated

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4
Q

3.1.1 Monomers and polymers

What is a Hydrolysis Reaction?

A

A hydrolysis reaction breaks a chemical bond between two molecules by the use of a water molecule

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5
Q

3.1.2 Carbohydrates

What are Carbohydrates?

A

Carbohydrates are molecules which consist only of carbon, hydrogen and oxygen and they are
long chains of sugar units called saccharides

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6
Q

3.1.2 Carbohydrates

What are monosaccharides? What are the three most common examples?

A

Monosaccharides are the simplest carbohydrates and are monomers from which larger
carbohydrates are made. Glucose, galactose and fructose are common monosaccharides

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7
Q

3.1.2 Carbohydrates

What is the reaction between two monosaccharides. What is the bond formed?

A

A condensation reaction occurs between two monosaccharides. The bond formed is called a (1,6) or (1,4) Glycosidic Bond

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8
Q

3.1.2 Carbohydrates

Name the three Monosaccharides What is the molecular formula?

A

Glucose, Fructose and Galactose.

Molecular formula: C(6)H(12)O(6)

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9
Q

3.1.2 Carbohydrates

What are disaccharides?

A

Disaccharides are formed when two monomers react together.

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10
Q

3.1.2 Carbohydrates

How are these disaccharides formed? :

  • Maltose
  • Sucrose
  • Lactose
A

Maltose: two glucose molecules
Sucrose: Glucose + Fructose
Lactose: Glucose + Galactose

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11
Q

3.1.2 Carbohydrates

what is glucose?

A

glucose is used in respiration and comes from carbohydrates we ingest and digest

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12
Q

3.1.2 Carbohydrates

What are the two isomers of glucose? Draw the structures

A

Alpha and Beta

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13
Q

3.1.2 Carbohydrates

What is a polysaccharide? Give examples

A 
a carbohydrate whose molecules consist of a number of sugar molecules bonded together.
Examples:
- Starch
- Cellulose 
- Glycogen
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14
Q

3.1.2 Carbohydrates

Describe the structure and function of Starch

A

Starch is the storage polymer of α glucose in plant cells

  • insoluble so will not affect cell water potential
  • compact so a lot of energy can be stored in a small space

Starch is a mix of 2 different polysaccharides:
1 ) Amylose: a long chain of α-glucose monomers joined by 1,4-glycosidic bonds. The chain coils in a spiral shape, held together by hydrogen bonds. This shape makes starch well suited to energy storage as it is compact, so takes up little space in the cell, and not very soluble in water, so does not affect the water potential of the cell.
2 ) Amylopectin: branched chains of α-glucose monomers joined by 1,4-glycosidic bonds and 1,6-glycosidic bonds.
- The 1,6-glycosidic bonds form the links which make branches.
- branches mean there are many glucose molecules accessible on the end of chains which can be easily broken off by hydrolysis for use in respiration. Therefore amylopectin can provide a rapid supply of energy.

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15
Q

3.1.2 Carbohydrates

Describe the structure and function of Cellulose

A

Cellulose is a component of cells walls in plants
- is composed of long, unbranched chains of
beta glucose (β) which are joined by glycosidic bonds
- Microfibrils are strong threads which are
made of long cellulose chains running parallel to one another that are joined together by
hydrogen bonds forming strong cross linkages.
- important in stopping the cell wall
from bursting under osmotic pressure. This is because it exerts inward pressure that stops the
influx of water. This means that cells stay turgid and rigid, helping to maximise the surface area
of plants for photosynthesis.

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16
Q

3.1.2 Carbohydrates

Describe the structure and function of Glycogen

A

Glycogen is the main energy storage molecule in animals
- formed from many molecules of
alpha glucose (α) joined together by 1, 4 and 1, 6 glycosidic bonds
- has a large number of side
branches meaning that energy can be released quickly as enzymes can act simultaneously on
these branches.
- it is a relatively large but compact molecule thus maximising the amount of energy it can store.
- being insoluble means it will not affect the water
potential of cells and cannot diffuse out of cells

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17
Q

3.1.2 Carbohydrates

Which biochemical tests are suitable for these samples:

  • reducing sugars
  • lipids
  • non-reducing sugars
  • starch
  • protein
A
  • reducing sugars= Benedicts Test
  • lipids- Emulsion Test
  • non-reducing sugars- Benedicts Test
  • starch- Iodine Test
  • protein- Buiret Test
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18
Q

3.1.2 Carbohydrates

What is the test for lipids? What is the method?

A

Emulsion test for Lipids

  1. Dissolve sample in ethanol
  2. Add an equal volume of water and shake the test tube
  3. A positive result will produce a milky white emulsion
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19
Q

3.1.2 Carbohydrates

What is the test for reducing sugars? What is the method?

Study These Flashcards
A

The Benedict’s test for reducing sugars: -

  1. Heat the test sample with Benedict’s Reagent.
  2. Observe the colour change.
  3. A brick red precipitate indicates the presence of a reducing sugar.
20
Q

3.1.2 Carbohydrates

What is the test for non- reducing sugars? What is the method?

Study These Flashcards
A

The Benedict’s test for non-reducing sugars: -

  1. Heat the test sample with dilute hydrochloric acid.
  2. Neutralise the test sample by adding sodium hydrocarbonate.
  3. Heat the test sample with Benedict’s Reagent.
  4. Observe the colour change.
  5. A brick red precipitate indicates the presence of a reducing sugar.
21
Q

3.1.2 Carbohydrates

What is the test for starch? What is the method?

Study These Flashcards
A

The Iodine Test for Starch:

  1. To test for the presence of Starch in a sample…
  2. Add 10 drops of Iodine in Potassium Iodide Solution to the test sample.
  3. Observe the results: Positive results will show a Purple [blue-black] colour.
22
Q

3.1.2 Carbohydrates

What is the test for protein? What is the method?

Study These Flashcards
A

The Biuret Test for Proteins
- Add 2 cm3 of the liquid food sample* to a clean, dry test tube
- Add 2 cm3 of Biuret Reagent.
Repeat steps the steps above with de-ionized water to prepare a negative control and with albumin (egg white) to prepare a positive control.
- Shake well and allow the mixture to stand for 5 minutes

23
Q

3.1.2 Carbohydrates

What are the three main reducing sugars?

Study These Flashcards
A

Glucose

Fructose

Lactose

24
Q

3.1.2 Carbohydrates

What is the main non-reducing sugar?

25
3.1.3 Lipids What are Lipids?
Lipids are biological molecules made of carbon, hydrogen and oxygen. They don't dissolve in water (hydrophobic molecule) and don't form polymers.
26
3.1.3 Lipids What are the main types of Lipids?
triglycerides and phospholipids.
27
3.1.3 Lipids What are Triglycerides? What is the bond formed?
Triglycerides are formed by the condensation of one molecule of glycerol and three molecules of fatty acid. An ester bond is formed after the condensation reaction.
28
3.1.3 Lipids What is the difference between saturated and unsaturated fatty acids?
``` Saturated: BOND- contain only single carbon bonds STRUCTURE- straight chain molecule MELTING POINT- higher melting point which means it is a solid at room temperature LOCATION- found in animal fats ``` ``` Unsaturated: BOND- contain carbon to carbon double bonds STRUCTURE- linked molecule MELTING POINT- lower melting point LOCATION- found in plant oils ```
29
3.1.3 Lipids How is a triglyceride related to its function?
- High number of carbon-hydrogen bonds therefore they are an excellent energy store - A low mass to energy ratio meaning that they are a good storage molecule, with a lot of energy being stored in a small volume. This is beneficial for animals as it is less mass to move around - Insoluble in water therefore no effect on osmosis in the cells
30
3.1.3 Lipids What is the functions of lipids?
source of energy- release twice the amount of energy as carbohydrates waterproofing- lipids are insoluble in water therefore are useful for waterproofing insulation- fats are slow conductors of heat and when stored beneath the body surface help to retain heat. The also act as an electric insulator in the myelin sheath of a plant cell protection- fat is often stored around the delicate organs, such as the kidney
31
3.1.3 Lipids What is a Phospholipid?
A Phospholipid is similar to lipids however the fatty acid molecules is replaced by a phosphate molecule.
32
3.1.3 Lipids Compare a fatty acid molecule (triglycerides) and a phospholipid
(s) both have glycerol backbone (s) both contain the elements C, H and O (s) both formed by condensation reaction (d) Triglyceride has one glycerol and three molecules of fatty acid whereas Phospholipid has one glycerol, two fatty acid molecules and a phosphate group (d) FAs are hydrophobic (repel water) whereas PLs are hydrophilic (attract water)
33
3.1.3 Lipids What is the relationship between phospholipids and water?
A molecule thats has two ends which act differently is said to be 'polar'. - A hydrophilic 'head'- interacts with and attracted to water (not fat) - A hydrophobic 'tail'- orients itself away from water but mixes readily with Polar phospholipid molecules position themselves in water so that the hydrophilic head is close to the water ads possible whilst the hydrophobic tail is far away from the water as far as possible.
34
3.1.3 Lipids How is a phospholipid related to its function?
- the hydrophilic phosphate heads help the phosphate molecule to hold at the surface of the cell membrane. - the hydrophilic tail
35
3.1.3 Lipids What is the similarities and differences between carbohydrates and lipids?
Both carbohydrates and lipids have the same function which is to store energy. - Carbohydrates and lipids both contain carbon (C), hydrogen (H), and oxygen (0) - Carbohydrates are used for energy (glucose). - Fats are used for energy after they are broken into fatty acids.
36
3.1.3 Lipids What is the relation between carbohydrates and lipids?
The phospholipid structure allows them to combine with carbohydrates to form glycolipids within the cell surface membrane. This is important in cell recognition
37
3.1.4 Proteins What are proteins? What molecules does it contain? Draw the general structure
Amino acids are the monomers from which proteins are made. Amino acids contain: - central carbon atom - an amino group (NH2) - carboxylic acid group - variable R group
38
3.1.4 Proteins What bond forms when two amino acids react?
A peptide bond
39
3.1.4 Proteins What are the two types of polypeptide bonds? What's the difference?
* Dipeptides are formed by the condensation of two amino acids. * Polypeptides are formed by the condensation of many amino acids.
40
3.1.4 Proteins How many amino acids is there? How do they differ?
20 They differ by R group
41
3.1.4 Proteins How do dipeptides and polypeptides form?
- Condensation reaction forms a peptide bond (between amin group and carboxyl group) and eliminates a water molecules
42
3.1.4 Proteins Define PRIMARY structure of a protein
- order and number of amino acids in a protein | - determines the proteins function in the end
43
3.1.4 Proteins Define SECONDARY structure of a protein
Three secondary structure is the shape that the chain of amino acids form - either alpha helix or beta pleated sheet
44
3.1.4 Proteins Define TERTIARY structure of a protein
• Tertiary structure of proteins is the 3D shape of the protein and is formed from further twisting and folding. A number of different bonds maintain the structure, these are: - Disulfide bridges - interactions between the sulfur in the R group of the amino acid cysteine these are strong and not easily broken. - Ionic bonds - form between the carboxyl and amino groups that are not involved in the peptide bond. They are easily broken by pH and are weaker than disulfide bridges. - Hydrogen bonds - numerous and easily broken
45
3.1.4 Proteins Difference between Carbohydrates, Lipids and Proteins
Carbohydrates and Lipids contain the elements Carbon, Hydrogen and Oxygen vs Proteins contain the elements Carbon, Hydrogen, Oxygen, and Nitrogen Starch and cellulose found in plants vs Glycogen found in animals Glycogen and starch monomers are alpha glucose vs Cellulose monomer is beta glucose Starch and Glycogen coiled structure vs Cellulose straight
46
3.1.4 Proteins Define QUATERNARY structure of a protein
Proteins consisting of more than one amino acid chain | - may be non protein (prosthetic groups) within polypeptide chain

biology YEAR1 (3 decks)

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