3.1 Biological molecules Flashcards
(100 cards)
1
Q
Monomer
A
- The smaller units from which larger molecules are made
INSERT IMAGE HERE
2
Q
Polymer
A
- Molecules made from a large number of monomers joined together
INSERT IMAGE HERE
3
Q
Monosaccharide
A
- The monomers from which larger carbohydrates are made
- e.g. glucose, fructose, galactose
INSERT IMAGE HERE
4
Q
Disaccharide
A
- Formed by the condensation of two monosaccharides
- held together by a glycosidic bond
- e.g. maltose, sucrose, lactose
INSERT IMAGE HERE
5
Q
Polysaccharide
A
- Formed by the condensation of many glucose units
- held by glycosidic bonds
- e.g. starch, glycogen, cellulose
INSERT IMAGE HERE
6
Q
Cellulose
A
- Polysaccharide in plant cell walls
- formed by the condensation of β-glucose
INSERT IMAGE HERE
7
Q
Glycogen
A
- Polysaccharide in animals
- formed by the condensation of α-glucose
INSERT IMAGE HERE
8
Q
Starch
A
- Polysaccharide in plants
- formed by the condensation of α-glucose
- contains two polymers – amylose and amylopectin
INSERT IMAGE HERE
9
Q
Glycosidic bond
A
- C–O–C link
- between two sugar molecules
- formed by a condensation reaction
- it is a covalent bond
10
Q
Amylose
A
- Polysaccharide in starch
- made of α-glucose
- joined by 1,4-glycosidic bonds
- coils to form a helix
INSERT IMAGE HERE
11
Q
Amylopectin
A
- Polysaccharide in starch
- made of α-glucose
- joined by 1,4 and 1,6-glycosidic bonds
- branched structure
INSERT IMAGE HERE
12
Q
Condensation reaction
A
- A reaction that joins two molecules together
- with the formation of a chemical bond
- involves the elimination of a molecule of water
13
Q
Hydrolysis reaction
A
- A reaction that breaks a chemical bond
- between two molecules
- involves the use of a water molecule
14
Q
Fibrils
A
- Long, straight chains of β-glucose glucose
- held together by many hydrogen bonds
INSERT IMAGE HERE
15
Q
Triglyceride
A
- Formed by the condensation of one molecule of glycerol and three molecules of fatty acids
- forming 3 ester bonds
INSERT IMAGE HERE
16
Q
Phospholipid
A
- Formed by the condensation of one molecule of glycerol and two molecules of fatty acid
- held by two ester bonds
- a phosphate group is attached to the glycerol
INSERT IMAGE HERE
17
Q
Induced-fit model
A
- The enzyme active site is not initially complementary to the substrate
- the active site moulds around the substrate
- this puts tension on bonds
- lowers the activation energy
18
Q
Competitive inhibitor
A
- A molecule that is the same/similar shape as the substrate
- binds to the active site
- prevents enzyme-substrate complexes from forming
INSERT IMAGE HERE
19
Q
Non-competitive inhibitor
A
- A molecule that binds to an enzyme at the allosteric site
- causing the active site to change shape
- preventing enzyme-substrate complexes from forming
INSERT IMAGE HERE
20
Q
Primary structure
A
- The sequence of amino acids on a polypeptide chain
INSERT IMAGE HERE
21
Q
Secondary structure
A
- The folding or coiling
- to create a β pleated sheet or an α helix
- held in place by hydrogen bonds
INSERT IMAGE HERE
22
Q
Tertiary structure
A
- The further folding
- to create a unique 3D shape
- held in place by hydrogen, ionic and sometimes disulfide bonds
INSERT IMAGE HERE
23
Q
Quaternary structure
A
- More than one polypeptide chain in a protein
INSERT IMAGE HERE
24
Q
Peptide bond
A
- Covalent bond joining amino acids together in proteins
- C–N link between two amino acid molecules
- formed by a condensation reaction
25
What is the effect of temperature on enzyme-controlled reaction?
* At low temperatures, there is not enough kinetic energy for **successful collisions** between the enzyme and substrate.
* At too high a temperature, **enzymes denature**, the active site changes shape and enzyme-substrate complexes cannot form.
26
What is the effect of pH on enzyme-controlled reaction?
* Too high or too low a pH will **interfere with the charges** in the amino acids in the active site.
* This **breaks the ionic and hydrogen bonds** holding the tertiary structure in place
* ∴ the **active site changes shape** and the enzyme denatures.
* Different enzymes have a different optimal pH.
27
What is the effect of substrate concentration on enzyme-controlled reaction?
* At low substrate concentrations, there will be **fewer collisions** between the enzyme and substrate.
* At high substrate concentrations, the **rate plateaus**
* because all the **enzyme active sites are saturated**.
28
What is the effect of enzyme concentration on enzyme-controlled reaction?
* At low enzyme concentrations, there will be **fewer collisions** between the enzyme and substrate.
* At high enzyme concentrations, the **rate plateaus**
* because there are more **enzymes than the substrate**, so many empty active sites.
29
Ester bond
* **–COO–** chemical bond
* formed between **glycerol** and **fatty acids**
30
Hydrophilic
* The ability to mix, interact or
**attract water**
31
Hydrophobic
* The tendency to **repel** and not mix with **water**
32
Glucose
* **Monosaccharide** that exists as two isomers
* β glucose and α glucose
| INSERT IMAGE HERE
33
Galactose
* An example of a **monosaccharide** that forms lactose
34
Fructose
* An example of a **monosaccharide** that forms sucrose
35
Isomer
* Molecules with the **same molecular formula**
* but the atoms are **arranged differently**
36
Maltose
* **Disaccharide**
* formed by the condensation
* of **two glucose** molecules
| INSERT IMAGE HERE
37
Lactose
* **Disaccharide**
* formed by the condensation
* of a **glucose** molecule and a **galactose** molecule
38
Sucrose
* **Disaccharide**
* formed by the condensation
* of a **glucose** molecule and a **fructose** molecule
39
Polypeptide
* **Polymer** chain of a protein
* made up of **amino acids**
* bonded together by **peptide bonds**
* following **condensation** reactions
| INSERT IMAGE HERE
40
Amino acid
* The **monomer of a protein**
* formed from C,H,O,N
* contains a carboxyl group, amine group and an R group
| INSERT IMAGE HERE
41
Carboxyl group
* **COOH** group
* made up of a C with hydroxyl (OH) and carbonyl (double-bonded O) group bonded to it
* found in **amino acids** and **fatty acids**
| INSERT IMAGE HERE
42
Amine group
* **NH₂ group** found on amino acids
| INSERT IMAGE HERE
43
R group on amino acids
* The **variable group**
* the part of each of the 20 amino acids that is different
44
α helix
* A **secondary structure** in proteins
* a coiled shape held in place by **hydrogen bonds**
| INSERT IMAGE HERE
45
β pleated sheet
* A **secondary structure** in proteins
* a folded, pleated shape
* held in place by **hydrogen bonds**
| INSERT IMAGE HERE
46
Hydrogen bonds
* **Weak** bond
* forms between **H and O**
* in many biological molecules e.g. proteins, water, DNA, tRNA
47
Ionic bonds
* A bond that forms **between the R** groups of different amino acids
* in the **tertiary structure** of proteins
48
Disulfide bonds
* A **strong covalent bond**
* between **two sulfur atoms in the R groups** of different amino acids
* in the **tertiary structure** of proteins
49
Active site
* **Unique-shaped** part of an enzyme
* that the **substrate binds** to
| INSERT IMAGE HERE
50
Activation energy
* The minimum amount of **energy required** for a **reaction** to occur
51
Enzyme-substrate complex
* forms when an enzyme and substrate collide and bind
* resulting in a **lowered activation energy**
| INSERT IMAGE HERE
52
Denature
* When the **active site changes shape**
* so the substrate can no longer bind
53
Enzyme-inhibitor complex
* The structure that forms when an **enzyme and inhibitor collide** and bind
* prevents enzyme-substrate complexes from forming
54
Saturated fatty acid
* A long **hydrocarbon chain** with a **carboxyl** group at one end
* only **single bonds** between carbon atoms
| INSERT IMAGE HERE
55
Unsaturated fatty acid
* A long **hydrocarbon chain** with a carboxyl group at one end
* at least one **double bond between carbon** atoms
| INSERT IMAGE HERE
56
Polar molecule
* A molecule that has an uneven distribution of **charge**
57
Phospholipid bilayer
* Phospholipids have **two charged regions**
* in water, they are positioned so that the heads are exposed to water and the tails are not
| INSERT IMAGE HERE
58
Plasma membrane
* **Phospholipid bilayer**
* cell surface membranes and organelle membranes
59
Reducing sugar
* sugars that can **reduce Cu²⁺ ions** in Benedict’s reagent to **Cu⁺ ions** in the form of **copper (I) oxide**
* which forms a **brick-red** precipitate
60
Test for reducing sugar
* Add **Benedict's** reagent
* **heat**
* observe green/yellow/orange/brick red precipitate
| INSERT IMAGE HERE
61
How does the structure of a triglyceride relate to it's function?
* large ratio of energy-storing carbon-hydrogen bonds compared to the number of carbon atoms; a **lot of energy is stored in the molecule**
* high ratio of hydrogen to oxygen atoms they **act as a metabolic water source**
* **do not affect water potentials** and osmosis
* have a relatively **low mass**
62
How does the structure of a phospholipid relate to it's function?
* Phospholipids have two charged regions, so they are **polar**.
* In water, they are positioned so that the heads are exposed to water and the tails are not.
* This forms a **phospholipid bilayer** which makes up the **plasma membrane around cells**.
63
How does the structure of a triglyceride and phospholipid differ?
* A phospholipid has **one fewer fatty acid chain**
* which is **replaced by a phosphate group**
## Footnote
[CHECK THE 2+]
64
What is the difference between saturated and unsaturated fatty acid?
* A saturated fatty acid has **no double bonds** between carbon atoms
* where as unsaturated fatty acids had **at least one double bond between carbon atoms**
65
Non-reducing sugar
* a sugar **unable to reduce Cu²⁺**
* the glycosidic bond must be hydrolysed to expose the reducing group
* e.g. **sucrose**
66
Test for non-reducing sugar
* Following a **negative Benedict's** test
* **boil** sample in **acid** and then **neutralise** with alkaline
* add **Benedict's** reagent and **heat**
* observe orange/brick red colour
| INSERT IMAGE HERE
67
Test for starch
* Add **iodine**
* turns **blue/black**
| INSERT IMAGE HERE
68
Test for lipids
* Add **ethanol** and shake to dissolve
* then add **water**
* **white emulsion** forms
| INSERT IMAGE HERE
69
Test for protein
* Add biuret
* turns purple
| INSERT IMAGE HERE
70
Nucleotide
* The **monomer** of DNA and RNA
* contains a **pentose** sugar, a **phosphate** group and a **nitrogenous base**
| INSERT IMAGE HERE
71
Nitrogenous base
* Part of a **nucleotide**
* adenine, guanine, cytosine, thymine and uracil
72
DNA nucleotide
* The **monomer of DNA**
* contains a deoxyribose sugar, a phosphate group and a nitrogenous base
| INSERT IMAGE HERE
73
Polynucleotide
* DNA **polymer**
* many nucleotides joined together via a **condensation reaction**
* joined by **phosphodiester bonds**
| INSERT IMAGE HERE
74
Phosphodiester bond
* Bond joining **two nucleotides** together
* forms between a **phosphate** group and the **pentose** sugar
75
Complementary base pairs
* The base pairs that align opposite each other and form hydrogen bonds
* **adenine** and **thymine/uracil**
* **guanine** and **cytosine**
76
Ribose
* **pentose** sugar
* found in **RNA** nucleotide and **ATP**
77
Uracil
* **Nitrogenous base**
* found in **RNA** instead of thymine
78
mRNA
* a copy of a gene
* **single-strand** polymer of RNA
| INSERT IMAGE HERE
79
tRNA
* found only in the cytoplasm
* single-stranded but folded to create a shape that looks like a **cloverleaf**
* held in place by **hydrogen** bonds
| INSERT IMAGE HERE
80
rRNA
* rRNA combines with protein to make **ribosomes**
81
DNA template strand
* A DNA strand that is used to make a new **DNA copy** from
* both DNA strands in the double helix are used as templates in **DNA replication**
82
DNA polymerase
* An enzyme in DNA replication
* joins together **adjacent nucleotides**
83
Semi-conservative replication
* DNA replication is semi-conservative replication
* **one strand** is from the **parental** DNA and **one strand** is newly **synthesised**
84
DNA helicase
* Enzyme that **breaks hydrogen bonds** between the two chains of DNA in a double helix
* causes the **two strands to separate**
* involved in DNA replication and transcription
85
Large latent heat of vaporisation
* a lot of energy is required to convert water from its **liquid state to a gaseous state**
* this is due to the **hydrogen bonds**, as energy is needed to break these to turn it into a gas
* means water can provide a **cooling effect**
86
High specific heat capacity
* a lot of energy is required to **raise the temperature** of the water
* because some of the heat energy is used to **break the hydrogen bonds** between water molecules
* important so water can act as a **temperature buffer**
87
Metabolite
* Water is involved in many **reactions**
* such as **photosynthesis**, **hydrolysis**, and **condensation** reactions
88
Solvent
* **Water** is a good solvent
* meaning many substances **dissolve** in it
* **polar** (charged) molecules dissolve readily in water due to the fact water is polar
89
Strong cohesion
* water molecules ‘stick’ together due to **hydrogen bonds**
* results in water moving up the xylem as a **continuous column** of water
* provides **surface tension**, creating a habitat on the surface of the water for small invertebrates
90
ATP synthase
* Enzyme that catalyses the **synthesis of ATP** from ADP + Pi
91
ATP hydrolase
* Enzyme that catalyses the **hydrolysis of ATP** into ADP + Pi
92
Phosphorylation
* The **addition of a phosphate** group to a molecule
* making the molecule more **reactive**/it gains energy
93
Structure of water
* Water is a polar molecule
* the oxygen atom is slightly **negative**
* the hydrogen atoms are slightly **positive**
| INSERT IMAGE HERE
94
Dipeptide
* **Two amino acids** bonded together by a **peptide bond**
* formed by a **condensation** reaction
| INSERT IMAGE HERE
95
RNA nucleotide
* **monomer** of RNA
* composed of a **phosphate group**, **ribose** and a **nitrogenous base**
* has the base **uracil** instead of thymine
| INSERT IMAGE HERE
96
Role of hydrogen ions
* **determine the pH**
* the more hydrogen ions, the more acidic the conditions are
* an important role in **chemiosmosis** in respiration and photosynthesis
97
Role of iron ions
* a compound of **haemoglobin**
* involved in oxygen transport
98
Role of sodium ions in co-transport
* involved in co-transport for absorption of **glucose** and **amino acids** in the ileum
99
Role of phosphate ions
* as a component of **DNA**, **RNA** and **ATP**
* **phosphodiester bond** in DNA and RNA forms between the phosphate group and the pentose sugar
100
Fatty acid structure
* **carboxyl group** and a long **hydrocarbon chain**
* can be **saturated** or **unsaturated**
| INSERT IMAGE HERE
