Biological molecules Flashcards
(102 cards)
1
Q
What are the 6 main elements that make up the complex molecules found in living things?
A
- S: Sulfur
- P: Phosphoris
- O: Oxygen
- N: Nitrogen
- C: Carbon
- H: Hydrogen
2
Q
What is a molecule?
A
A group (2 or more) atoms bonded (covalently) together.
3
Q
Are all molecules compunds? Explain
A
No
O2 is a molecule made from two oxygen molecules bonded together, therefore it is a molecule that is an element not a compund.
4
Q
What are the 4 main types of maromolecules that make up living things?
A
- Carbohydrates
- Proteins
- Lipids (including fats)
- Nucleic acids (DNA and RNA)
5
Q
What is an organic molecule?
A
A molecule that cotains carbon (and hydrogen).
6
Q
What are macromolecules?
A
Molecules made from large numbers (hundreds or thousands) of atoms.
7
Q
What are monomers and polymers are?
A
Monomers: Small molecules that join together to make polymers
Polymers: Long chains of similar molecules (monomers joined together)
8
Q
Name as many polymers found in living things as you can.
A
Carbohydrate polymers: Starch, cellulose, glycogen.
Nucleic acids: DNA and RNA
Polypeptides: The polymers that form proteins.
9
Q
What elements are carbohydrates made from?
A
Carbon
Hydrogen
Oxygen
10
Q
What is the ratio of hydrogen to oxygen atoms in carbohydrates?
A
2:1 (hydrogen:oxygen)
11
Q
Name three monosaccharides.
A
Glucose
Fructose
Galactose
12
Q
Name 3 disaccharides
A
Maltose
Sucrose
Lactose
13
Q
What monosaccharides join to form maltose?
A
2 alpha-glucose molecules
14
Q
What monosaccharides join to form sucrose?
A
An alpha-glucose and a fructose molecule
15
Q
What monosaccharides join to form lactose?
A
An alpha-glucose and a galactose molecule
16
Q
What type of bonds is formed during condensation of two monosaccharides?
A
A glycosidic bond
17
Q
Alpha glucose, beta glucose and galactose are isomers. What does the term isomer mean?
A
Molecules with the same chemical formula but different arrangements of atoms.
18
Q
Which two polysaccharides are used for storage of glucose?
A
Glycogen
Starch
19
Q
Which two polysaccharides are found in plants?
A
Cellulose
Starch
20
Q
Which polysaccharides are found in animal cells?
A
Glycogen
21
Q
Which polysaccharides might you find in the digestive system of herbivores (plant eaters)?
A
Starch
Cellulose
22
Q
Which polysaccharides are made from alpha glucose?
A
Starch
Glycogen
23
Q
Which polysaccharides is made from beta-glucose?
A
Cellulose
24
Q
What two molecules is starch made from?
A
Amylose
Amylopectin
25
Describe the structure of amylose.
* A chain
* (of) Alpha glucose molecules
* Bonded by 1,4-glycosidic bonds
* Coiled into spirals
26
Describe the structure of amylopectin.
* Branched chains
* (of) Alpha glucose molecules
* Bonded by 1,4-and 1,6-glycosidic bonds
27
Describe the structure of glycogen.
* Branched chains
* (of) Alpha glucose molecules
* Bonded by 1,4-and 1,6-glycosidic bonds
28
In what way do the structure of glycogen and amylopectin differ?
* Glycogen has more branches (more 1,6-glycosidic bonds).
29
In what ways are glycogen and starch adapted to their function as storage molecules?
1. They are insoluble
2. They are easy to make
3. They are easy to break down
30
Why do storage molecules need to be insoluble?
1. So that they do not alter the water potential of the cell: Cause water to leave or enter the cell.
2. So that they stay in the desired location. Soluble molecules would diffuse to other parts of the cell organism.
31
Why do storage molecules need to be easy to break down?
So that glucose can be made available quickly for respiration (to release energy)
32
Where is starch stored in plants?
In leaves (overnight storage)
In seeds
In bulbs and tubers (winter storage)
33
Where is glycogen stored in animals?
(Small reserves) In muscle cells
(Large reserves) In the liver
34
What is the function of cellulose?
It is a structural molecule found in plant cell walls.
35
What monomers is cellulose made from?
Beta glucose
36
What type of bonds hold the beta-glucose molecules together in cellulose?
1,4 glycosidic bonds
37
Cellulose chains are linked together to form microfibrils. What type of bonds hold the cellulose chain/molecules together?
Hydrogen bonds
38
Cellulose is difficult to break down. Explain why.
Because:
* Each cellulose molecule only has two ends (no branches) where digestion can begin.
* The ends are embeded within microfibrils so are difficult for enzymes to get to.
39
As well as being difficult to break down, how else is cellulose adapted to its function?
1. It's insoluble.
2. Cellulose microfibrils and firers are extremelly strong.
3. It's easy to make.
40
What elements are proteins made from?
Carbon, hydrogen, oxygen, nitrogen and sulfur
41
What monomers are polypeptides made from?
Amino acids
42
What type of bond forms between amino acids during condensation?
Peptide bonds
43
Amino acids are made from a central carbon atom, bonded to a hydrogen atom and 3 other groups. What are the 3 other groups?
1. Carboxyl group (COOH)
2. Amino group (NH2)
3. R-group (variable group)
44
What is meant by the PRIMARY structure of a protein?
* Number
* Type
* Order
* of **amino acids**
* In the polypeptide chains
45
What type of bonds are involved in maintaining the primary structure?
Peptide bonds
46
What is meant by the SECONDARY structure of a protein?
The bending and folding to give an alpha-helix or beta-pleated sheet.
47
What type of bonds maintain the secondary structure in proteins?
Hydrogen bonds
48
What is meant by the TERTIARY structure of a protein?
The **bending and folding** of the polypeptide chains
To give them their **globular** or **fibrous** structure.
49
What type of bonds maintain the tertiary structure of a protein?
Hydrogen bonds
Ionic bonds
Disulfide bonds
50
What is meant by the QUATERNARY structure of a protein?
The bonding of two or more polypeptides
And/or other groups
51
What type of bonds maintain the quaternary structure of a protein?
Hydrogen bonds
Ionic bonds
Disulfide bonds
52
Triglycerides (fast and oils) are lipids. What other molecules are liids?
* Waxes
* Steriods
* Sterols
* Phospholipids
53
What elements are lipids made from?
* Carbon
* Hydrogen
* Oxygen
54
What are lipids used for in living things?
* Energy storage
* Insulation
* Protecting vital organs
* Waterproofing
* Plasma membranes
55
Why is more energy stred as lipids than as gycerol in animals?
Twice as much energy stored per gram in lipids
56
What are lipids made from?
Fatty acids
Alcohols
57
What are triglycerides made from?
THREE Fatty acids
Glycerol (an alcohol)
58
Through want type of reaction do fatty acids become bonded to glycerol?
Condensaton
59
Describe or draw the structure of glycerol.
3 carbon atoms (saturated)
Each carbon atoms is bonded to a hydrogen atom and a hydroxyl group (OH)
The end carbon atoms are also bonded to an additional hydrogen atom.
60
Describe the structure of a **saturated** fatty acid.
A carboxyl group (COOH)
Bonded to a hydrocarbon chain
**Saturated:** All the carbon atoms are bonded to each other by single bonds
61
Describe the structure of a **unsaturated** fatty acid.
A carboxyl group (COOH)
Bonded to a hydrocarbon chain
**Unaturated:** One or more pairs of carbon atoms are bonded t each other by double bonds.
62
* What are the two types of nuclei acids?
DNA (deoxyribonucleic acids)
RNA (Ribonucleic acids)
63
What monomers are nucleic acids made from?
Nucleotides
64
What elements are nucleic acids made from?
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorus
65
What groups are nucleotides made from? How do these differ in DNA and RNA?
1. Pentose sugar (Deoxyribose in DNA and Ribose in RNA)
2. Phosphate group
3. Nitrogen containing base (Adenine, Cytosine, Guanine or Thymine in DNA, Thymine replaced by Uracil in RNA)
66
What type of bonds form between nucleotides during condensation reactions?
Phosphodiester bonds
67
DNA is made from two polynucleotide chains that are bonded together. What type of bonds hold the chains together?
Hydrogen bonds.
68
Hydrogen bonds form between nitogen containing bases. Which bases bond to each other (are complementary)?
Adenine bonds to thymine (or Uracil in RNA)
Guanine bonds to cytosine
69
Describe the structure of DNA.
1. **Two** (antiparallel) **polynucleotide chains**: Chains of nucleotides bonded by phosphodiester bonds.
2. Bonded to each other by **hydrogen bonds**.
3. Between **complementary bases**: A to T and C to G.
4. Twisted into a **double helix**.
70
What are the three main stages in DNA replication?
1. The polynucleotides strands (unwind and) seperate.
2. Free DNA nucleotides bond to exposed bases on the template strand.
3. New nucleotides bond (phosphodiester) together.
71
What is the role of DNA helicase during DNA replication?
It breaks the hydrogen bons between the polynucleotide strands, allowing them to unwind and seperate.
72
What is the role of DNA polymerase during DNA replication?
It catalyses the formation of condensation reactions between nucleotides to form phosphodiester bonds, creating the sugar phosphate backbone.
73
Why is DNA replication called semi-conservative replication?
One original polynucleotide strand remains intact (is conserved) and one new complementary strand is made.
74
What is ATP made from?
1. Ribose
2. Adenine
3. Three inorganic phosphate groups
75
Whys is ATP described as a 'nucleotide derivative'
Because it is a modified (two phosphate groups have been added) RNA nucleotide.
76
Whys is ATP described as the immediate energy source.
Because ATP is the molecule that directly provides energy to all the enery requiring processes that take place in living things.
77
Give three examples of processes that require energy from ATP.
1. **Biosynthesis**: Protein synthesis, DNA replication, synthesis of phospholipids.
2. **Muscle contraction**
3. **Active transport**: Moving particles across plasma membranes against their concentration gradient.
4. **Cytoplasmic transport:** Vesicles or organelles can be transported along microtubule tracks using molecular motor proteins.
78
In what ways is ATP adapted to its function?
**It is small and soluble**: so can diffuse rapidly to the areas of the cells where it is needed.
**It can release energy through a single hydrolysis reaction:** Thererefore making energy available very quickly.
79
Describe how ATP is synthesised.
1. Made from ADP and an inorganic phosphate group.
2. Condensation reaction (H2O also made).
3. Catalysed by ATP synthase.
4. Energy provided by respiration (or photosynthesis).
80
Water is a solvent? Why is this important for living organisms?
1. Most metabolic reactions take place in solution.
2. Substances are easier to transport in solution.
81
Water molecules are cohesive? Why is this important for living organisms?
1. Helps water transport in plants.
2. Supports transport in other organisms.
82
Water has a high latent heat of vaporisation? Why is this important for living organisms?
It allows organisms to cool down (e.g through sweating, panting and transpiration) without significant water loss.
83
Water has a high specific heat capacity? Why is this important for living organisms?
1. It helps organisms maintain a **stable** internal **temperature**.
2. It provides a **stable** external **temperature** for water bourne organisms.
84
Explain why water molecules are polar.
* The shared electrons are pulled towards the oxygen nucleus.
* Giving the hydrogen atoms a slight positive charge.
* The unshared negative electrons on the oxygen atom, give it a slight negative charge.
85
Explain why water molecules are cohesive.
1. The negatively charged oxygen atoms of water molecules attract the positively charged hydrogen atoms of other water molecules.
2. Forming hydrogen bonds.
86
What are ions?
Atoms or groups of atoms that have an electric charge.
87
What are positively charged ions called?
Cations
88
What are negatively charged ions called?
Anions
89
What type of ions are at the centre of each of the polypeptides in haemoglobin?
Iron ions
90
What type of ions determine the pH of a region?
Hydrogen ions
91
Glucose and amino acids are transported into cells alongisde which type of ions? What is this process called?
Sodium ions
Co-transport
92
How do catalysts speed up the rate of reaction?
By reducing activation energy.
Increasing the proprtion of collisions that are successful.
93
What is an intracellular enzyme? Give an example?
An enzyme that is active within cells. E.g DNA helicase, DNA polymerase, ATP synthase and ATP hydrolase.
94
What is an extracellular enzyme? Give an example?
An enzyme that is active outside of cells. E.g All the enzymes in the digestive system: Pepsin, salivary amylase etc.
95
What is **activation energy**?
How much energy you have to put into a system to make a chemical reaction occur.
How much energy reactant /substrate molecules need to react
96
What part of the enzyme bonds to the substrate?
The active site
97
The shape of an enzyme and the substrate for the enzyme is catalyses are described as...
complementary
98
Describe the lock and key model of enzyme action.
The enzyme's active site and substrate have **complimentary shapes.**
Like a lock and key.
The substrate binds to the active site forming an enzyme-substrate complex.
99
What are the limitations of the lock and key model?
* It does not take into account the fact that enzymes change shape when the substarte bonds to the active site.
* It does not explain how enzymes reduce activation energy.
100
Describe the induced-fit model of enzyme action.
* The enzyme's active site and substrate have complimentary shapes.
* The substrate binds to the active site forming an enzyme-substrate complex.
* As the substrate enters the active site the enzyme changes shape slightly.
* This exerts a force/puts pressure/puts stress on the bonds in the substrate.
* This brings the substarte molecules closer together overcoming repulsive forces between them.
101
What do we call the pH or temperature at which an enzyme works best.
The optimum pH/temperature.
102
