Building Blocks of Cells Flashcards
1
Q
What are atoms made up of?
A
- Positive nucleus surrounded by negative electrons
- Electrons are configured in energy levels (shells)
- The further from the nucleus the higher the energy
2
Q
What determines the types of compounds that form?
A
- Large EN difference = ironic compound e.g. NaCl
- Small EN difference = polar covalent compound e.g. H2O
- Very small EN difference = non-polar covalent compound e.g. O2
3
Q
What determines the polarity of molecules?
A
- Electron sharing in covalent compounds is not always even and depends on the difference in EN and the molecule’s shape
- Non-polar = equally shared
- Polar = unequally shared
- Partly polar and partly non-polar = amphipathic
4
Q
What are intermolecular forces?
A
- Weak forces
- Hydrogen bonds between some polar groups where delta +ve H is bound to a small highly EN atom (F, O, N)
- Electrostatic interactions
- Dispersion forces: can occur between non-polar molecules
5
Q
How does water bond?
A
- Each molecule of H2O can form 4 hydrogen bonds
- Solid water (ice) has a regular crystalline structure due to hydrogen bonding
- Volume expands when it freezes (so cells burst)
- Water is a versatile solvent for polar and ionic substances
- Water forms hydration shells around macromolecules
- Hydrophobic: repelled from water, usually non-polar
- Hydrophilic: attracted to water, usually polar and soluble
6
Q
How does carbon bond?
A
FFF
- Has four valence electrons so can covalently bond with up to four other atoms
- Flexibility in making diverse carbon structures
- Functional groups impart diverse chemical properties
7
Q
What are carbon macromolecules?
A
Large polymers formed by dehydration and broken down by glycolysis
8
Q
What are the types of carbon macromolecules?
A
PLNC
- Proteins
- Lipids
- Nucleic acids
- Carbohydrates
9
Q
What are the types of carbohydrates?
A
Monosaccharides:
- Simple sugars (CH2O)n
- e.g. glucose and fructose
Disaccharides:
- Two monosaccharides covalently joined by a glycosidic bond
- Synthesised by dehydration reaction
- Used for energy
- e.g. sucrose and lactose
Polysaccharides:
- Many monosaccharides joined by glycosidic bonds
- Starch: CHO storage in plants
- Glycogen: CHO storage in animals
- Cellulose: structural support in plants
10
Q
What are lipids?
A
Diverse group of macromolecules that are insoluble and all or mostly hydrophobic
11
Q
What are the types of lipids
A
FWPS
- Fats
- Waxes
- Phospholipids
- Steroids
12
Q
What are fats?
A
- 1 glycerol molecule covalently bonded to 3 fatty acid molecules (triglyceride)
- Allows very compact energy storage
- e.g. butter (saturated) and oil (unsaturated)
13
Q
What are phospholipids?
A
- Amphipathic
- Main component of cellular membranes
- Polar: phosphate containing head group and glycerol
- Non polar: 2 fatty acid tails
14
Q
What are waxes?
A
- Mainly fatty acids joined covalently to other chemical groups
- e.g. beeswax and waxy cuticle on leaves
15
Q
What are steroids?
A
- Covalently linked rings
- e.g. cholesterol, oestrogen, testosterone
16
Q
What are nucleic acids?
A
- Polymers of nucleotides joined together by phosphodiester bonds
- A nucleotide contains: phosphate, pentose, base
- Polynucleotides contain genetic information in their sequence of nitrogenous bases
- Have a 5’ to 3’ orientation determined by carbon numbering
- Nitrogenous bases can only hydrogen bond with compatible bases
- Adjacent nucleotides with compatible base sequences can bond
17
Q
What is DNA made of?
A
- The pentose is deoxyribose
- Exists as two polynucleotides
- Hydrogen bonds between complementary bases
- Two strands are antiparallel
- Provides a ‘backup’ copy
18
Q
What is RNA made of?
A
- The pentose is ribose
- Single stranded
- Uracil instead of thymine (more stable)
