Unit 1 - Biochemistry Flashcards
1
Q
Describe the atom
A
- Basic unit of life
- Smallest unit of an element that still retains the properties of that element
- Composed of protons/neutrons/electrons
2
Q
What are elements?
A
- Pure substances consisting of all the same type of atom
- Cannot be broken down chemically into simpler substances
- 90% of an organism’s mass is composed of C, H, O, N
3
Q
What are isotopes?
A
- Atoms of the same element with different numbers of neutrons, they each have different masses
- Some are radioactive, meaning their nuclei are unstable and always break down
4
Q
What is a compound?
A
- Chemical combination of 2/more elements in definite proportions
- Chemical/physical properties of a compound are different than the properties of the individual elements that compose them
5
Q
Describe ionic bonds
A
- Formed when one/more electrons are transferred from one atom to another
6
Q
Describe covalent bonds
A
- Electrons are shared between atoms instead of being transferred
- Polar: electrons are shared unequally
- Non-polar: electrons are shared equally
7
Q
Which end of an H2O molecule will always have more electrons?
A
- The oxygen end, as it has a much stronger attraction for electrons
8
Q
What is a hydrogen bond?
A
- Weak chemical bond formed when a slightly positive hydrogen atom of one molecule is attracted to the negative atom of another molecule
- Single H2O molecule can form 4 w/ each other at one time, which is the cause behind H2O’s unique properties
- They break/reform/form often
9
Q
What happens to hydrogen bonds in the three states of water?
A
- Solid state: all molecules are H-bonded, bonds do not break
- Liquid state: an equal number of bonds are formed/broken at any time
- Gaseous state: at high temps, H-bonds are completely broken and the molecules escape into the air as a gas
10
Q
What two forces of attraction are present in water molecules?
A
- Cohesion: attraction b/w molecules of the same substance
- Adhesion: attraction b/w molecules of different substances
11
Q
What is a mixture and its two types that are made w/ water?
A
- Mixture: substance composed of elements/composed that are physically but not chemically combined
~ Solution: homogenous mixture w/ a solute and solvent
~ Suspension: mixture of water and undissolved materials (ex: blood)
12
Q
What are some ways water makes life on earth possible?
A
- Water’s cohesion: at a wide range of temps, cohesion makes water remain a liquid, so it does not turn into a gas or solid
- Water stabilizes temps on Earth: it can absorb/release large amounts of heat to cool/warm landmasses, like a heat bank
- Evaporative cooling: property of a liquid where a surface becomes cooler in evaporation, helps plants transpire and animals sweat to keep them cool
- Water dissolves many substances
- Surface ice helps insulate bodies of water during the cold to keep organisms alive under the ice
13
Q
What is an acid and a base?
A
- Acid: solution that forms H+ ions in solution, pH less than 7
- Base: solution that forms OH- ions in solution, pH more than 7
14
Q
What is a buffer?
A
- Substances produced by cells that prevent sudden changes in pH, to ensure chemical reactions run smoothly
15
Q
What are inorganic vs. organic compounds?
A
- Organic: compounds containing hydrocarbons and carbon-carbon bonds
-Inorganic: do not contain carbon
16
Q
What structures can carbon-carbon bonds create?
A
- Straight chains
- Branched chains
- Rings
~ Chains are almost unlimited in size
17
Q
What characteristics of carbon make possible the building of a variety of molecules?
A
- 4 valence electrons that form strong, stable covalent bonds
- Readily forms bonds w/ itself and other elements including sulfur, phosphorus, oxygen, nitrogen, hydrogen
- Bonds w/ itself to form straight/branched chains or rings
- Chains are almost unlimited in size
- Tendency to bond w/ itself results in variety of organic molecules
- 3-D shape determines the properties/functions of the molecule within living systems
- Do not dissolve readily in water
- Readily available and abundant
- Only carbon has these characteristics
18
Q
Define a macromolecule
A
- Larger molecule made of smaller molecules
- 4 types: proteins, lipids, carbs, nucleic acids
- Polymerization: large compounds are built by the joining together of many smaller molecules
19
Q
What is a monomer vs. a polymer?
A
- Monomers: smaller repeating subunit of molecules that make up polymers
- Polymer: Long molecule consisting of many monomers linked by covalent bonds
20
Q
Explain condensation reactions
A
- Attaches monomers together to form a polymer
- Two molecules are covalently bonded to one another through the loss of a water molecule
- Each monomer contributes part of the water molecule lost (H and OH)
- Cell must expend energy to carry out condensation
- Enzymes are required
21
Q
Explain hydrolysis reactions
A
- Polymers are broken down into monomers
- Reverse of condensation
- Water is used to break down the polymer and the water breaks the bond linking each monomer
4.
22
Q
Describe carbohydrates
A
- Made of C, H, O in a 1:2:1 ratio
- Examples: sugars, starches, cellulose
- Known as quick-energy foods as they immediately supply energy for cellular activities
- Two functions: main energy source for most living things, structural purposes for some
- Monomers are simple sugars like glucose
- Classified by their number of sugar molecules (mono, di-saccharide)
23
Q
What are isomers?
A
- Monosaccharides w/ the same formula but different arrangement of atoms
- This difference makes only small changes in the chemical properties of the sugars
- The changes are recognized by enzymes/proteins and can then therefore have major biological effects
24
Q
What are the different types of isomers?
A
- Structural: compounds have the same atoms bonded in a different way
- Stereoisomers: same atoms are bonded in the same way, but arranged differently in space
~ Geometric: different physical but similar chemical properties
~ Optical: similar physical and chemical properties, only cell proteins/enzymes can distinguish them
25
Q
What is the difference b/w an alpha and beta glucose?
A
- Alpha: OH groups are on opposite sides of the molecule
- Beta: OH groups are on the same side of the molecule
26
Q
What are polysaccharides and their function?
A
- Are made of 3/more monosaccharides
- Used as storage material and can be hydrolyzed to provide free sugars for energy
- Can also be used as building material or for protection
27
Q
What are the most common polysaccharides?
A
- Starch: used for excess glucose storage in plants only
- Glycogen: used for excess glucose storage in animals only, produced in the liver
- Cellulose: structural polysaccharide found in the cell wall of plants to give them strength, also found in wood/paper
28
Q
What is amylopectin?
A
- Type of starch and polymer made of glucose molecules
- Consists mainly of a(1-4) links but also has branches made w/ a(1-6) links
~ Branches produce a compact structure that can rapidly be broken down for energy
29
Q
What is cellulose?
A
- Found in plants only, makes tough cell walls
- Structural function
- Composed of long glucose chains held together mainly by B(1-4) linkages-these links allow for inter/intra chain H-bonds
30
Q
Why can’t we break down cellulose?
A
- No mammal makes the necessary enzymes for breaking down cellulose
- Animals that do consume lots of cellulose have symbiotic bacteria that helps them digest it - We still need cellulose to stimulate secretion of mucus in the lining of the digestive tract
31
Q
What is chitin?
A
- Used by arthropods to build their exoskeleton
32
Q
What are lipids?
A
- Large, nonpolar organic molecules
- Higher ratio of C and H than O, so they can store more energy per gram
- Insoluble, hydrophobic
- Ex: fats, oils, waxes
- Diverse in form/function
33
Q
List the types of lipids
A
- Steroids
- Fatty acids
- Phospholipids
- Waxes
34
Q
Name the differences b/w saturated and unsaturated fats
A
- Saturated: no C-C double bonds, solid at room temp
- Unsaturated: at least 1 C-C double bond, liquid at room temp
35
Q
What is a triglyceride?
A
- Composed of 3 fatty acids attached to 1 glycerol
36
Q
What is a phospholipid?
A
- Composed of 2 fatty acids and 1 glycerol
- Structural component of cell membrane, forms bilayer to separate the inside/outside of the cell
37
Q
What are steroids?
A
- Lipids w/ a 4 carbon ring framework
- Can be used to treat inflammation (ex: asthma)
- Anabolic steroids mimic male sex hormones to build muscle mass
~ Used by cancer/AIDS patients, abused by others - Ex: cholesterol, vitamin D2, cortisol, testosterone
38
Q
What are waxes?
A
- Waterproof, form protective coatings on outer surfaces such as feathers, leaves, fruits exoskeletons, etc.
- Contain fatty acids
39
Q
What are proteins?
A
- Macromolecules made of C, O, H, N
- Monomers are amino acids (20 of them, either essential/non-essential)
40
Q
What does the basic structure of an amino acid consist of?
A
- A carboxyl group (COOH)
- A single H atom
- An amino group (NH2)
- An R group (rest of molecule)
~ All are covalently bonded to central C atom
41
Q
What is a peptide bond?
A
- A covalent bond formed b/w the carboxyl group of one amino acid and the amino group of another amino acid through a condensation reaction
42
Q
What is a dipeptide?
A
- Two amino acids joined by a peptide bond
43
Q
What is a polypeptide?
A
- Long chain of amino acids joined by peptide bonds (sequence of amino acids determines protein and its function)
44
Q
What is a functional protein?
A
- A macromolecule that consists of one/more polypeptide chains folded, coiled, and twisted into specific shapes
- A protein’s function is determined by its unique 3D shape as well as its ability to recognize and bind to some molecules
45
Q
What are some uses for proteins?
A
- Enzymes
- Hormones
- Transport proteins
- Contractile proteins
- Antibodies
- Membrane proteins
- Structural proteins
46
Q
What are enzymes?
A
- Proteins that speed up chemical reactions of a cell
- Without them, reactions would be too slow for the cell to survive
47
Q
What is the equation for an enzyme-substrate reaction?
A
- Enzyme + Substrate –> E.S Complex –> Unchanged Enzyme –> New Product
- Reactions depend on a physical fit b/w the enzyme + substrate
48
Q
What are nucleic acids?
A
- Large and complex organic molecules that store/transfer vital info to the cell
- Contain the elements C, H, O, N, P
- DNA (nucleus) and RNA (cytoplasm–>ribosomes)
- Monomers are nucleotides
