Biochemistry Flashcards
Ionic Bonds
Occur when atoms either donate or accept electrons from another atom.
What are the three types of chemical bonds?
- Covalent
- Ionic
- Hydrogen
Cation
The atom that DONATES an electron in an ionic bond becomes POSITIVE (+).
Anion
The atom that ACCEPTS an electron in the ionic bond becomes NEGATIVE (-).
Salts
When an ionic bond forms between mineral compounds.
Electrolytes
Salts able to transmit electrical energy that are important in biochemical processes.
When dissolved in water, what do acids release?
Hydrogen ions
When dissolved in water, what do bases release?
Hydroxyl ions
____ occur when two atoms each have an unpaired electron in their outer orbitals.
Covalent bonds!
• Each atom exerts a force on the unpaired electron of the other, pulling them together.
• The unpaired electrons are then shared.
___ is the sharing of electrons equally in a covalent bond.
Nonpolar bond
Polar covalent bond
Unequal sharing of electrons between two atoms causing one end of the molecule to have a slight positive charge and the other end to have a slight negative charge. WATER!
Properties of water
- Water is the universal solvent.
- Water is an ideal transport medium.
- Water has a high heat capacity and a high heat of vaporization.
- Water is used for lubrication.
Hydrogen bonding
Occurs when there’s a weak attraction between a slightly negative atom in a polar covalent bond and a slightly positive hydrogen atom involved in a second polar covalent bond.
Cohesion of water molecules results in:
High surface tension of water.
Adhesion refers to:
The attraction between water molecules and other charged surfaces.
Types of compounds:
Inorganic and organic
Inorganic compounds
Those that don’t contain hydrocarbons (carbon and hydrogen bonded) together, such as salts and water.
Organic compounds
- Characterized by the presence of hydrocarbons.
- The hydrocarbon groups are usually bonded to another group of atoms known as the functional group that’s unique to each type of organic compound.
Types of organic compounds
- Carbohydrates
- proteins
- lipids
- nucleic acids
Carbohydrates
- Consist of carbon, hydrogen, and oxygen in a 1:2:1 ratio.
* Cells use them for energy as well as structural materials.
Three classes of carbohydrates:
- Monosaccharides
- Oligosaccharides
- Polysaccharides
Monosaccharides
Simple sugars composed of only one monomer. Examples are glucose fructose and ribose.
Oligosaccharides
Short chains of sugar monomers covalently bonded together. If they contain only two sugar monomers, they are known as disaccharides. Examples of disaccharides are lactose (milk sugar) and sucrose (table sugar).
Polysaccharides
Complex carbohydrates with many sugar monomers that form chains or branches. These monomers may be of different types and may number in the thousands. Examples include glycogen, starch, and cellulose.
Lipids
- Fats and other oily substances.
- Cells use them for energy storage, structural support, and as signaling molecules.
- Composed of fatty acids attached to glycerol.
Proteins
- Form enzymes and hormones and control all metabolic and biochemical reactions and processes in cells.
- Composed of chains of amino acids joined by peptide bonds.
There are ___ different amino acids in the body that contain a ___ bound to an ___, a ___, and a ___.
20 Carbon atom Amino group Carboxyl group Side chain (R)
A protein’s secondary structure is formed by___.
Hydrogen bonds at intervals along the length of the amino acid chain that cause it to coil or bend.
___ causes further bending and looping of the protein and makes up its third structural level.
Bonding of certain amino acids
The fourth level of protein structure is reached when___.
Hydrogen bonds or bonds between R groups join two or more polypeptide chains together.
The process of transcribing and translating the genetic message into a protein requires the molecule___.
Ribonucleic acid
Enzymes
Proteins that act as catalysts to speed up the rate of a metabolic reaction.
Small organic compounds that contain one or more phosphate groups and a five carbon sugar attached to a nitrogenous base are called___.
Nucleotides
Example: ATP
The phosphate bonds of ATP contain energy that’s released when enzymes break off ATPs outer phosphate group and attach it to another molecule by the process known as___.
Phosphorylation
The bases in DNA are:
- Adenine
- Guanine
- Cytosine
- Thymine
The bases in RNA are:
- Adenine
- Guanine
- Cytosine
- Uracil
Characteristics of DNA:
- DNA exists as a double-stranded molecule.
- Twisted into a double helix.
- Bases always link in either adenine-thymine or cytosine-guanine pairs.
Characteristics of RNA:
- Single-stranded molecule
2. Three types: messenger RNA, ribosomal RNA, transfer RNA
The first step in protein synthesis is___.
Transcription; enzymes bind to the DNA molecule at the location of a gene to unwind and uncoil the molecule.
A ___ marks the end of a gene.
Stop sequence.
Protein synthesis occurs at the___.
Ribosome
Each of the 20 amino acids found in proteins of living things has a specific set of base triplets referred to as a ___ on the mRNA.
Codon
___ are changes in DNA that can result in abnormal protein synthesis.
Mutations
Types of mutations:
- Point mutations– one nitrogen base is substituted for another.
- Nonsense mutations– A change in a codon for an amino acid into a stop codon occurs.
- Frameshift mutations– Nucleotide bases are either added or deleted, causing a change in the entire sequence of amino acids.
___, which carry electrical messages from one region to another, are long and thin.
Nerve cells
___, which produce movement in the body by shortening in length, are long, cylindrical selves packed full of contractile proteins.
Muscle cells
Cell membrane
- The structure surrounding the cell that forms a barrier between the inside of the cell and the outside.
- Composed of a double layer of phospholipids (barrier), which are embedded with protein molecules (channels/carriers).
The outer surface of the cell membrane also contains___, which are structures through which hormones and other chemicals outside of the cell can bind.
Receptors; this binding action signals the cell to carry out particular functions.