Lecture 3 Flashcards
What atoms make up more than 99% of the cell mass
C, N, O, H
What is the atomic number
number of protons or # of electrons
How to calculate atomic weight
number of protons + # neutrons
What is an isotope
same number of protons different number of neutrons
What’s the difference between an element and an atom?
- element is a substance that can’t be broken down to any other chemical form; made up of a single type of atom
- atom is the smallest part of and element that still retains its distinctive chemical properties
what is composed of elements
a periodic table
Whats the difference between a molecule and a compound
- a molecule has two or more atoms join together chemically
- a compound is a molecule that contains at least 2 different elements
What determines how atoms interact
outermost electron because unfilled electron shells are less stable that a filled one therefore an atom with an unfilled electron shell will interact with another atom to complete their outermost cell
What is a covalent bond
- strong bonds being formed by the sharing of electrons between adjacent atoms
- the shared electrons complete the outer shell of both atoms
What is bond length
when attractive forces (+ and -) and repulsive forces (+ and +) are in balance
Compare single vs. double bonds
- single bonds: free rotation around the bond axis when a single pair of electrons is shared
- double bonds: no free rotation around the bond axis when two pairs of electrons are shared
What is bond strength/ dissociation energy
the amount of energy required to break a chemical bond
what is electronegativity and what is its implication on covalent bonds
- generally, a single covalent bond between two atoms results in an unequal sharing of electrons due to the difference in electronegativity resulting in polar covalent bonds
- electronegativity is the indication of an atoms ability to attract an electron
What is a dipole moment
- it measures the polarity of a bond or molecule
- it is a vector quantity and is the sum of the magnitude and direction of each individual bond dipole
what are non-Covalent interaction and give examples
- bond that does not involve sharing electrons
- individually weak, but cumulatively very strong
- examples: charge-charge electrostatic interactions, hydrogen bonds, Van Der Waals
What feature of non covalent bonds are important to the dynamic nature of the cell?
- non covalent interactions are weak enough that they are continually being formed and reformed at room temperature
ionic bonds
- result from a gain or loss of electron
- generally from atoms with only 1 or 2 electrons in their outer shell
- two atoms held together with electrostatic interactions
Hydrogen bond
- an interaction between a covalently bonded hydrogen atom on a donor group and a pair of non bonded electrons on a acceptor group
what is a donor group and hydrogen acceptors
- donor group is a hydrogen attached to an electronegative atom (usually N or O)
- hydrogen acceptors are electronegative atoms (usually N or O)
acid
substances that release protons when dissolved in water
base
substance that accepts protons when dissolved in water
What is sugars general formula
(CH2O)n
What are sugars
- they are called carbohydrates because of their composition
- the simplest sugars are called monosaccharides
- monosaccharides can be joined together through glycosidic bonds to form disaccharides ( 2 monomers together), oligosaccharides (2-10 monomers) and polysaccharides (>10 monomers)
What are sugars used for
- energy source (ex. glucose or can be stored as glycogen)
- can be used for structure (ex. cellulose that forms cell wall)
- slime, mucus
- modification of lipids and proteins
- involved in information storage of our DNA
what does TAG stand for
Triacyglycerols
What are fatty Acids (FA)
- hydrocarbon chain that contribute to the makeup of fats and membrane lipids
- FAs from TAG which serve as an energy source
- Fas form membrane lipids which contribute to membrane structure and function
how are amino acids joined together
with peptide bonds
what are polypeptides
they are long chains of amino acids
What are amino acids
- they are the subunits of proteins
- they have the same basic structure with a variable side chain (R)
How do amino acids form the final 3D structure of a protein
- they fold by using covalent and non covalent interactions
What are nucleotides
- they are the subunits of DNA and RNA
- base + sugar + phosphate (AMP)
what is a nucleoside
base + sugar (adenosine)
what does RNA and DNA stand for
- RNA (ribonucleic acid)
- DNA (deoxyribonucleic acid)
What are the functions of nucleotide functions
- short term carriers of chemical energy (ATP)
- storage and retrieval of biological information (DNA, RNA)
Macromolecules are the most ______. of the organic molecules in a living cell
abundant
How are macromolecules made
from monomers (the subunits: sugar, amino acids, nucleotides)
What is native state
- in general all molecules of a given protein or RNA species adopt the same 3D conformation despite the countless folding possibilities
- in general dictated by non covalent bonds (electrostatic interactions, van Der Waal interactions, hydrogen bonds, hydrophobic interactions)
What effect do non covalent interactions have on macromolecules
- non covalent interactions allow macromolecule to act as building blocks to form much larger structures
