Ch 2: Chemical Components of Cells Flashcards
What are the primary four elements that make up a cell’s mass?
C, H, N, O make up 96% of a cell’s mass
What determines the atomic number of an atom?
The number of electrons
What is the most abundant molecule in a cell?
Later makes up 70% of a cell’s mass
What are the main categories of molecules that make up a cell?
1) sugars
2) fatty acids
3) amino acids
4) nucleotides
Sugars overview
Primary source of chemical energy for cells
Join together to form polysaccharides or shorter oligosacchardes
Important for central metabolism in all organisms–we share the same process with everything, bacteria included
In water sugars tend to form into rings
Fatty acid overview
Rich energy source by primary role is to form lipids that assemble into cell membranes
Consists of a carboxylic acid (-COOH) (hydrophilic) attached to a long hydrocarbon chain (hydrophobic)
Starting point for the synthesis of phospholipids
When the hydrocarbon chain is missing and hydrogen and has a double-bond, the tail kinks and it is called unsaturated, and doesn’t pack as well together (more liquid at room temp)
When the hydrocarbon tail is full of hydrogen atoms and no double bonds the tails are straight and pack together well and are more likely to be solids
Macromolecules
The majority of the dry mass of a cell
Polymer molecule formed from covalently linked subunits of polysaccharides, proteins, and nucleic acids
Protein overview
Formed from 20 different types of amino acids covalently joined by peptide bonds into long polypeptide chains
Nucleotides overview
DNA, RNA, and energy-transfer reactions in cells
A nucleoside linked to a phosphate
How protein, DNA, and RNA are synthesized
Chained together from subunits by repetitive condensation reactions
Types of weak, non-covalent interactions in cells
1) hydrogen bonds
2) electrostatic attractions
3) van der Waals attractions
4) hydrophobic force
Acid
A molecule that releases a proton when dissolved in water
This generates hydronium ions (H3O +)
Lowers the ph
Amino acid
Contains:
- an amino group
- a carboxyl group
- an alpha-carbon
- a side chain
Serves as the building block of proteins
Life uses 20 amino acids
ATP
Activated carrier that is the main carrier of energy in cells
Nucleoside triphosphate composed of adenine, ribose, and three phosphate groups
Avogadro’s number
The number of molecules in a mole: 6x10^23
The quantity of a substance equal to its molecular weight in grams
Base
Molecule that accepts a proton when dissolved in water, creating OH- by removing the proton from water
Buffer
Mixture of weak acids and bases that maintains the ph of a solution by releasing and taking up protons
Chemical group
a combination of atoms such as a hydroxyl group (-OH) or an amino group (-NH2) with distinct chemical and physical properties that influences the behavior of the molecule in which it resides
condensation reaction
covalent bond that happens between two molecules that expels a water atom.
Used to build polymers such as proteins, polysaccharides, and nucleic acids
electronegativity
the tendency of an atom to attract electrons
Electrostatic Attraction
force the draws together oppositely charged atoms (ex ionic bonds and the attractions between molecules containing polar covalent bonds)
Hydrogen bond
weak non-covalent interaction between a positively charged hydrogen atom in one molecule and a negatively charged atom (such as oxygen or nitrogen) in another.
Key to the structure and properties of water
Hydrolysis
reaction that cleaves a covalent bond and consumes a water molecule–adds on -H to one end and an -OH to the other end
The reverse of a condensation reaction
hydronium ion
the form taken by a proton (H+) in an aqueous solution (H3O+)
Hydrophobic force
non covalent interaction that forces together the hydrophobic portiosn of dissolved molecules to minimize the disruption of the hydrogen-bonded network of water
causes phospholipids to form into a bilayer
helps proteins fold into compact, globular shapes
Ionic Bond
when one atom donates an electron to another. Both atoms become electrically charged
Atoms held together by ionic bonds are typically called salts rather than molecules
Lipid
organic molecule that is insoluble in water
typically long hydrocarbon chains or multiple rings
phospholipid is one class of lipid
Formula/Structure of an amino acid
1) alpha carbon atom
2) amino group
3) carboxyl group
4) side chain
Phosphates in nucleotides
normally joined to the C-5 hydroxyl of the ribose or deoxyribose sugar
can be mono, di, or tri
Makes the nucleotide negatively charged
Nucleotide structure
a nitrogen-containing base, a five-carbon sugar (pentose), and one phosphate group
Nucleic Acids
nucleotides joined by phsophodiester bonds between the 5’ and 3’ carbon atoms of adjacent sugar rings
formed by adding onto the 3’ end
Formed from:
1) base
2) phosphates
3) 5-carbon sugar (ribonucleic acid or deoxyribonucleic acid)
Phospholipid
Makes the phospholipid bilayer
Hydrophilic head:
a) polar group
b) phosphate
c) glycerol
Two hydrophobic fatty acid tails
Nucleotide base
nitrogen-containing ring compounds, either pyrimidine (cytosine, thymine, uracil) or purine (adenine, guanine)
What kind of molecule does this picture represent? What are the different components called?
Phospholipid
from the bottom up:
- fatty acid chain
- glycerol
- phosphate group
- polar head group
What kind of molecule is this? Name all parts on the molecule
Amino acid molecule
Left–>right: amino group, alpha carbon, side chain, and carboxylic acid group.
What part of the molecule is charged?
the phosphate group is negatively charged
How do protein, nucleic acid, and polysaccharide molecules polymerize (grow in length)
By condensation reactions. A molecule of water is lost with the addition of each monomer to to the growing polymer chain.
