Origins and Biomolecules (Lec. 2) Flashcards
Ch. 1 pg. 4-17 and Ch. 2 pg. 47-55 and Ch. 3 pg. 81-85
Explain how the first cell originated
The enclosure of self-replicating RNA in a membrane composed of phospholipids
What molecule can catalyze its own replication?
RNA
What is the basic component of biological membranes?
Phospholipids
Describe the major steps in the evolution of metabolism
Glycolysis (breakdown of organic molecules in the absence of oxygen), then photosynthesis (harnessing sunlight energy), then oxidative metabolism (generating energy from organic molecules using highly reactive O2)
How did the first cells obtain energy?
Glycolysis
Outline the evolution of eukaryotic cells and multicellular organisms
Eukarya arose through endosymbiosis. Aerobic bacteria (which became mitochondria) and photosynthetic bacteria (which became chloroplasts) lived inside an archaeal ancestor.
Explain the properties of different types of chemical bonds
Covalent bonds have shared electrons and are mostly single bonds. They can vary in polarity. Ionic bonds are between elements that are very different electronegatively. Hydrogen bonds form between polar molecules. Hydrophobic interactions form between nonpolar molecules. Van der Waals interactions occur when any two atoms are close together.
Diagram the structure of a simple carbohydrate
It’s a carbon chain
Compare the structures of fatty acids and phospholipids.
Fatty acids are long hydrocarbon chains with a carboxyl group at one end. Phospholipids consist of two fatty acids joined to a polar head group.
Contrast the structures of RNA and DNA
Nucleic acids contain purine and pyrimidine bases linked to phosphorylated sugars. RNA is single stranded, DNA is double stranded.
Can you explain why lipid bilayers form?
Yes
Distinguish molecules that can diffuse through a lipid bilayer from those that require transporters to cross a membrane.
Only small, uncharged molecules can diffuse freely through the membrane. Channel proteins form open pores through the membrane, allowing the free passage of any molecule of the appropriate size. Carrier proteins selectively bind and transport specific small molecules. Molecules can be transported in an energetically unfavorable direction across a membrane through active transport.
Interpret the first and second laws of thermodynamics.
First law: conservation of energy: the total energy of a system and its surroundings remains constant.
Second law: entropy (the degree of disorder in a system) increases over time.
Explain how changes in Gibbs free energy determine the direction of chemical reactions.
Change in Gibbs free energy (delta G) = change in enthalpy (the heat released or absorbed during a chemical reaction, delta H) - T(Kelvin) * change in entropy (delta S).
If delta G < 0, then the reaction will proceed in the forward direction. If delta G > 0, the reaction will proceed in the reverse direction.
Summarize the role of ATP in cell physiology.
ATP acts as a store of free energy within the cell.
What are anabolic reactions?
They consume energy by building complex molecules from similar molecules.
What are catabolic reactions?
They release energy by breaking down complex molecules into simpler molecules.
Can you explain dehydration reactions and hydrolysis?
Yes
What are the functions of carbohydrates?
Energy storage (starch and glycogen), structure (cellulose and chitin), and signaling (can be attached to proteins inside the cell and on the surface).
What are the functions of lipids?
Energy storage (triglycerides), formation of cell membranes (phospholipids), and signaling (glycolipids and cholesterol).
What are the functions of nucleic acids?
Both long- and short-term information storage. Nucleotides are also used for energy (ATP) and signaling (cAMP).
