Exam 1 Flashcards
(74 cards)
• Diversity of Life
o Vertebrate animals, invertebrates, plants, protists, bacteria, and viruses (?)
o All life forms are composed of inert molecules that obey physical and chemical laws that describe nonliving things
• To be alive:
o Has to be a defined collection of molecules that interact with each other through chemical means
• 3 characteristics to distinguish living from nonliving
o Degree of chemical complexity and organization
• Living = high degree of both
o Ability to extract, transform, and use energy from environment to maintain structures and do work
o Ability to precisely self-replicate and self-assemble
• Biochemistry is
to explain diversity and complexity in unifying chemical terms
o All organisms are amazingly similar at the cellular and chemical level
o Biochemistry describes in molecular terms the structures, mechanisms, and chemical processes shared by all organisms
• Practical Applications of this knowledge
o Medicine
o Agriculture
o Nutrition
o Industry
• Though all organisms share a fundamental UNITY in biochemistry terms, there are actually
very few generalizations that are completely correct for every organism under every condition
• All known cells grouped in 2 categories
o Prokaryotic: no true nucleus
• Eubacteria (true)
• Archaebacteria (extremophiles)
o Eukaryotic true nucleus present
• Fungi, protists, plants, animals
• Evidence suggest that eukaryotes evolved from
the same branch that gave rise to the Archaebacteria
o We are more closely related to extreme bacteria than regular bacteria
• Difference between Prokaryotes and Eukaryotes
o Cell Size: Prokaryotes smaller than Eukaryotes
o —-Genome (+/- histones, location): Euk. Located in nucleus; Pro located in space (nucleoid region – not an organelle) inside prok.
• Euk. Have specific proteins (histone proteins) that bind to DNA
• Prok. Doesn’t have histon proteins
o Cell Division (fission vs. mitosis): Prok – fission; Euk. – Mitosis
o Membrane-bound Organelles: Prok. Do not have membrane-bound organelles; Euk. Have many types of them
o Nutrition: Prok. Obtain nutrition through absorption; Euk. Absorption and ingestion
o Energy Metabolism (+/- Mitochondria): Prok. No mitochondria to act in synthesis of ATP (do it differently); Euk. Have mitochondria
o Cytoskeleton: Pro lack substantial cytoskeleton; Euk cytoskeleton very complex made of microfilaments and microtubule network
o Intracellular Movement: must have cytoskeleton to work
• Generated by cytoskeleton
• Prok. Can’t do it but they can do diffusion movement
• Euk. Can do both
o —Give 2 or 3 examples of nonmembrane bound organelles and their functions
- Ribosomes: site of protein synthesis
- Microtubules
- Microfilaments
o —Give 2 or 3 examples of single membrane organelles and their functions
- Vacuoles
- ER
- Golgi
- Lysosomes
o —Give 2 or 3 examples of double membrane organelles that have 2 bilayers and 4 leaflets and their functions
- Mitochondria – site of ATP production
- Nucleus – site of DNA storage in Eukaryote
- Chloroplast
o Rough ER in some cases has ribosomes on membrane
- ** Do not use function of ribosome
- Function is to take newly translated protein and modify the protein
o A cell wall is not the same as a cell membrane
- No cell wall in animals, only cell membranes
- In plants, cell membrane is surrounded by cell wall
• Organelle means
little organ; specific defined structure that is found in cytoplasm that is going to perform a specific function
• C, H, O, and N account for about
99% of the weight of biological molecules
• There are 4 major groups of biological macromolecules
o Proteins
o Carbohydrates
o Lipids
o Nucleic Acids
• What was the origin of all this carbon, hydrogen, oxygen, and nitrogen?
o Masses of hydrogen from a particle explosion would collect to the point of clusters and the overall gravity was so great it caused a compression and a fussion (nuclear fussing of two atoms to create a new atom) reaction was started creating Helium (stars)
o Then Helium fused, etc.
o Stars burned out and collapsed and explode and scatter all the elements that were present in the star is spewed out into space which also has mass and then gravity took those elements and created rocky mass (Earth)
• —Polyampholytes
o Molecules having many acidic and basic groups (Ex. PROTEINS)
• —Polyelectrolytes
o Molecules that carry multiples of only one type of charge
• Cationic (Multiple (+) charges) OR Anionic (Multiple (-) Charges)
• Ex. NUCLEIC ACIDS
• —Functional Groups
o Functional groups are the reactive groups on molecules
o The hydrocarbon backbones of those molecules are very stable
• FIGURE 1-15, PAGE 12
• ENOL GROUP IS INCORRECT IN 5TH EDITION OF TEXTBOOK
o —KNOW ALL FUNCTIONAL GROUPS FROM FIGURE 1-15 EXCEPT ENOL GROUP
• He will draw some and ask for names or he will give names and ask us to draw or supply the missing name or structure
• —INTERACTION BETWEEN MOLECULES
Weak and Strong
Weak interactions
• Typically less than 1/20th the strength of a covalent bond
• Occur thru short-range, non-covalent forces
• A) Hydrogen Bonds (Look up)
• –N–H O–
• Always involve hydrogen
• B) van der Waals Forces
• Weak attraction between any 2 atoms due to their fluctuating (unstable) electrical charges
• van der Waals REPULSION (strong) occurs if 2 atoms are brought close together
• C) Hydrophobic Forces
• Water will force hydrophobic groups together. This lessens the disruptive effect on the H-bonded water lattice.
• Bunch together in the middle of the protein to stay away from water
• D) Ionic Bonds
• Ionic interactions occur between either fully charged or partially charged groups
• In the absence of water, ionic forces are very strong
o EX. NaCl crystal
• Ionic bonds are WEAK in aqueous solution as the charged groups are shielded from each other by water molecules
• Opposite charges attract
• Ionic bods are weakened even more by the presence of salts. Salt atoms form COUNTERIONS around the major charged groups.
• Salt ions that weaken the positive charge are counterions which shield the positive charge from interacting with other ions
• Despite weakening by water and counterions, ionic bonds are important in biological systems
o EX) Binding of substrates in active site
Strong Interactions
• A) COVALENT BONDS (only strong bond)
• Much stronger than any of the interactions previously mentioned
• Consists of a shared pair of electrons between two atoms
• Reactants are either:
o NUCLEOPHILES: electron rich
o Or ELECTROPHILES: electron deficient
• Biologically important nucleophiles typically contain O, S, or N
o Ex) R—O(-) with the oxygen being the nucleophile
• Biologically important electrophiles include:
o H+
o Metal Cations (Cu+, Zn+, etc.)
o Some types of cofactors (particularly derivatives of vitamins B1 and B6
