Bio5A Topic One: Chemical Context of Life
Bio5A Topic One: Chemical Context of Life Biol 5A
Popular in Intro: Cell and Molecular Biology
Popular in Biology
This 2 page Class Notes was uploaded by Akash Patel on Monday March 28, 2016. The Class Notes belongs to Biol 5A at University of California Riverside taught by Sean Cutler in Winter 2016. Since its upload, it has received 21 views. For similar materials see Intro: Cell and Molecular Biology in Biology at University of California Riverside.
Reviews for Bio5A Topic One: Chemical Context of Life
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 03/28/16
TOPIC ONE: CHEMICAL CONTEXT OF LIFE ● All matter consists of elements that can be broken down by chemical reactions ○ Elements combine together to form compounds that have different characteristics than their elements ○ 92 elements found in nature, 25 are essential for human life ■ Carbon, hydrogen, oxygen, and nitrogen make up 96% of the mass of the human body ● Atoms are composed of neutrons, protons, and electrons ○ Nucleus consists of neutrons and protons (similar in mass of 1.7x10^24g=1 Da) ○ Electrons have a mass of 9.1x10^28g (1/2000 that of neutrons and protons) found around the nucleus ○ the identity of a particular element is dictated by the number of protons (atomic number) ○ mass number specifies the total number of neutrons and protons in an atom and approximates the atomic mass ● Atoms of identical atomic numbers but different numbers of neutrons are isotopes ○ Radioactive decay: one of the neutrons decays into a proton and electron (+ antineutrino) ○ Stability of an isotope is given by its halflife ■ N(t)=No(½)^1/t(½) ■ N(t):amount remaining, No=initial amount, t:time elapsed, and t(½):halflife ○ Isotopes can be substituted for a particular atom without affecting that atom’s chemical properties. ○ Radioactive atoms can be used to follow biochemical reactions or to detect biomolecules because the energy and particles produced by radioactive decay can be detected and measured ○ Radioactively labeled glucose detects cancer cells ○ Highenergy radioactivity can penetrate cells: can produce Xray images, sterilize food, treat cancer (damages DNA molecules ● The number of electrons in an atom determines its chemical reactivity ○ Electrons in outer shells have a higher potential energy ○ Electrons can absorb energy and occupy a higher energy level, or release energy and move to a lower energy level ○ If valence shell is complete, the atom is unreactive ○ Covalent bond: 2 atoms share a pair of valence electrons ○ The number of bonds that an atom can form is that atom’s valence ○ Different atoms can attract electrons with different strengths, defining their electronegativity ■ 2 atoms with similar electronegativity that form a covalent bond are nonpolar covalent bonds ● Always true for bonds between similar atoms ■ 2 atoms with different electronegativity that form a covalent bond are polar covalent bonds ○ When an electron is transferred to another atom, an ionic bond is formed ○ Covalent bonds are the strongest bonds in nature but weaker bonds (especially when their effects are added together) occur between many biomolecules ○ A hydrogen bond is a weak, noncovalent interaction that occurs between a hydrogen that is covalently bonded to an electronegative atom (N,O, F) and another electronegative atom (N or O) ■ form between water molecules ■ hold together the base pairs of doublestranded nucleic acids ■ contribute to stabilizing interactions between proteins or between proteins and DNA ○ Van der Waal interactions are shortlived regions of partial charge ■ stabilize interactions that occur among large macromolecules, including DNA and proteins
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'