091709-BCH311

091709-BCH311 - Biochemical Buffers A buffer is something...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Biochemical Buffers A buffer is something that resists change - in terms of acid and base chemistry, a buffer solution tends to resist change in pH when small or moderate amounts of a strong acid or strong base are added A buffer solution consists of a mixture of a weak acid (HA) and its conjugate base (A- ), a commonly used example of a buffer is a mixture of monohydrogen phosphate (HPO 4 2- ) and dihydrogen phosphate (H 2 PO 4- ) Many biological reactions will not take place unless the pH remains within fairly narrow limits Analysis of the titration curve of a buffer can yield important insight into when a particular buffer might be chosen for a particular reaction A buffer solution can maintain the pH at a relatively constant value because of the presence of appreciable amounts of both the acid and its conjugate base The two major buffering systems in living organisms are H 2 PO 4- /HPO 4 2- (cells) and H 2 CO 3 /HCO 3- (blood) Fig. 2-13b, p. 51 Fig. 2-15, p. 57 Biochemical Buffers The H 2 PO 4- /HPO 4 2- pair is a suitable buffer at a pH near 7.2 The plateau region in a titration curve, where the pH does not change rapidly, covers a pH range extending approximately one pH unit on either side of the p K a Table 2-8, p. 60 Summary 2-5, p. 61 Fig. 1-1, p. 2 The Three Domains of Life All living organisms fall into one of three large groups ( or domains ) that deFne three branches of evolution from a common progenitor Two large groups of single-celled microorganisms can be distinguished on genetic and biochemical grounds: Bacteria and Archaea Bacteria inhabit soils, surface waters and the tissues of other living or decaying organisms The Archaea, recognized as a distinct domain by Carl Woese in the 1980s, inhabit extreme environments, such as salt lakes, hot springs, highly acidic bogs, and the ocean depths Archaea and Bacteria diverged early in evolution All eukaryotic organisms, which make up the third domain, Eukarya, evolved from the same branch that gave rise to the Archaea: eukaryotes are therefore more closely related to archaea than to bacteria The Three Domains of Life Phylogeny of the three domains of life - the basis for family trees is often similarity in nucleotide sequence of the ribosomal RNAs; the more similar the sequence, the closer the location of the branches The Three Domains of Life Within the domains of Archaea and Bacteria are subgroups distinguished by their habitats In aerobic habitats where oxygen is abundant, organisms derive energy from the transfer of electrons from fuel molecules to oxygen In anaerobic habitats, virtually devoid of oxygen, organisms obtain energy by transferring electrons to nitrate (forming N 2 ), sulfate (forming H 2 S), or CO 2 (forming CH 4 ) Obligate anaerobes die when exposed to oxygen, while facultative anaerobes can live with or without oxygen Organisms can also be classiFed according to how they obtain the energy and...
View Full Document

Page1 / 61

091709-BCH311 - Biochemical Buffers A buffer is something...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online