Ch.5 - Biological MoleculesWorksheetSee all chapters
All Chapters
Ch.1 - Introduction to Biology
Ch.2 - Chemistry
Ch.3 - Water
Ch.4 - Carbon
Ch.5 - Biological Molecules
Ch.6 - Cells
Ch.7 - The Membrane
Ch.8 - Energy and Metabolism
Ch.9 - Respiration
Ch.10 - Photosynthesis
Ch.11 - Cell Signaling
Ch.12 - Cell Division
Ch.13 - Meiosis
Ch.14 - Mendelian Genetics
Ch.15 - Chromosomal Theory of Inheritance
Ch.16 - DNA Synthesis
Ch.17 - Gene Expression
Ch.18 - Regulation of Expression
Ch.19 - Viruses
Ch.20 - Biotechnology
Ch.21 - Genomics
Ch.22 - Development
Ch.23 - Evolution by Natural Selection
Ch.24 - Evolution of Populations
Ch.25 - Speciation
Ch.26 - History of Life on Earth
Ch.27 - Phylogeny
Ch.28 - Prokaryotes
Ch.29 - Protists
Ch.30 - Plants
Ch.31 - Fungi
Ch.32 - Overview of Animals
Ch.33 - Invertebrates
Ch.34 - Vertebrates
Ch.35 - Plant Anatomy
Ch.36 - Vascular Plant Transport
Ch.37 - Soil
Ch.38 - Plant Reproduction
Ch.39 - Plant Sensation and Response
Ch.40 - Animal Form and Function
Ch.41 - Digestive System
Ch.42 - Circulatory System
Ch.43 - Immune System
Ch.44 - Osmoregulation and Excretion
Ch.45 - Endocrine System
Ch.46 - Animal Reproduction
Ch.47 - Nervous System
Ch.48 - Sensory Systems
Ch.49 - Muscle Systems
Ch.50 - Ecology
Ch.51 - Animal Behavior
Ch.52 - Population Ecology
Ch.53 - Community Ecology
Ch.54 - Ecosystems
Ch.55 - Conservation Biology
Sections
Polymers
Carbohydrates
Proteins
Nucleic Acids
Lipids
Additional Practice
Cumulative Macromolecules

Solution: Given the following equilibrium, at what pH would the molecule most likely be in a zwitterionic form?H3N+-CH2-COOH ⇌ H3N+-CH2-COO- ⇌ H2N-CH2-COO-                          pKa1: 2.4                     pKa2: 9.6A. 1.2B. 2.4C. 6.7D. 10.5E. 13.7

Problem

Given the following equilibrium, at what pH would the molecule most likely be in a zwitterionic form?

H3N+-CH2-COOH ⇌ H3N+-CH2-COO- ⇌ H2N-CH2-COO-

                          pKa1: 2.4                     pKa2: 9.6

A. 1.2

B. 2.4

C. 6.7

D. 10.5

E. 13.7

Solution

Amino acids, peptides, and proteins can have different net charges, depending on the pH and the amount of ionizable groups present in the molecule. The given molecule is glycine, which only has two ionizable groups.

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