OpenStax-CNX module: m59427
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Bis2A: 3.0 Introduction to
∗
Biological Macromolecules
The BIS2A Team
This work is produced by OpenStax-CNX and licensed under the
Creative Commons Attribution License 4.0†
Abstract
This module will discuss the general structure of the macromolecules.
1 Context for molecular chemistry in BIS2A
Before you start
If necessary please review module 1.2 for a description of the Design Challenge rubric.
The context for this module
In BIS2A we are concerned primarily with developing a functional understanding of a biological cell. In the
context of a design problem we might say that we want to solve the problem of building a cell. If we break
this big task down into smaller problems or alternatively ask what types of things do we need to understand
in order to do this, it would be reasonable to conclude that understanding what the cell is made of would be
important. That said, it isn't sucient to appreciate WHAT the cell is made of but if we can't to understand
some of the behaviors we see, we also need to understand the PROPERTIES of the materials that make up
the cell. This requires us to dig into a little bit of chemistry - the science of the "stu" (matter) that makes
up the world we know. This prospect of talking about molecular chemistry and thermodynamics makes
some students of biology apprehensive. Hopefully, however, we will show that many of the vast number of
biological processes that we care about arise directly from the chemical properties of the "stu" that makes
up life and that developing a functional understanding of some basic chemical concepts can be tremendously
useful in thinking about how to solves problems in medicine, energy, and environment by attacking them at
their core.
Dening subproblems and goals
High order problem: Understand how to build a cell
Sub-goal: Learn and classify the molecular components of the cell and understructure how their chemical properties can translate into and inuence their biological functions.
∗ Version
1.1: Jan 5, 2016 4:49 pm -0600
† http://creativecommons.org/licenses/by/4.0/
http://cnx.org/content/m59427/1.1/
OpenStax-CNX module: m59427
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Figure 1: The four major macromolecules studied in this class (proteins, carbohydrates, lipids, nucleic
acids) compose the majority of everyday food items, such as this cheeseburger.
Source: mcdonalds.com.au/sites/mcdonalds.com.au/les/hero_pdt_cheeseburger.png
Importance of chemical composition
As a student in BIS2A, you will be asked to classify macromolecule into groups by looking at their chemical
composition and based on this composition also infer some of the properties they might have (review modules
2.0-2.3). For example, carbohydrates typically have multiple hydroxyl groups. Hydroxyl groups are polar
functional groups capable of forming hydrogen bonds. Therefore, some of the biologically relevant properties
of various carbohydrates can be understood at some level by a balance between how they my tend to form
hydrogen bonds with water, themselves or other molecules.
Linking structure to function
Each macromolecule plays a specic role in the overall functioning of a cell. The chemical properties and
structure of a macromolecule will be directly related to its function. For example, the structure of a phospholipid can be broken down into two groups, a hydrophilic head group and a hydrophobic tail group. Each
of these groups plays a role in not only the assembly of the cell membrane but also in the selectivity of
substances that can/cannot cross the membrane.
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