Lecture Biology (7th edition) - Chapter 2: The chemical context of life

This chapter will also make connections to the themes introduced in Chapter 1. One of these themes is the organization of life into a hierarchy of structural levels, with new properties emerging at each successive level. Emergent properties are apparent even at the lowest levels of biological organization - the ordering of atoms into molecules and the interactions of those molecules. The intricate structures and complex functions of all living organisms arise from these interactions. | Chapter 2 The Chemical Context of Life Overview: Chemical Foundations of Biology The bombardier beetle uses chemistry to defend itself Figure Concept : Matter consists of chemical elements in pure form and in combinations called compounds Elements and Compounds Organisms are composed of matter, which is anything that takes up space and has mass Matter is made up of elements, substances that cannot be broken down to other substances by chemical reactions Sodium Chloride Sodium Chloride + A compound Is a substance consisting of two or more elements combined in a fixed ratio Has characteristics different from those of its elements Figure Essential Elements of Life Essential elements Include carbon, hydrogen, oxygen, and nitrogen Make up 96% of living matter A few other elements Make up the remaining 4% of living matter Table (a) Nitrogen deficiency (b) Iodine deficiency The effects of essential element deficiencies Figure Trace elements Are required by an organism in only minute quantities Concept : An element’s properties depend on the structure of its atoms Each element Consists of a certain kind of atom that is different from those of other elements An atom Is the smallest unit of matter that still retains the properties of an element Subatomic Particles Atoms of each element Are composed of even smaller parts called subatomic particles Relevant subatomic particles include Neutrons, which have no electrical charge Protons, which are positively charged Electrons, which are negatively charged Protons and neutrons Are found in the atomic nucleus Electrons Surround the nucleus in a “cloud” Nucleus (a) (b) In this even more simplified model, the electrons are shown as two small blue spheres on a circle around the nucleus. Cloud of negative charge (2 electrons) Electrons This model represents the electrons as a cloud of negative charge, as if we had taken many snapshots of the 2 electrons over time, with each dot representing an electron‘s . | Chapter 2 The Chemical Context of Life Overview: Chemical Foundations of Biology The bombardier beetle uses chemistry to defend itself Figure Concept : Matter consists of chemical elements in pure form and in combinations called compounds Elements and Compounds Organisms are composed of matter, which is anything that takes up space and has mass Matter is made up of elements, substances that cannot be broken down to other substances by chemical reactions Sodium Chloride Sodium Chloride + A compound Is a substance consisting of two or more elements combined in a fixed ratio Has characteristics different from those of its elements Figure Essential Elements of Life Essential elements Include carbon, hydrogen, oxygen, and nitrogen Make up 96% of living matter A few other elements Make up the remaining 4% of living matter Table (a) Nitrogen deficiency (b) Iodine deficiency The effects of essential element deficiencies Figure Trace elements Are required by an organism in

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39    71    1    29-03-2024
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