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Questions and Answers
What is the largest element that can be formed through nuclear fusion reactions in stars?
What is the largest element that can be formed through nuclear fusion reactions in stars?
How are elements heavier than iron typically formed?
How are elements heavier than iron typically formed?
Which of the following statements best describes the relative abundance of elements formed in stars?
Which of the following statements best describes the relative abundance of elements formed in stars?
What is the primary method used to synthesize transuranium elements?
What is the primary method used to synthesize transuranium elements?
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Which of the following elements is the most abundant by percentage on Earth?
Which of the following elements is the most abundant by percentage on Earth?
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What characteristic do the major or 'bulk' elements in cells tend to have?
What characteristic do the major or 'bulk' elements in cells tend to have?
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Which characteristic is NOT typical of ‘major’ elements found in living cells?
Which characteristic is NOT typical of ‘major’ elements found in living cells?
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What is a key feature contributing to carbon's ability to form a wide variety of compounds?
What is a key feature contributing to carbon's ability to form a wide variety of compounds?
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Which property of carbon makes it ideally suited for forming stable bonds?
Which property of carbon makes it ideally suited for forming stable bonds?
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What is the term used to describe the ability of carbon to form long chains with itself?
What is the term used to describe the ability of carbon to form long chains with itself?
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Why is silicon less suitable than carbon for building biological molecules, despite being more abundant?
Why is silicon less suitable than carbon for building biological molecules, despite being more abundant?
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What structural feature of nitrogen atoms leads to relatively low bond energy in N-N single bonds?
What structural feature of nitrogen atoms leads to relatively low bond energy in N-N single bonds?
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Why are extended chains of nitrogen atoms considered very unstable?
Why are extended chains of nitrogen atoms considered very unstable?
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What is a key characteristic of boron compounds that limits their stability?
What is a key characteristic of boron compounds that limits their stability?
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What is a reason why some elements are not incorporated into biological systems, despite their abundance?
What is a reason why some elements are not incorporated into biological systems, despite their abundance?
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Which of the following elements is mentioned as being used in treatment of bipolar conditions?
Which of the following elements is mentioned as being used in treatment of bipolar conditions?
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What is considered the fundamental building block of cells in the context of biochemistry?
What is considered the fundamental building block of cells in the context of biochemistry?
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Which process is NOT primarily responsible for the formation of elements according to the lecture?
Which process is NOT primarily responsible for the formation of elements according to the lecture?
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What are the two elements primarily formed immediately after the Big Bang?
What are the two elements primarily formed immediately after the Big Bang?
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What is the primary requirement for fusion reactions to occur in the core of stars?
What is the primary requirement for fusion reactions to occur in the core of stars?
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What leads to the release of elements formed in stars?
What leads to the release of elements formed in stars?
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What causes a star to collapse after the exhaustion of its hydrogen fuel?
What causes a star to collapse after the exhaustion of its hydrogen fuel?
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What happens after a star's core collapses and the core temperature rises?
What happens after a star's core collapses and the core temperature rises?
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What makes elements other than hydrogen and helium different from those that are formed during the early stages of the Universe?
What makes elements other than hydrogen and helium different from those that are formed during the early stages of the Universe?
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Study Notes
BCHEM 151: Biochemistry - Lecture 1
- Course: Biochemistry 151
- Lecturer: Amma Larbi, PhD
- Lecture Topic: Elemental Composition of Cells
-
Study Objectives:
- Origin of elements
- List of elements in living cells
- Reasons for the inclusion/exclusion of elements in cells
- Role of carbon in forming compounds
Introduction
- Living cells/organisms are formed from elements organized into recognizable structural components.
- Atoms/elements are the basic building blocks in biochemistry, while cells are fundamental building blocks in other contexts
Origin of Elements
- Elements formed through:
- Big Bang
- Fusion reactions in stars
- Artificial synthesis
The Big Bang Theory
- Explosion of incredibly hot, dense primordial matter.
- Led to the formation of Hydrogen and Helium.
- Gravity brought together gas clouds that collapsed into galaxies and stars.
- Elements beyond Hydrogen and Helium were formed in the centers of these stars, then released upon their explosion.
Fusion Reactions in Stars
- High temperatures and reactant concentrations are essential in the stellar core for forming elements.
- High temperatures overcome electrostatic repulsion between positively charged nuclei.
- Fusion reactions release heat and light, contributing to the star's formation from gas clouds.
- Star explosion releases a considerable amount of energy.
Stellar Lifecycles
- Majority of visible stars emit light through hydrogen fusion into helium.
- Hydrogen in stars is used up; faster in larger stars.
- Star core temperature drops and the star collapses.
- The heat releases causes the core temperature to rise and ignite helium, subsequently becoming bigger and redder.
- Fusion processes continue (fusion of helium and other elements)
- The largest atom formed through fusion is iron.
- Elements larger than iron form from neutrons produced in star explosions capturing nuclei of iron atoms.
Laboratory Synthesis of Elements
- Elements beyond atomic number 92 (transuranium elements) are synthesized by high-energy particle accelerators(in cyclotrons)
- Example: Californium created through the fusion of C-12 and U-238.
Elements Utilized to Form Cells
- Over 117 elements exist, but only a fraction are found in cells.
- Earth's most abundant element percentages: Oxygen (48.86%), Iron (18.84%), Silicon (13.96%), Magnesium (12.42%)
- Carbon percentage in Earth is ~0.10%
- Main Ions in biological systems: (e.g., Cu²⁺, Mg²⁺, Ca²⁺, Na⁺, K⁺)
- Major elements (Bulk elements) found in organic molecules: CHONPS (carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur).
- Trace elements: involved in crucial processes, including Na, K, Mg, Ca, B, V, Mn, Fe, Co, Ni, Cu, Zn, Si, Se, Cl, Br, and Cr.
Striking Features of Major Elements
- Majority are p-block elements.
- Capable of forming covalent bonds.
- Non-metals
- Relatively small atomic sizes.
- Neither too reactive nor inert.
Why is Carbon Unique?
- Carbon exhibits an ideal size for forming stable covalent bonds.
- Tetravalent nature allowing forming chains through catenation.
- Ability to form multiple bonds with other atoms and itself.
Other Elements Capable of Multiple Bonds
- Silicon (group IVA) is also tetravalent.
- Si-Si bonds are rare and weak due to the larger size of Silicon atoms.
- Silicon has strong Si-O bonds, creating stable inert chains.
- Carbon is preferred in living organisms despite Silicon's abundance.
Properties of Nitrogen and Boron:
- Nitrogen's ability to form bonds and the effects of lone electron pairs on the stability of N-N bonds.
- Boron's electron deficiency and impact on boron compound stability.
Reasons for Excluding Certain Elements:
- Artificial nature of some elements
- Inert nature of some elements
- Toxic nature of some elements
- Radioactivity of some elements
Non-Essential Elements with Beneficial Roles
- Some elements that aren't crucial for life still provide benefits, such as:
- Lithium compounds for schizophrenia treatment.
- Platinum/gold complexes in treating cancer and arthritis.
- Kaolin (aluminum-containing mineral) as an anti-diarrheal agent.
Additional Resources
- YouTube videos on Stellar Hypothesis, from the Big Bang to the Present, and Beyond the Big Bang explosion (videos are provided).
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Description
Explore the elemental composition of cells in this first lecture of Biochemistry 151. Understand the origin of elements, the list of essential elements in living organisms, and the significance of carbon in molecular formation. This lecture sets the foundation for understanding the building blocks of life.
