Biomolecules and Cells. Elements of Life A few major elements make up virtually all living things Roughly 96% of an organism’s mass (including humans)

Biomolecules and Cells

Elements of Life

• A few major elements make up virtually all living things

• Roughly 96% of an organism’s mass (including humans) is composed of just 4 elements– Oxygen– Carbon– Hydrogen– Nitrogen

Elements of Life

• Together, these 4 elements combine to make up almost all of the major organic and inorganic compounds in our bodies.

• The need for more of these elements to grow, reproduce, and make and use energy underlies almost all of the competition and struggles of life

Elements of Life

• Organic compounds always contain 1 key element ?

Elements of Life

• Organic compounds always contain 1 key element ?– Carbon

Though not all carbon containing compounds are organic

Elements of Life

• Important Inorganic Compounds in the body?

Elements of Life

• Important Inorganic Compounds in the body?– H2O (typically 60-80% of living things)

– CO2

– Fe– Minerals (Bones, teeth)– Salts and Ion Electrolytes

Elements of Life

• Important Organic Compounds in the body?

Elements of Life

• Important Organic Compounds in the body?

• Key Organic compounds typically fall under classes of Macromolecules:– Proteins– Nucleic Acids– Carbohydrates– Lipids

Elements of Life- Proteins

• Proteins are long, heavy organic compounds that have a function and whose function depends on the 3-D structure of the molecule(s)

• Proteins are polymers (polypeptides) made up of amino acid monomers bonded together to form a chain


• Proteins consist primarily of C,H, O, & N– Also contain S (only macromolecule group that does…)

• The protein structure is determined by the sequence of amino acids, which is determined by the genetic sequence of DNA.

• This causes the protein to fold in certain ways to give the protein its 3-D conformation

• Proteins are made using RNA in a process called Translation


• Protein functions include:– Structural support for cells and tissues– Energy production, storage, and consumption

(Metabolism)– Signaling• Hormones, signal peptides, immune system

– Enzymes• Chemical catalysts that increase reaction speed, or help

the reaction to occur in the first place

Elements of Life- Nucleic Acids

• Nucleic Acids chains consist of nucleotides which consist of:– Nitrogenous Base (A,C,G,T)– Sugar molecule (deoxyribose or ribose- hence the

name)– Phosphate backbone (negatively charged)

• Genetic information encoded in DNA• Expressed from DNA to RNA in Transcription

Elements of Life- Nucleic Acids

• Nucleic Acids consist mainly of C,H,O,N and P due to the phosphate backbone

• In humans and other Eukaryotes, the DNA is stored in the cell inside a membrane bound organelle called the Nucleus

Elements of Life- Carbohydrates

• Carbohydrates are hydrates of Carbon. This means they have the general formula (CH2O)n

• Consist only of C,H, and O. Lack the other elements except in rare cases

• Exist as monomers (single sugars) or polymers of sugars (disaccharides and polysaccharides)– Disaccharides have two monomers (Sucrose)– Polysaccharides have many monomers (Starch)


• Cellulose is the most abundant organic compound on Earth.– Consists of glucose molecules bound together to

form a polymer– Forms wood, bark, leaves, and other fibrous

structures in plants

• Why isn’t it easily digested like glucose or other starches?


Image from FAMU

Elements of Life- Lipids

• Diverse group of compounds that share the main characteristic of being non-polar, hydrophobic

• Main functions are in cell membranes, energy storage, and steroid hormones

• Consist primarily of C and H, with some O and P

Elements of Life- Lipids

• Cell membranes consist mainly of phospholipids– These compounds contain a non-polar lipid “tail”

end, and a polar “head” end consisting of a phosphate ion

– In water, phospholipids align to create a bilayer that is polar on the surfaces and non-polar in the interior

Cells and Levels of Organization

• Cells are the smallest unit of life that can act independently and have all of the characteristics of living things

– Eukaryotes: Membrane bound Nucleus and organelles- Plants, Animals, Fungi, protists

– Prokaryotes: No membrane bound organelles or nucleus. Typically single celled- Bacteria and Archaea

Cells and Levels of Organization

• In Eurkaryotes, matter is organized into increasingly complex levels that allow for more complex roles and functions.

• Atoms-> Molecules -> Macromolecules-> Organelles -> Cells -> Tissues -> Organs -> Organ Systems -> Organism

Questions ?

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Biomolecules and Cells. Elements of Life A few major elements make up virtually all living things Roughly 96% of an organism’s mass (including humans)