Molecular Biology and Characteristics of Living Organisms

Molecules and Living Things

• Molecules are made up of two or more atoms chemically bonded and are the building blocks of living and nonliving things.
• There are different types of molecules, including homonuclear diatomic molecules (e.g., O2) and heteronuclear diatomic molecules (e.g., NaCl).
• Carbon is a common organic molecule found in all living things.
• To be considered a living organism, an entity must meet eight criteria, including growing and developing, evolving, responding to the environment, being made of cells, reproducing, having a genetic code, maintaining homeostasis, and obtaining and using energy.
• The four macromolecules essential for life are proteins, lipids, carbohydrates, and nucleic acids.
• Proteins are the largest macromolecule and make up about 20% of human body weight.
• Water is a common molecule found in all living organisms and is only 0.27 nanometers wide.

Measuring Molecules

• Measuring molecules can be tricky, and there are several different approaches.
• Nanometers and angstroms are metric units used to measure molecules, with one nanometer equal to one-billionth of a meter.
• Molecular weight is a common way to measure the size of molecules, calculated by summing the atomic weights of each atom in the molecule.

Density

• Density is a measurement of how compact something is, with more material or molecules squeezed into a space making it denser.
• Density affects everyday life, including how clouds float at different altitudes, why objects float or sink in water, and how gases move in the atmosphere.
• Examples of dense materials include lead, gold, brass, most metals, and rocks like granite.
• Typically, solids are denser than liquids, and liquids are denser than gases.
• Density can be calculated using the equation density = mass / volume.

Buoyancy

• Buoyancy is the ability of an object to float when submerged in a fluid.
• An object experiences a force from the fluid called fluid pressure, which increases with depth and creates an upward buoyant force.
• Archimedes' Principle states that the buoyant force of an object is equal to the weight of the fluid displaced by the object.
• The buoyant force can be calculated using the variables density, volume, and acceleration due to gravity.

Scientific Method

• The scientific method is a series of steps used by scientists to answer questions about the world.
• The steps include coming up with a question, conducting background research, creating a hypothesis, conducting an experiment, analyzing data, forming a conclusion, and peer review.
• Biases can impact the validity of an experiment if they affect the way a scientist follows the procedure.
• Experiments that follow the scientific method can be replicated and may become a theory if supported enough times.

Experimental Design

• The experimental design is an invaluable process in the scientific community to provide data to support or refute a hypothesis.
• The five steps of the experimental design are defining variables, formulating hypotheses, creating an experimental design process, assigning subjects, and measuring the dependent variable.

Science Experiments

• A science experiment is a way of figuring out the structure and behavior of the world using a systematic method.
• In an experiment, one variable (the independent variable) is changed, and its effect on another variable (the dependent variable) is measured.
• Everything else must be kept the same to ensure a fair test.
• The accuracy of data refers to how close it is to being correct, while the reproducibility (or precision) of data refers to how close together the measurements are.

Molecules and Living Things

• Molecules are made up of two or more atoms chemically bonded and are the building blocks of living and nonliving things.
• There are different types of molecules, including homonuclear diatomic molecules (e.g., O2) and heteronuclear diatomic molecules (e.g., NaCl).
• Carbon is a common organic molecule found in all living things.
• To be considered a living organism, an entity must meet eight criteria, including growing and developing, evolving, responding to the environment, being made of cells, reproducing, having a genetic code, maintaining homeostasis, and obtaining and using energy.
• The four macromolecules essential for life are proteins, lipids, carbohydrates, and nucleic acids.
• Proteins are the largest macromolecule and make up about 20% of human body weight.
• Water is a common molecule found in all living organisms and is only 0.27 nanometers wide.

Measuring Molecules

• Measuring molecules can be tricky, and there are several different approaches.
• Nanometers and angstroms are metric units used to measure molecules, with one nanometer equal to one-billionth of a meter.
• Molecular weight is a common way to measure the size of molecules, calculated by summing the atomic weights of each atom in the molecule.

Density

• Density is a measurement of how compact something is, with more material or molecules squeezed into a space making it denser.
• Density affects everyday life, including how clouds float at different altitudes, why objects float or sink in water, and how gases move in the atmosphere.
• Examples of dense materials include lead, gold, brass, most metals, and rocks like granite.
• Typically, solids are denser than liquids, and liquids are denser than gases.
• Density can be calculated using the equation density = mass / volume.

Buoyancy

• Buoyancy is the ability of an object to float when submerged in a fluid.
• An object experiences a force from the fluid called fluid pressure, which increases with depth and creates an upward buoyant force.
• Archimedes' Principle states that the buoyant force of an object is equal to the weight of the fluid displaced by the object.
• The buoyant force can be calculated using the variables density, volume, and acceleration due to gravity.

Scientific Method

• The scientific method is a series of steps used by scientists to answer questions about the world.
• The steps include coming up with a question, conducting background research, creating a hypothesis, conducting an experiment, analyzing data, forming a conclusion, and peer review.
• Biases can impact the validity of an experiment if they affect the way a scientist follows the procedure.
• Experiments that follow the scientific method can be replicated and may become a theory if supported enough times.

Experimental Design

• The experimental design is an invaluable process in the scientific community to provide data to support or refute a hypothesis.
• The five steps of the experimental design are defining variables, formulating hypotheses, creating an experimental design process, assigning subjects, and measuring the dependent variable.

Science Experiments

• A science experiment is a way of figuring out the structure and behavior of the world using a systematic method.
• In an experiment, one variable (the independent variable) is changed, and its effect on another variable (the dependent variable) is measured.
• Everything else must be kept the same to ensure a fair test.
• The accuracy of data refers to how close it is to being correct, while the reproducibility (or precision) of data refers to how close together the measurements are.

Learn about the composition of molecules, types of diatomic molecules, and the eight criteria that define a living organism.