Fundamentals of Biology

Study Notes

Biology is the science that studies living organisms, their interactions with each other, and their environment.
It attempts to describe and understand the nature of the universe.
Biology encompasses many branches.
All living organisms share key properties, including order, response to stimuli, reproduction, growth and development, regulation, homeostasis, energy processing, and adaptation.

Organisms are highly organized, even down to single-celled organisms.
Inside each cell, atoms form molecules, and these molecules make organelles.
In multicellular organisms, cells form tissues, tissues form organs, and organs form systems.

Organisms respond to diverse stimuli.
Examples of responses include plants bending towards light, climbing fences or walls, or responding to touch.
Bacteria can move towards or away from chemicals (chemotaxis) or light (phototaxis).
Positive responses involve movement towards a stimulus.
Negative responses involve movement away from a stimulus.

Single-celled organisms reproduce by duplicating their DNA and then dividing it equally to form two new cells.
Multicellular organisms reproduce by producing sex germline cells that will form new individuals.
DNA contains genes that pass from parents to offspring.
This ensures that offspring belong to the same species and share similar characteristics.

Genes in the DNA contain the instructions for growth and development in all organisms.

Regulation refers to the coordination of internal functions, such as nutrient transport, blood flow, waste removal, and body cooling.

Homeostasis is the ability of an organism to maintain constant internal conditions.
Cells need to maintain optimal conditions like temperature, pH, and ion concentration for proper function.
Organisms maintain internal conditions within a narrow range despite environmental changes.
Organisms living in cold climates, like polar bears, have body structures such as fur, feathers, blubber, and fat to withstand low temperatures.
In hot climates, organisms use methods such as perspiration in humans and panting in dogs to shed excess body heat.

All organisms use a source of energy for their metabolic activities.
Plants capture sunlight energy and convert it into chemical energy. Animals then use this chemical energy.

Elements in various combinations comprise all matter, including living things.
Abundant elements in living organisms include carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus.
These elements form the protients, carbohydrates, lipids, and nucleic acids
The four elements common to all living organisms are oxygen (O), carbon (C), nitrogen (N), and hydrogen (H).
Oxygen constitutes 65% of human composition, 21% of the atmosphere, and 46% of Earth's crust.
Carbon makes up 18% of human composition, with trace amounts in both the atmosphere and Earth's crust.
Hydrogen constitutes 10% of human composition, with trace amounts in the atmosphere and 0.1% in Earth's crust.
Nitrogen accounts for 3% of human composition and 78% of the atmosphere, with trace amounts in Earth's crust.

Macromolecules are large polymers made up of monomers.
Organisms obtain nutrients from food to survive.
The four major classes of macromolecules are carbohydrates, lipids, proteins, and nucleic acids.
These classes are organic, containing carbon, and may contain hydrogen, oxygen, and nitrogen.
Macromolecules also make up the majority of the cell's dry mass, while water makes up the majority of the complete cell mass.

Monomers combine with each other using covalent bonds to form large polymers when water molecules are released.

Polymers are broken down into monomers using water molecules.
Two components result from the breakdown of one polymer: one part gains a hydrogen atom (H+), and the other part gains a hydroxyl molecule (OH-).

Digestive Enzymes: Amylase, Lipase, pepsin, trypsin helps the digestion of food into monomers
Transport: Hemoglobin, albumin helps transport oxygen & nutrients in blood & lymph
Structural: Actin, tubulin, keratin forms the Cytoskeleton
Hormones: Insulin, thyroxin coordinate body functions
Defense: Immunoglobulins aid in immunity
Contractile: Actin, myosin aids in muscle comtraction
Storage: Legume storage proteins and egg white albumin provides nourishments to the embryo in early development