Human Biology Lecture 1: What is Life, Ch. 1

Hierarchy of Life

*atom*: the smallest unit of an element composed of protons, neutrons, and electrons *molecule*: union of two or more atoms of the same or different elements *cell*: the smallest structural and functional unit of all living things *tissue*: group of similar cells that have the same structure and function *organ*: composed of tissues functioning together for a specific task *organ system*: composed of several organs working together *organism*: collection of organ systems *population*: organisms of the same species in a particular area *community*: interacting populations in a particular area *ecosystem*: a community plus the physical environment *biosphere*: regions of the Earth's crust, waters, and atmosphere inhabited by living organisms

1. Made of Cells/Organized

-Cells are the basic structural and physiological units of all living organisms -Cells are both distinct entities and building blocks of more complex organisms -Hierarchy of Life

Eukarya: Kingdom Plants

-Certain algae, mosses, ferns, conifers, and flowering plants -Multicellular, usually with specialized tissues, containing complex cells -Photosynthesize food

3. Eukarya

-Divided into one of four *kingdoms*: plants, fungi, animals, and protists

6. Pass Hereditary Information to Offspring

-Evolution occurs in populations (we are not evolving) -DNA= deoxyribonucleic acid, contains genetic information of all life -Genes= contain the DNA, short sequences of hereditary material that specify the instructions for a specific trait -Mutation= basis of evolutionary change! -Evolution: process by which a population changes over time...occurs through natural selection...when a new variation arises that is beneficial, those members tend to survive and have more offspring, therefore each generation will have more members with that variation which represents an adaptation to the environment

4. Respond to Stimuli

-External (visual; phobia; phototropism when plant placed at window, loud noise, hot stove) vs Internal (blood clotting; hunger)

5. Reproduce and Grow

-Fertilization, Zygote, Growth, Development -Reproduce= pass on genetic information to the next generation -Growth= increase in size and often number of cells -Development= all the changes that occur from the time the egg is fertilized until death -Information in DNA contained in genes

3. Maintain Homeostasis

-Homeostasis= the ability of a cell or an organism to maintain an internal environment that operates under specific conditions -All the systems of the human body help maintain homeostasis -EX. heart rate (70-80 bpm), blood pressure (120/70), body temperature (98.6), amount of water in the body, blood sugar -Why do you cover yourself with a blanket when sleeping? Your metabolism slows down at night-->temp slows down, in heaviest sleep when temp is lowest, temp highest before going to sleep *A high fever in the morning is reason to worry

Eukarya: Kingdom Fungi

-Molds, mushrooms, yeasts, ringworms -Mostly multicellular filaments with specialized, complex cells -Absorb food

2. Acquire Materials and Energy

-Photosynthesis, Respiration, Fermentation, Metabolism, Anabolism, Catabolism -Metabolism= all the chemical reactions that occur within a cell -ATP=energy of a cell -We need oxygen for energy, it allows us to generate more ATP that is required for the energy transformation process

1. Bacteria

-Prokaryotic cells of various shapes -Adaptations to all environments -Absorb, photosynthesize, or chemosynthesize food

2. Archaea

-Prokaryotic cells of various shapes -Adaptations to extreme environments -Absorb or chemosynthesize food

Eukarya: Kingdom Animals

-Sponges, worms, insects, fish, frogs, turtles -Multicellular with specialized tissues containing complex cells -Ingest food -Most organisms in this kingdom are invertebrates (worms, etc); vertebrates are animals that have a nerve cord protected by a vertebral column *Humans did NOT evolve from apes--> humans and apes share a COMMON ANCESTOR *Humans: highly developed brain, abstract thinking, upright stance, creative language, usage of a variety of tools

Name a Biological Entity that does Not Fall into the Category of Living Organisms

-Viruses: capsule made of proteins but don't have membranes (not made of cells); also need a host to reproduce (cannot reproduce alone) -Prions: (proteins)

The Tree of Life: Humans are Related to Other Animals: *The Three Domains*

1. Bacteria: contain prokaryotes (one-celled organisms that lack a nucleus) 2. Archaea: contain prokaryotes (one-celled organisms that lack a nucleus) 3. Eukarya: Contain cells that possess a nucleus, some are single-celled, others are multicellular

The Characteristics of Life

1. Made of Cells (Organized) 2. Acquire Materials and Energy 3. Maintain Homeostasis 4. Respond to Stimuli 5. Reproduce and Grow 6. Pass Hereditary Information to Offspring