Biology: Science of Life What do Biologists do? Study past, present and future life Interactions, structures, functions Solve biological problems Agriculture Disease Conservation/Remediation to maintain diversity of life

What is life? We decide Has or once had the following characteristics: 1+ cells Organized/Complex Grows and develops Maintain Homeostasis Reproduces Responds to Stimuli Uses Energy Adaptations Evolve Humans have constructed this definition of life? What about viruses? What about evolution?

The cell is the basic unit of life Organized/Complex 1+ cells The cell is the basic unit of life unicellular v. multicellular v. acellular Organized/Complex Chemical complexity for structure and function Structural organization: Atoms molecules cells tissues organs organ systems organism (assuming multicellular) How do we amend this sequence if the organism is unicellular? Consider an example or analogy to describe the meaning of “basic unit” Growth and development are different

Growth: addition of mass Homeostasis Regulate internal conditions ex: temp, water, blood sugar Grow/develop Growth: addition of mass Increase cell size and/or increase cell number How does a unicellular grow; a multicellular? Development: change over time Go through stages of maturity Consider an example or analogy to describe the meaning of “basic unit” Growth and development are different

Respond to Stimuli Stimulus response Use Energy Able to process and react to internal/external environ. Stimulus response Use Energy Get/make food (chemical energy) to fuel metabolism, convert energy (ATP) to power processes, maintain chemical disequilibrium Categorizations for how “food” is obtained by life: Autotroph (chemoautotroph or photoautotroph) Heterotroph (by ingestion or by absorption) Species concept is under scrutiny because it does not always play out – what about hybrids? What is external stimuli? What is internal stimuli – think about blood sugar, temp, water balance… We will talk about ATP a lot…it is the energy currency of the cell Adaptation does not happen to individuals and time refers to generations

More on Autotrophy… There are two general processes: ___________________ use sun as energy needed to make food ____________________ use chemicals as energy to drive “food making” process Hydrothermal deep sea vents

Adaptations/Evolution Reproduce Species = group of organisms that can interbreed to produce viable (fertile) offspring What about individuals that cannot bear offspring?? Adaptations/Evolution Change in inherited traits (genetics) in a population/species over time (generations) due to reproduction Genetic variation is a generally good thing for species survival Individuals do not biologically evolve! Species concept is under scrutiny because it does not always play out – what about hybrids? What is external stimuli? What is internal stimuli – think about blood sugar, temp, water balance… We will talk about ATP a lot…it is the energy currency of the cell Adaptation does not happen to individuals and time refers to generations

Details on Characteristics Cells: Unicellular Multicellular 1st life forms Evolved later 1 cell More than one cell All bacteria, most protists, some fungi All animals, all plants, some fungi GROW by cell enlargement only GROW by cell enlargement and cell division REPRODUCE by cell division (asexual reproduction/cloning) REPRODUCE mainly by making specialized cells that combine sexually

Details on Characteristics II REPRODUCTION: Asexual Sexual Evolved first Evolved later Unicellular organisms divide to make more identical unicellulars Multicellular organisms use meiosis to make sperm/egg One “parent” – contributes 100% of genetic info Two “parents” – each contribute 50% of genetic info Make a clone – no genetic variation between generations Genetically different offspring – more variation in population – GOOD for survivability/evolution

Details on Characteristics III Energy use Autotrophs Heterotrophs BOTH versions of organisms convert “food” energy into ATP energy to power their cellular processes!! All plants, some bacteria, some protists All animals, All fungi, some bacteria, some protists (NOTE: some plants can do this too! “carnivorous plants –VFT!) AKA “producers” AKA “consumers” Make own food Eat other organisms or the products of other organisms Two versions: Photosynthesis Chemosynthesis

Details on Characteristics IV Adaptation/Response Adaptation (evolution) Response (to stimuli) Long-term Short-term Population response to changing environmental conditions Immediate feedback to stimuli More genetic variability in the population = the better able the population can adapt EX: adaption as a result of changing climate – thicker fur EX: response to changing temperatures – burrow, put on a coat

Life vs. Viruses Viruses: are acellular Bacteria (2 kingdoms), protists, fungi, plants and animals are living; viruses are NOT living things exhibit ALL characteristics of life NOTE: if you need a microscope to see, it is called a “microbe” or “microorganism”; if it causes disease we called a “pathogen”. MOST bacteria do not cause human illness! Viruses: are acellular do not (generally) reproduce themselves do not use energy/ have a metabolism

Chapter 1.1 Big Concepts Understand that there are 6 kingdoms (big categories!) of life and viruses are not included in any of them Reproduction of life can be sexual or asexual Obtain energy via heterotrophy and/or autotrophy (chemoautotroph, photoautotroph) Evolution results in adaptations in a population Viruses are acellular; Life consists of prokaryotic or eukaryotic cells and is unicellular or multicellular Living things can regulate their internal conditions (homeostasis)