Studying Life

Studying Life We know Biology means the study of life but… What does it mean to be “alive?”

Characteristics of Living Things There are a few characteristics we use to describe a living thing…

Characteristics of Living Things Are made up of one or more cells Reproduce Are based on a universal genetic code (DNA)

Characteristics of Living Things Grow and develop Obtain and use materials and energy Respond to their environment

Characteristics of Living Things Maintain a stable internal environment (homeostasis) As a group will change over time (evolution)

Characteristics of Living Things Is a firefly alive?

Characteristics of Living Things Is fire alive?

Made up of Cells Some organisms are unicellular - single celled Cell – smallest unit of an organism that can be considered alive Some organisms are unicellular - single celled Others are multicellular – many cells Multicellular organisms have very diverse cells…they can contain trillions of cells!

Made up of Cells

Reproduction All organisms produce new organisms through reproduction Sexual Reproduction – cells from two different parents combine to form the first new cell of a new organism Asexual Reproduction – new organisms forms from a single parent, an identical clone

Reproduction

A Universal Genetic Code Offspring usually resemble their parents In asexual reproduction the offspring is an exact copy of the parent Flies produce flies, dogs produce dogs, and maple trees produce maple trees

A Universal Genetic Code Deoxyribonucleic Acid (DNA) – a molecule that carries genetic information; found in all living things

Growth and Development All living things grow during at least part of their lives Growth can only occur in two ways… In what two ways can an organism grow in size?

Growth and Development Single celled organisms grow by increasing in size Multicellular organisms can grow by increasing their number of cells Multicellular organisms develop from a single celled egg through mitosis, or cell division

Need for Materials and Energy All organisms need materials and energy to grow and to stay alive Metabolism – the chemical reactions that occur within an organism to build up or break down materials How do you get your energy? How to plants get theirs?

Response to the Environment Organisms need to be able to detect and respond to changes around them Stimulus – a signal that causes an organism to respond External…the temperature in the room Internal…the amount of sugar in your blood

HOMEOSTASIS Most organisms need to keep their internal conditions constant Temperature, amount of water, etc. Homeostasis – Process of maintaining a stable internal environment

HOMEOSTASIS Similar to the thermostat in your house… When you become cold, your body triggers you muscles to shiver to increase your body temperature When you become too warm, your body triggers your sweat glands to sweat, bringing your body temperature back down

Feedback Mechanism

Blood Sugar In order to maintain homeostasis you must constantly regulate your body Insulin and blood sugar High levels of sugar in blood  Insulin released Low levels of sugar in blood  Glucagon released

Homeostasis and Blood Sugar

Evolution Evolution – a change in a group of organisms over time Evolution can occur over just a few generations Over thousands or even millions of years evolution becomes much more dramatic

Branches of Biology Biology is broken into many different categories of study…

Zoology Study animals

Botany Study of plants

Paleontology Study of ancient life

Physiology Study of the function of parts of organisms

Ecology The study of interactions between living things