Introduction to Biology

What is Biology?

• It is the scientific study of life and living organisms
• It explores structure, function, growth, origin, evolution, and distribution

What do Biologists do?

• They study the diversity of life, which helps in understanding living things' characteristics and qualities
• Diseases are researched to determine their causes, how the body fights them, and how they spread
• Technologies are developed to meet human needs using scientific knowledge; e.g., prosthetic limb technology
• Agriculture is improved by studying and genetically engineering plants for insect and disease resistance

Key People in Biology

• Ibn al-Baytar was a biologist
• He is the author of "Al-Mughni fi al-Adwiyah al-Mufrada" (The Sufficient Book on Simple Drugs)
• Carl Linnaeus developed a system for naming and classifying living things based on their shapes and behavior

Characteristics of a Living Organism

• Multicellular organisms are organized into cells, tissues, organs, and systems
• Reproduction is the process that increases the number of individuals in a species
• A stimulus causes a reaction in a living creature
• Internal stimuli include feeling hungry
• External stimuli include temperature of the ocean
• Response is an organism's reaction to stimuli

Homeostasis

• An organism maintains homeostasis by regulating its internal mechanisms to survive
• Example of homeostasis: Painting helps a dog maintain internal homeostasis
• Homeostasis is defined as organizing an organism's internal conditions to survive

Adaptation

• Adaptation involves genetic characteristics and factors that help an organism respond to its environment
• Adaptation is not shaped changes with age, size changes with age, or temporary change in behavior
• Adaptation desert plants may have few pores, or leaves that roll but they will not have increased leaf surface area

The Scientific Method

• Ask a question based on observation
• Observation is a direct way of collecting information in an organized way
• If something strange is noticed, more information should be collected about it
• The first research step when noticing a new phenomenon is to formulate a hypothesis
• A hypothesis is a testable explanation of a situation
• An experiment includes a set of data, to test a particular hypothesis
• The independent variable is something that you do that affects the outcome of the experiment such as watering plants
• The is the result based on your work in the experiment such as the growth of plants

Biological Classification

• Domain is the broadest category
• It consists of one or more kingdoms
• Bacteria and Archaea are classified as prokaryotes
• Prokaryotes are single-celled organisms that don't have a nucleus membrane
• Archaea and Bacteria are similar because they both do not contain a membrane

Viral Diseases

• Viruses are nonliving strands of genetic material within a capsid (protein coat)
• Viruses are neither eukaryotes nor prokaryotes
• A retrovirus has RNA instead of DNA
• Human immunodeficiency virus (HIV) is a common retrovirus that causes AIDS, along with influenza and Tobacco Mosaic Virus
• Polio vaccine consists of weakened or inactivated poliovirus
• The hepatitis C vaccine is made from an inactive part of the hepatitis C virus

Examples of diseases

• Sexually-transmitted diseases include AIDS and Genital herpes
• Respiratory diseases include Influenza, and the common cold
• Childhood diseases include Mumps, and Measles
• Nervous System Diseases include Polio, and Rabies
• Other diseases include Hepatitis C (Liver), and Smallpox

Prions

• Are neither prokaryotes nor viruses
• Prions replicate and spread within the brain, causing diseases, such as Creutzfeldt-Jakob disease (CJD) and mad cow disease
• Creutzfeldt-Jakob disease (CJD) involves prions infecting nerve cells in the brain, causing them to burst

Modern Classification and Domains

• Modern classification contains three domains that divide into several kingdoms
• The archaeabacteria contains Kingdom of Archaea (prokaryotes)
• Eubacteria contains Kingdom of Bacteria (prokaryotes)
• Eukarya contains Kingdoms of Protista, Fungi, Plantae, and Animalia (Eukaryotes)
• Bacteria are prokaryotic organisms containing peptidoglycan in their cell walls
• Bacteria are resistant to antibiotics because they have a cell wall
• Archaea are prokaryotic organisms that do not contain peptidoglycan in their cell walls
• Many Archaea live in extremely harsh environments

Types of Prokaryotes

• Halophilic Prokaryotes live in very salty environments
• Thermoacidophiles live in temperatures above 80°C and pH between 1 and 2
• Methanogens are found in sewage/swamps, use carbon dioxide, and produce methane gas

Bacteria Stricture

• Chromosomal DNA bacteria contains a single circular chromosome
• Capsule prevents cell from dying and provides protection
• Pili are tail-like structures used for movement
• Flagella is located between the capsule and provides protection for bacteria against antibiotics

Gram Stain

• A fundamental technique in microbiology to differentiate bacterial species into two main groups: Gram-positive and Gram-negative bacteria
• Gram stain reacts with peptidoglycan in the cell wall of bacteria, thus helping doctors to detect bacterial diseases
• Gram stain is not useful for detecting archaea because archaea don't have peptidoglycan

Protozoa

• Single-celled eukaryotic organisms classified by food sources and locomotion
• Animal-like protists obtain food by eating other organisms (heterotrophs); example: Amoeba
• Plant-like protists carry out photosynthesis to produce their own food (autotrophs); example: kelp
• Fungus-like protists obtain food by absorbing organic material from other organisms (heterotrophs); example: Water Molds

Flagellates

• Use flagella for movement
• Example: Trypanosomes
• A parasite that causes African sleeping sickness, transmitted by the bite of an infected Tsetse fly
• American sleeping sickness (Chagas disease), transmitted by kissing bug or Bed bug
• Giardia lamblia is a parasite that lives in the intestines of humans who drink contaminated water

Algea (Plant-like Protists)

• Have chlorophyll for photosynthesis
• They have a cell wall and chlorophyll
• Euglenoids have both plant and animal structures and contains a light-sensitive receptor (eye spot)
• Dinoflagellates have both animal and plant structures and can cause red tide when toxic organisms grow

Fungi

• Heterotrophic organisms that depend on others to obtain food and break down food using enzymes before absorbing it
• They possess cell walls containing chitin
• Can be unicellular (yeast) or multicellular (mushrooms)
• Hyphae and mycelium are building blocks of mushrooms
• They include molds, yeast, and mushrooms
• Reproduce sexually through meiosis and spore production