Introduction to Biology - Lecture 1

• Introduction to Biology is Lecture 1 for Nursing students in Biology, Biophysics, and Biochemistry for the academic year 2023-2024, taught by Prof. Laura Pacini.
• Biology seeks to understand life at various levels, from the molecular and cellular levels to entire biosphere ecosystems.
• Biology is the study of life, attempting to define what makes something alive and what characteristics define life.

Characteristics of Living Organisms

• Living organisms are highly organized compared to inanimate objects, composed of cells, and capable of reproducing themselves.
• They rely on a universal Genetic Code, and grow and develop over time.
• Living organisms show adaptation to their environment (Evolution).
• Living organisms take energy and matter from the environment and transform it.
• Living organisms display homeostasis by maintaining a relatively constant internal environment.
• Stimuli are responded to.

Levels of Hierarchical Organization

• Cellular: atoms, molecules, organelles, cells, the basic unit of life.
• Organismal: tissues, organs, and organ systems.
• Populational: population and community.
• Ecosystem.
• Biosphere: Earth is an ecosystem.

Reproduction

• All living things reproduce, producing new similar organisms.
• Asexual Reproduction: Single cells produce offspring identical to themselves.
• Sexual Reproduction: Cells from two parents unite to form the first cell of a new organism.

Growth and Development

• GROWTH is the increase in size and mass, especially in single-celled organisms like bacteria.
• Multicellular organisms increase size and cell number.
• DEVELOPMENT involves transformation during the life of an organism.

Homeostasis

• Living organisms can display homeostasis

Response to Stimuli

• Living things detect and respond to their environment.
• A stimulus is a signal to which an organism responds.

Energy

• Metabolism encompasses chemical reactions in living cells, providing energy for growth, reproduction, building, maintenance of structures, and responses to the environment.
• Photosynthesis and cellular respiration are key processes.
• All living organisms are composed of similar molecules and participate in similar chemical reactions.
• Cells function as biochemical factories, utilizing atoms (food/matter) and energy.
• Metabolism includes all chemical reactions needed to sustain an organism

Cell Biology

• Cell biology explains diseases can be explained by, and often relate to a dysfunction at the cellular level.
• Hypercholesterolemia involves defective uptake of lipoproteins.
• Cystic Fibrosis involves the misfolding of a key protein.
• Hypertension is caused by defective cell-cell adhesion in the kidneys.
• Muscular dystrophy is caused by defective interaction between plasma membrane and cytoskeleton.
• Cancer is caused by errors in cell division, migration, growth or signaling.
• Understanding cell structure is fundamental in biology for medicine, and understanding disease mechanisms..
• Aspects of biology crucial for medicine include: pharmacology, genetics, microbiology, immunology, research, technological innovation, diagnosis, treatment, and ethical considerations.

Universal Features of Cells

• Cells are the universal building blocks of life, coming in small, membrane-enclosed units.
• Cells contain a concentrated aqueous solution of chemicals
• Cells are endowed with the ability to create copies of themselves by growing and dividing in two.
• Tremendous diversity shows in the form and function of living organisms.
• Organisms share characteristics that distinguish them from non-living things, therefore cells share fundamental similarities internally.
• Cells vary in appearance, size, shape, chemical requirement, and function.

Tree Of Life

• The Tree of Life has three primary branches: Bacteria, Archaea, and Eukaryotes.
• Prokaryotes lack a nucleus or other membrane-enclosed compartments and distinct organelles, including Bacteria and Archaea.
• Eukaryotes have a membrane-enclosed nucleus and other membrane-enclosed compartments or organelles, including Animals, Plants, Fungi, and Protists.