Lecture 1: Cells

What is science?

A. A collection of facts

B. A collection of organized facts

C. A method for building and organizing knowledge

D. Stuff I read in a textbook

C. A method for building and organizing knowledge

How is scientific knowledge gained?

A. It is passed down orally from generation to generation.

B. It is all written up on Wikipedia by some smart person.

C. It is extracted from textbook pages.

D. It is developed over time by application of the scientific method.

D. It is developed over time by application of the scientific method

Three Approaches to the study of Biology

• Reductionist

• Systems biology

• Synthetic Biology

Reductionist

• A scientific approach - traditional
  hypothesis - based approach

• Knowledge of how each part of the whole works can describe the character of the whole.

• Underlying assumption - we
  can understand the system by understanding
  each part

Systems Biology

• Analysis of the system as a whole – driven by technical advances

• Understanding the complexity of life based on holistic approaches.

• Underlying assumption: assumes the whole is more than the sum of its parts and require multiple components to work together, or synergize.

Synthetic Biology

• Designed and construction of new biological parts and devices that have specific properties and functions.

• System oriented

• Can involve many fields including biology, informatics, chemistry, physics, computation and engineering.

• Applications to medicine, industry, the environment.

• Underlying Assumption: We can make biology better than it is.

Which of the following could be a goal of
synthetic biology?
a) create a living cell in the laboratory.
b) develop novel life forms.
c) “custom build” a particular species of an existing
organism.
d) All of these are possible goals of synthetic biology.

d) All of these are possible goals of synthetic biology.

Characteristics of Life

• Cellular Organization

• Metabolism

• Homeostasis

• Reproduction

• Heredity

Cell

• The smallest structural and functional unit of an organism

Cell Theory

• All living organisms are either cells or they are organisms composed of many cells

• All cells arise from pre-existing cells.

Cells and Characteristics of Life

• Cells have Cellular Organization

• Are able to carry out all of the necessary chemical reactions for life - metabolism

• Regulate their internal environment - homeostasis

• Reproduce and give rise to new generations of cells

• Pass genetic information from one generation to the next - heredity

Additional Requirements for long-term survival of cells

• Sense and Respond to Stimuli

• Repair themselves

• Evolve

Prokaryotes

• Bacteria

• Smaller, Unbound Nucleoid, No Membrane Bound Organelles, Complex Cell Wall, No Cytoskeleton, Simple Appendages

Eukaryotes

• Protists, Fungi, Animals, Plants

• Membrane Bound Nucleus, Complex Appendages, Membrane Bound Organelles, Simple Cell Wall, Cytoskeleton, Bigger, Mitosis

Similarities between Eukaryotes and Prokaryotes

• Flagella

• Plasma Membrane

• Cell Division

• Cytoplasm

• Ribosomes

• Chromosomes

Plasma Membrane

• Specialized lipid bilayer

• Functions:

  • Serves as a barrier that separates the inside of the cell from its immediate environment.

  • Regulates which substances pass into and out of the cell — it is semi-permeable

Metabolism

• Vast array of physical and chemical interaction that occur in a cell.

• Pathways are remarkably conserved

Bacteria

• Probably first organisms to evolve

• Includes photosynthetic cyanobacteria

• Laboratory strains - E. coli

Archaea

• Includes the extremophiles

  • Halophiles

  • Acidophiles

  • Thermophiles

Five Kingdoms if Eukaryotes

• Kingdom Protozoa — e.g. Amoebozoa, Choanozoa, Excavata

• Kingdom Chromista — e.g. Alveolata, cryptophytes, Heterokonta (stramenopiles), Haptophyta, Rhizaria

• Kingdom Fungi – e.g. yeast, mold, mushrooms

• Kingdom Plantae — e.g. glaucophytes, red and green algae, land plants

• Kingdom Animalia – e.g. multicellular organisms (our primary focus in this class)

Phagocytosis

• Cell eating

• Internalizing large particulates

• Usually done by Eukaryotic Cells

Theory Endosymbiosis

• Serves as evidence for the origin of mitochindria and chloroplats

Cytoskeleton of Eukaryotic Cells

• Facilitates cell specialization
  and multicellular organization

• Maintains cellular shape and
  facilitates changes in shape

• Organizes organelles and
  other cellular structures within
  the cytoplasm

• Organize transport of
  intracellular components within
  and outside of eukaryotic cells

• Regulates segregation of
  chromosomes during cell
  division cytoskeleton.

Differentiation

• During development of a multicellular organism, eukaryotic cells differentiate to produce many functionally and structurally distinct cell types.

• Ex: Nerve Cells, Red Blood Cells, Smooth Muscles

Viroids

• small, circular RNA molecules (smallest known infectious agents)
  – 300-400 nt long, do not encode proteins
  – i.e. plant diseases – “cadang-cadang disease” of coconut palm
  – Mechanism: RNA-mediated gene silencing? (prevents normal function of mRNAs in cells)

Prions

• Proteinaceous infectious particles containing no
  nucleic acids
  – i.e. “scrapie,” “Mad cow disease”
  – Mechanism: abnormally folded version of a cellular protein causes cellular proteins to misfold

Viruses

• Pathogens smaller and simpler
  than the smallest bacteria
  – Genetic material (can be
  DNA or RNA in multiple
  forms) – viral classification
  – Protein capsule
  – Some have lipid envelope

• Viruses are obligate parasites

  • Viruses are not living because they need a cellular host to grow and reproduce.

  • Can exist outside the host as a virion.