CELL MOL LT1

• cell: basic unit of all living things
• Cell Biology

  • study of the structure, function, and behavior of cells
• Molecular Biology

  • study of the composition, structure, and interactions of cellular molecules
  • biomolecules such as nucleic acids, proteins and carbohydrates
• reductionist - we try to understand the components (e.g., of a cell) to understand the whole
• • Robert Hooke (mid-1600s): coined the word cell when he looked at cork under a microscope
  • “cells” from cork
  • pores like honeycomb
• • Anton van Leeuwenhoek (1670s): first described living cells with such detail
  • “animalcules” from pond water
• Matthias Scheliden (1838): plant cells
• • Theodor Schwann (1839): animal cells
• Rudolf Virchow (1855) omni cellula e cellula  means “all cells come from cells”
• Tenets of Cell Theory

  1. All living organisms are composed of one or more cells.
  2. The cell is the structural unit of life.
  3. Cells can arise only by division from a preexisting cell. (Omnis cellula e cellulaI)
• heredity: centreal efnition of life
• 1. Cells are highly complex and organized

  • Emergent properties: the whole is more than the sum of its parts
  • as organization increases, complexity also increases
  • There is order, consistency, and organization in life.
• All cells replicate theirherditary information by templated polymerization
• Cells possess a genetic program and the means to use it
• bonds between base pairs are weak comapred to sugar-phosphate backbone
• Cells are capable of producing more of themselves
• Cells acquire and utilize energy
• Entropy is the spontaneous production of disorder.
• • autotrophs: produce their own food for energy
• • heterotrophs: eat other organisms to get proteins and energy
• Cells carry out a variety of chemical reactions
• Cells carry out a variety of chemical reactions
• • Enzymes are the proteins that catalyze a metabolic reaction.
• • Adenosine triphosphate (ATP) is the most basic energy source.
• • Food intake is broken down to simpler molecules to produce energy.
• ATP is bonded by phosphoanhydride bonds
• 1. Cells engage in mechanical activities
• Cells are able to respond to stimuli
• Bacterias may emit some type of chemical, which serves as the stimuli.
• Lack of stimuli of cells = apoptosis
• Cells are capable of self-regulation
• Apoptosis are necessary to avoid replication of damaged cells.
• Structural Homology = common ancestor
• Biochemical Homology = same gene sequence and hence, same gene function
• Mutations are necessary agents for evolution.
• • Genetic innovation new genes are generated from preexisting genes (no gene is entirely new)
• Mutations can be done through substitiution, insertion, deletion, inversion
• bacterial conjugation allows horizontal transfer of genetic material between bacteria
• Plasmids are usually transferred or copied for the purpose of antibiotic resistance.
• What evidence suggesrs that organisms are derived from a common ancestor?

  • Identical genetic language
  • Information is encoded in DNA, hence we use the same mechanism for replication, transcription, and translation.
  • Common set of metabolic pathways
  • Common structural functions of supra molecular complexes
  • Common origin ⇨ specializations and divergences
  • leads to the production of other cells