DEV2011 Lecture Notes - Lecture 2: Rudolf Virchow, Fluid Mosaic Model, Robert Hooke
25 May 2018
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Lecture 2 – Cells: Organelles and Functional Compartments
Mammalian Cell
• Robert Hooke (17th century)
o Discovered piece of cork was composed of cells
Cell Theory (Rudolf Virchow 1859)
• 3 basic components
o All organisms are composed of cells
o Cell is basic unit of life
o Cells are produced by the division of pre-existing cells
• Modern Cell Theory
o Cells contain hereditary information → passed on
o All cells are comprised of the same chemical mix
o Cells carry out all basic chemical and physiological processes within
themselves
o Cellular activity depends on activities of subcellular structures
Why are we Made up of Individual Cells
• Efficiency
o Surface area increases
o Nutrient/oxygen supply and waste disposal
• Specialisation
o Numerous small cells allow for specialisation
▪ Different cells have different functions
• *Average human composed of ~100 trillion cells
Subcellular Compartments
Cell (plasma) Membrane
• Fluid mosaic model
• Separates living cells from nonliving surroundings
• Selectively permeable
o Transport selected molecules
• Incorporates receptors that allows the cell to respond to signals from outside
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o Communication between cells drives development
o Critical for cell-cell communication
o Continuously receiving signals from external sources
o Extra signals → cells grow + divide or differentiate (change gene
expression pattern and structure → function)
o If cell receives no signals → cell dies (apoptotic cell)
o Extracellular signal molecule never enters pathway → alters receptor
protein to activate signalling pathway within the cell → pass signal
down the cell
• Structure
o Phospholipids, proteins and other macromolecules
Mitochondria
• Site of cellular respiration
• Cellular metabolism – Krebs cycle (production of ATP)
• Function
o Cell differentiation, cell death (apoptosis)
o Some control over cell cycle and growth
• Theory of origin
o Formed by endosymbiosis
• Passed down maternally only
o Sperm head can’t fit in mitochondria
• Second location of DNA in a cell
o Genes code for many proteins requires for mitochondrial function
• Mitochondria rich cell types
o Skeletal and cardiac muscle
o Sperm (tail)
o Renal tubular cells
• Defects – exercise intolerance (minor)
• Serious: Leber hereditary optic neuropathy (LHON)
o Loss of vision
o Caused by mutation in I NADH dehydrogenase subunit 4 of
mitochondrial respiratory chain
o Three person in vitra fertilisation
▪ Person will have 2 mothers and 1 father
▪ Remove nucleus so replaced with mitochondria from second
women
The Nucleus
• Contains
o Nucleoplasm
o Nuclear envelope – protective membrane
o Nuclear pores – protein trafficking
o Nucleolus – site of ribosome assembly
• Contains majority of DNA
• DNA wrapped around histone proteins – chromatin
• Non dividing cells
o Chromatin is not formed into chromosomes (only occurs during
mitosis or meiosis) – dispersed throughout nucleus in two major forms
▪ Heterochromatin (dark regions)
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find more resources at oneclass.com
Document Summary
Lecture 2 cells: organelles and functional compartments. Mammalian cell: robert hooke (17th century, discovered piece of cork was composed of cells. Why are we made up of individual cells: efficiency, surface area increases, nutrient/oxygen supply and waste disposal, specialisation, numerous small cells allow for specialisation, different cells have different functions, *average human composed of ~100 trillion cells. Cell (plasma) membrane: fluid mosaic model, separates living cells from nonliving surroundings, selectively permeable, transport selected molecules. Cytoplasm: location of many cellular organelles, many complex cellular chemical reactions take place there, glycolysis, gluconeogenesis, biosynthesis of sugars, fatty acids and amino acids, rna modification, protein synthesis, many cellular organelles are located. Cilia: protrusions from the cell surface, motile, respiratory surfaces, fallopian tubes, immotile. Involved in cellular signalling: number of development disorders to issues of the cilia ciliopathies", e. g. Oral facial digital (ofd) syndrome type i aka papillon-league- Psaume syndrome x linked (predominantly in females)
