Introduction to Cells
- Created by: sofiedb
- Created on: 20-11-17 17:57
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- Introduction to cells (smallest unit of life)
- Cell theory
- living organisms are composed of 1+ cells
- cells are the basic units of structure & organisation in organisms
- cells come from pre-existing cells
- Microscope
- light microscope: all plant & animal tissues are made up of individual cells (structure)
- electron microscope (higher resolution): full complexities of internal fine structure of cells - ultrastructure
- "the evolution of multicellular organisms allowed cell specialization and cell replacement."
- advantage of multicellular: severe damage to cell does not mean end of organism
- Virus: non-living (protein coat & DNA/RNA // no metabolism & reproduction & no cellular structure (functions may be carried out by infected host cell)
- advantage of multicellular: severe damage to cell does not mean end of organism
- Organisms
- Unicellular organisms (bacteria, archaea, protozoa, unicellular algae)
- A single, living cell can carry out all life functions
- Multicellular organisms
- Increase in organism's size --> cell differentiation --> emergent properties
- Stem cells --> specialisation (self-replicate/ differentiation
- synthesis of certain proteins triggers specialised development of a specific cell & its descendants
- totipotent: any type, rise to complete organism
- pluripotent: all body cells, no rise to complete organism
- multipotent: several closely related types
- unipotent: associated cell type
- embryo: important source of stem cells
- 1. removal of nucleus from donor egg cell
- 2. nuclear transfer of host DNA from somatic cells
- 3. 4-cell-stage
- 4. blastocyst
- 5. embryo stem culture containing DNA from adult host
- 4. blastocyst
- 3. 4-cell-stage
- 2. nuclear transfer of host DNA from somatic cells
- 1. removal of nucleus from donor egg cell
- Stargardt's disease (retinal cells)/leukaemia (haematopoetic stem cells)
- sources
- specially created embryos
- umbilical cord blood
- low risk of tumour formation/ less concern/less accumulated mutations
- limited cells
- low risk of tumour formation/ less concern/less accumulated mutations
- adult's own tissue
- low risk of tumour formation/no issue with consent
- limited cell types/high chance of genetic damage (mutations during lifetime)
- low risk of tumour formation/no issue with consent
- Unicellular organisms (bacteria, archaea, protozoa, unicellular algae)
- Life functions (MR H. GREN)
- Metabolism: regular set of life-supporting reactions that take place within the cells
- Response: reaction to changes in the environment
- Homeostasis: the maintenance of a constant internal environment by regulating internal cell conditions
- Growth: a positive change in size/shape over time
- Reproduction: production of offspring to pass on genetic information to the next generation
- Excretion: removal of waste products of metabolism and other unimportant materials
- SA:V
- import of molecules & expulsion of waste products through plasma membrane
- SA to small:V too large - not enough import/excretion (division)
- import of molecules & expulsion of waste products through plasma membrane
- Cell theory
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