Inside the Cell 1
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- Created by: amazingemilyjones
- Created on: 14-04-19 10:17
Inside the Cell 1
Inside the Cell 1
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Prokarotes
Prokaryotes vs. Eukaryotes
- Bacteria are the oldest and simplest prokaryote
- Prokaryotes lack internal compartmentalisation seen in eukaryotes
- Prokaryotic genome has less DNA
- Can have diffuse location within cell compared to eukaryotes which have a true membrane-bound nucleus
- Most prokaryotes have plasmids
- small ring-shaped DNA molecules containing a few genes
- Plasmid function:
- Fertility -transfer of genetic material between two bacteria
- Resistance - antibiotics
- Degradative - digestion of organic substances
- Virulence - turn the bacterium into a pathogen
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Bacterial Plasmids
- Short, circular and double-stranded segment of DNA in the cytoplasm separate from main bacterial chromosome
- Capable of autonomous replication
- Can transfer genes from one cell to another
- Acts as a vector in genetic engineering
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Prokaryotes vs. Eukaryotes
Eukaryotes
Organelles
- Eukaryotic cells have an elaborate system of internal membrane-bound compartments (organelles)
- Provide specialised environments
- Facilitate processes with different chemical requirements
- Each organelle has one or more compartments
- Organelles act autonomously or cooperate to accomplish a given function
- E.g.: protein trafficking involves the endoplasmic reticulum and Golgi apparatus
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Cytoplasm
- Area contained by the plasma membrane
- Contains many membrane-bound compartments
- membranes facilitate distinct environments within organelles
- Defined as everything excluding the nucleus
- Contrast with cytosol - fluid elements of cytoplasm
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Cell Cytosol
- Largest compartment of the cell
- Composition
- Densely-packed molecules
- Aqueous gel, molecular soup
- Site of many essential chemical reactions
- Site of many essential chemical reactions
- Early steps in nutrient breakdown
- ATP generation (glycolysis)
- Manufacture of proteins
- Signalling transduction
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Mitochondria
- Prsesent in all eukaryotic cells
- Function: cellular respiration
- Convert energy usable by cells
- ATP
- Cytosol: anaerobic glycolysis
- Mitochondrion: pyruvate oxidation
- Convert energy usable by cells
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Mitochondria
- Mitochondria remain fixed in some cells associated at sites requiring most energy
- Muscle
- Brain
- Number of mitochondria can very within a cell and between cell types
- Liver ~1000-2000 per cell; 20% of cell volume
- Numbers/size can increase in muscle cells
- Exercise can increase mitochondria numbers in muscle cells as cells adapt to higher energy requirements
- Mitochondria are made up of four separate components
- Outer membrane, intermembrane space, inner membrane, matrix
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Outer Membrane and Intermembrane Space
- Outer membrane
- Structure: similar to plasma membrane
- Functions
- Separation of internal and external environments
- Role in cell death
- disruption of outer membrane allows proteins from intermembrane space to leak into cytosol
- Intermembrane space
- Cytochrome C
- essential component of the electron transport chain
- important in apoptosis (release into the cytosol)
- Cytochrome C
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Inner Membrane
- Highly folded to form cristae
- Increase surface area of inner membrane (5x larger than outer membrane)
- Enhance ability to produce ATP
- Mitochondria of cells with ATP demand contain more cristae compared to a typical microchondria
- E.g. muscle cells vs. skin cells
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Matrix
- Contains most of mitochondrial proteins/enzymes (>100)
- Pyruvate and fatty acid oxidation
- Citric acid cycle
- Mitochondrial ribosomes, tRNA and mtDNA and several copies of the mitochondrial genome
- 37 total genes that encode:
- tRNA and rRNA
- Inner membrane proteins
- 37 total genes that encode:
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Lysosomes
- Principal sites of intracellular digestion
- Produced from golgi
- Contain many hydrolytic enzymes
- Lipases
- Carbohydrases
- Nucleases
- Proteases
- pH dependent activity
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Lysosomes
- Function - digestion of macromolecules from:
- Phagocytosis
- (external pathogens)
- Endocytosis
- receptor recycling
- Autophagy
- excess/old organelles
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