91161 Cell Biology and Genetics
91161 Cell Biology and Genetics Cells Cells – smallest/basic unit of organisation that perform all activities required for life
Cell Theory Scientists Contributions Robert Hooke (1665) – discovered cells Looked through microscope at dead cells from bark of oak tree Antony Van Leeuwenhoek (1674) – described algae Spirogyra (1674)
Mathias Schleiden (1838) & Theodor Schwann (1839) – proposed the Cell Theory
Principles 1. All organisms are composed of cells 2. Cells are the smallest living things 3. Cells arise only from pre-existing cells Classification Taxonomy (Carl Linnaeus) – classifies species into groups of increasing breadth Domain
Three-domain system Kingdom
Phylum
Class
Order
Family
Genus
Species
Prokaryotes – Domain Bacteria and Domain Archaea Eukaryotes – Domain Eukarya 3 multicellular kingdoms – plantae, fungi, Animalia
Size
Small – sufficient surface area to support metabolic needs Bigger = longer diffusion rate SA:V Ratio – increase size, V increases 10x faster than SA
Types Prokaryotes
Eukaryotes – Plant/Animals
Size
Smaller (0.5-5um)
Larger (10-100um)
Nucleus
No
True, double membrane & nucleoli
Cytoplasm
Enzymes & genetic material
Cytosol & organelles
Membrane Bound Organelles
No
Yes
Mitochondria
No
Yes
Chloroplasts
No
Plant cells
Endoplasmic reticulum
No
Yes
Ribosomes
Small, 20nm (70S)
Large, 30nm (80S)
Chromosomes
In nucleoid (unbounded)
In nucleus
Circular (bacteria = plasmid), less DNA
Multiple, linear, 1000x DNA
DNA + proteins form chromatin Cell wall
Bacteria – peptidoglycan
Cellulose or chitin
Archaea – polysaccharides & proteins ATP synthesis
Plasma Membrane
Mitchondria
Organisation
Simple internal structure
Complex – compartmentalised functions
Unicellular or colony
Unicellular or multicellular
Cells perform many functions
Cells perform specific functions
Bacteria
Archaea cells contain small membrane-bound organelles, bacteria don’t Endospores – help survive in harsh conditions
Shapes Cocci (spheres) Bacilli (rods) Spirals (spirillum) Vibrio (curved) Peptidoglycan – network of sugar polymers cross-linked by polypeptides Gram Stain – classifies bacteria into Gram-+ve/-ve based on cell wall composition Gram-ve = less peptidoglycan Structures Fimbriae (attachment pili) – stick to their substrate or other cells in colony Sex Pili – longer, allow prokaryotes to exchange DNA Motility – flagella (1/10 width of eukaryotes)
Nucleus
Enclosed by Nuclear envelope (double), separates contents from cytoplasm Pores regulate diffusion of molecules from nucleus Nuclear Lamina – maintains shape, composed of protein Contain Chromosomes, made up if chromatin (DNA & protein) Nucleolus – synthesises ribosomal subunits (rRNA & protein)
Endomembrane System
Series of membranes throughout cytoplasm Regulates protein traffic and performs metabolic functions
1. Endoplasmic Reticulum
Continuous network of membranes with nuclear envelope Separates lumen from cytosol Ribosomes – site of protein synthesis Composition – Ribosomal RNA and proteins Location – within cytosol or attached to internal membranes Cytosol – free ribosomes Outside ER or nuclear envelop – bound ribosomes
Cell Theory Scientists Contributions Robert Hooke (1665) – discovered cells Looked through microscope at dead cells from bark of oak tree Antony Van Leeuwenhoek (1674) – described algae Spirogyra (1674)
Mathias Schleiden (1838) & Theodor Schwann (1839) – proposed the Cell Theory
Principles 1. All organisms are composed of cells 2. Cells are the smallest living things 3. Cells arise only from pre-existing cells Classification Taxonomy (Carl Linnaeus) – classifies species into groups of increasing breadth Domain
Three-domain system Kingdom
Phylum
Class
Order
Family
Genus
Species
Prokaryotes – Domain Bacteria and Domain Archaea Eukaryotes – Domain Eukarya 3 multicellular kingdoms – plantae, fungi, Animalia
Size
Small – sufficient surface area to support metabolic needs Bigger = longer diffusion rate SA:V Ratio – increase size, V increases 10x faster than SA
Types Prokaryotes
Eukaryotes – Plant/Animals
Size
Smaller (0.5-5um)
Larger (10-100um)
Nucleus
No
True, double membrane & nucleoli
Cytoplasm
Enzymes & genetic material
Cytosol & organelles
Membrane Bound Organelles
No
Yes
Mitochondria
No
Yes
Chloroplasts
No
Plant cells
Endoplasmic reticulum
No
Yes
Ribosomes
Small, 20nm (70S)
Large, 30nm (80S)
Chromosomes
In nucleoid (unbounded)
In nucleus
Circular (bacteria = plasmid), less DNA
Multiple, linear, 1000x DNA
DNA + proteins form chromatin Cell wall
Bacteria – peptidoglycan
Cellulose or chitin
Archaea – polysaccharides & proteins ATP synthesis
Plasma Membrane
Mitchondria
Organisation
Simple internal structure
Complex – compartmentalised functions
Unicellular or colony
Unicellular or multicellular
Cells perform many functions
Cells perform specific functions
Bacteria
Archaea cells contain small membrane-bound organelles, bacteria don’t Endospores – help survive in harsh conditions
Shapes Cocci (spheres) Bacilli (rods) Spirals (spirillum) Vibrio (curved) Peptidoglycan – network of sugar polymers cross-linked by polypeptides Gram Stain – classifies bacteria into Gram-+ve/-ve based on cell wall composition Gram-ve = less peptidoglycan Structures Fimbriae (attachment pili) – stick to their substrate or other cells in colony Sex Pili – longer, allow prokaryotes to exchange DNA Motility – flagella (1/10 width of eukaryotes)
Nucleus
Enclosed by Nuclear envelope (double), separates contents from cytoplasm Pores regulate diffusion of molecules from nucleus Nuclear Lamina – maintains shape, composed of protein Contain Chromosomes, made up if chromatin (DNA & protein) Nucleolus – synthesises ribosomal subunits (rRNA & protein)
Endomembrane System
Series of membranes throughout cytoplasm Regulates protein traffic and performs metabolic functions
1. Endoplasmic Reticulum
Continuous network of membranes with nuclear envelope Separates lumen from cytosol Ribosomes – site of protein synthesis Composition – Ribosomal RNA and proteins Location – within cytosol or attached to internal membranes Cytosol – free ribosomes Outside ER or nuclear envelop – bound ribosomes
