Download Cells and Structure

Cell Structure
Schleiden, Schwann and Virchow - 1800s
The cell is the basic and smallest unit of life
All cells arise from pre-existing cells
The cell is the working unit of organisms
All cells perform the following
functions
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Obtain and metabolize nutrients
Grow and develop
Respond to environment
Adapt and genetically evolve
Use DNA for information storage
All cells are made of…
Lipids: membranes, energy
Carbohydrates: walls, energy
Nucleic Acids: genetic information, protein
synthesis
Proteins: many things - enzymes, antibodies…
Cell Types
Prokaryotic Cells
Simpler, smaller, and the most
primitive
Lack a nucleus and organelles
Include Eubacteria and Archaea
Eukaryotic Cells
More complex, larger, and more
modern
Have a nucleus and organelles
Include Fungi, Algae, Protozoa,
Animals, Plants
Prokaryotic cell
Prokaryotic Cells In Detail
Cell Membrane
Same as eukaryotic BUT
ALSO contain metabolic enzymes
Prokaryotes resemble naked organelles
External Structure of Prokaryotic
Cells
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Glycocalyces
“sugar cup”
Attach to surfaces
Prevent phagocytosis
Streptococcus
pneumoniae &
Klebsiella pneumoniae
Flagella
• Movement
• Arrangements:
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Peritrichous
Polar
Amphitrichous
Show taxis:
Chemo/photo
Fimbriae & Pili
• Fimbriae: sticky,
proteinaceous bristle
like projections for
adherance
• Pili: protein pilin, for
movement
Cell walls
• Peptidogylcan:
polysaccharide of
alternating sugars
• Two types:
• Gram +
• Gram –
Gram (+) = THICK, naked peptidoglycan
Gram (-) = THIN peptidoglycan, outer
membrane
Cell Membrane
Selectively permeable barrier
Built of phospholipid bilayer and proteins
Proteins act as receptors and pores
Animal cells contain cholesterol in membranes
Fungi have ergosterol
Non-Gram Staining Bacteria
Mycobacteria - wax coat, e.g. TB and leprosy
Mycoplasma - no walls, e.g. walking pneumonia
Cytoplasm
Contain genetic
material
Site of replication,
transcription, and
translation
• Ribosomes
• Inclusions
• Gas vesicles
Endospores
• Highly resistant
• Vegetative cell
sporulates
• Bacillus
• Clostridium
Prokaryotic Chromosomes
Circular DNA - half to one million base pairs
One copy of each chromosome (haploid)
Many Also Have Plasmids
Sometimes called “mini-chromosomes”
Small circles of DNA - 10,000 base pairs
Carry emergency genes - e.g. drug resistance
Can be passed around during bacterial mating
In Lab, You Will Be Responsible For…
Gram Staining
Capsules
Flagella
Spores
Pili/Fimbrae
Fat/PHB Granules
Eukaryotic Cells
Eukaryotic Walls Vary…
Location - just outside membrane
Plants = cellulose (chain of glucose)
Algae = cellulose or minerals (silica, calcium…)
Insect and Fungi = chitin (chain of NAG)
Animals and protozoa lack walls
Eukaryotic Chromosomes
Linear DNA = at least 1 million base pairs
Two copies of each chromosome (diploid)
Viruses and Non-Living Agents
Not made of cells or classified as life
Cannot carry out life functions without a host
Contain a few genes that make few proteins