the cell cell theory: all living things contain cells. all cells come from other cells
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VirusesAre viruses living?
Influenza virus (an Orthomyxovirus)
According to cell theory no.
However they do contain organic molecules (DNA or RNA & protein) and can replicate themselves using a host cell, so some biologists say yes.
This demonstrates the rule, that for every rule in biology, we can usually find at least 1 exception
Prokaryotic cells
• Do they have a nucleus?• Do they have organelles?• How big are they?• Examples include
Escherichia coli bacteria Streptococcus pnemoniae
no
Very small - usually 1 – 10 m
no
Bacteria, blue green bacteria
Eukaryotic cells
• Do they have a nucleus?• Do they have organelles?• How big are they?• Examples include
yes
yes
Larger than bacteria – usually 20 – 500 m
Plants, animals, fungi, Protista
Nucleus
Main function Control centre – contains the genetic blueprint (genes) forcoding proteins, hence controls all cell activities
Ribosomes
Main function Site of protein synthesisSome are found free in the cytoplasmMost are found attached to the endoplasmic reticulum
Vacuoles
Main function Storage of food and waterIn plants provides strength and structure to cell
Plant cells usually have 1 large oneAnimal cells usually have several smaller ones
Contractile vacuole
Main function Pumps out excess water, hence maintaining water balance in the cell
Only found in some unicellular organisms
Cytoskeleton
Microfilaments are thin fibres that are made mostly of the protein actin. Microfilament fibres can change length when supplied with energy by ATP, and so they allow cells to change shape. They also guide the movements of organelles within the cell. Interactions of actin and the protein myosin are important in contraction of muscle cells.
Intermediate fibres (intermediate filaments) are somewhat larger in diameter than are microfilaments, and are made of several different proteins. Intermediate fibres form a 3-D network throughout the cell that forms much of the framework of the cell and holds the organelles in position.
Microtubules are about 24 nanometers in diameter, somewhat thicker than microfilaments or intermediate fibres. Microtubules are hollow and composed largely of the protein tubulin. Microtubules help to position, anchor, and move organelles. They are also important in cellular reproduction and in the movements of cells. Microtubules are important components of both cilia and flagella, and of centrioles.
Animal cells
Special features include: No cell wallNo chloroplastsVacuoles usually small and numerousCentrioles
What type of cell am I?
plant
plantanimal
animalProkaryotic Prokaryotic
Label the cellsCell wall
Cell membrane Cell
membrane
nucleusnucleus
nucleolusnucleolus
Nuclearmembrane
Nuclearmembrane
Chromatin/DNAChromatin/DNA
mitochondrion
mitochondrion
cytoplasm
lysosome
chloroplast
centrioles
Golgi body
vacuole
Rough endoplasmicreticulum
cytoplasm
Smooth endoplasmicreticulum
Rough endoplasmicreticulum
ribosomes
vacuole
Smooth endoplasmicreticulum
Identify the organelles
Cell wall
Cell wall
nucleus
nucleus
mitochondrion
nucleolus
nucleolus
nucleolus
vacuole
vacuole
Nuclearmembrane
cytoplasmchloroplast
chloroplast
Rough endoplasmicreticulum
Nuclear pore
Identify the function of these• cell membrane
• cell wall
• cytoplasm
• nucleus
• nucleolus
• nuclear membrane
• mitochondria• Golgi body
Provides a medium for reactions & site for organelles
Controls entry and exit of substances
Provides structure and support
Control centre – contains the genetic blueprint (genes) forcoding proteins, hence controls all cell activities
Site of RNA production & storage
Keeps DNA within nucleus
Site of aerobic respiration – energy production
Packaging for secretion
Identify the function of these
• endoplasmic reticulum • ribosomes• lysosomes• centrioles• cilia/flagella• chloroplasts• vacuole• contractile vacuole
Transport system, site for reactions to occur
Site of protein synthesis. Some are found free in the cytoplasmMost are found attached to the endoplasmic reticulum
Site of photosynthesis
Storage of food and waterIn plants provides strength and structure to cell
Storage of wastesMost contain enzymes that break down substances
Forms spindle during cell division
Movement
Pumps out excess water, hence maintaining water balance in the cell