Module 1 Flashcards
Cells as the Basis of life
What is a prokaryote?
Prokaryotic cells are those without a nucleus or membrane bound organelles.
A prokaryote is an organism made of prokaryotic cells. Most are unicellular organisms with pili and flagella, but some exist in units/colonies
What is the structure of a prokaryotic cell?
Has ribosomes, cytoplasm and genetic material (DNA in the form of one circular chromosome).
Range from 0.1-5μm in size with large SA/V ratio.
surrounded by a cell membrane, peptidoglycan (bacteria only) cell wall and a protective carbohydrate Capsule outside that
What are Archaea?
Type of prokaryote that are extremophiles (live in extreme environments)
Methanogens produce methane and live in anaerobic environments (no oxygen)
Halophiles live in salty environments
Thermophiles in hot
Psychrophiles in cold
What are Bacteria?
Type of prokaryote, oldest life form
Adaptable and can survive in all environments
Need minimal oxygen
Obtain energy through photosynthesis or chemosynthesis
What is a eukaryotic cell?
Eukaryotic cells have a nucleus and membrane bound organelles
They are larger, 10-100μm, and more complex
Most form multicellular organisms and can sexually reproduce.
Have linear DNA contained in the nucleus
What is the nucleus?
Cells control centre and storage of DNA
needed for growth, repair and functioning
What is the Nucleolus?
Place of ribosome production, found in nucleus and made of protiens and RNA (ribonucleic acid)
What are ribosomes?
non-membrane bound blobs, mostly connected to ER and made of rRNA (ribosomal RNA) and protein
produce protein
What is Endoplasmic reticulum?
A network of interconnected membranes, some of which are attached to the nucleus and split into
Rough ER: has ribosomes attached and is involved in modifying and processing protiens
Smooth ER: Produces lipids & doesn’t have ribosomes
What are lysosomes?
The cells digestive system, contains digestive enzymes to break down substances
What is the golgi body?
Also called golgi apparatus, made of stacked membrane sacs, not interconnected that process and package the cells proteins and lipids
What is chloroplasts?
An organelle unique to plant cells that has a double membrane, their own DNA and chlorphyll.
They perform photosynthesis
What is the mitochondria?
A double membraned organelle that performs chemical respiration to provide power to the cell. Different cell types have different amount of mitochondria, relating to how much energy required.
What is the cell membrane?
A semi-permeable membrane around the cell that regulates what enters and exits the cell, aswell as seperating intracellular fluid (cytopasm) from external environment
Also involved in cell communication and recognition
What is the cell wall?
A wall around plant, fungal and prokaryotic cells that gives it structural strength and protection.
Surrounds the cell membrane
What is the cytoplasm?
A gel-like fluid that fills the cell, maintaining an optimal environment
All other organelles are suspended inside it
Also acts as a medium for chemical reactions within the cell
What is the cytoskeleton?
A network of microtubules, microfilaments and intermediate filaments
Holds organelles in place and maintains cells shape
What are centrioles?
Pair of organelles made from microtubules involved in cell division, pulling apart chromosomes
What are the pili & flagella?
Hair like appendages outside the cell membrane involved in the movement of the cell
Flagella is like a tail, Pili covers all of the cell
What is the vacuole?
A vesicle that contains fluid and stires substances for the cell
Plant cells have one big vacuole
Animal cells have multiple small vacuoles
How does a light microscope work?
Visible light shines through the specimen, (either a whole organism, smear of cells, or thin slice)
Then it travels through the objective and ocular lenses, refracting it to create a magnified image
The total magnifaction = Ocular lens x Objective lens\
or magnification = magnified size/actual size
Why are specimens stained?
Specimens are stained with dye, which stains some components of the cell to increase the contrast between structures
How does an electron microscope work?
It uses a beam of electrons controleld by electromagnets under vacuum conditions to magnify the specimen
The electrons scatter when they hit the specimen which is detected by a computer which turns it into an image
Transmission electron microscope: broad beam shot
Scanning electron microscope: super fine beam scanned across specimen
How does the phospholipid bilayer work?
It has 2 layers of phospholipid molecules each with a
Hydrophilic (water loving) phosphate head facing outside
Hydrophobic (water hater) 2 lipid tails facing inside
