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52 Cards in this Set
- Front
- Back
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What is a eukaryotic cell? |
A eukaryote is any organism whose cells contain a nucleus and other organelles enclosed within membranes. |
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Examples of eukaryotic cell |
Plant cells,animal cells,fungi,yeast, algae |
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Features of eukaryotic cells |
-Nucleolus is present -Nuclear envelope -Ribosomes(80s) -Membrane bound organelles e.g mitochondria -Cell wall made of cellulose(plants), chitin(fungi) -Endoplasmic reticulum ,Golgi apparatus,Lysosomes present -Chromosomes present in which DNA is located -Chloroplasts present in plants and algae |
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What is a prokaryotic cell? |
Prokaryotic cells are those that do not have a membrane-bound nucleus. |
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Examples of prokaryotic cell |
Bacteria,archae |
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Functions of prokaryotic cell |
-No nucleolus is present -No true nucleus -Ribosomes (70s) -No membrane bound organelles -No chloroplasts but has some photosynthetic regions -Cell wall made up of peptidoglycan -No endoplasmic reticulum,lysosomes, Golgi apparatus -Circular strands of DNA but no chromosomes |
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What are the 3 membrane-bound organelles in plant cells? |
-Nucleus -Mitochondria -Chloroplasts |
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Non-membrane bound organelles |
-Cytoskeleton -Centrioles -Ribosome |
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Membrane bound organelles |
-Nucleus -Chloroplasts -Mitochondria -ER -Lysosomes -Vacuole -Golgi apparatus -Nucleolus |
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Differentiation |
Process by which cells become specialised for different functions e.g embroyonic stem cell |
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Tissues |
A group of similar cells organised into a structural unit that serves a particular function e.g epithelical tissue |
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Organs |
An organ is a combination of tissues that are coordinated to perform a variety of functions e.g stomach |
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Organ system |
Systems may be grouped together to perform a particular function e.g digestive system |
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Why do different differentiated cells have a different nu,ber of each organelles? |
Becuase different organelles in different differentiated cells have a particular function e.g muscles cells need mitochondria (for respiration) for contraction and relaxation of muscle |
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Which organs are hard to identify? |
Blood vessels. Blood capillaries are not organs. They are only made up of 1 tissue Arteries and veins are both organs- they are made up of epithelial muscle and connective tissue |
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Magnification |
How many times bigger the image is when compared to the object |
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Resolution |
Ability to distinguish between obkects on an image |
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Resolve power |
Resolving power depends on the wavelength or form of radiation used |
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Magnification-formula |
Magnification= size of image/size of object |
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Optical telescope |
Uses rays of light to pass through the specimen and produce an image on the retina of your eye |
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Transmission electron microsope |
Uses beams of electrons and use magnets to focus the electron beams |
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Scanning electron microscope |
-Type of microscope that produces images of a sample by scanning it with a focused beam of electrons -Used to visualise surface structures of an organism or cell -Beam is focussed by 1 or 2 condensed lenses |
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Advantages of optical telescope |
-Inexpensive -Easy to maintain -Easy to prepare specimens and view them |
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Disdvantages of optical telescope |
-Can only see large organlles in a cell |
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Advantages of SEM |
-Produces 3D image -Image bulk materials -Easy to use |
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Disadvantages of SEM |
-Resolutions not as good as TEM -Specimen preparation can produce artefacts -Only see the surface of the organelle |
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Advantages of TEM |
-Better resolution than SEM -Shorter wavelength so you can see details of the cell organelles |
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Disadvantages of TEM |
-Difficult to visualise structures -Produce black and white images -Expensive |
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Cell fractionation |
Cell fractionation allows you to seperate individual cell orgenelles |
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Homogenisation |
-Cells are broken up by a homgeniser (blender) -It releases organelles from the cell -Resultant fluid(homogenate) is filtered to remove any complete cells and large peices of debris |
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Ultracentrifugations |
-A process where fragments in the filtered homogenate are separated in a centrifuge(spins at a very high speed creating a centrifugal force) -The tube of filtrate is placed in the centrifuge and spun at a slow speed -Heaviest organelles, nuclei are forced to the bottom of the tube, where it forms a thin sediment -Fluid at top of the tube (supernatant) is removed, leaving the sediment of nuclei -The supernatant is transferred to another tube and spun in the centrifuge at a faster speed than before. -The next heaviest organelles, mitochondria are forced to the bottom of the tube -Process is continued |
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Order of ultracentrifugation |
-Nucleus -Chloroplast -Mitochondria -Endoplasmic reticulum -Golgi appartus -Ribosome |
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Cold solution? |
To reduce enzyme activity that might break down organelles |
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Buffered solution? |
So the PH doesn't fluctuate. Any change in PH can alter the structure of the functioning of enzymes |
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Isotonic solution? |
-Prevents osmosis -Prevent organelles from bursting or shrinking as a result of osmotic gain or loss of water |
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Prokaryotic cell structure |
-Cell wall -Capsule -Cell surface membrane -Circular DNA -Plasmid |
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Prokaryotic cell structure --->CELL WALL |
-Cell wall--->Protects against mechanical damage. --->Physical barrier that excludes certain substances |
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--->CAPSULE |
-Protects bacterium from other cells and helps groups of bacteria to stick together for further protection |
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--->CELL SURFACE MEMBRANE |
-Acts as a differentially permeable layer,which controls the entry and exit of chemicals |
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--->CIRCULAR DNA |
-Possesses genetic information for replication of bacterial cells |
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--->PLASMID |
-Possesses genes that may aid the survival of bacteria in adverse conditions. e.g produces enzymes that break down antibodies |
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Viruses |
-Acellular, non-living particles -Contains nucleic acids such as DNA but can only multiply inside living host cells -Nucleic acid is enclosed within a protein coat called capsid -Capsids have attachment proteins which are essential to allow virus to identify and attach to a host cell |
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Cell cycle |
3 stages--->Interphase --->Nuclear division --->Divsion of cytokinesis |
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Interphase |
Occupies most of the cell cycle, is sometimes known as resting phase because no division takes place |
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Nuclear division |
-When nucleus divides into 2(mitosis) or 4 (meiosis) |
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Division of cytoplasm |
-Follows nuclear divsion and is the process by which cytoplasm divides to produce 2 new cells (mitosis) or 4 new cells(meiosis) |
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G1 |
-Cellular contents excluding chromosomes are duplicated -Hence total cell mass and mass of DNA per cell increases |
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S |
DNA replication-46 chromosomes are duplicated by the cell -DNA mass increases and total cell mass increases too |
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G2 |
-The cells 'double checks' the duplicated chromosomes for error -Growth and preparation for mitosis -DNA mass doesn't increase but total cell mass increases |
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Mitosis |
-Produces 2 daughter diploid cells that have the same number of chromosomes as the parent cell and each other |
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Mitosis -1 |
-Division of a cell causes 2 daughter cells to have the same DNA as parent cell -Mitosis proceded by period where no divsion occurs called interphase |
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Interphase -1 |
Where cellular activity occurs. replication of DNA. The 2 copies of DNA after replication remain joined at the centromere |
