Basic components of living things

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Describe the gram stain technique
Used to differentiate between gram + and - bacteria, crystal violet and iodine are added to slide which is then washed with alcohol, +=blue/purple, negative then stained with safranin=red
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Describe the acid fast staining technique
Differentiates different species of mycobacterium from other bacteria, lipid solvent carries carbolfuchins into cells, then washed with dilute acid-alcohol solution, mycobacterium= red, other bacteria lose stain and then exposed to methylene blue
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Fixing
Chemicals like formaldehyde are used to preserve specimens in as near natural state as possible
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Sectioning
Specimens are dehydrated with alcohols and then placed in a mould with wax or resin to form a hard block which can then be sliced thinly with a knife called a microtome
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Staining
Specimens are often treated with multiple stains to show different structures
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Mounting
Specimens are secured to a microscope slide and a coverslip placed on top
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Magnification formula
Size of image divided by actual size of object
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Magnification
How much bigger the image size is in comparison to the object
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Resolution
The ability to distinguish between two given points
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Light microscope advantages and disadvantages
Coloured image, cheaper, smaller and more portable, samples alive, lower resolution and magnification
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TEM advantages and disadvantages
Higher resolution than the other (0.5nm), powerful magnification, only used on thin specimens, must be placed in vacuum, black and white images produced
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SEM advantages and disadvantages
Can be used on thick specimens, 3D image, expensive, large, lower resolution that TEMs (3-10nm)
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How does a laser scanning focal microscope work
Moves a single spot of focused light across a specimen, this causes fluorescence from dye labelled components
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LSCM advantages and disadvantages
Both 2D and 3D images, higher intensities because of laser used which improves illumination
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Prokaryotic
Single celled organisms with a simple structure of a single undivided internal area called the cytoplasm
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Eukaryotic
Make up multi-cellular organisms with a much more complicated internal structure, containing a membrane bound nucleus and cytoplasm which contains many membrane bound organelles
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Nucleus
Contains genetic info, biggest single organelle in the cell
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What forms chromosomes
DNA associates with a protein called histones which together form a complex called chromatin which coils and condenses to form chromosomes
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Nucleolus
Produces ribosomes, composed of proteins and RNA
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Mitochondria
Site of the final stages of aerobic respiration, double membrane, contain a small amount of their own DNA called mtDNA, can also produce their own enzymes and reproduce themselves
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Vesicles
Membraneous sacs that have storage and transport roles, single membrane with fluid inside, transports material inside the cell
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Lysosomes
Specialised form of vesicles that contain hydrolytic enzyme, break down waste material in cells, and pathogens
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Cytoskeleton
Present throughout the cytoplasm of all eukaryotic cells, network of fibres necessary for the shape and stability of a cell, holds organelles in place
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Microfilaments
Contractile fibres formed from the protein actin, responsible for cell movement and cell contraction during cytokinesis
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Microtubules
Globular tubulin proteins polymerise to form tubes that are used to form scaffold-like structure that determines the shape of a cell, a track for the movement of organelles, spindle fibres are made up of microtubules
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Intermediate fibres
Give mechanical strength to cells and help maintain their integrity
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Centrioles
Component of the cytoskeleton, composed of microtubules, two associated centrioles form a centrosome which assembles and organises the spindle fibres during cell division
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Flagella and cilia
Extensions that protrude from some cell types, flagella are longer but cilia are typically present in larger numbers, flagella enables motility and can detect chemical changes in the cell environment, cilia can be mobile or stationary
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Endoplasmic Reticulum
Network of membranes enclosing flattened sacs called cisternae, smooth ER is responsible for lipid and carb synthesis and storage, rough ER is responsible for the synthesis and transport of proteins
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Ribosomes
Can be free floating in the cytoplasm or attached to rough ER, not surrounded by a membrane, instructed of RNA molecules made in the nucleolus, site of protein synthesis
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Golgi body
Similar in structure to smooth ER, compact structure formed of cisternae and contains no ribosomes, modifies and packages proteins
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Protein production
Synthesised on ribosomes bound to rough ER, pass into the cisternae and are packaged into vesicles
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Name of the vesicles that carry proteins to be released from the cell?
Secretory vesicles
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What are cell walls in plants mostly made up of
Cellulose
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Features of plant cell walls
Freely permeable, provide the structure of the cell, acts as a defence mechanism
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What are prokaryotic cell walls made from
Peptidoglycan/ murein
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What are vacuoles
Membrane lined sacs in the cytoplasm containing cell sap
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Chloroplasts
Responsible for photosynthesis, found in leaves and stems, double membrane structure with fluid enclosed (stroma), internal network of membranes form flattened sacs called thylakoids,
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Where do light dependent reactions occur?
Grana, in the chlorophyll pigments
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Can chloroplasts make their own proteins?
Yes because they have their own DNA and ribosomes
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Other cards in this set

Card 2

Front

Describe the acid fast staining technique

Back

Differentiates different species of mycobacterium from other bacteria, lipid solvent carries carbolfuchins into cells, then washed with dilute acid-alcohol solution, mycobacterium= red, other bacteria lose stain and then exposed to methylene blue

Card 3

Front

Fixing

Back

Preview of the front of card 3

Card 4

Front

Sectioning

Back

Preview of the front of card 4

Card 5

Front

Staining

Back

Preview of the front of card 5
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