Cell Structure Flashcards
Electron micrograph
Photograph of an image seen using an electron microscope
What is magnification
The number of times larger an image appears, compared with the size of the object
What is the formula for magnification
Magnification = size of image / size of real object
What are organelles
Small structures within cells, each of which has a specific function
What is a photo micrograph
Photograph of an image seen using an optical microscope
What is resolution
The smallest distance at which separate objects can be distinguished
What does the cell theory state
- all living things are composed of cells
- the cell is the smallest unit of life
- cells only arise from pre-existing cells
How does a light/optical microscope work
Uses visible light which is reflected through a specimen
What type of image is produced by an optical microscope
Magnified image of the object
- 2D
- colored
- magnification limit = 1000x
- resolution limit = 200nm
What are the pros of optical microscopes
- cheap
- small
- portable
- living specimens
- colored image
Cons of optical microscopes
- poor resolution
- can’t view organelles
How do transmission electron microscopes (TEM) work
- specimen is dehydrated and stained
- electron beams them pass through
What type of image is produced by a TEM
- 2D image
- black and white image
- magnification limit = 5,000,000x
- resolution limit = 1nm
What are the pros of TEM
- high magnification
- excellent resolution
Cons of TEM
- no living specimen (vacuum)
- black and white
- complex staining process
- artifacts can result
- large
- expensive
- need skill and training to use
How do scanning electron microscopes (SEM) work
- electrons are shot at the specimen
- electrons don’t pass through
- electrons ‘bounce of’
What type of image does a SEM produce
- 3D image
- black and white (programs can add colour)
- magnification limit = 30,000x
- resolution limit = 10nm
Pros of SEM
- 3D image
- don’ need a thin section
- high magnification
Cons of SEM
- can’t view internal structures
- not as high resolution as TEM
- specimen has to be in a vacuum with a thin layer of metal
- needs skill and training to use
- large
- expensive
How do scanning laser confocal microscopes work
- uses fluorescent tags (molecules that can be attached to certain things)
- uses laser light to scan an object
- object is displayed on a computer screen
What type of image is produced by a laser scanning confocal microscope
- high resolution to show high contrast
- view movement
- view an object a certain depth within a cell/sample
What are the pros of scanning laser confocal microscopes
- can focus on objects at different depths
- can observe cells as well as whole objects
- used in medical profession
- can use living specimens
Cons of laser scanning confocal microscopes
- resolution lower than SEM
- very expensive
- limited number of wavelengths
Why do electron microscopes have a higher resolving power
- light microscopes use a light beam to view the specimen
- light beams have a long wavelength
- low resolution
- electron microscopes use beams of electrons
- electrons have a short wavelength
- high resolution
What are the different parts of a light microscope
- eyepiece
- tube
- arm
- objective lens
- stage
- sample clamps
- corse focus
- fine focus
- light
- base
Steps to making a slide
- sharp blade to cut a thin slice of tissue
- use the thinnest slide allowing for max light to get through
- wet mount to prevent dehydration
- place stain at the edge of the sample
- lower cover slip at an angle
- use blotting paper to get rid of any extra
- use more then one stain to improve contrast
- squash slide to easier see individual cells
Why do you use stain
- increase contrast
- identify named organelles/ more visible
- clear image
What is differential staining
- allows for more contrast
- distinguishes different organelles
What does iodine let you see
- light
- blue/black
Stains starch containing tissues
What does methylene blue allow you to see
- light
- blue
Stains nuclei of animal cells
What does to toluidine blue let you see
- light
- various
Metachromatic stain, reacts with different compounds to give different colours
What does gold/osmium allow you to see
- electron
- B&W
Electron-dense heavy metal stain used to absorb electrons
What does eosin allow you to see
- light
- purple
Proteins (cytoplasm)
What does sudan red allow you to see
- light
- red
Cell membrane
What does phalloidin allow you to see
- light
- green
Cytoskeleton
What does acetic orcein allow you to see
- light
- red
Stains nucleon of animal cells
What does gram allow you to see
- pink or purple
Bacteria
What is the mnemonic for drawing biological drawings
PILATES
What does PILATES stand for
Pencil
Individual cells (do not draw)
Lines
Annotate
Title
Enormous
Scale
What is an eyepiece graticule
A measuring device. It is placed in the eyepiece of a microscope and acts as a ruler when you view an object under the microscope
What is a stage graticule
A precise measuring devise. It is a small scale that is placed on a microscope stage and used to calibrate the value of eyepiece divisions at different magnifications.
What structures are found in eukaryotic animal cells
- nucleus
- nucleolus
- mitochondrion
- free ribosomes (80S)
- endoplasmic reticulum (rough/smooth)
- Golgi body
- vesicles
- lysosomes
- flagellum
- cilia
- centrioles
- cytoskeleton
What is the function on the nucleus, nuclear envelope and nucleolus
- separate nucleus from rest of cell
- allow for some dissolved substances and ribosomes through
- pores allow large substances to leave or enter the nucleus
- ribosomes are made in the nucleolus
- contain chromosomes
What is the function of the mitochondria
- ATP production in aerobic respiration
- self replicating
- abundant in necessary cells
What is the function of ribosomes
- protein synthesis
What is the function of the endoplasmic reticulum
Rough
- intracellular transport system
- large surface area for ribosomes
Smooth
- contain catalyst enzymes
- involved in absorption, synthesis and transport of lipids
What is the function of the Golgi body
- proteins are modified (sugar, lipids, 3D forms)
- proteins packed into vesicles which are stored or moved to plasma membrane
What is the function of vesicles
- transport materials from inside the cell
- transport = inside cell
- secretory = outside cell
What is the function of lysosomes
- separate hydraulic enzymes from the rest of the cell
- engulf old organelles/foreign matter and digest them
What is the function of the flagellum
- allows the cell to move
What is the function of the cilia and undulipodia
- beat and move the band of mucus
- nearly all cells have one acting as an antena
- movement
What is the function of the centrioles
- cell division
Organelles that are found in eukaryotic plant cells
- nucleus
- nucleolus
- mitochondria
- ribosomes (80S)
- endoplasmic reticulum
- Golgi apparatus
- vesicles
- lysosomes
- flagellum
- cilia
- chloroplasts
- permanent vacuole
- amyloplasts
- cell wall
- plasmodesmata
What is the function of the chloroplast
- photosynthesis
What is the function of the permanent vacuole
- stores cell sap
- provides structure to cells
What is the function of the amyloplasts
- stores amylopectin
What is the function of the plasmodesmata
- cytoplasmic extensions
- produced as cells divide
What is the function of the cell wall
- provide strength and support
- maintain the cell’s shape
What is the cytoskeleton made form
- microtubules
- actin filaments
- intermediate filaments
What is the function of the cytoskeleton
- provides strength
- transport within cells
- allows for cell movement
How does protein synthesis take place
- transcription takes place in the nucleus
R.E.R - protein synthesis - proteins are folded
- transport vesicle carries these protein along the cytoskeleton
- modification takes place in the Golgi body
- secretory vesicles carry theses proteins out of the cell
- exocytosis
Similarities between prokaryotic and eukaryotic cells
Both have
- plasma membrane
- cytoplasm
- ribosomes
- DNA and RNA
Differences between eukaryotic and prokaryotic cells
Prokaryotic cells
- much smaller
- have less well-developed cytoskeleton
- no centrioles
- no nucleus
- no membrane bound organelles
- peptidoglycan cell wall (not cellulose)
- smaller ribosomes
- naked DNA
What else do some prokaryotic cells have
- protective waxy capsule around cell wall
- small loops of DNA (plasmids)
- flagella
- pili
What is a pili
- smaller hair-like projection
- enables bacteria to adhere to host cells
- allows passage of plasmid DNA from one cell to another
