2.1 - Cell Structure Flashcards
What is magnification?
It is how many times bigger an image is compares to its actual size
What is resolution?
It is the ability to differentiate between two points
What are the pros of a (optical)light microscope?
- Relatively cheap
- Easy to use
- Portable, can be used in the field
- Can study living specimen or dead specimen
- Clearly see some of the larger structures in cells
- Fast preparation
What are the cons of a (optical) light microscope?
- Low resolution so they are unable to look at small organelles clearly eg. Ribosomes
What is a light microscope used to look at?
It can be used to view both living and dead specimens.
How does a light microscope produce an image?
It uses a glass lenses to focus the light to produce an image on the retina
How does an electron microscope work?
An electron beam is fired at a specimen and they are focussed by electromagnets, this happens in a vacuum.
Why is an electron microscope in a vacuum?
It is in a vacuum so that the electrons don’t collide with air particles.
What is used to stain specimen for an electron microscope?
Heavy metals like uranium or lead.
What is an electron microscope used to look at?
Small organelles and internal structures in dead specimen
What are the two types of electron microscopes?
-Transmission electron microscopes(TEM)
-Scanning electron microscopes(SEM)
What is the difference between a TEM and an SEM?
TEM:
-Electrons pass through the specimen
-Magnification is up to x500,000
-Resolution is up to 0.5nm
SEM:
-Electrons reflected off of the surface of the specimen
-Magnification is up to x100,000
-Resolution is between 3-10nm
What is a dry mount?
When the specimen is just covered by the cover slip
What is a wet mount?
When the specimen has water or a stain added to it before the cover slip is put on
What is a squash mount?
A wet mount that is the pushed down so there is only a thin layer for the light to pass through
What is a smear mount?
When the edge of another slide is used to smear the sample to create a thin and even layer, a cover slide is then added(usually blood).
What are an eyepiece graticule and a stage micrometer used for?
Calibrating a microscope
How do you calibrate a microscope?
1) Line up the stage micrometer and the eyepiece graticule whilst looking through the eyepiece
2) Count how many divisions on the eyepiece graticule fit into one division on the micrometer
3) This can be used to work out what one division on the eyepiece graticule is worth on the current magnification
Example of microscope calibration
One division on the micrometer=10um
Micrometer - 1 division(10um)
Stage graticule - 2 divisions
10/2=5um
What is the magnification calculation?
Size of image / Actual size
I.
A. M.
What are crystal violet and methylene blue?
Chemical stains that are positively charged, so are attracted to any negatively charged materials
What is gram staining?
-It is where you use crystal violet and saffron.
-Crystal violet turns gram positive bacteria blue/purple
-Saffron turns gram-negative bacteria red
Why is gram staining important?
It helps medics know what antibiotics to prescribe
What is a laser scanning microscope?
A microscope that uses a fine laser to illuminate the specimen
What is used to stain specimen for a laser microscope?
Fluorescent dye
What are the pros of laser scanning microscopes?
-High resolution
-Depth selectivity
-View sections of tiny structures
-Creates a 3D image
What are the cons of a laser microscope?
- Expensive
What are the cons of both electron microscopes?
- They are both expensive
- They require a lot of training
What ave eukaryotic cells?
Eukaryotic cells are membrane bound organelles.
What are types of eukaryotic cells?
- Animal cells
- Plant cells
What are features of an animal cell?
- Mitochondria
- Centriole
- Lysosome
- Golgi body
- Plasma membrane
- Nucleus
- Nucleolus
- Nuclear envelope
- Ribosomes
- Rough endoplasmic reticulum (RER)
- Smooth endoplasmic reticulum (SER)
What are the features of a plant cell?
- The same as an animal cell
- Cellulose cell wall
- Permanent vacuole
- Chloroplasts
What is the function of mitochondria?
It is where aerobic respiration takes place so it can release energy to be used in the cell
What is the function of a centriole?
Pulls the chromosomes/chromatids to the opposite poles of the cells in mitosis and meiosis
What is the function of a lysosome?
It is a for of vesicle that contains hydrolytic enzymes (digestive enzyme) because it digest things inside the cell
What is the function of the Golgi body/apparatus?
It processes and packages proteins
What is the function of the plasma membrane?
It controls the movement of substances in and out of the cell
What is the function of the nucleus?
It contains the cells DNA
What is the function of the nucleolus?
It contains RNA for protein synthesis
What is the function of the nuclear envelope?
it separates its contents from the rest of the cell
What is the function of ribosomes?
It is the site of protein synthesis
What is the function of the rough ER?
It synthesises and packages proteins
What is the function of the smooth ER?
- It synthesises lipids and carbohydrates
- Contains enzymes that catalyse reactions involved with lipid metabolism
What is the function of a cellulose cell wall?
It provides strength and structure to the cell
What is the function of a permanent vacuole?
It contains water and solutes that make the cell turgid (swollen)
What is the function of a chloroplast?
Site of photosynthesis (contains chlorophyll to absorb the light needed)
What is a prokaryotic cell?
A cell that does not contain a nucleus
What are types of prokaryotic cells?
- Bacteria
- Archaea
What are features of a prokaryotic cell?
- Plasma membrane
- Peptidoglycan cell wall
- Ribosomes
- Plasmids
- Cilia
- Flagellum
- Cytoplasm
What is a plasmids?
A single loop of DNA
What is cilia?
Hair-like structure that is found on the membrane
What is the function of the flagellum?
A tail that spins to allow mobility
What is the function of cytoplasm?
- The site of chemical reactions
- What the organelles are surrounded by
What is a cytoskeleton?
Proteins and fibres that are need for cell shape and stability
What are the three things that make up the cytoskeleton?
- Microfilaments
- Microtubules
- Intermediate fibres
What are microfilaments used for?
They are used in cell movement (contract the cell in cytokinesis)
What are microtubules used for?
- They give the cell structure and its shape
- They act as tracks for organelles to move around on
What are intermediate fibres used for?
- They give the cell its strength
- Helps maintain its integrity
How do organelles work together to make proteins?
- mRNA copy is made in the nucleus
- mRNA leaves the nucleus through the nuclear pores
- mRNA attaches to the ribosomes on the rough ER so that the ribosomes can read the instructions and assemble the protein
- The protein is then pinched off in a vesicle and travels to the golgi body
- The vesicle fuses with the golgi body
- The golgi body processes and packages the protein ready for it to be released
- The protein is then pinched off into another vesicle that fuses with the plasma membrane so the protein can be released
How doe yeast divide?
Budding
Does yeast contain a nucleus?
Yes
What is the cell wall in yeast made of?
Chitin
Does yeast contain ribosomes?
Yes
