2.1 Cell structure Flashcards
What is a light microscope?
A microscope that uses visible light to magnify and observe small objects or organisms that are living.
What are the advantages of light microscopes?
You can view specimens in colour.
You can view specimens in real time.
What are the disadvantages of light microscopes?
It has a low magnification (*1500)
It has a low resolution (200mm)
It is difficult to see organelles of the cell.
How do you calculate magnification?
Magnification = image size / Actual size
What can you see with a light microscope?
Even at maximum magnification, it is only possible to observe the larger features of the cells such as the nucleus or chromosomes during mitosis.
What are the two different types of electron microscopes?
Transmission electron microscope
Scanning electron microscope
How does a transmission electron microscope work?
It uses electrons to produce 2D image of the inside of a cell. they have a maximum magnification of *200,000
How does a scanning electron microscope work?
It uses a beam of electrons to produce 3D images of the outside surface of cells. they have a maximum magnification of *200,000
What are the advantages of electron microscopes?
Higher resolution and magnification capabilities
What are the disadvantages of electron microscopes?
You can only view dead specimens
Specimens can be viewed only in black and white
Expensive and need training to use them.
What is a laser scanning microscope?
it uses lasers to produce images at different depths within the cell.
What are the advantages of laser scanning microscopes?
You can view living cells in colour,
You can observe cells in real time,
Sections can be made through the cell either vertically or horizontally.
What are the disadvantages of laser scanning microscopes?
Magnification and resolution are low compared to electron microscopes,
require training to use them,
Expensive
What is magnification?
The number of times greater the image is then the specimen.
What is resolution?
The ability to distinguish between two points on an image. the higher the resolution, the sharper the image.
What are the different types of microscopes?
Light microscopes,
Transmission electron microscope,
Scanning electron microscope,
Laser scanning microscope
How do you prepare a microscope slide?
Take a thin slice of your specimen and place it onto a clean microscope slide, add a drop of water or stain onto the specimen, take a clean cover slip and lower onto the specimen, taking care to avoid air bubbles.
Why are stains used?
To highlight particular organelle, e.g. red blood cells and white blood cells.
To distinguish different tissue types, e.g. smooth muscle tissue.
How do you use an eyepiece graticule?
Line up the eyepiece graticule and the stage micrometer, using the *4 objective lens. Once lined up you can use it to measure objects on the microscope stage.
What is the function of the nucleus?
The nucleus is the control centre of the cell, responsible for storing and protecting the cell’s DNA, and regulating gene expression and cell activities.
What is the function of the nucleolus?
Ribosome production
What is the function of the nuclear envelope?
Separates the nucleus from the cytoplasm and regulate the passage of molecules in and out of the nucleus
What is the function of mitochondria?
Energy production and site of respiration.
What is the function of the Golgi body?
Protein modification and packaging.
What is the function of the rough endoplasmic reticulum?
Contains ribosomes, transport proteins
What is the function of the smooth endoplasmic reticulum?
Lipid synthesis and detoxification
What is the function of the chloroplasts?
The function of the chloroplasts is to carry out photosynthesis, converting sunlight into chemical energy in the form of glucose.
What organelles do eukaryotic cells have?
They are animal, plant and fungi cells. They contain a nucleus, nuclear envelope and nucleolus, cytoplasm, cytoskeleton, plasma membrane, mitochondria, Golgi apparatus, RER, SER< small vesicles and ribosomes.
What is the function of the ribosomes?
Protein synthesis
What is the function of centrioles?
Cell division - chromosomes attach to spindle and pull them apart. they are involved in formation of cilia and undulipodia and absent in higher plants.
What is the function of the cytoskeleton?
Structural support and cell movement
What is the function of the cellulose cell wall?
It provides the cell walls of plants with support and strength, maintains the cells shape, contributes to strength and support of the whole plant, are permeable and allow solutions to pas through
How are proteins made?
they are produced by the nucleus and ribosomes by the processes of transcription and translation.
How are proteins produced?
Each gene in the nucleus codes for a particular protein. When the cell wants to make a protein, a messenger RNA (mRNA) copy is made of the gene. The mRNA moves out of the nucleus and travels to ribosomes on the rough ER. Ribosomes translate the mRNA and produce the protein. The protein travels through the rough ER and is packaged into vesicles to travel to the Golgi body.
What organelles do prokaryotic cells have?
Like eukaryotic cells they have a plasma membrane, cytoplasm, ribosomes for assembling amino acids into proteins, DNA and RNA. They also differ as they are much smaller, have less well-developed cytoskeleton with no centrioles, they don’t have a nucleus, the organelles aren’t membrane-bound and their cell wall is made of peptidoglycan.
