2.1 cell structure Flashcards
Name the 4 types of microscopes.
Optical microscope
Transmission electron microscope
Scanning electron microscope
Laser scanning confocal microscope
What is an optical microscope?
It produces a 2D image and visible light passes through the specimen.
What is a transmission electron microscope?
Electrons pass through a specimen to a detector. Produces a 2D image
What is a scanning electron microscope?
Specimen is coated in metal, electrons scan across surface and electrons bounce off to detectors. Produces a 3D image.
What is a laser scanning confocal microscope?
Laser scans across specimen but scans at different depths to view different layers. Produces a 3D image of interior.
Pros of optical microscopes.
Can view living organisms.
Cons of optical microscopes.
Lower resolution and magnification than electron microscope.
Pros of electron microscopes.
Higher resolution and magnification
Scanning electron microscope produces 3D images.
Cons of electron microscopes.
Thin specimen required
Can only view dead specimens
Complicated processing which can result in artefacts.
Pros of laser scanning confocal microscopes.
Can view living organisms
3D images
Higher resolution than optical microscope
Cons of laser scanning confocal microscopes.
Lower resolution than electron microscopes.
What does resolution mean?
Smallest distance apart where 2 objects are seen as separate.
How can you increase contrast?
By adding a stain. (differential stain)
What is the magnification equation?
Image size = actual size x magnification
What is a graticule?
A ruler which is fitted into the eyepiece of a microscope.
Why do we use graticules?
Used to measure specimens.
What is a stage micrometer?
Microscopic ruler on a microscope slide.
What does the nucleoplasm do?
Chemical reactions take place.
What does the nuclear membrane do?
Breaks up the DNA from cytoplasm.
What does the nucleolus do?
It is a dense region of RNA
What do nuclear pores do?
Allow transport between nucleus and cytoplasm.
What does the matrix in mitochondria do?
A liquid where chemical reactions take place.
What do 70S proteins do?
Site of protein synthesis.
What does circular DNA do?
Contains genetic info.
What does the outer and inner mitochondrial membrane do?
Create a partially permeable membrane.
What do ribosomes do in the RER?
Copy of a gene passes through them and it reads the code to make the protein.
Why do RER have a large surface area?
For protein synthesis.
Why happens in the golgi apparatus?
Protein from the RER passes through layers of the golgi and the protein pinches off and is enclosed in a vesicle.
What is the role of the smooth endoplasmic reticulum?
Produces lipids and carbohydrates?
What is a vesicle?
An organelle which transports substances around, into or out of cells.
What is a lysosome?
Vesicle containing digestive enzymes.
Name the 7 features of chloroplasts.
Inner membrane Outer membrane Stroma Granum Thylakoids Integranal lamellae Inter membrane compartment
Chloroplasts are the site of what?
Photosynthesis
Role of the vacuole?
Support the plant
It’s surrounded by a membrane called the tonoplast.
Function and features of ribosomes.
Made of ribosomal RNA
Made in nucleolus
Protein synthesis.
Role of centrioles?
Contain microtubules which are made of tubulin protein.
Before the cell divides the spindle, made of threads of tubulin, forms the centrioles.
Centrioles form cillia & undulipodia.
Role of cilia and undulipodia?
Contain microtubules
Formed by centrioles
Cilia: move materials along surface of cell
Undulipodia: moves cell itself
Role of cytoskeleton?
Protein microfilaments give support and mechanical strength.
Role of cellulose cell wall
Strength, support, shape
Role of flagellum?
Allow bacteria to move.
Role of pili?
Small, hair like structures that allow bacteria to adhere to each other or to host cells.
What is the nucleoid?
Circular DNA
What is a plasmid?
A DNA loop.
Name the 8 structures oh prokaryotes?
Capsule Ribosome Flagellum Pili Plasma membrane Nucleoid Plasmid Peptidoglycan cell wall
