2 Basic components of living systems Flashcards
(36 cards)
How is a dry mount prepared?
- Solid specimens are viewed whole or cut into very thin slices (sectioning)
- Specimen is placed on the centre of slide and a cover slip is placed over sample
How is a wet mount prepared?
- Specimens are suspended in a liquid such as water or an immersion oil.
- A cover slip is placed on from an angle.
- E.g aquatic samples can be viewed this way
What is a squash slide?
1) A wet mount is first prepared
2) The sample is squashed between two slides
E.g root tip squashes used to look at cell division
What is a smear slide?
1) The edge of a slide is used to smear the sample creating a thin even coating
2) A cover slip is then placed over the sample
E.g sample of blood to view cells in blood
What is resolution?
The ability to see individual objects as seperate entities.
What is magnification?
Magnification is how many times larger the image is than the actual size of object being viewed.
How do you calculate magnification?
Size of object/actual side of object
Image/Actual
How many micrometers in 1 millimetre?
1000
How many nanometers in 1 micrometer?
1000
What is electron microscopy?
- Where a microscope employs a beam of electrons to illuminate the specimen.
- Produces black and white images
What are the two types of electron microscope?
Transmission electron microscope, scanning electron microscope
What is a transmission electron microscope?
- A microscope where a beam of electrons is transmitted through specimen and focused to produce image.
- Best resolution (better than SEM) with resolving power of 0.5nm.
What is a scanning electron microscope?
- A microscope where a beam of electrons is sent across surface of specimen and reflected electrons are collected.
- Resolving power from 3-10nm.
- Produces 3D images
What is a laser scanning confocal microscope?
A microscope that employs a laser beam and a pin-hole aperture to produce an image with a very high resolution.
- Used in diagnosis of diseases in eyes
What is the nucleus?
- The nucleus contains coded genetic information in the form of DNA molecules.
- DNA directs the synthesis of proteins required by the cell.
- Controls metabolic activities of the cell
What does the nuclear envelope & pore do?
- The nuclear envelope protects the DNA from damage in cytoplasm.
- The nuclear pores allow RNA molecules to leave the nucleus for protein synthesis
What is the nucleolus?
- An area within the nucleus and is responsible for producing ribosomes.
What are mitochondria?
- The site of cellular respiration
- Has a double membrane
- Inner membrane folded to form cristae
- The fluid is called the matrix
What are vesicles?
Membranous sacs that are used to transport materials in the cell
What are lysosomes?
- Specialised forms of vesicles that contain hydrolytic enzymes.
- Responsible for breaking down waste material in cells, even old organelles
- Plays an important role in immune system as they are responsible for breaking own pathogens.
What is the cytoskeleton?
- A network of fibres necessary for the shape and stability of a cell.
- Responsible for cell movement, cell contraction. movement of organelles
What are the three components of a cytoskeleton?
1) Microfilaments- Made from protein called actin. Responsible for cell movement and contraction during cytokinesis
2) Microtubules- Determines shape of the cell, spindle fibres are made from microtubules, track movement or organelles around cell
3) Intermediate fibres- These fibres give mechanical strength to cells and help maintain their integrity.
What are centrioles?
- Component of the cytoskeleton composed of microtubules
What is endoplasmic reticulum?
A network of membranes enclosing flattened sacs called cisternae, connected to the outer membrane of the nucleus.
