Unit 1 Flashcards
(30 cards)
What is the resolution and magnification of a TEM (Transition Electron Miscroscope) ?
Resolution - 0.1nm
Magnification - x500,000
What is the resolution and magnification of a SEM? (Scanning Electron Microscope) ?
Resolution - 0.1nm
Magnification - x100,000
What’s the difference between SEM and TEM?
SEM gives a 3D picture and cell surfaces can be seen
TEM gives a 2D picture allows details of the organelles to be seen
What is magnification?
Magnification is the number of times larger the image is compared to the object
What is resolution?
Resolution is the degree to which it is possible to distinguish between 2 objects that are very close together. It allows to see detail.
What is staining samples needed for the use of light and electron microscopy?
Biological material isn’t coloured so it’s difficult to distinguish the features of a cell.
Iodine or methylene blue are used for staining
White blood cells cannot be seen without staining
What is the equation of Magnification?
Image size / actual size
Describe how the organelles are involved in the production and secretion of proteins
1) The gene containing the instructions for the production of the hormones is copied onto a piece of mRNA
2) mRNA leaves the nucleus through the nuclear pores
3) mRNA attaches to a ribosome
4) Ribosome reads the instructions to assemble the protein
5) Molecules are pinched off in vesicles from the Golgi apparatus and move towards the cell surface membrane
6) Vesicle fuses with Golgi apparatus
7) Golgi apparatus processes and packages the molecules ready for release
8) Molecules are pinched off in vesicles for the Golgi apparatus and move towards the cell surface membrane
9) Vesicles fuse with cell surface membrane
10) Cell surface membrane opens to release molecules outside by exocytosis
What is the importance of the cytoskeleton within the cell?
Provides strength, stability and support to cells
Determines the shape and changes the shape by moving the membrane for endo and exocytosis
Holds organelles in place
They make up centrioles and sprinkle fibres
They allow whole cells to move using cilia and flagella
What is the difference between prokaryotic cells and eukaryotic cells?
Prokaryotic don’t have a true nucleus
They don’t have membrane bound organelles
Cell wall made of peptidoglycan not cellulose
Smaller ribosomes
ATP occurs in mesosomes
What is the difference between plant and animal cells?
Plant cells have a cell wall and it is made of cellulose
Plant cells also have a permanent vacuole which maintains the cells stability by making it turgid as it increases the pressure inside the cell.
What is the resolution and magnification of a light microscope?
Resolution - 200nm
Magnification - x1500
Outline the roles of membranes at the surface of cells
Separate cell contents from the outside environment
Cell recognition and signalling
Regulating the transport of materials into and out of the cell
Outline the roles of membranes within cells
Form organelles
Isolate the contents of the organelles and form metabolic pathways
Site for attachment of enzymes and ribosomes
Creation of concentration gradients
What is a plasma cell surface?
Membranes are partially permeable barriers
Describe the role of a phospholipid
It has a hydrophobic head and a fatty acid tail. They form a bilayer.
They are fluid so components can move around freely. They act as a barrier selecting what goes in and out of the cell. They are permeable to small non polar molecules , but impermeable to large molecules and ions.
Describe the role of cholesterol
Gives the membrane stability
Describe the role of glycolipids
They are used for cell signalling, cell surface antigens and cell adhesions
Describe the role of proteins
Channel proteins allow the movement of some substances such as large molecules
Carrier proteins actively move substances across the cell surface membrane
What is the role of glycoproteins
They are protein molecules with a carbohydrate attached.
They act as antigens
Enable the identification of cells as self or non self
Used in cell signalling
Act as receptors or binding sites for hormones
They have a specific shape that is complimentary to the shape of the communicating molecules which binds to the receptor
Allow cell adhesion to hold cells together in a tissue
How does changing the temperature affect he surface membrane?
Increasing the temperature means the the molecules gain more kinetic energy which increases its permeability.
The membrane structure is disrupted as the phospholipid bilayer melts.
Membrane proteins and carrier proteins denature and are unable to function.
What is meant by cell signalling?
Process that leads to communication and coordination between cells
What is the function of the squamous epithelium?
To provide a thin surface for a short diffusion distance
What is thee function of elastic tissue in the gas exchange system?
Allows walls to stretch and recoil
