Cell structure Flashcards
(33 cards)
What is resolution?
The ability to distinguish two objects as separate from each other
Allows details to be see with clarity.
It’s determined by the wavelength of light or electron beam.
What is magnification?
The number of times an image is greater than the object.
It increases the ability to see details
State the resolution and magnification that can be achieved using a light microscope.
Magnification: x1500
Resolution: 200 micrometers
State the resolution and magnification that can be achieved using a transmission electron microscope.
Magnification: x500,00
Resolution: 0.1 nm
State the resolution and magnification that can be achieved using a scanning electron microscope.
Magnification: x100,000
Resolution: 0.1nm
Explain how samples are stained in a light microscope.
Uses a machine with metal knife to cut thin sections
Then placed on a glass slide
Uses dyes e.g iodine, methyl blue, acetic orcein
Explain how staining is used in TEM
Uses salts of heavy metals to absorb electrons after it has been sectioned using a diamond knife. It’s placed on a copper grid with a mesh.
Why do you need to stain samples?
It is necessary to give contrast between structures.
Stains are taken up differently by objects with different densities
What is the equation to calculate actual image size?
Actual image size = image size/magnification
Units must always be in micrometers!!!!
1mm = 1,000 micro metres 1cm= 10,000 micrometers
State the function and structure of the plasma membrane
Made of lipids and proteins and creates the outer surface of animal cells.
Used in cell signalling and regulates the movement of substances
State the function and structure of the cell wall
Made from cellulose network
Rigid structure that surrounds plant cells and prokaryotes and supports cell
State the function and structure of the centriole
Small hollow cylinder containing microtubules
Involved in separation of chromosomes in cell division
State the function and structure of the nucleus
Large organelle surprised by nuclear envelope contains many pores
Contains chromatin and often a structure called nucleolus
Pores allow RNA to move between the nucleus and the cytoplasm
State the function and structure of the lysosomes
A round organelle surrounded by a membrane with no clear internal structure
Contains digestive enzymes
Kept separate from the cytoplasm by the surrounding membrane
State the function and structure of the ribosomes
A very small organelles that floats free in the cytoplasm or is attached to RER
Site where proteins are made
State the function and structure of the mitochondria
Usually oval shaped or sausage shaped
Contains a matrix which have enzymes
The site of anaerobic respiration
Found in large numbers in cells that are very active eg muscle cells
State the function and structure of the smooth endoplasmic reticulum
Similar to REM except there are no ribosomes
Synthesises and processes lipids
State the function and structure of the REM
A system of membranes enclosing a fluid filled space
Surface is covered in ribosomes
Folds and processes proteins by adding sugar
State the function and structure of the cilia
Small hair like structures found in large numbers
Microtubules allow cilia to move substances along the wall
State the function and structure of the vesicles
A small fluid filled sax
Transports substances and between organelles
State the function and structure of the Golgi apparatus
Fluid filled flattened sacs
Processes and packages new lipids and proteins and also makes liposomes which are useful for transporting hydrophilic substances
State the function and structure of the chloroplast
A small flattened structure
Contains thylakoids and grana
Site where photosynthesis takes place
State the function and structure of the undulipodia
Like cilia but longer
Protrude from cell membrane
Propel the cell forward eg sperm
Outline a way in which organelles work together
Instructions to make a hormone are in the DNA in the nucleus. That hormone can be a protein.
The specific instruction to make that protein is in a gene on a chromosome in the DNA.
The Nucleus copies the information from the DNA to the mRNA which leaves the nucleus through a pore on the envelope
The mRNA attaches itself to a ribosome on the RER
The ribosome uses the information to process the protein using codes and amino acids
The assembled protein is pinched off in a vesicles an transported to the Golgi apparatus
The Golgi packages the protein and can also modify it so it is ready to release
The protein is now packaged into vesicle and moved to the cell surface membrane, where it is secreted outside
