• Created by: Laellex
  • Created on: 01-04-16 18:57
What are microscopes?
Instruments that provide a magnified image of an object
1 of 77
What is the resolving power of light microscopes?
2 of 77
Resolving power of electron microscopes?
3 of 77
Why do electron microscopes have a greater resolving power?
Because electron beams have shorter wavelengths than light rays
4 of 77
What is resolution?
The minimum distance apart 2 objects can be in order to appear as separate items
5 of 77
What is magnification?
How many times bigger an image produced is compared to the object under the microscope
6 of 77
Greater resolution means what?
More detail and greater clarity of the image produced
7 of 77
What happens if you increase magnification?
The image increases in size, and more detail is revealed
8 of 77
What happens if you increase magnification beyond the resolving power of a microscope?
The object appears bigger, but blurred
9 of 77
What is cell fractionation?
A process where cells are broken up and organelles isolated
10 of 77
What is the purpose of cell fractionation?
To study the structure and function of various organelles
11 of 77
Why is the solution buffered?
To prevent fluctuation of pH, which may affect the cells structure and enzymes activity
12 of 77
Why is the solution cold?
To reduce enzyme activity that may break down organelles
13 of 77
Why is the solution isotonic?
To prevent the cells from bursting/shrinking as a result of osmotic gain/loss of water
14 of 77
What are the 2 stages in cell fractionation?
Homogenation & ultracentrifugation
15 of 77
Why is the solution homogenised?
Blended: to break cells and release organelles & Filterd: to remove large pieces of debris and unbroken cells
16 of 77
What is the basis of ultracentrifugation?
Centrifugal force + densities of organelles
17 of 77
Order of most dense organelles to least?
Nucleus, (chloroplasts in plants), mitochondria, other organelles
18 of 77
Advantages of the TEM?
High resolution images + allows you to see the ultra structure of cells
19 of 77
Disadvantages of the TEM?
Specimen must be thin, complex staining process, must be in a vacuum, resolution of 0.1nm is not always achieved
20 of 77
Advantages of SEM?
Produces a 3D image, specimen doesn't need to be thin
21 of 77
Disadvantage of SEM?
Has a lower resolution than TEM's of 20nm
22 of 77
Examples of eukaryotic cells?
Animal, plant, fungal and algal cells
23 of 77
What additional features do plant cells have (compared to animal cells)?
Cellulose cell wall, chloroplasts + vacuole
24 of 77
What are fungal cell walls made of?
25 of 77
What do fungal cells not have, why?
Chloroplast- as they don't photosynthesise
26 of 77
What is differentiation?
How genetically identical embryonic cells mature and become specialised to perform specific functions
27 of 77
Which type of organisms have cells that become specialised?
Eukaryotes/multicellular organisms
28 of 77
How does specialisation occur?
A specific combination of genes in a cell are expressed (switched on) and others repressed (switched off)
29 of 77
What structural differences make a cell better adapted to its function?
Number of each organelle + shape of cell
30 of 77
What is a tissue?
A group of similar cells that work together perform a specific fucntion
31 of 77
Two examples of tissues?
Epithelial tissue, xylem
32 of 77
What is an organ?
A combination of tissue that work to perform a specific function
33 of 77
Why are capillaries not organs, whilst arteries and veins are?
Because arteries and veins are made up of a combination of tissues, while capillaries are made up of just one
34 of 77
What is an organ system?
A group of organs collectively working to perform particular functions more efficiently
35 of 77
Examples of organ systems?
Digestive system, circulatory systems, respiratory system
36 of 77
Examples of prokaryotes
Bacteria and viruses
37 of 77
How are prokaryotes different to eukaryotes?
Smaller, no distinct nucleus, no membrane-bound organelles, smaller ribosome (70s)
38 of 77
What are bacteria cells successful at?
39 of 77
What is the cell wall of bacteria made of?
Murein; a polymer of polysaccharides and peptides (peptidoglycan)
40 of 77
What do bacteria secrete for protection?
A capsule of mucilaginous slim around the murein wall
41 of 77
What does the capsule also allow?
Bacterial cells to attach together for added protection
42 of 77
What are plasmids?
Small, circular pieces of DNA
43 of 77
What other use do plasmids have?
They are vectors for genetic engineering
44 of 77
What do plasmids do?
They give the bacteria resistance to harmful chemicals e.g. They produce enzymes that break down antibiotics
45 of 77
Bacterial cells don't have a distinct nucleus, instead...?
A circular strands of DNA
46 of 77
What does the circular strand of DNA contain?
The genetic information for replication
47 of 77
What are viruses?
Acellular, non-living particles
48 of 77
What do viruses consist of?
Nucleic acids (DNA or RNA) surrounded by a protein coat- capsid
49 of 77
What is the virus HIV further surrounded by?
A lipid envelope
50 of 77
Where do viruses replicate?
Inside a host cell of another organisms
51 of 77
How do they attach to host cell?
By attachment proteins on their surface
52 of 77
What do attachment proteins also allow?
Viruses to identify host cells
53 of 77
Before mitosis what process occurs?
Interphase- DNA replicates and remains joined at centromere
54 of 77
Which type of organisms cells undergo mitosis?
55 of 77
What is mitosis?
Cell division that produces 2 daughter cells genetically identical to the parent cell
56 of 77
What is mitosis part of?
The cell cycle
57 of 77
What are the 4 stages of Mitosis?
Prophase, metapahse, anaphase, telophase + cytokinesis
58 of 77
What type of cell division occurs in prokaryotic cells?
Binary fission
59 of 77
What results from binary fission?
2 genetically identical daughter cells. Each having a single circular DNA strand and a variable number of plasmids
60 of 77
Why can't viruses undergo cell divison?
Because they are non-living
61 of 77
How do viruses replicate?
By attaching to a host cell by their attachment proteins and injecting their viral nucleic acids
62 of 77
How do the viral nucleic acids affect the host cell?
The genetic info (DNA/RNA) provides instructions for the host cells metabolic processes. They start producing viral components which are assembled to make new viruses
63 of 77
In multicellular organisms, do all cells have the ability to divide?
64 of 77
What process do eukaryotic cells unable to divide follow?
The cell cycle
65 of 77
What are the three stages of the cell cycle?
Interphase (DNA replication), nuclear division (nucleus divides into 2 or 4) + cytokinesis (cytoplasm divides)
66 of 77
What does uncontrolled cell division lead to?
Tumours and therefore cancer
67 of 77
What is uncontrolled cell disivion the result of?
A mutation to genes that control mitosis and the cell cycle
68 of 77
When does a tumour become cancerous?
If it changes from a benign to a malignant
69 of 77
What is a tumour?
A group of abnormal cells
70 of 77
What are the features of malignant tumours?
Grow rapidly, less compact + more likely to be life-threatning
71 of 77
Features of benign tumours?
Grow more slowly, more compact + less-likely to be life-threatning
72 of 77
Define 'cancer'
A disease caused by growth disorder of cells
73 of 77
How is cancer often treated?
By disrupting the cell cycle, thus cell division. This ceases the cancer growth
74 of 77
How do drugs (chemotherapy) disrupt the cell cycle?
1) prevent DNA replication 2) inhibit metaphase stage by interfering with spindle formation
75 of 77
What's the problem with these drugs?
They also disrupt the cell cycle of normal cells
76 of 77
Why are drugs more effective at killing cancer cells than normal cells?
It is more effective against rapidly dividing cells + cancer cells have a fast rate of division
77 of 77

Other cards in this set

Card 2


What is the resolving power of light microscopes?



Card 3


Resolving power of electron microscopes?


Preview of the front of card 3

Card 4


Why do electron microscopes have a greater resolving power?


Preview of the front of card 4

Card 5


What is resolution?


Preview of the front of card 5
View more cards


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Cellular processes and structure resources »