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Flashcards in Cells and viruses Deck (51)
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What does the cell theory state

New cells are formed from other existing cells and that a cell is a fundamental unit of structure, function, and organisation in all living organisms


What is an exception to the cell theory rule

Viruses are an exception because they aren't made up of cells


In complex organisms, what do cells make

Specialised cells -->Tissue-->Organs-->System-->Organisms


Give an example of prokaryotes



What is bacteria made up off

.Cell wall
.70S ribosome


Describe the cell wall of bacteria

.Made up of peptidoglycan which is very thick and protective. Some retain purple stain = gram-positive
.In others the cell wall is thin and does not hold the purple stain. This is known as Gram-negative. The stain turns red


Describe the Plasmids in a prokaryote

.Smaller,circular, a single length of DNA
.They often contain genes that aid the bacterium survival


Describe the Nucleoid in a prokaryote

.Circular DNA molecule
.DNA is folded in a region which is the nucleoid


Describe the 70S ribosomes in prokaryotes

.They make proteins
.Size of the ribosome is 70s in prokaryotes


What are Eukaryotes made up of

.Golgi apparatus
.80S ribosome


Describe the nucleolus

.Region of dense DNA and protein which makes ribosomes


Describe the nucleus

.Surrounded by a double membrane with pores
.Stores DNA


Describe the centrioles

.Two hallow cylinders
.Arranged at right angles to each other
Makes a spindle in cell division


Describe the lysosomes

.Enclosed by a single membrane
.Containing digestive enzymes
.Destroys old organelles and pathogens


Describe the Golgi apparatus

.Seres of single, curved sacs enclosed by a membrane
.Each sac is smaller than the previous one
.Many vesicles luser around it
.Modifies proteins and packages them in vesicles for transport


Describe the 80S ribosome

.Site of protein synthesis


Describe the mitochondria

.Creates ATP in a process known as cellular respiration
.Can survive on its own as it has its own DNA and ribosome (endosymbiotic theory)
.Contain folded inner membrane = cristae
.Stalked particles and matrix are also within the organelle


Describe the sER

.A series of single, tubular sacs made of membrane
.Lipids are made here


Describe the rER

. A series of single, flattened sacs enclosed by a membrane
.Ribosomes on the surface
.Protein made here


How is image size calculated

Image size = actual size X magnification


What is meant by resolution

Being able to see two objects as distinct


What is the resolution of the following:
b)Light microscope
c)Electron microscope

b)0.2 micrometer
C)1 nanometer


What's the wavelength of:
b)electron beam



When does light microscope work

When light passes through a specimen so that it can enter the eye
The specimen must be thin


What is staining used to do

To give structure color and contrast and allow identification


What are 4 common stains used
what are they used for

1)Iodine solution -stains starch blue-black
2)Ethanoic orcein - stains DNA reddish-purple
3)Methylene blue - stains nuclei and chromosomes blue
4)Phloroglucinol - Stains lignin, found in plant cells, red


Explain the disadvantage of the EM

1)All specimens are examined in a vacuum so it is impossible to look at living material
2)The treatment is likely to result in artefacts
3)EMs are still extremely expensive to buy, run and maintain


What is a light microscope

LM is a relative sample piece of equipment but it must be set up and used correctly to get the best results


What is the set-up of the light microscope

1)Revolve the turret so that the low power lens is pointing down
2)Place the slide on the stage
3)Look through the eyepiece and adjust the mirror to bring light into the field of view
4)Turn the coarse focus knob until the specimen is in the focus
5)Adjust condenser for best lightening
6)Move to a higher power lens when necessary by revolving the turret, readjusting the condenser if needed


How is the eye-piece lens calibrated

1)Place a stage micrometer slide on the microscope stage
2)Focus on the scale under a low power lens
3)Align the scales of the eyepiece graticule in and the stage micrometer in the field of view
4)Count the number of divisions of the eyepiece graticule equivalent to a known length on the stage micrometer
5)Work out the length of each eyepiece unit
6)Repeat for the other objective lenses