Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > A2.2 Cell structure > Flashcards

A2.2 Cell structure Flashcards

1
Q

when were microscopes first invented?

A

17th century and led to discovery of cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is fluorescence?

A

absorbance of light and re-emission at a longer wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is immunofluorescence?

A

a development of fluorescent staining

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how does immunofluorescence work?

A

antibodies that bind to a specific chemical in the cell are produced, a fluorescent marker is linked to the antibodies, images produced of cells treated with these antibodies show the cell structure overlain with the bright colour of the fluorescent marker where the specific chemical occurs in the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how can multicoloured fluorescent images be produced?

A

using multiple types of antibodies with fluorescent markers of different colours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what happens when the resolution of the microscope has been exceeded?

A

magnification can be increased with a microscope until a point beyond which the image can no longer be focused sharply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is resolution?

A

the ability of a microscope to show 2 close objects separately in the image; the shorter the wavelength, the higher the resolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what did electron microscopes allow for?

A

to investigate the detailed structure(ultrastructure) of cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is freeze-fracture electron microscopy?

A

used to produce images of surfaces within cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how does freeze-fracture work?

A

sample is plunged into liquefied propane at -190 so it rapidly freezes; steel blade used to fracture the frozen sample; fracture goes thru weakest points of cells; vapour of platinum or carbon is fired onto the fracture surface at angle of 35 to form a coating; creates a replica of the fracture surface; replica is removed from sample and examined w electron microscope; usually 2nm but thickness varies bc of angles at which coating is applied; gives the impression of a 3D image with shadowing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

where is the weakest point in cells?

A

usually the middle of membranes between the 2 layers of phospholipid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is cryogenic electron microscopy?

A

used for researching the structure of proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

how does cryo-EM work?

A

thin layer of protein solution applied to a grid then flash-frozen with liquid ethane at -183 to create smooth vitreous ice and prevent the formation of water crystals; grid placed in electron microscope and detectors record patterns of electrons transmitted by individual protein molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is used to produce a 3D image of the protein molecules in cryo-EM?

A

computer algorithms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what does cryo-EM analyse and what does it allow for?

A

analyses proteins at the instant in time when the water around them froze, allows scientists to research proteins that change from one form to another as they carry out their function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the cellular structures found in all living organisms?

A

DNA as genetic material(needed for producing mRNA by transcription so proteins can be synthesised); cytoplasm composed mainly of water(contains enzymes which catalyse chemical reactions); plasma membrane composed of lipids(controls movement of substances in and out of cell and allows different chemical conditions to be maintained inside the cell from the outside eg pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the cell wall made of in prokaryotes?

A

peptidoglycan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

which ribosomes are in prokaryote cells?

A

70s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

which components of the cell have 1 membrane?

A

rough ER, smooth ER, golgi, lysosomes, vesicles, vacuoles

20
Q

which components of the cell have 2 membranes?

A

nucleus, mitochondria, chloroplasts

21
Q

why do animal cells not have cell walls?

A

allows them to take in food by endocytosis but makes them vulnerable to bursting if too much water enters by osmosis

22
Q

which 2 types of small temporary vacuole occur in some animal cells?

A

contractile vacuoles that expel excess water by exocytosis and food vacuoles that digest food or pathogens taken in by endocytosis

23
Q

what are plastids and where are they?

A

family of double-membraned organelles, plant cells have varied types such as chloroplasts(photosynthesis) and amyloplasts(to store starch) animal and fungus cells have no plastids

24
Q

what are centrioles?

A

hollow cylinders containing a ring of microtubules arranged at right angles to each other, centrioles are involved in producing spindle fibres for cell division

25
Q

cells with no nucleus?

A

anucleate-cannot transcribe DNA to make mRNA and cant synthesise proteins

26
Q

cell structure in RBCs

A

no nucleus so there’s more space for haemoglobin; cytoplasm has no nucleus, mitochondria or ribosomes; without source of proteins for repair or other functions they have a limited lifespan usually 4 months

27
Q

cell structure in phloem sieve tube elements

A

subunits of the tubes that transport sugar-containing sap in plants; initially have a nucleus but breaks down so sap can flow more easily; supplied with proteins by adjacent companion cells which have a nucleus and rough ER

28
Q

cell structure in skeletal muscle

A

made up of muscle fibres, each fibre is enclosed inside a plasma membrane like a cell

29
Q

why do muscle cells have striated appearance?

A

regular arrays of protein filaments used in muscle contraction

30
Q

cell structure of aseptate fungi

A

consist of thread-like structures called hyphae, there are long undivided sections of hypha which contain many nuclei

31
Q

what does endosymbiotic theory explain?

A

how eukaryotic cells originated

32
Q

what is the endosymbiotic theory?

A

proposes that some of the organelles within eukaryotes were once free-living prokaryotes, ingested by a larger cell where they stayed and provided a benefit causing the larger cell to eventually become a eukaryote

33
Q

what are the 3 distinct similarities between chloroplasts and mitochondria that proves endosymbiosis?

A

chloroplasts and mitochondria reproduce by binary fission just like prokaryotes; both contain DNA similar to prokaryotes; both have their own 70s ribosomes just like prokaryotes

34
Q

what is compartmentalisation?

A

division of parts of the cell into internal structures called organelles

35
Q

eg of prokaryotes

A

bacteria, archea

36
Q

function of nucleoid in prokaryotes

A

region containing genetic info-DNA is circular and naked(not associated with protein)

37
Q

function of pili in prokaryotes

A

protein filaments used for bacterial adhesion and conjugation

38
Q

how does TEM(transmission electron microscope) work?

A

a beam of electrons passes thru a thin section of a specimen, areas that absorb the electrons appear darker on the electron micrograph

39
Q

how does SEM(scanning electron microscope) work?

A

in a scanning electron microscope a beam of electrons passes across the surface and scatter; the pattern of scattering builds up a 3D image depending on the contours of the specimen

40
Q

limitations when using electron microscopes?

A

whole system must be in a vacuum so living specimens cant be seen; a complex staining processes needed which might introduce artefacts into the image; specimens need to be v thin esp for TEM so electrons can pass through;

41
Q

why is a vacuum needed inside the body of an electron microscope?

A

electrons are deflected when they strike molecules of the gases which make up air making it difficult to focus the electron beam, producing a vacuum in the microscope stops this

42
Q

what is an artefact?

A

an object observed in an image of a specimen seen in a microscope which is not part of the specimen in real life, result of the preparation of specimen for microscopy

43
Q

mitochondria structure

A

oval shaped, bound by a double membrane called the envelope, inner membrane is folded to form projections called cristae with a matrix on the inside containing all the enzymes needed for respiration

44
Q

function and structure of RER

A

series of flattened sacs enclosed by a membrane with ribosomes on the surface,RER folds and processes proteins made on the ribosomes

45
Q

function and structure of SER

A

system of membrane bound sacs, SER produces and processes lipids

46
Q

why is the resolution of a light microscope low?

A

because it uses light with a long wavelength

Biology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions