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Biology OCR-A > 2.1.1 Cell Structure > Flashcards

2.1.1 Cell Structure Flashcards

1
Q

cell ultrastructure

A

the detail revealed by the electron microscope, structures found inside the cell are called organelles

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2
Q

division of labour

A

each organelle has a specific role within the cell and they work together to aid the cells survival

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3
Q

how does a light microscope work

A

uses visible light to look at a small sample in colour and the sample can be living

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4
Q

stain defenition

A

coloured chemicals that bind to molecules in a specimen

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5
Q

uses of stains

A
  • makes cells visible
  • increases contrast as different organelles take up
    different amounts of the stain
  • details can be seen
  • organelles identified
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6
Q

examples of stains

A

iodine, eosin, acidified phloroglucinol, acetic orcein, light green

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7
Q

conversion rates of units

A 
1m = 1000mm
1mm = 1000micrometres
1micrometre = 1000nm
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8
Q

magnification

A

the number of times larger the image is compared with the actual size of an object

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9
Q

resolution

A

the ability to distinguish between two separate points that are very close together giving more detail and clarity

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10
Q

eyepiece graticule

A

printed scale in the microscope which is divided into 100 epu (eyepiece units)

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11
Q

stage micrometer

A

a microscope slide that has a fine and accurate scale engraved on it, is usually 1mm long and divided into 100 units so each division is 10micrometres

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12
Q

how to calibrate the eyepiece graticule

A

1) place the stage micrometer on the microscope and focus on low power
2) line up stage micrometer and eyepiece graticule
3) count the divisions on the eyepiece graticule that correspond to 1mm on the stage micrometer
4) calculate distance in micrometres of one division on the eyepiece graticule
5) repeat for medium and high power

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13
Q

how to draw cells

A

1) no shading
2) PENCIL
3) straight label lines using pencil and ruler
4) clear annotations
5) no shading and clear lines
6) include scale bar if appropriate

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14
Q

how does a laser scanning microscope work

A

a laser is pointed at the sample and scans across giving a 3D image showing depth (useful in medicine)

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15
Q

how does a transmission electron microscope (TEM) work

A

sample is first dried in ethanol and coated in gold, then electron beams pass through the sample, focused by magnets giving 2D surface images showing internal structures

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16
Q

how does a scanning electron microscope (SEM) work

A

electrons bounce off the surface of the sample providing a 3D surface image

17
Q

resolution of light/tem/sem

A

light - 200nm
sem - 2nm
tem - 0.2nm

18
Q

maximum magnification of light/sem/tem

A

light - x2000
sem - x200,000
tem - x2,000,000

19
Q

nucleus structure and function

A

double membrane bound nuclear envelope - encloses DNA inside of nucleus
nuclear pores - mRNA leaves via them
nucleoplasm - contains chromatin
nucleolus - manufactures ribosomes
outer membrane is continuous with rough er - allows easy transport of substances

20
Q

endoplasmic reticulum structure and function

A

a system of hollow tubes and sacs - allows trasnport within a cell
rough er has ribosomes which synthesise proteins
smooth er has no ribosomes and synthesises lipids and steroids
cisternae - gaps inside the hollow tubes and sacs

21
Q

ribosome structure and function

A

two subunits of rRNA and protein which provide binding site for mRNA and contain enzymes
22nm (80S) in eukaryotic cells
18nm (70S) in prokaryotic/chloroplasts/mitochondria
found free in the cytoplasm and attached to the rer as ribosomes can move along mRNA

22
Q

golgi apparatus structure and function

A

flattened membrane bound cavities called cisternae stacked in top of eachother which modify and packages carbs and proteins into vesicles
produce lysosomes and secretory vesicles which fuse with plasma membrane for excretion

23
Q

lysosome structure and function

A

vesicles which contain hydrolytic enzymes

isolate potentially harmful enzymes and break down material ingested by WBC, break down old and dead cells

24
Q

mitochondria structure and function

A

double membrane bound which isolates reactions in aerobic respiration for the production of ATP
inner membrane folds to form cristae to increase sa for enzymes to be attached
matrix contains:
-18nm ribosomes (for proteinsynthesis)
-DNA (codes for proteins)
-enzymes (aerobic respiration)

25
Q

chloroplasts structure and function

A 
double membrane bound to isolate photosynthetic reactions
membrane bound sacs called thylakoids stacked into grana connected by lamellae to increase sa for chlorophyll to attach
stroma contains:
-enzymes (photosynthetic reactions)
-starch grains (carbohydrate store)
- 18nm ribosomes (proteinsynthesis)
-DNA (codes for proteinsynthesis)
-lipid droplets (for membranes)
26
Q

centrioles structure and function

A

two centrioles found in all animal cells perpendicular to eachother next to the nucleus, composed of 9 sets of 3 microtubules
found in:
-algae
-fungi
-NOT plant cells
form the spindle fibres during nuclear division to control the separation of chromatids and chromosomes

27
Q

cytoskeleton structure and function

A

-microtubules (fine hollow tubes)
-microfilaments (small solid protein fibres)
enable movement of vesicles, support cell organelle position, strengthen cells and help to maintain shape

28
Q

flagella and cilia structure and function

A

2 microtubules surrounded by 9 pairs of microtubules, brings about movement

eukaryotes: undulipodia
prokaryotes: flagellum

29
Q

vacuoles structure and function

A

common and large in plant cells, membrane is called the tonoplast
maintain turgor for support and used for storage of cell sap/sugars/pigments etc

30
Q

plant cell walls structure and function

A

secreted by the living cell, rigid and permeable, made of cellulose, modified by lignin, contains pores which are penetrated by plasmodsmata, the middle lamella cements cells together which is composed of pectic substances

  • support
  • protection
  • prevents osmotic bursting
31
Q

structures always present in prokaryotes

A
  • cytoskeleton (protein fibres)
  • plasma membrane (controls what enters/leaves the cell)
  • cytoplasm (site of anaerobic respiration)
  • ribosome (18nm)
  • circular DNA (naked DNA)
  • nucleoid (area where DNA found)
  • cell wall (made of murien)
32
Q

structures sometimes present in prokaryotes

A
  • flagellum (movement in corkscrew motion)
  • infolding of plasma membrane (nitrogen fixation/form photosynthetic membrane)
  • mesosome (aerobic respiration)
  • plasmid (small circle of DNA)
  • pili (attachment to other cells/reproduction)

Biology OCR-A (2 decks)

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