2.1 - cell structure * Flashcards

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1
Q

plasma membrane?

A
  • on surface of animal cells + between cell membrane and cell wall in plant cells and prokaryotes.
  • made of lipids and proteins mainly.
  • regulates movement of substances in and out of cell.
  • has receptor molecules to respond to chemicals.
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2
Q

cell wall?

A

made of cellulose + supports plant cells

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3
Q

nucleus?

A
  • surrounded by nuclear envelope (double membrane) which has pores
  • contains chromatin (DNA + proteins) + nucleolus
  • controls cells activities, DNA contains instructions to make proteins, pores allow substances (eg: RNA) to move between nucleus and cytoplasm, nucleolus makes ribosomes
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4
Q

lysosome?

A
  • round, membrane surrounded, no clear structure
  • contains digestive enzymes which digest invading cells or break down worn out cell components
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5
Q

ribosome?

A
  • has small and large subsections
  • very small, site of protein synthesis
  • either floats around cytoplasm or attached to RER
  • made of proteins and RNA, not membrane bound
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6
Q

rough endoplasmic reticulum (RER)?

A
  • system of membranes enclosing a fluid-filled space + surface is
    covered with ribosomes
  • folds and processes proteins
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7
Q

smooth endoplasmic reticulum (SER)?

A
  • no ribosomes
  • synthesises + processes lipids
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8
Q

vesicle?

A
  • small membrane-bound, fluid-filled sac in cytoplasm
  • transports substances in/out cell via plasma membrane
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9
Q

golgi apparatus?

A
  • group of membrane-bound, fluid-filled, flattened sacs, vesicles at edge of sacs
  • processes and packages new lipids and proteins + males lysosomes
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10
Q

mitochondrion?

A
  • oval shaped
  • double membrane - inner one is folded to form cristae structures - inside is matrix which contains enzymes involved in respiration
  • site of aerobic respiration + produces ATP
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11
Q

chloroplast?

A
  • small + flat
  • double membrane - membrane stacked up to form grana - which are linked together by lamellae (thin pieces of thylakoid membrane)
  • site of photosynthesis
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12
Q

centriole?

A
  • small hollow cylinders - made of microtubules (tiny protein cylinders)
  • involved with the separation of chromosomes during cell division
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13
Q

cilia?

A
  • small hair-like structures
  • have an outer membrane and ring of nine pairs of protein microtubules inside with two microtubules in middle
  • microtubules allow cilia to move
  • this movement used by cell to move substances along cell surface
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14
Q

flagellum?

A
  • stick out from the cell surface and surrounded by plasma membrane
  • two microtubules in the centre and nine pairs around the edge
  • microtubules contract to make flagellum move
  • flagella used to propel cells forward
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15
Q

plant vacuole?

A
  • single sac filled with fluid of salts, sugars + amino acids
  • surrounded by membrane called tonoplast
  • store water, nutrients + waste materials until cell can get rid of them
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16
Q

light microscope?

A
  • poor resolution due to long wavelength of light
  • living samples can be examined + a colour image is obtained
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17
Q

cytoskeleton?

A
  • network of fibres found within cytoplasm all over cell
  • consists of microfilaments, microtubules + intermediate fibres
  • provides mechanical strength + maintains shape and stability
  • microfilaments responsible for cell movement
  • microtubules responsible for creating scaffold like structure
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18
Q

transmission electron microscope?

A
  • high magnification and resolution
  • think specimens stained + placed in vacuum
  • electron gun produces beam of electrons that passes through specimen
  • some parts of specimen absorb electrons making them appear darker
  • 2D image produced showing detailed internal structure
19
Q

scanning electron microscope?

A
  • high magnification and resolution
  • produces 3D image
  • electrons bounce off specimen surface to create image
20
Q

laser scanning confocal microscope?

A
  • high resolution + 3D imaging
  • high light intensity illuminates specimen stained with fluorescent dye
  • creates 3D images of tiny structures like embryos that would be hard to section
21
Q

resolution?

A
  • the minimum distance between two objects in which they can still be viewed as separate
  • in an optical microscope this is determined by wavelength of light
  • in an electron microscope this is determined by wavelength of beam of electrons
22
Q

magnification?

A
  • refers to how many times larger the image is compared to the object
23
Q

how many types of slide preparation for light microscopes are there?

A

four (4)

24
Q

dry mount slide prep?

A

thin slices of whole specimens viewed with just a coverslip placed on top, eg: hair or plant tissue

25
Q

wet mount slide prep?

A

water added to specimen before lowering coverslip with mounted needle to prevent air bubbles, eg: aquatic organisms

26
Q

squash slide slide prep?

A

wet mount then push down on coverslip to ensure a layer thin enough to be able to pass light through, eg: root tip squash sample to view chromosomes in mitosis

27
Q

smear slide prep?

A
  • use edge of another slide to smear sample across slide
  • creating smooth even coated specimen with coverslip placed on top
  • eg: blood cells
28
Q

eye piece graticule?

A
  • a scale on a glass disc inside light microscopes
  • used to measure size of objects being viewed under microscope
  • each time you change objective lens and magnification you have to calibrate eyepiece
29
Q

how to calibrate an eyepiece?

A
  1. line up stage micrometer and eyepiece graticule whilst looking through eyepiece
  2. count how many divisions on eyepiece graticule fit into one division on micrometer scale
  3. each division on micrometer is 10 micrometers, so if two divisions of eyepiece graticule fit into one micrometer division, one division on the eyepiece graticule would be 5 micrometers
30
Q

magnification equation?

A

image size / actual size

31
Q

differential staining?

A

technique involving many chemical stains being used to stain different parts of the cell in different colours

32
Q

four common stains and what they’re used for?

A

iodine = cell walls
methylene blue = cell membrane + nuclear envelope
gentian violet = bacterial cell walls
acetic orcein = DNA

33
Q

gram staining?

A

using crystal violet and safranin to identify specific types of bacteria

34
Q

rules for biological drawings?

A
  • draw in pencil
  • state magnification
  • title the diagram
  • only used solid lines that don’t overlap
  • dont colour in or shade
35
Q

sectioning?

A

to section a specimen they are embedded in wax to stop them distorting when being cut

36
Q

advantages + disadvantages of staining?

A

+: being able to identify organelles and distinguish between different organelles

-: you need to develop a stain, requires training, stains are costly

37
Q

contents of animal cell?

A

nucleus, RER, SER, mitochondrion, ribosomes, plasma membrane, cytoplasm, lysosomes, golgi apparatus

38
Q

contents of plant cell?

A

all from animal cell + cell wall, vacuole, chloroplasts + plasmodesma

39
Q

production and secretion of proteins?

A
  1. polypeptide chains synthesised on RER
  2. polypeptide chains move to cisternae in RER and are packaged into vesicles to be sent to the golgi apparatus via cytoskeleton
  3. in the golgi apparatus, the proteins are modified and packaged into vesicles
  4. the secretory vesicles carry the proteins to the cell surface membrane where it fuses and releases the protein by exocytosis
40
Q

prokaryotic cells compared to eukaryotic are…

A
  • much smaller
  • have no membrane bound organelles
  • DNA that’s not within a nucleus
  • peptidoglycan cell wall
  • smaller ribosomes
  • circular DNA
  • may also contain plasmids and flagellum
41
Q

skeleton?

A
  • protein fibres
  • for stability and shape
  • allow movement eg: mitosis
42
Q

uses of prokaryotes?

A
  • fermentation
  • penicillin
  • yoghurt making
  • on skin as protective layer
  • intestinal digestion
43
Q

examples of proteins?

A

keratin, collagen, enzymes, hormones, muscles