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Biology > Basic structure of living systems > Flashcards

Basic structure of living systems Flashcards

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1
Q

Dry mount preparation

A
  • solid species viewed whole or cut into thin slices with a sharp blade
  • specimen placed on centre of slide and cover slip placed over sample
  • Eg. hair, pollen, dust
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2
Q

Wet mount

A
  • specimens viewed suspended in water or immersion oil
  • cover slip placed on from angle
  • Eg. aquatic samples
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3
Q

Squash slides

A
  • wet mount is prepared
  • lens tissue used to gently press down on cover slip
  • damage to cover slip can be avoided by squashing between 2 microscope slides
  • Eg. root tip squashes to look at cell division
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4
Q

Smear slides

A
  • edge of a slide used to smear sample creating thin even coating
  • cover slip placed over sample
  • Eg. blood samples to view cells
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5
Q

why is staining used?

A
  • easier to distinguish between different components under microscope - more visible
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6
Q

examples of stain that can be used to see nuclei?

A

methylene blue,

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7
Q

Rules for scientific drawing

A
  • title
  • magnification
  • sharp pencil plane white paper
  • no sketch lines
  • no shade
  • labels
  • correct proportions
  • label lines with ruler, not crossing and no arrow heads
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8
Q

magnification definition and equation

A

how many times larger the image is than the actual size of the specimen
actual size=image/magnification

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9
Q

resolution

A

ability to distinguish between 2 close together objects

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10
Q

light microscope magnification and resolution

A
  • x1500
  • 250nm
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11
Q

Transmission electron microscope - how does it work and magnification

A
  • electrons pass through and around specimen, giving contrast
  • 2D
  • x 500,000
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12
Q

Scanning electron microscope - how does it work and magnification

A
  • electrons reflect off sample - do not go through or pass around
  • 3D
  • x 100,000
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13
Q

why can’t electron microscopes see in colour?

A
  • there is only one wavelength transmitting (electrons) rather than visible light
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14
Q

advantages of electron microscope

A
  • 0.2nm resolution - 100x more than light microscope
  • structured detailed images of organelles in cells
  • SEM is 3D - uncovers details of cellular tissue arrangement
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15
Q

disadvantages of electron microscopes

A
  • electron beams deflected by air molecules so sample need to be in vacuum - has to be dead
  • expensive - £250,000
  • preparing slides requires high skill level and training
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16
Q

what is eukaryote?

A
  • organism with one or more cells containing DNA in membrane-bound nucleus
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17
Q

Nucleus function

A
  • houses nearly all cells’ genetic material
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18
Q

chromatin

A
  • consists of DNA and proteins
  • found in nucleus
  • seen as darker patches on light micrograph
19
Q

nucleolus

A
  • makes RNA which is made into ribosomes - move out of nucleus to outside of rough endoplasmic reticulum
  • found in nucleus
20
Q

nuclear envelope

A
  • surrounds nucleolus
  • made of inner and outer membranes with fluid separating them
  • marked with nuclear pores for exchange of large molecules
21
Q

mitochondria

A
  • energy generator
  • has inner and outer membrane
  • inner membrane covered in enzymes to catalyse aerobic respiration to produce ATP
  • 2-5 micrometers long
22
Q

cristae

A
  • found in mitochondria
  • inner membrane folds inwards - inner folds are cristae
  • project into matrix
23
Q

matrix

A
  • liquid inside inner membrane of mitochondria
24
Q

ribosomes

A
  • found in cytoplasm or rough endoplasmic reticulum
  • consists of 2 sub-units
  • site of protein-synthesis - where proteins are made
  • acts as assembly line for coded info from nucleus to be used to make proteins from amino acids
25
Q

Golgi apparatus

A
  • stack of membrane-bound flattened sacs
  • receives proteins and modifies them
  • may add sugar molecules
  • packages modified proteins into vesicles to be transported
26
Q

lysosomes

A
  • spherical sacs surrounded by single membrane
  • specialised vesicles containing digestive enzymes to break down materials
27
Q

rough endoplasmic reticulum

A
  • consists of flattened membrane-bound sacs called cisternae
  • studded with ribosomes
  • transports proteins made on ribosomes
  • some proteins secreted, others placed on surface of cell membrane
28
Q

smooth endoplasmic reticulum

A
  • same structure as rough endoplasmic reticulum but no ribosomes
  • involved in making lipids the cell needs
29
Q

centrioles

A
  • self-replicating organelles made up 9 bundles of microtubules - 9+2 arrangement
  • only found in animal cells
  • help in organising cell division - form spindle fibres
30
Q

cilia and flagella function

A
  • locomotion in individual organisms
  • move fluid or materials past a cell or group of cells in multi-cellular organisms
31
Q

chloroplasts

A
  • use CO2, water and light to build sugars
  • present in all green plants
  • double membrane bound
32
Q

stroma

A
  • liquid in chloroplasts - 1st stage of photosynthesis
  • contains sacks of thylakoid membranes called grana - 2nd stage photosynthesis
33
Q

vacuole

A
  • have membrane called tonoplast filled with cell sap
  • important in keeping cell turgid
34
Q

cell wall

A
  • gives support and structure
  • made of cellulose
  • can act as carbohydrate store
  • has plasmodesmata - pores to let substances in and out and connect cells together
35
Q

endosymbiosis theory

A
  • mitochondria and chloroplasts were formerly free-living bacteria (prokaryotes)
  • these were taken inside another cell as an endosybiont
  • led to evolution of eukaryotic cells
36
Q

DNA in prokaryotes

A
  • generally only one molecules of DNA - a chromosome super coiled to make it compact
37
Q

ribosomes in prokaryotes

A
  • smaller than eukaryote’s
  • eukaryotes - 80S, prokaryotes - 70S
  • not involved in formation of more complex proteins
38
Q

what is cell wall prokaryotes made of?

A
  • peptidoglycan or murein - complex polymer made from amino acids and sugars
39
Q

flagella prokaryotes

A
  • thinner than eukaryote’s
  • does not have 9+2 arrangement
  • energy to rotate flagella is formed not from ATP
  • attached to cell membrane by a basal body and rotated by molecular motor
40
Q

main components of cytoskelton

A

microfilaments (narrowest), intermediate fibres, microtubules (widest)

41
Q

microfilaments

A
  • narrow fibres containing the protein actin
  • actin fibres contract
  • invovled in cell movement eg. white blood cell out of blood into infected tissue
  • process of cytokinesis involves microfilaments
42
Q

intermediate fibres

A
  • made of lots of different proteins
  • strenghthen cell eg. skin cells under constant stress - help prevent stresses damaging them
43
Q

microtubules

A
  • tubulin subunits form polymers then form hollow microtubules
  • involved in movement of organelles eg. vesicles movement during secretion
  • form spindle fibres in cell division
  • help determine shape of cells

Biology (17 decks)

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