Basic structure of living systems Flashcards
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
2
Q
Wet mount
A
- specimens viewed suspended in water or immersion oil
- cover slip placed on from angle
- Eg. aquatic samples
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
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
5
Q
why is staining used?
A
- easier to distinguish between different components under microscope - more visible
6
Q
examples of stain that can be used to see nuclei?
A
methylene blue,
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
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
9
Q
resolution
A
ability to distinguish between 2 close together objects
10
Q
light microscope magnification and resolution
A
- x1500
- 250nm
11
Q
Transmission electron microscope - how does it work and magnification
A
- electrons pass through and around specimen, giving contrast
- 2D
- x 500,000
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
13
Q
why can’t electron microscopes see in colour?
A
- there is only one wavelength transmitting (electrons) rather than visible light
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
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
16
Q
what is eukaryote?
A
- organism with one or more cells containing DNA in membrane-bound nucleus
17
Q
Nucleus function
A
- houses nearly all cells’ genetic material
18
Q
chromatin
A
- consists of DNA and histones (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
- part of cytoskeleton
- tubulin proteins form hollow tubes
- act as tracks for movement of organelles eg. vesicles movement during secretion
- form spindle fibres in cell division
