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A-level Biology > Module 2.1 > Flashcards

Module 2.1 Flashcards

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1
Q

How to convert micrometres to nanometres

A

multiply *1000

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2
Q

the early microscopes vs modern ligh microscopes

A

-they both have an eyepiece lens , hey both have a stage for the speciment .
-both have a focsing dial .
-could mgnifya round 300 times .

-Wheareas a MODERN microscope can mgnify round 1000 times .

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3
Q

adavantges of light microscopes

A

-can be used on living cells , so we can explore porcesses such s cell division or movement of cells .
-cheap and easy to use
-portable .

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4
Q

disadvantages of light microscopes .

A

-need to use a stain to do this , and these can kill cells .
-Limtied resolution due to the nature of light itself .
-low mgnificationsm ( cannot see smaller strucutres)

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5
Q

A-level definition of resolution .

A

-Resolution is defined as the minium distance between two objetcs where they can sitll be seen as two separae objects .

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6
Q

What do you mean as the NATURE OF LIGHT .

A

-For a light microscope , the limit of resolution is around 200nm .
-The wavelength of visible light is around 400nm-700nm , if two objects are closer than 200 nm we cannot see tjem s two separate objetcs using a light microscopes.
Better to use an elecron microscope .

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7
Q

length of wavelength of light microscope

A

400-700 nm

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8
Q

How does a light microscope work ?

A

-light passes through the sample , if we were to view certain prt of the cell , the light we see will have already have passed thorugh parts of the cell , making the image blurred nd the resolution worse thn it coudl be .

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9
Q

so what has dramatically improved light microscopy ?

A

laser scanning confocal microscope .

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10
Q

How does a laser confocal microscope work ?

A

-A laser s used to scan the object we’re interested in .
-This allows us to view a precise layer f the object .
-Meaning the image is prodced t HIGHER RESOLUTION than conventional light microscopy-observe lviign specimens

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11
Q

Advantages of laser scanning confocal microscopes .

A

-We can produce three dimensional images of cells .
-HIH MAGNIFICAITON AND RESOLUTION
-This technique allows us to tag specific proteins + srucutures within cells .
-By using speical dyes adn anitbiodies , we can actually see porteins movign around in cells , helpign us to workout the fucntions of those portiens .

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12
Q

Working out magnification ?
Key; always keep all the units the same .
two types of questions on magnificationc an be asked .

A

-given a scale bar .
-given the equation for magnfiication .

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13
Q

check sheet for quesiton ; how do workout the diemeter of nuclesus (1)

A

-start by mesuring the length of the scale , abr in millimeers (using a ruelr) . E.g ,t he scal ebr is 10mm .
-READ ACCRUATELY UR RULER .

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14
Q

how do workout the diemeter of nuclesus (2)

A

Now use a ruler to measure the diameter of the nucleus in mm = 63mm .

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15
Q

workingss
scale bar 10mm
nucleus 63mm

A

63/10 =6.3 this tells us he nucelus is 6.3x bigger than the scale bar .

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16
Q

how do workout the diemeter of nuclesus (3)

A

Now we need to workout , how man times bigger the nucleus is compred to the scale br .

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17
Q

how do workout the diemeter of nuclesus (4)

A

the scale bar represents the distnce of micromentre . do 6.3*1 to get the actual diameter of the nucleus wichh is 6.3 um .

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18
Q

how do you workout out magnicaiiton .

A

magnificiation = image size / object sixze .

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19
Q

do the question on the sheet .

A

…

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20
Q

wavelength of laser scanning (confocal)

A

SAME AS LIGHT MICROSCOPE OR PTICAL micoroscope same thign (400-700 nm)

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21
Q

disadvanatges of laser scanning

A

-expensive
-requires training

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22
Q

The resolution of any light microscope ,w ill be limited DUE TO THE WAVELENTH OF LIGHT .

A

So eelctron microscopes were invented .

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23
Q

Why is the resoltuon of n electron light microscope soo good

A

-Electrons ahvea verys hort wavelength . So the resoltuiton is 2000 times better than a light microscope .

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24
Q

How can particles liek electrons have a wavelength ?

A

-As electrons have propeorties of both particles and waves sp can have a wavelength .

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25
Q

How does an electron microscope work s1

A

–Start with an electron gun , which is producing a beam of electrons .
-These electrons pass down the microsocope .

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26
Q

How does an electron microscope work s2

A

The insidie of an electron microsocpe contains a vacuum .
-So the elctrons can pss through withouth boucning off the molecules in the air .

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27
Q

How does an electron microscope work s3

A

-As electrons are negaitvelyc hagred , we can focus the electron beam , using electroamgnets . These re clled electromagnetic lenses .

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28
Q

How does an electron microscope work s4

A

The speciment is placed in both of the electron beams .
-Electrons can pass through some parts of the specimen more easily than other parts .

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29
Q

How does an electron microscope work s5

A

final image porduced ona fluorescent screen .

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30
Q

Advanatges of electron microscopes .

A

-Resoloution 2000x better than a light microscope .
-under goood conditiosn ,c an reosolve up to 0.1nm .
-we cana chicve a far greter level of magnificationbefore the image is blurred .
-Ribosomes +structure of cell membrane —> electron microscope .

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31
Q

Wha is the the wavelength odf an electron microscope

A

short - 0.004nm

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32
Q

Disadavantages of an electron microscope

A

-Interior is a vacuum ,s oc anot view libign specimens usin an electron microscope .
-Requires very careful staining of the specimen + specimen often has to be veryt hin .
-Can get ARTEFCTS - false imges creted by the staining process or the ocniditons inside the electron microscope . (So bioligusthere to chck what they seeing is real , not an artefct).

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33
Q

2 TYPES OF ELECTRON MICORSCOPE

A

-trnsmission electron microscopes
-scannign electron microscopes .

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34
Q

aDVANATGES OF TRANSMISSION ELECTRON MICROSCOPES

A

-ELECTRON BEAM PASSES THORUGH THE SPECIMEN .
-Produces glat 2 dimensional images .
-Very high resolution .
-highest magnifiction
-cleater smaller structures

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35
Q

disadvanatges of transmission electron micorscopes

A

-onyl works when specimen is thinly sliced .
-non-livign (vacuum)
-large equipment
-lots of training
VERY EXPENSIVE

-b+wvery expensive

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36
Q

How does a transmission electron microscope work ?

A

-beam of electrons pass thorgh the specimen stained with metal salts .
IT ALSO HAS THE HIGHEST MAGNIFICATIOn out of all microscopes .

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37
Q

SCANNING ELECTRON MICROSCOPE

A

-the electron beam does not pass through the specimen .
-Instead ,e elctrons are scattered from the surface of he specimen +dteected .
-produce three dimensional images , dpes not require speicmen to be thinlhys lcied.

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38
Q

diadanatge of scannign electorn micorscope

A

-Thet transmission electron microcope

-lessthan reslutio .
-ALSO requires h speicmen is coated ,w ith ametal sucha s gold , reading toa rtefats .
-very expnesive
-large eequpiment
-lots of training
-non-living cacuum

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39
Q

Slides can be observed the followign ways ;

A

…

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40
Q

Differentia staining

A

Dufferentua staining is when you stain a specimen with different stains that bind to specific cell strucutres so that they can be identified within a single prepration .

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41
Q

Stain - methylene blue

A

all purpose - nucleus dark blue

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42
Q

acetuc orcein

A

DNA (chromosomes dark red)

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43
Q

Sudan red

A

lipids red

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44
Q

iodine (potassu=ium idodide solution )

A

cellulose 9yellow) starch granules (blue /black)

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45
Q

check the sheet use of an eyepiece graticule and stage micrometer

A

-Mkae sure you are able to convert between all the units REVISE AND LEARN IT .

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46
Q

Why is a stage micrometer used ?

A

-Stage micrometer allows ut to calibrate the eyepeice graticule so we know how much eye peice graticule actually is .

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47
Q

Callibrate something (1)

A

-Look at the specimen using eye piecie graticules .
-EXAMPLE —> with of the cell is eyepiece;s (then callibrate this to find out what one eye piece is . )
EXAM TIP , WIDTH OF CELL IS 20 EYEPEICES THEN Cllibrate usign stage micrometer (slide you put on )

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48
Q

Callibrate something (2)

A

-Focus your microscope under the same magnifiction you looked at your specimen with .
-Make sure your eyepiec egraticule and stage micrometer are PAarallel .

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49
Q

for exmaple , lets say our eye peice uinits is 35 eyepeice units in 1mm

A

35 eyepiece units = 1mm
1 eyepiece =0.0285mm
1eyepiece=28.5 micrometres

MAKE SURE TO CONVERT INTO MICROMETRES .

THT 20 BEFROM BEFORE 20*28.5 MICROMETRES TO FIND THE WIDTH OF THE CELL .
0.571 MICROMETRES .
CHCK FOR UNITS and decimal places in question /

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50
Q

Exam questions example for callibration

A

the preparation + examinaiton of microscope slides for use in light micorsocopy .
-nclduign the use of an eyepice graticule and stage micrometr . HAVE aago at the exam questions in ms partners sleeve aswl as PMT .

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51
Q

euakryotic cells

A

Dna is contained in a membrane bound nuculeus .
(membrane bound –> surrounded by a membrane.)

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52
Q

-some eukaryotic cells can lose their nucleus as the develop (red blood cells i humans .)

A

-But vast majoirty of eukarytoic cells have a nculeus htorughou their lifespan.

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53
Q

Second key feature of eukarytoic cells

A

-Dna is tightly wrapped around proteins called histones .
(togehther the DNA AND HISTONE PROTEINS FORM CHROMSOOMES )

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54
Q

What is so good about tightly coling their dna into chromomsomes ?

A

-euakryotic cells can pack a gret deal of dna into their nucleus .

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55
Q

third key feeatures of eukaryotic cells

A

-Their Dna is a LINEAR MOLECUL
-“Linear “ , means that the ends of the DNA molecule ina cheomsome ,a re not joined together to form a loop ..

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56
Q

WE ALREADY SEEN - eukarytoic cells have a membrane bound nucleus ….

A

BUT THEY also contrian nuber of memrbane bound organelles .

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57
Q

All the organelles thar are emmebrane bound in a ANIMAL eukarytoic cells .

A

-Golgi apparatus .
-Endoplasmic reticulum .
-Mitochocndira .
-cytoplasm
-Nucleus .

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58
Q

All the organelles that are membrane bound in a Eukarytoic cell (Plants)

A

Everything in animal BUT ALSO
-Vacuole
-Cholroplasts

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59
Q

Fourth key feature of eukaryoitc cells .

A

-eukaryoitic cells also contain other organelles that are NOT membrane bound .
-AKAA RIBOSOMES .

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60
Q

Ribosomes are invovled in porteins ntheiss .
-Ribosomes are lso in prokaryotic cells

A

-but the ribosomes in euakryotic cells are larger thant hsoe in prokarytoes .
-Eukarytoic cells conaisns 8OS

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61
Q

The letter S

A

is simply a unit showinghow quicly organells make in a cneitrfurge

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62
Q

-Eukarytoic cells are surroudned bya cell surface memebrane .

A

This helps to control the meolcuels that can apss in + out of cells .

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63
Q

BUT , in plants + fngithe clel memebrne by a cell wall .

A

-Cell wall helps to maintain a strucutre of these cell .
-In plant cells the cell walls s amde of the plyscharide Cellulsoe .

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64
Q

Wht is the cell wall in fungi

A

polsacharide chitin .
-Animal cells don’t have cell wall .

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65
Q

key differences in prokarytoic cells and eukarytoic cells (1)

A

-prokaryoic cells are mcuh SMALLWE than eukyartoic cels .

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66
Q

key differences in prokarytoic cells and eukarytoic cells (2)

A

Prokarytoic cells have NO MEMRABNE MOUND ORAGNELLES AT ALL .
-Therefore , the Dna in prokarytoic cells is in the CYTOPLASMS rther than in the nucelus .
-Unlike eukrytic DNA is arranged into a circular chromosome with NO EFREE ENDS .

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67
Q

-The DNA in prokaryotes is not BOUND to histone proteins .

A

-Sometimes , bacterial cells contain small loops of DNA called plsmids .
-Plasminds usually contain a reltively small number of GENES .
-But these cn incldue genes which make the bacterium RESISTANT , to antibiotics .
-So plasmids are very important for bacterial .
CCONTRSTS EUAKRYOTES WHIVH DO NOT CONTAIN PLASMIDS .

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68
Q

PROKARYOTIC CELLS ALSO HAVE RIBOSOMES FOR Protein synthesis .
(but hty are smaller than eukarytoic cells )

A

-prokaryotic cells hav size 70s .

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69
Q

Prokarytoic cells (like bacteria) are surroudned y a cell wall .
-In bacteria , this is made from pentidoglcyen . Which is called murein .

A

-Peptidoglycen is a polymer formed between peptieds and polysccharide moelcuels .
-he bacterial cell wall helps to maintain the strcuture of the cell . (e.g water moves into the bacterial cell by osmosis , cell wall prevents the cell from bursing .)

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70
Q

Some bacteria porduce a slime cpsule ont he outside of the cell wll .

A

-slime capsules can help to rpotect the bacteira from PHAGOCYTISIS by white blood cells .

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71
Q

Other strucures of prokaryotic cells (1)

A

-Proakryotic cells ahve FLAGELUM –> helps them to move
- sperm (eukarytoic) also has flagellum ,
-But prokarytoic cells flagellum DIF trcutrr to eukayrotic flagellum

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72
Q

key differences in prokarytoic cells and eukarytoic cells (2)

A

-Some surfaces also have fine portein strans on their surfce clled pili .
-Pili help bacteria to attach to surfaces + also to attch to toher bacteira .
-When two bacteria are attached DNA cn be TRANSFERRED from one bacterium to another .

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73
Q

key differences in prokarytoic cells and eukarytoic cells (3)

A

-Lstly bacteria also contain lipid droplets + glycogen granuls .
-They act s nucirent stores for bacterial cells .

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74
Q

-Sometimes using an electron microscope ,w e can see infoldings in the cell memebrne of prokaryote cells .

A

-These are clled MESOSOME .
-Initially scientists thoguht they played a role in respiration .
-NOW scienists believe mesossomes are actuallh RTEFCTS . That are creted when bacterial cells re prepared for electron microscopy .

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75
Q

The importance of proteins to lviign organisms (1)

A

-Enzymes are proteins and enzymes are requiredfor all chemical reactions to take palce in cells .

76
Q

The importance of proteins to lviign organisms (2)

A

-Other proteins play a stuctural role in cells for example moving organneless where they are needed .

77
Q

The importance of proteins to lviign organisms (3)

A

Some porteins act a stransport mpelcules .
-Example the haemoglobin which transports ocxygen in malmmls .
-Portein synthesis is one of the most improtant funcitosn taking plac in cells .

78
Q

-Protein invovles several different organes
s1 of proteins syntheis

A

-the insutrctions for encoding the amino acid sequence of a portein are contained wthin the gene for that portein .
-These genes re part of the chromsomes which we find in the nucleus .

79
Q

s2 of portein synthesis

A

to syntheisse a protein , the genetic information is encdoed by that gene , si converted to messeneger RNA , or MRNA .
-The process is called trnscription .

80
Q

S3 this mRNA then recievs the nucleus .

A

-The ribosomes reads the information contained inthe mRNA and synthesis the proein moelcule .
-This is translation .

81
Q

If the portein remeians in the cytooplasms (for cellual rnezyms )

A

-translation will take place in a free ribosome in the cytoplasms .

82
Q

-However some porteins re secreed from thw CELLS .
e.g digestive enzyes + antibiotics .

A

SECREYED RIBSOMES are translaed on a ribosome + attached to the ROUGH ENDOPLSMIC RETICULUM .
-These porteins then mke there way through the the ROUGH ER + the goglig apparatus , before leaing the cell .

83
Q

STRUCTURE OF NUCLEUS (1)
-ncleus contains a material called nucleoplasms .

A

-Nucleoplasms contains moleucles sucha s NUCLEOTIDES + ENZYMES .
-Needed for DNA + RNA synthesis .

84
Q

STRUCTURE OF NUCLEUS (2)
-Nucleus contaisn a double membrane .
Scineitsts call this hte nuclear envleope

A

CHECK SHEET , for closeup of nuclear envelope .
-CONSISTS OF TWO phospholipidic bridges .

85
Q

STRUCTURE OF NUCLEUS (3)
-Wiithin the nuclear enveleope we find nucler pores .
-Function of nucler pores is to allow moleucles to ENTER + LEAVE the nucleus .
(e.g RNA nucleotides enter the neucloues htourhg the nuclear pores fromt he cytoplasms ).

A

-These nucleotides are used in the neucloues to synthesis messenegr RNA .
-The messenger RNA then leave the nucelus vi the ncuelar pores and UDNERGOES translation on a ribosome .

86
Q

STRUCTURE OF NUCLEUS (4)

A

-the outer memrbane of the neucleas envelope is contirnous withi the roun endoplsmic reticulum .
REMEMEBER this palys a key role in portein synehsis .

87
Q

STRUCTURE OF NUCLEUS (5)
-Electron micrograph of the neucleus .
-nucleus contains a dark mterial dcienstis call this THE chromatin .
-

A

-chromatin consits of DNA , coiled around proteins called hsitones .
-Together histones +DNA proteins form CHROMOSOMES .
-REMEMEBR that DNA IN A CHROMSOME IS A LINEAR MOELCULE - AKA end of DNA is not joined to form a loop .

88
Q

REMEMEBR , Chromsomes not visible inside the neucluess

A

UNless the cell is udnergoing mitosis or meisois .

89
Q

STRUCTURE OF NUCLEUS (6)
-Inside the neuclues we can see a region darker than the rest …

A

THIS SI CALLED THE Nucleollus
-The nuecpus is where a special tupe of RNA is orduced .
-CALLED ribsoomal RNA OR rRNA .
-Ribsomoes RN is part of the strucutre of ribsooems .

90
Q

NUCLEOLUS

A

-As well as formin g rna .
-nucleols is where RIBSOSOME SUBUNITS are assembled .

91
Q

One key idea about proteins

A

Once a protein has been formed , it then has to fold into a three dimensional shape .
-once a protein has folded it can be then be modified further , (E.g some proteins have carbohydrates molecules attacch them forming glycoproteins )
- modifications are initially important finding of those proteins .

92
Q

Second key idea about proteins

A

-cytoplasm
-organelles
-cell membrane (receptor proteins )
-secreted from cell (hromones + antibiotics )

93
Q

How proteins are targeted to differeent to different destinations every complex subjects .

A

But a lot of the targeting involves a rough endoplasmkc reticulum + Golgi apparatus

94
Q

Translation consists on ribosomes

A

-ribosomes have twO subunits
-each subunits contain a number number of different proteins ribosomes RNA

94
Q

In any cells , a large number of ribosomes are found in the cytoplasm .

A

These ribosomes translate proteins which remain in the cytoplasm

95
Q

Other ribosomes are found attached to the rough endoplasmkc reticulum

A

…

96
Q

Closeup of rough endoplasmic reticulum

A

-rough we contains sheets of membranes forming flattened sacs called cisternae

97
Q

Closeup of endoplasmic reticulum (2)

A

-these cisternae contain a range of different enzymes .
- these membrane of cisternae are covered will ribosomes .
-these ribosomes are where translation takes place for proteins which are secreted from the cell .
-As well as the proteins for the cell membrane

97
Q

RECAP OF ROUGH ENDOPLASMIC RETILCUM AND GOLGI APPARATUS

A

-Protieins are synthesised by rbosomes on the memrbane of he orugh ER .
-These proteins then move thorugh the rough ER , wbere theya remodifided example (a carbohydrate moelcule can be attracted to the portein to form a glycoprotein).

98
Q

RECAP OF ROUGH ENDOPLASMIC RETILCUM AND GOLGI APPARATUS (2)

A

-Proteins then leae the rough ER in vesicles .
-These vesicles carry the porteins ot the golgi apparatus .
-Int he golgi apparatus protiens are modified further ,
-Fianlly , the porteins are packagedi nto vesicles and leave the gogli apparatus .

99
Q

The destiantion of thes evesicles , depend ont he fucntion , of the portein .
(Soe porteins are secred from a cell ,w ehreas others form part of the cell memrbane .

A

-However , a numebr of protiens are packaged into VESICLES .
-Which go on to form Lysosomes .

100
Q

FIRST KEY FEATURE OF LYSOSOMES

A

-Lysosomes contain powerful digestive enzymes such as proteases .
-These idgest larger molecules into smaller osluble moelcules .

101
Q

SECOND KEY FEATURE OF LYSOSSMES

A

-The internal fluid in alsysosme is acidic .
-As lysosmes enzmes hve an optimum pH which is acidic .

102
Q

DFirst functions of lsysosmes

A

-Lysosmes play a lay role in pahgocytosis (white blood cells )

103
Q

Process of white blood cells about to ingest a bacteria (1)

A

-White blood cells forma vacuole around the bacteira .
-This vacuole is called a phagosome .

104
Q

Process of white blood cells about to ingest a bacteira (2)

A

Lysosomes now fuse with the phagosome .
-The lssosmes enzmes now idgest the bacteria + the soluble digestion now pulls into the cytoplasm .

105
Q

Lysosomes can be also be used to destroy organelles t hat are damged or re no longer fcnional .

A

in this case the organelle is surroudned by a vacuole and lsysomes fus with the acuole mebrane .
-again the lsysomes enzymes now digest the oragenelles the idgestion porducrs are absorbed int othe cytoplasms and can be reused to amke new organelles .

106
Q

second key fucnitons of lsysomes

A

-sometimes transfer their enzymes outside of the cell bye xocytosis .
-For example , to digest + remove the unwated portiens or dead cells .

107
Q

Mitochondira

A

-Found in all euakryotic organsims (inclduing animals , plants + fungi) .
-Mmotiochodnira paly a critical role in aerobic respiation to produce the energy carrying moelcule ATP .

108
Q

In aerobic respiration , the carbohdyrate glucose is broken down to carbondixoide + water .

A

-The enegry contained in the chmeicl bodns of glcuose is transferred t ATP .
-We can divide aaerobic respiation into a number of stages …

109
Q

The first stage of aerobic respiation ?

A

-CALLED glycolsysis .
-Glycolysis takes place in the cytoplasms .

110
Q

Second stage of aerobic respiation ?

A

The next two stages tak eplac ein the mitochodnira .
There are TWO .
-Krebs cycle
-Oxidative phospharglyation .

111
Q

Oxxidative phosporglation

A

is the stage ina erobic respition which requires xoygen

112
Q

KEY ; mitochodnira have double memrbane

A

Have the outer mtirochodnir mamerane + the inner mitochodnria memrbane .
-inebtween these memrbanes we have the intemembrane space .
-Within the mitochodnir we have a fluid called the matrix .

113
Q

Where does Kreb’s cycle take place ?

A

INT HE MITOCHODNIRA .
-The enzymes for krebs cycle are found int he matrix .

114
Q

Where are the enxymes or oxidative phosphorylation

A

-found in the inne rmitochonitsl memrbane .
-inner memrbane is highly folded . These foldd are called cristae .
-by folign the inner meebrane like this is a great deal of surface area for the enzymes needed ofr oxidaive phosporyaltion .

115
Q

-In the mitochodnira , we also find a loop of mitochodnira DNA .

A

-The DNA , contains the genes rqruied .
-For some of the enzymes inovled in aerobixc respration .
-Mitohcondira also contains miotochondiral ribsoomes .
-These synthesisie the proteins encoded by the mitochondiral DNA .

116
Q

-We find large numbers of motochodnira in cells which require lots of energy .
-For exmpale msucle cells which require a lot of energy for contraction .

A

-Also the number of cristae .
-This porvides an INCREASED surfce area for the enzymes needed for oxidative phosphorylation

117
Q

What are chloroplasts ?

A

organelles where photsynthesis take place .
-Find chloroplasts in plant cells that carry out photosynthesis .

118
Q

-We dont find choloroplasts in partd of the plant that…

A

DONT PHOTOSYNTHESISE .

119
Q

Just be looking at photshnthesis but not too into detai

A

…

120
Q

what happens during photosynthesis (1)

A

-the enegry from light is used to react carbondixoide with water to form oxygen + the carbodhyrate GLOUCSE .

121
Q

what happens during photosynthesis (2)

A

-The energy that ws trapped in photsyntehsis is now contained witht hechemcials onds in the glucos emoelcuece .

122
Q

KEY ; photsynthesis actually consits of TWO sets of reaction .

A

-light dependant
-light independant

123
Q
A
124
Q

light dependant reactions

A

-use chlorphyll to harvest ligth eenrgy .
-the energy is then transferred into the CHEMICAL BONDS OD OTHER MOLECULES SUCH AS atp .
-mENAING LIght dpenedat reactions only take place int he presecne of lgiht .

125
Q

light indpeendant reactions

A

these are reactions which GLUCOSEis ormed .
-These reactions do not reuire lgiht .
-Mening lifht independant reactions take place in light + dark conditions .

126
Q

structure of chloroplast (1)

A

-Just like mitochodnir , chloroplast has a DOUBLE MEMRBANE .
-these memrbanes can control which molecules enter + leave the chloroplast .

127
Q

strcuture of chloroplast (2)

A

-Inside the hcloroplst , we find ememrbane - bound flattened discs . THESE ARE CALLED THYLAKOIDS .
-THylakoids are where light dpeendant reactiosn take place .
-Thyakoids contain chlorpyll + enzymes needed for the light dependant rections .

128
Q

strucutre of chloroplasts - THYLAKOID PART B

A

-Thylakoids are stacked on top of eachother .
- a stack of thylakoids are called a granum ,
-Bys tacking the thylakodis , into granum , LIGHT cn be absorbed more effciently .

129
Q

Thylakodi part c

A

-thylakoids on different granum are connected ot eachother by lattened memernes called lmellae .
-The lamellae plays role in the light dpeendant reactions .
-Allows chemicals to pass between the grana .

130
Q

structure of chloroplast (3)

A

-Chloroplasts contain a fluid amtrial called the STROMA .
-The stroma is where light indpendnt reactions take place.
-the stroma contains enzyms needed for light independan reactions .

131
Q

As we have seen , the end porduct of photosyntheiss is the carbohdyrate glucose .

A

-The glcose cn be converted into the polsccharide starch .
-Whcih is stored int he chloroplast as starch GRANUMLES .

132
Q

just like moochondira , chlrooplasts also contain a loop of DNA .

A

This DNA contains egenes which encode som of h eportiens needed for phtosysntheis .
-CHloroplasts also contain ribosomes .
-These ribosoems synthesis the porteins enocded by the chloroplst DNA .

133
Q

-Withitn cells , we also find a complex network of portein fibres , runnign throughout the cytoplasm.

A

SCIENITSTS call these porteins the CYTOSKELETON .
-The cytoskeleton has three main components , each crries out a speicfic role ..

134
Q

wITHIN THE CELLS ,W E ALSO FIND A COMPEX NETWORK of portien firbes running throughout the cytoplasms .

A

-Microfilaments (narrowest diameter
-Intermdite fibres (diameter inebetween the two)
-Microtubulues (greatest diameter)

135
Q

Microfilaments fucntions (1)

A

-Microfilaments are narrow fibres conaining the portein ACTIN .
-tThese actin fibres can CONTRACT .
-MICROFILAMENTS are invovled in cell moevment (when white blood cells move out of the blood sream nd into infecgted tissue.)

136
Q

micorfilaments fucntions (2)

A

-microfilaments also playa rold during cell division .
part of cell divisio is called cytoenesisi .
-DURING ctyokenesis ,t he cell memerbane is packed inwards .
-dividing the cytoplasms intwo wo ,t his process invoves the action of mcirofilaments.

137
Q

Intermeidate fibres fucntions

A

-intrrmeidite fibres are fromed a nnuber of differeitn protiens .
-THE ROLE of intermeidte fibres is or strengthen the cell .
(example skin cells are constantlt subjected to mechicla stressed due to mvoement) .
-itnermidte firbes help to prevent these stresses froM DAMAGIN THE CELLS .

138
Q

Microtubules functions (1)

A

-microtubules are fromed from subunits of the protein tubulin .
-tubulin subunits assemble to form tubulin polmers then form hollow microtubules .
THESE MICORTUBULES PLA A NUMBER OF ROLES ;
microtuubles are inovled int he moemvemnt of
rganelles (for exple vesicle movmemnt during secretion )

139
Q

micortubules fucntions (2)

A

2.Microtubules form the pindle fibres which ae invovled in the meovment of chromosomes duin mtiosis and meisosis .
3.yb forming a complex netowrk int hecytoplasms , micotueules help to determine the SHAPE of cells .

140
Q

Micortubules play another important role in the eukartoic cells .

A

IN THE CENTRIOLES .
-wE FIND A PAIR OF CENTIROLES IN lots OF DIFFERENT EUkarytoic cells . iNCLUDING ANIMALS CELLS .

141
Q

Certain relarvely ismple plants + allgae can have centrioles.

A

BUT WE DONT find centrioes in flowering plant cells as well as MOST UNGI .

142
Q

centrioles are made of microtubules .

A

-THe wo ceintrioels lie at right angles to eachother and are often found near the nucleous .
-TOGETHER w cal the pair of centrioles the eCENTROOMSOE .

143
Q

FIrst KEY funciton of centrioles .

A

-firstly during mtiosis and meisosis , centrioles play a role in the assemble o SPINDLE FIBRES (pindle fibres are doemws deom microubule)
-How these micortubules are arranged into spindle fiibres may beo rganised by the centrioles.

143
Q

First key fucntion of centrioles (2)

A

-Plant cells also form from SPINDLE FIRBED durignc ell divisions .
-BUT FLOWERING PLANTS DO NOT CONTAIN CENITRILES menaing cenrioles are NOT ESSENITAL for spindle assembly.

144
Q

Second key function of cenrioles (1)

A

cwentrioles also paly a keyr ole in eukaryotes in cillia and flagella .
-cillia are hair like organelles tthat extend from the surface of certain cells .
-by beating in WAVES , these cillia can wft dust particles along the trachea + push them out of the lungs .

145
Q

second key function of centrioles (2)

A

-we also find cillia in the fallopian tube .
-where theyw aft an egg cells towards the uterus .
-Some cillai do not MOVE , instea they play a role in SNESNING the chmicals aroudn the cell .
-Example int he sensory cells linig the nose .

146
Q

````````````````````````````````Flagellum
(as well as the differences in the cilli + flagell)

A

-Whip-like orgnalle that ewe find ont he surface of certain cells (sperm cells(
-The ROLE of the flagellm is to MOVE THE CELL .
-Flagella are LOGER htan cillia .
-If a flagellum is PRESENT in an eukaryotic cell there onlyone .
-Wheres cels can have a LARGE number of cilia .

147
Q

COMMOn things in flagella and cillia

A

+-Both shre a common structure.
-Runnign throught he center , we fine nine pairs o MICORTUBULES arranged ina CIRCL .
-With another pair of micorutules in the center .
-scienitsts clal this the 9+2 STRUCUTRE .
-Usin energy from TP , the pairs of microtubulescan move relative to hte pirs next tohem .
-This creates a BENING motion of there organelles .

148
Q

How does cillium orflagelluum form >

A

-It dpeends ont he comples ofportiens .
-A key prt of this porteins complex is a centrioles .
so FORMATION OF CCILLIA + FLAGELLS IS ANOTHER FUNCTION OF CENTRIOLES

149
Q

Functions of cell wall

A

-provides strength to the plst cell.
-This is really imporant as palnt cells face a signifcant challenge due to water .
-Water is an essential reactant for photysnthsis .
-for other reCTIONS TAKING PLACE IN PLANT CELL .
-meaning water moelcules have to enter + lela the plan cell .

150
Q

If the water potential outisde the plant cell is GREATER thn inside , then there iwll be net inflow of water moelcules by osmosis .

A

-This created a great deal of hydrostatic pressure inside the plnt cell oushing outwards .
-So the plan cell wall must be mechanicallys trong enough to resist the hydrostatic pressure .

151
Q

When a plant cell is filled with wter . THe outward hydrostatic pressure moelcule cell wall rigid .

A

-This helps to support the whole of the plnt . (can see the importance of this by tody at a plant which has wilted )

152
Q

Under certain conditions plants can loose woo mcuhw ater .
-noww the indivudal plant cells ae no longer filled with water .

A

Reducing the hydrostatic pressue pressing into the cell wall .
-Now the plant cell walls are no longer RIGID + plant can no longer maintian its strcutre .
-Causing plant too wilt .

153
Q

-So mechanical strength is a key feture of the plnt cell wall .
-Like i said before , water moelcules mus be bale to enter + lave the plant cell .

A

-So as well as being mechanically strong .
-The pln cell wall is also permeable to water meolcuesl .
-The plnt cell wall is mde up of the polysacharide cellulose.

154
Q

An indvidual cellulose molecule is a polymer of beta glucose .
-Cellulose moelcule can form hydrogen bonds withe chother .

A

-forming larger strcutrues clled micorifbirls .
-these cellulose micorifrils form mesh-like strcutre int he plant cell .
-This micoofibril mesh is extremelys trong and contrubtes to mechanical strength of the plan cell wll .

155
Q

-What is inbetween the plant cell wall?

A

-We find a laye of mterial called the middle lamella .
-THe middle lameela consits of polysacchrides .As well calcium + magnesium ions .
-THe jpb of the lamella is to ct as a glue between planr cells .

156
Q

-Apart from in plant cells we also find cell walls in algae + fungi

A

again the cell wall gices the cell rigid ity and contributes to the clel shape .
-IN ALGAE - THE Cell wall can contain BOTH GLYCOPRTEINS AND CELLULOSE .
-Whereas in fungi CELLW ALL IS MAD EOF THE POLYSACCHRIDE CHITIN AND WELL AS OTHER POLSYACCCHARIDES AND GLYCOPORTEINS.

157
Q

consolidation

A

-microscope produce linear magnicition so it appears 100 times wider na

158
Q

Consolidation on magnification whay tho or magnification do they produce ?

A

Linear magnification , soecimen sppesrs to be HUDNRED times more magnified than it rlly is

159
Q

Optical microscopes consolidation

A

Magnification up to 1500x
400 700 nm js visible light anyhting closer 200 nm appear as a one object

160
Q

Consolidation how to use a lihjt microscope one

A
  1. The dodcimdn is on a slide placed on to the stage and clipped into place
161
Q

Consolidation Joe to use a light microscope. 2

A

By rotating the nose Peice to the lowest power smallest objective lense is placed over the specimen

162
Q

Consolidation , how to use a light microscope 3

A

Adjust the coarse focusing knob while looking I yk the eyepiece until the image you see is in clear focus

163
Q

How to use a light microscope part four

A

Whilst viewing the image adjust the iris dislhragm for optimum lihjt .

164
Q

How to use anlihjtnkirodcopenpartn!5

A

Make sure that the object you wish to view is directly over the hole in the stage

Now rotate the nose piece and bring * 10 objective into the place over soecimen .

  • look down and ocular tube and use the fine focus image .
165
Q

Hwo to use light microscopenpartn6

A

Reoratvatartb5 using *40 objective lengs,

166
Q

A photo go graph or the image seen using an optical micro pad ?

A

Is called a photomicrograph

167
Q

Transmission electron microscope

A

Specimen has to be chemically fixed by being dehydrated n stained
- beam of electrons PASS THROIHJ

  • some electrons pass through a ndanre focused on screen

-2d black n white image okaydngallednepectro micrograph

168
Q

Scanning electron

A

Electrons jus bounce off
Give 3D image image is black n white but software can add false colour

  • specimen has to be placed in vacuum and coated w a metal stains I’m both electron. Sn be hazardous to hsrd
169
Q

How do u observe unstainednspecimens

A
  • many biological specimens are colourless and transparent , some use light interference rather than light absorption in order to produce a clear image without staining .
    .¥’s use dadk a dark background which is illuminated
170
Q

What do the specimens have to be in order to be observed

A

Dehydrated
Embedding in wax to prevent distortion during slicing .
/ special instrument tk Mel tkkk slices called sections. And moire don chemical tl preened

171
Q

Check page 33 to do a graticule

A

…

172
Q

If cells are eukaryotic they whay dobtjeybahhwb

A

A nucleus surrounded by a kickers ekehleop containing ska organised and wound into linear chromosomes .
An area inside the nucleus called the micleplis containing rna where chromosomes unwind tjrnmircleolid kd also involved on making ribosomes

Cytoskeleton we know

Pas membrane

Menrskennoj f or Hanwell’s

Small vesicles

173
Q

Consolidation of membrane organelles

A

Covered by a membrane

To keep organelles dlesrsfe from rest do fhag ks a discrete compartment .

174
Q

What does the nuclear ekeceope do

A

Nuclear envelope departed the contents of the nucleus from the rest of the cell

In some regions outer mnonner mementos and inner fuse togeyher at thsr points some iffeplved sulsuwhyejfes pass through
A rotesnallpemalrhebsihsuakfes sicjbas messenger eman .

175
Q

Rough Ed

A

System of membranes containing fluid fills cisterns conginuous with nuclear mdlejdksednskdnosncosfed with finosomoles .

176
Q

Red function

A

Red is the intraveillsf transport surely gjrncodysdnse forl channels for transport gong substances from one cell to sklfjer .
/ provide a large surface adww for ribosomes which assemble amino acids into proteins .

These proteins fhen wdivrl pas thru memernsmd intoncosyemr where they are transported into gooo apparatus dormleoceoroknskdnpadoahokg z

177
Q

Ser

A

System of membranes containing fluid filled cavities fisherman’s rjaybare continuous nkk clear memenrkse

NO RINOSOMES

178
Q

Function of ser

A

Contains enzymes which catalyse reactions involved wofinlipidnkefhaolosk XD
Such as
Synthesis of coolest roll
Synthesis of lipids
Dunfejsodnofnsteroidnjrlmomed

Mingoglrf on absorption ofnsuntjedidnwjdnrrajsportnfrom the gut

179
Q

Golgi apparatus function

A

Consists od a stack of membrane bound flattened sacs secretory cescicles being material go and from golginspparafis .

180
Q

Function of Golgi apparatus

A

Proteins are lsocioed for example hun
Adding sugar make gymcyopeoreins

Adding lipid to make lipoproteins

Proteins are then packaged into vesicles fhay are pijxuednoffnjnrhenneroresnijnanxell or moved to the plasma membranes

181
Q

Vacuole structure and functions

A

Vacuole is surrounded by a membrane called the tonkplwst as contains fluids.

Only plant cells have a large permanent vacuole filled worj splitter maintaining cell stability as it pushes against cell wall skiing kt turgid espeidslt on non eoodg plants

182
Q

Undulipodiukn

A

Only tupenofncelnoknuiskksntonjahebajnijdiliprofik longer than coloikmodnsperrmwtodokspundupiloppdonind w flagella and enables spermatozoa to lvoe

183
Q

Learn page 42 .

A

…

184
Q

Glance over page 42

A

…

A-level Biology (21 decks)

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