topic 2 - cells Flashcards
(94 cards)
1
Q
strutcutres within the neuculeus
A
neuclear envelope - double envelope
neuclear pores
neucleoplasm - granualr jelly like mateiral
chromozones - protein bound linear dna
neuclouous - small sphere inside this is the site of rna production and makes ribsomes
2
Q
fnuctin of neucles
A
site of dna replicatoin and transcription ( makinng of rna )
contains the genetic code for each cell
3
Q
edoplasmic reticulum - strutcure
A
rough and smooth er both have folded membrenes called cisternae
rough have chromozones on the cisternae
4
Q
function of endoplasmic reticulum
A
RER - protien synthesys
SER - synthesys and store lipids and carbs
5
Q
golgi appararus - structure
A
folded membrene make cisternae
secretart cesticles pinch of from the cisternae
6
Q
golgi apparatus and vesicles - function
A
add cars to protiens to form glycoprotiens
produce secretory enzymes
secrete carbohydrates
transport, modify and store lipids
form lysozomes
molecules are labeld with their destination
7
Q
lysozomes structure
A
bags of digestive emzymes - can contain up to 50 enzymes.
8
Q
lyspzpmes function
A
hydrolise phagocytotic cells
completely break down dead body cells
exocytosis - release enzymes to outside of the cell to destriy materal
digest worn out organels for reuse of amterials
9
Q
mitochondria structure
A
double membrene
inner membrene called cristae
fluid ctnre called mitochondrial matrix
loop of mitochondrial dna
10
Q
mitochondria function
A
site of aerobic resporatoin
site of atp production
dna to code for enzumes needed in respiration
11
Q
ribozomes streutcure
A
small made up of two sub units of protien and rna
12
Q
robozomes fucntoin
A
site of priten synethsys
13
Q
vacuole structure
A
filled with fluid surrounded by a single membrene - tonoplast
14
Q
vacuole function
A
make cells tugrid and therefore provide support
temprary store of suagrs and amino acid
pigmant may colour petals attratcing polinators
15
Q
cholroplats structure
A
surrounded by a double membrene
contrain thylakiods ( folded membrenes embreded with pigment )
fluid filled stroma contains enzyme for photosynthesys found in plants
16
Q
key difference between prokaryotic and eukaryotic cells
A
the cells are miuch smaller ]
no membrene bound organelles
smaller ribosomes
no neuculeus
cell walled made of muerin
they may also contain
plasmids, flagela, a capsule around the cell
17
Q
define magnification
A
how many times larger the image is comared to the object
18
Q
define resolution
A
the minimum distance between two objects in wich they can still be views as seperate
the resolution of a light microscope is determined by the wavlenength of light and the wavelenegth of the beam of electrong derermines the resolution in electron microscope
19
Q
optical microscooe - key points
A
a beam of light is condensed to creat an image
poorer resolutioun is due to light having a longer wavelength
lower magnification
colour images
can view living samples
20
Q
electron microscope ( key points )
A
scanning or transmission
a beam pf elecvtrons is considred to creat the image, electromagnets are used to condense the beam
higher resolving power as electrons have a short wavelength
hgiher magnification
black and white images
sample must be in a vacume therefore non living
21
Q
how do transmission electron microscopes work?
A
- thin specifmine is stained and placed in a vacume
electron gun produces a beam of electrons that pass through the specimen
some parts absorb the electrons and appear dark
image is 2d and shoes the internla structure of cells
22
Q
how do scanning electron microscpoes work?
A
do not need to be thin.
electronsd are beamed onto the surfsce and scattred in different ways depending on the contours
prodcing a 3d image
23
Q
image size= ?
A
actual size x magnification
i = am
24
Q
how to convert!!
A
metre
millimitre
micrometre
nanometre
25
cell fractionation solution - 3 conditions and why?
cold - reduce enzume activity, when the cell brekas open enzymes are realeased wich could damage the organelles
isotonic - same water potential to prevent osmosis causing the cells to shrivel or burst
buffred - the sulution has a pH buffeer to prevent damage to organelles
26
two steps to the process of fractionation
homogenisation
ultracentrifugation
27
outline step one of cell fractionation
homogenisation
cell must be broken open using a blender
cells are blended in a cold isotonic buffered solution
solution is fulred to remove large cell debri
28
outline the steps of differential ceitrifugation
centrifuge spins and the centrifugal forces scause pellets of the most dense organels to fomr at the bottom
centrufuge is first spunat low speends and this process is repeated at increasingly faster speeds
each time the supernatant is removed leacing behing a pelet of organells
29
heaviest - lightest - differential centrifugation
nucleui
chloroplats
mitochondria
lysozomes
endoplasmic reticulum
ribosomes
30
what arr the three phases of the cell cycle?
interphase
neuclear division
cytokenesis - division of the cytoplmasn to creat new cells
31
mitosis four key stages
prophase
metaphase
anaphase
telophase
32
reuslts of mitosis
one round of division
genetically ideittcal cells are made
diploid cells are made
growth and repair e.g clonail expansion of b cells
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outline prophase
chromozones condense and become visible
34
outline metaphase
chromonseones align along the equator of the cell, spindle fubred released from the poles now attatch to the centromere and chromtid
35
outline anaphase
the spindle fibred start to retraxct and pull the centromere and chromotids rhey are bounf towats the oposite ples
centromere divided in teo snd indivial chromatids and pulled to each oposite pole
this stage rewuiured energy in the form of atp
36
outline telophase
chromonses are now at each pole and become konger and thinner again
the spindle fubres desintegrate and the neucleus starts to reform
37
mitotic index is?
( the number of cells in mitossi / the total number of cells ) x 100
38
binary fission in prokaryotic cells
repliaton of circular dna and plasmids
division of the cytoplasm to produce two daughter cells each with a snigle copy of the circular dna and a variable number of plasmids
39
why do viruses not under go cell division?
they are non living
they inject their neucleic acid into the host and the host cell replicates the virus particles
40
what is the cell membrene called?
phospholipid bylayer
41
hydro...
hydropohpbic tail
hydrophilic head
42
what is colestrols purpose in the membrene
restirct larteral movement of other molecules in the membrene. this is useful as it makes the me,brene less flid at hight empretruews and prevents water and disolved ions leaking out of the cell
43
different types of protiens in the membrene
peripheral protiens provide medhanical support so they are conected to protiens or lipids to make glychoproptiens and glycholipids. the function of these is cell recognition as receptors
intergrap protiens are protien carriers or chal proriens involved in the transport of molecule across the membrene
protien chalens form rubes filled with water to enable water soluble ions to diffuse
carrier protiens will bind to other alrger moelcules such as glucose or amino acids and change shape to transport them to the other saide of the membrene
44
molecules that passs through the plasam membrene
lipid soluble subsutances and very small molecules
44
molecules that can not pass through the membrene
water soluble subcustances and alrge molecules
( sodium ions )
( glucos )
45
simple difusion
the net movement of moleucles from an area of higher conetrantaion to an area of lower contentratoin until equilibrrium is reached., this process does not require atp
46
facilitated diffusion
passive process but different from simple diffusion as pprotiens are used to transport molecules
the movement of ions and polar molecules wich can not simply difuse can be transport across by fd using protien chanels and carirer protiens
47
how to protien channels work?
fomr tubes filled with water and enabled wayter solubule ions to pass through the membrene
this is still electivre and the chanel is only open in the presence of certsin ions
48
how do carrier pritens work?
will bind with a molecule e.g glucos this will change the sdhape of the priotien
the shape change enables the molecule to be released to the other side of the membrene
49
what is osmosis
movement of water from an are of higher water potentials to an area of lower water potental
acorss a partially permebable membnrene
50
what is water pottential
the pressure created by water molecules and is measured in kpa
pure water has a warer potental of 0
51
what is an isotonic solution?
the water potential is the same in the solution and the cell within the solution
52
what is a hypotonic solutoin?
the water potential of a solution is more positive ( closwe to zero ) than the cell
53
hypertonic solution?
the water potential pf the solution of mroe negative than the cell
54
what is active trnapsort?
the movement of subcustnve from a low contentration to a high conetration using metaboilic energy and a carrier protien
55
steps to a active tranpsort using a carrier protien?
1. transport is thorugh carirer protiens spanning the cell membrene
2. molecule binds to a receptor complementory in shape to the protien
3. atp binds to the carrirer prietien from the indise of the cvell and is hydrolised into adp and +pi
4. this causes the carrier pritoen to change shape and release hte molecule onto the other side
5. the phosphate ion is then released and the protien returns to its original shape
56
co transport of glucose and sodium ions ion the ileum
to absorb glucose from the lumen to the gut there must be a higher concentratoin of glucose in the lumen compared to the epithelial cell ( for facilitaed diffusion )
but
there is usually more glucos in the epithelial cells
thjis is why active tranpsort and co trnapsort are reuqired
57
co tranpsort of glucose and sodium ions in the ileum
sodium ions are activelty transported out of the epitheilial cells into the blood
thhis reduced the sodium ion concentratoin in the epithelial cell
sodium ions can then difuse from the lumen down their cocentration gradient into the epithelial cell
the protien the sodium ions difucse thorugh is a co trnapsorter protien so either gluce or amino acids can also attatch and are transported into the epithelial cell against their concentraoitn gradient
58
cells may be adapted for rapid trnapsort scross their internal or external membrenes by:
an increase in surface area
an increase in the number of pritein chanels and carrier molecules in their membrenes
59
how can lymphocytes distinguish betwen pathogens and self cells?
each type of cell has specific molecules on its surface that identify it.
these molecules are usually protiens as their 3d teritary structuire enables lots of unique and identifiyable shapes to be made
60
if a non self cell is detected a repsonse will be triggered to destroy the cell
these different surface molecules enable them to identify?
- pathogens
- cells from other roganisdms of the same species
- abnormal body cells
- toxins
61
what are antigens?
molecules that generate an imune repsonse bt lymphocyte cells when detected in the body
they are uaually protiens and are locsted on the surface of cells
62
what is antigen varibaility?
pathogenic dna can mutate frequently
if a mutatoin occues in the gene wich codes for the antigen the dshape of the antigen will change.
any previous immunity to this pathogen ( wither naturally occusing or atriifcially ) if no longer effective
this is becuase the memory cells will have a memory of the old antigen shape
e.g the influenza virus changes its antigens very quickly, therefore we need a new flu vacine each year
63
what is the difference between phagocytes and lymphocytes?
phagocytes - non specific
lymphocytes - specific
64
steps to phagocytosis
phagocytes are in the blood and tissues
any chemicals or debris resleasded by the pathogen or abnormal cells will attrasct the phagocytes and they will move toward the cells
there are many receptor binding points on the surface of the phagocytes they will attatch to chemicals or antigens on the pathogen via these recptors
the phagocyte changes shape to move around the pahtogen and engulf it
once engulphed the pathogen is contained with a phagozome vesicle
a lysozome within the phagocyte will fuse with the phagozome to reslease its contents
the lysozome enzyme is relased into the phagozome
this is a lytic enzymw wich hydrolises the pathogen
65
what do cell mediated responses involve?
t cells and body cells
66
where to t cells marture?
thymus.
67
what are antigen presenting cells?
any cell that presents a non self antigen on its surface.
68
what are types of antigen presenritng cells?
infected body cells will presenrt viral antigens on its surface
a macrophage wich has engulphed and sdestroyed a pathofen will presernt the antgens on their surface
cells of a transplanted organ wull have different shaped antigens on their surface conmapred to your self cell antigens
cancer sells will have abnornal shaped self cell antigens
69
steps to the cell mediated reposnse
1. once a pathogen has been engulphed and destroyed by a phagocyte the antigens are positiojned on the cell surface
2. this is now called an antigen presenting cell
3. helpcer t cells have receptors on their surface wich can attatch to the antigens on the apc
4. once attatched this activates the helper t cells to divide by mitosis to replicarte and make a alrge number of clones
4. cloned helper t cells differentiare into different cells
- some reaim has helpter t cells and activate b lymphocytes
- some stimulate macrophages to perform mroe phagocytosis
- some becuase memory cells for that shaped antgen
- some became cytotoxic t cells ( killer t cells )
70
what are cytotoxic t cells?
these cells destroy abnormal or infected cells
they release a protein, perforin wich embeds in the cell surface membrene that makes a pore ( a hole ) so any subcustance can enter or leave a cell
71
what do cytotoxic t cells cause?
cell death
this is more common in viral infections becuase viruses infect body cells
body cells are sarificed to prevent viral replicatoin
this is why you gert a sore throat
72
what are lymphocytes
white vlood cells involved in the specific imune response
73
where are lympocites made and matured
bone marrow
b cells mature here to
74
steps to b cell activation.
antigens in the blood colide with their complementty antibody on a b cell
the b cell takes in the antigen by endocytosis and then presents it on its cell surface membrene
when this b cell colides with a helper t cell receptor this activates the b cell to go thorugh clonial expansion and differentiation
b cells undergo mitosis to make large numners of cells these differentiate into plasma cells or memory b cells
plasma cells make anti bodies
b cells can divide rapidyl into plasma cells when re infected with the same pathogen to make large numbers of antibodies rapidly
75
memory b cells live for...
decades
76
memory b cells do not make antubodies rather they?
divide by mitosis and make plasma cells rapidley if they clode with an sntigen they have previously enountred
this results in large numbers of antibodies being produced rapidly that the pathogen is destroyed before any symptoms can occur
77
what is agglutinaton ?
antibodies are flexible and can bind to multiple antigens and clump them together
this makes it easier for phagocytes to locate and destroy the pathogens
78
what is passive imunity?
antibodies are introduced into the body
the pathogen doesnt enter the body so plasma cells and memory cells are not made
no long term immunity
e.g naitbodies passed to a fetus thorugh placenta or through breast milk to a baby
79
what is active immunity?
imunity created by your own imune system following exposure to the pathogen or its antigen
80
what is antural active immunity?
following infextion and the creation of the bodys own anti bodiies or memory cells
81
what is artifical active immunity
following the introduction of a weakned version of the pathiden or antigens via a vaccine
82
how do vaccines work?
small amounts of weakned or dead pathofens are introduced into the mouth or by injection
exposure to the antigens activasted the b cell to go thorugh clonail expansion and differentatoin
b cells undergo mitosis to make large numbers of cells rhese differenriate into plasma cells or memory b cells
plasma cells make antibodies
b memory cells can divide rapidly into plasma cells when reinfected witht he same pathogen to make large numbers of antibodies rapidly
83
what is herd immunity
if enough of the population are vaccinated the pathfgeon can no spead easiuly among the popualtion
this privides protection for those who are not able to get vaccinated
84
hiv strutcture ( 4 components )
core - genetic material ( rna ) and the enzyme reverse transcriptase wich is needed fo viral infectoin
capsid - outer protien coat
envelope
envolope - extras outer layer
protien attatchments - on the evterior of the envoleope to allow the virus to attatch to the hosts helper t cell
85
repliatoin of hiv in helper t cells
hiv is transported around the blood until it attstched to a. cd4 protien on the helper t cells
the hiv protiem capsule then fuses wirth the helper t cell membrene enableing the rna and enzymes from the hiv to enter
the hiv enzyme reverse transcriptase coppised the viral rna into a dna copy and moves to the helper t cell neuculsi, this is why it is called a retrovirus
here mrna is transcribed and the helper t cell starts to creat ivral protiens to make new viral particles
86
aids is when the ...
replicsting viruses in the helper t cells interfere with their normal fucntoining of the imune system
with the helper t cells being destroyed by the virus the host is a ubable to produce an adequite response to other pathogens and is left vulnerable to infectoins and calcer
it is the distruction of the imune system that lead to death rather than the hiv directly
87
what are monoclonal antibodies
a single type of anti body that can be iscolated and cloned
88
moncolonal anti bodies have been created for:
medical treamtnet
diagnosis
pregnancy tests
89
what is indirect moncolonal antibody therapy
drugs attatched to them
delivreded directly to cnacer cells and kill them
reeucded the harmful side effects of chemotherapy
often refered to as bullet drugs
90
monoclonal antibodies can be used to test for:
pregnancy
influenza
hepatitis
chlamydia
prostate cancer
this works via the eliza test
91
eliza test - use of two antibodies!
first mobile antibodu competelemtry to the antibody being trsted foand had colourred
a second antibody compeltementry in shape to the antigen is imoblised in test
a third antobody is imoblised and is completemrry to the shape of the first antbody
92
steps of the eliza test
add the test sample from as patent to the base of the beaker
wash to remove any unbond test sample
add an antibody compeltemtry in shape to the antigen you are testing the presence of in the test sample
washto remove any unbound antibody
add a second antibdoy that is compeltentry to the shape of the first antibody and binds to the first the second antibody has an enzyme attratced to it. rinse the unbound antibodies off
the substrate for the enzyme wich is colourless is added
the substrate produces coloured products in the presence of the enzyme
the presnce of the colour indicated the presence of the antigewn in the test sample and the intensity of the colour indicates the quanitity present
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