Topic 2 Flashcards
1
Q
what are cell surface membranes?
A
-surrounded by cells
-control what enterd and leaves( seperate cell enviroment from external enviroment)
-act as barriers between organelle (in cell) and cytoplasim(enviroment)
-regulate movemant of substances
2
Q
how do cells move accross cell surface membrane?
A
-diffusion
-osmosis
-active transport
3
Q
what do partialy permeable membranes do?
A
let some moleculs through
4
Q
what is contained within a fluid mosiac model? (7)
A
-glycoprotien
-glycolipid
-phospholipid
-protien channel
-protien
-cholestrol
-carrier protien
(protiens, carbohydrates and lipids)
5
Q
what is a bilayer in a fluid mosiac model?
A
is where phospholipid moleculs form continous, double layer
which is fluid as phospholipids are constantlt moving
(contains cholestral)
basis of all cell membranes
6
Q
why are protiens ( like channel protiens and carrier protiens ) scattered through bilayer?
A
- to allow large moleculs and water soluble ions to diffuse through membrane
-carriers specificly bind to ions/moleculs. and change shape in order to move moleculs
7
Q
what are receptor protiens?
A
-allow cell to detect chemicals released from other cells.
that theb gives signal to cell to respond
8
Q
what are glycoprotiens?
A
protiens with carbohydrates attatched to them / carbohydrate chain attatched to extrinsic protiens on outer cell membrane surface
function
•recognition site ( acts as cell surface receptors, for hormones)
• helps cell attatch to one another (form tissues)
•allow cell to recognise one another
9
Q
what are glycolipids?
A
lipids with carbohydrates attatched
-carvohydrate covalently bonded with lipids
-the carbohydrate region extends from phospholipid bilayer into watery enciroment outside cell
functions:
•recognition site (acts as a cell surface receptor)
•maintain stability if membrane
•helps cell attatch to one another and form tissues
10
Q
what are phospholipids? (3pts)
A
form a barrier to dissolves substances
-has a polar ‘head’ that is hydrophic (attract water) and faces water on either side of membrane( consists of phosphate group)
-has non polar ‘tail’ hydrophobic( repel water) which is in the centre, so the membrane doesnt allow water soluble substances to diffuse through it, as they are polar (consit of fatty acids )( not want to interact with water)
[[only water and smal non polar sunstances can diffuse through it]]
11
Q
what are cholestrol? (4pts)
A
-they are present in all cell membranes which fit between phospholipids
(which park phospholipids close together, so they can restrict movemant of phospholipids,
making cell membrane less fluid and more rigid)
-gives membrane stability-
•prevent loss of water and dissolved ions from cell
•helps mantain shape of animal cells
•has hydrophobic regions, so creates further barrier to polar substances moving through membrane
12
Q
what is it called the fluid mosiac model?
A
-fluid: phospholipids moleculs move around within each layer. so lelmbrsne is flexable and change shape( diffuse in areas where needed
-mosiac: studded with protien moleculs and arrangment of protiens varies when looked at above
13
Q
what is magnification and its formula?
A
magnification is hiw much bigger image is
magnification= size of image
______________
size of real object
14
Q
how many millimetres in a micrometre?
A
0.0001 (
15
Q
how many millimetres in a nanometre? (nm)
A
0.000001 mm
16
Q
what is resolution?
A
how well image is distuinhished between two points that are close together
17
Q
what are light microscopes?
A
-use light to form image
-max resolution 0.2 micrometres (view organelles less than 0.2um)
-max magnification x1500
-cheap
-see cells and tissue organisation
-see cell behaviour
-easy to use
18
Q
what are electron microscopes?
A
-use electrons to form image
-high resolution(max: 0.0002micrometres)
-look at lots of organelles
-produce balck and white images coloured by computer
-short wavelength
-resolve objects 0.0001 micrometers apart
19
Q
what are types of electron microscopes?
A
-transmission electron microscopes (TEM)
-scannning electron microscopes
(SEM)
20
Q
what are transmission electron microscopes?
A
use electromagnets/ electron gun to focus beam of electrons, thats transmitted through specimen
-darker images are caused when denser parts of specimen absorbs more electron
-gives photomicrograph
21
Q
what are ADV and DSV of transmission electron microscopes?
A
adv
-give high resolution images( see internal structure of organelles)
dsv
-view specimen in vacum, so not good at looking at living organisms(kills them)
-difficult preparing specimen cause artefacts from ‘staining’ procces
-only used on thin specimen
22
Q
what are scanning electron microscopes?
A
-scan beam of electrons accros specimen. Which knocks electrons from specimen( produce pattern of scatters electrons and secondary electrons produced) , that are gathred in cathode ray tube to form 3D image
-these can be used on thick soecimen but give lower resolution image than transmission electron microscope (better than light)
(and only on non living specimen)
23
Q
how do you look at organelles under electron microscope?
A
-first seperating them from rest lf cell via cell fractionation
24
Q
what are the steps to cell fractionation?
A
1-homogenisation
2-filtration
3-ultracentrifugation
25
what is homogenisation procces during cell fractionation and how are these conditions maintained?
-procces of breaking cells
grind cells in blender to BREAK plasma membrane and RELEASE orgenelles into solution
-solution kept ice cold to REDUCE activity of enzymes that break down organelles
-solution be isotonic: prevents DAMAGE to organeles via osmosis
(add buffer solution to maintain pH)
26
what does it mean if solution is isotonic?
-has same concentration of chemical ad cells being broken down
27
what is filteration procces of cell fractionation?
-filtred solution through gauze. which seperates large cell debri from organelles
due to organelles being more smaller than debris, allowing them to pass through gauze
28
what is ultracentrifugation procces during cell fractionation?
-seperating particle organelles from others
cell fragments poured into tube, then out inti centrifuge and spyn at low speed
causing heavy organelles to go to bottom of tube, forming thick sedimant called **pellet**
whilst rest if organelles suspended in fluid above sedimant called **supernant**
supernant is then draines and put into another tube, and spun faster
procces repeated till all organeles seperated
29
what is the seperation order of organelles during ultracentrifugation?
-Nuclei
-Chloroplast (only in plant)
-Mitochondria
-Lysomes
-Endoplasmic reticlum
-Ribosomes
30
hiw do you make a temporary mount of pieice of object to observe for optical microscopes?
1.pipetting small water drop onto slide centre
2. use tweezers to place thin specimen section on top of water droplet on side (make sire **thick** specimen became thin)
3. add stain droplet to highlight objects in cell
4. add cover slip by standing slip upright on slide next to water droplet
-carefully tilting and lower to cover specimen (avoid bubbkes as tbey construct view)
31
what are arrefacts?
-things seen down microscope, not part of soecimen observed
which are commin in electromicrographic as specimen need lot of prepirarion to view under electron microscope
32
what do you use on light microscope to measure size of object?
-eyepiece graticule
33
what is the eye piece graticule?
- glass disc placed in eyepiece of microscope
-has scales etched onto glass disc
-is visible when looking down eyepiece
- BUT must be calibrated for particular objective lense
(so its sensible to record calibration result and leave it attatched)
34
how do you calibrate an eyepiece graticule?
-use special microscope slide called stage micrometer (that has scale etched on it)
and get it lined up with the eyepiece graticule
35
what is the ultrastructure of a cell?
the internal structure of a cell that suits it for its job
36
what is the nucleas?
-contains organisms hereditry material and controls cell activity
-prominent feature of eukaryotic cell
-controls cell centre through MRNA & (message rna to RER) tRNA production and protien synthesis
-retains genetic material in cell in DNA/ chromosomes
-manufactures ribosomal RNA and ribisomes
37
what are the parts of a nucleas (5)?
-nuclear envelope
-nuclear porse
-nucleoplasm
-chromosomes
-nucleolus
38
what is a nuclear envelope?
-double membrane, surrounding nucleas
•outer membrane is continous with endoplasmic recticulim of cell and ribisomes on surface
•controls entry and exit of material in nucleas
•contains reactions taking place in it
39
what are nuclear porses
-allow passage of large moleculs out of nucleas
(usualy 3000 pores in nucleas)
40
what is a nucleopsm?
-granular, jelly like material that makes up bulk part of nucleas
41
what are chromosomes?
consists of protien-bound, linear DNA
42
what is a nucleolus?
-small spherical region within nucleoplasm, that manufactures ribisomal RNA and assembels ribisomes
(mRNA, message rna?)
(are multiple of them)
43
what is diffusion?
net movemant of moleculs from region of high concentration to region of low concentration until reach equalibriam
44
what are particles doing?
constantly moving fron kinetic energy
,have random motion
,bouncing of one another
45
what is facilitated diffusion?
movemant of moleculs made easier by transmembrane channels and carriers that span membrane
-(in protien channels and carrier protiens)
-(passive)
46
what are protien channels?
-form water filled hydrophilic channels accros membrane to allow water-soluble ions to pass through
-if ion not present, channel remains closed
-ions bind with protien causing it to change shape in a way which closes and opens on one side of membrane
47
what are carrier protiens?
-they span plasma membrane
-bind with protien, causing it to change shape in way molecule is relased in the inside of membra e
-no external energy needed
48
what are mitochondrion?
-they are rod shaped and 1-10 micrometres, that has double membrane and inner membrane folded to form extensions called cristate(has high amounta). also contain a matrix
-contain respiration stages(krebs cycle and oxidative phosphorylation pathway)
-produce ATP fron glucose
-lots in cells
49
why do is there a high amiunt if mitochondria and cristate in cells?
-due to cells having high levels of metabolic activity
50
what occurs in mitochondira in epithelical cell?
-absorbtion of lots of atp via active transport
51
what is a cristate?
-has large surface area for enzyme attatchment and other protiens used in respiration
-an extension of the inner membrane
52
what is a matrix?
-(makes up majority of mitochondrion)
cintains protiens lipids, ribosomes and dna to allow it to control production of their own protien (materials and substance that make up vacant spaces in cell/organelle)
53
what is chloroplast?
they are discd shape(2-10 micrometrrs long) which carry out photosynthesis
contain:
-chloroplast envelope
-grana
-thylakoids
-chlotophyll
-stroma
(has DNA and ribisomes to easily manufacture protien for photosynthesis)
54
what is the grana?
-they are stacks of thylakoid that contain chlorophyll
-some have tubular extensions with thylakoids adjacent to grana
-the granal membrane has large surface area to attatch chlorpyhll, electron carriers, enzymes in an orderly fashion
(involves in first stage of photosynethesis)(light absorbptoin)
55
what is the stroma?
fluid filled matrix
-contains starch grains
-contains enzymes to make sugers for second stage of photosynthesis( synthesis of sugers)
-encircles grana and thyakloid
56
what is the endoplasmic reticulum?
a three dimensional system of sheet like membrane, spreading through cytoplasm thats continous with outer nuclear membrane
(which contains cristeranea)
57
what are the two types of endoplasmic reticulum?
-rough enoplasmic reticulum (RER)
-Smooth endoplasmic Reticulum (SER)
58
what is the rough endoplasmic reticulum?
ribisomes present on outer surface membrane
-has large surface area for protien/ glycoprotien synthesis
-has pathway for material(PROTIEN) transport throughout cell
59
what is the smooth endoplasmic reticulum?
-there tubular in appearance, but lack ribisomes on the surface
-is where carbohydrate/lipid synthesis, storage and transportarion takes place
60
what does it mean if a cell has lots of endoplasmic reticulum?
the cell stores large qauntities of carbohydrate, protiens and lipids
61
what is the golgi apparatus?
-it contains membrane stacks ( flattened sacs/cristernae with vesicles)(which are hollow and small)
-the protiens and lipids produce by the ER are strictly passed through golgi
-modifies lipids/ protiens (by adding non protien compartments like carbohydrate) [form glycoprotien]
- labals them so they can be stored and sent to the right location. Then transported into Golgi vesicles, that are pinched off from Golgi cristernae ends.
Vesicles may move to cell surface membrane , fusing with membrane to release conteents to outside of cell via exocytosis (a form of active transport)
62
what can the golgi apparatus produce?
-security enzymes
-lysomes( developed in security cells
63
what are lysomes?
Vesicles that contains enzymes (protease, lipase, lysozymes)
They are then either released to outside of cell or into phagocytic vesicles in cell
-contains up to 50 enzymes
(1 micrometer in diameter)
-abundunt in security cells , epithelical, phagocytes, cell
64
what are the four functiona of lysomes?
• hydrolise material ingested by phagocytic cells
• release enzymes to outside of cell (exocytes) to destroy material around cell
• digest warn out organelles so usefal chemicals (from cell) are used
• break down cells after death (autolysis)
65
what are ribisomes?
small cytoplasmic granules in cytoplasm/ associated with RER
-Has a large and small subunit that contains ribosomal rna and protien
-site of protein synthesis
two types:
-80s: in eukaryotic cell
(25 nanometer diameter)
-70s: in prokaryotic cells, mitochondria, chloroplast
occurs in vast numbers
(25% of dry mass of cell)
66
what is the cell wall?
-consists of celloluse in matrix that that has microfibril to provide strength , strengthening cell wall.
-has middle lamella: thin layer that marks boundry between adjacent cell wall & cements adjacents cells together
-provides mechanical strength (to prevent cell bursting under pressure) and (as a whole)
-also contributes water movemant through plant (apoplast pathway )
67
what are algae cell walls made of?
celloluse
glycoprotien
68
what are fungi cell walls contain?
mixture of chitin, glycon and glycoprotien
69
what are vacuoles?
-fluid filled sacs bounded by tonoplast( single membrane around it)
Cell Sap [contains salts, sugers, amino acids. and anthocyanins pigament]
Functions:
• support herbacous (woody) plants making then turgid
•sugers and amino acids act as temporary food sources
•has pigments that might colour pelets to attract polinating insects
70
what has a single lagre vacoule
mature plant cells
71
what is osmosis?
passage of water from region of high water potential to region of low water potential through selctively permeable membrane
72
what are selectivly/semi permeable memrbanes?
-membranes permeable to water and small molecules (not large molecules
73
what is a solute?
substance dissolved in solvent
74
what is consisted in a solution?
solute + solvent
75
what is water potential?
(kilopascal) kPa
pressure created by water moleculs
[also referred to as hydrostatic pressure]
76
what happens when you add a solute to water?
lowers water potential ( as water potential is awlays less than zero)
77
why are water molecules and solute always in net movemant
due ti their kinetic energy
78
what has the highest water potential?
pure water (has 0kPa)
79
what happens when a cell is placed in a higher water potential region?
cell will absorb water, and the cell surface membrane will break, bursting cell and releasing contents
80
what happens when the cell is placed in a region of low water potential?
water will leave the cell by osmosis, cell will sheink, becoming shrivled
81
what conditions do animal cells live in? (Reference to 🔱)
one where liquid has same water potential as cell
82
what does it mean if the cell surface membrane is thin during osmosis?
it means it will be flexible but not able to stretch enough to consume water in a high water potential region
83
what are the 5 functions of the golgi apparatus?
-add carbohydrates to protiens to form glycoprotiens
-produce secretory enzymes (secreted by pancrease ones)
- secrete carbohydrates (ones used in making cell walls)
- transport, modify & store lipids
- form lysosomes
84
what do multicellular organism contain?
specalised cells that can evolve organelles to perform oarticular role
85
what are the first cell groups?
embryos, that are initially identical( with same genes, these genes go into most of the cell to progresss development of certain cells)
86
what happens when embryos go through maturity?
they take on own individual characteristics for job
87
how are cells produced?
by mitotic division from fertalised evgs
88
how do cells become specallised?
-when any genes become switched on, in any cell, at any time, where rest of genes are switched of.
89
what do specalised cells have?
varied number of organelles (and vary in shapes)
90
what are tissues?
similar cells aggregated together
91
what are two examples of tissues?
• epithelial tissues
• xylem
92
what are epithelial tissues?
found in animals
-line surface of organs and often have secretory function.
-some made of thin, flat cells that line organs where diffusion take place (alveoli, cilitated epithelium lines duct)
-has cillia used to move mucus over epithelial surface
93
what are xylem tissues?
in plants
-consist of similar cell types.
-transport water and mineral ions throughout plant & gives mechanical supprt
94
what are organs?
-tissues aggregated into organs
-combination of tissues coordinated to perform variety of functions
95
what are examples of organs?
-stomach
-leaf
-veins and arteries
-(not blood cappilaries)
96
what is the stomach organ?
organ involved in digestion
-has muscle to churn & mix stomach contents tissues
-epithelium tissues to protect stomach wall and produce secretions
-has conective tissues to hold together other tissues
97
what is the leaf?
-paliside mesophyl tissues made of leaf paliside cells that carry out photosynthesis
-spongy mesophyll adapted for gaseous diffusion
-phloem transport organic material away from leaf
-xylem teansport water & ions into leaf
98
what are organ systems?
organs working together as a single unit
99
what are examples of organ systems?
• digestive system: digest & procces food (salivary goand, oesophogus, stomach, duodenum, ileum, pancrease, liver)
• respiratory system: used for breating and gas exchange. (trachea, bronchi &lungs)
• circulatory system: pumps and circulates blood. (heart, arteries, veins)
100
what is an eukaryotic cell? (8)
are larger and have nucleas bounded by nuclear envelope
[grouped in eukarya]
-distinct nucleas with nuclear envelope
-DNA associated with protiens called histones
-no plasmids, DNA is linear
-membrane-bounded organelles
-chloroplast present in plants & algae
-Ribisomes larger (80s)
-cell wall made of cellulose (chitin in fungi)
-has no capsule
[membrane have ester linkage ]
101
what is a prokaryotic cell? (8)
are smaller and have no nucleas and nuclear envelope
-DNA in form of curcular strands (plasmids)
-no true nucleas
-DNA not associated with protiens
-no membrane-bounded organelles
-no chloroplast (BUT bacterial chlorophyll on cell surface membrane)
-ribisomes smaller (70s)
-cell wall made of murein (peptidoylycan)
-have outer mucilaginous layer called capsule
102
what is a bacteria cell?
-group of single celled prokaryotes
-(0.1-10 micrometers)
-in every habitat of world
-contains cell wall, capsule, cell surface membrane, circular strand of dna, plasmids.
-cell wall made of murein
-DNA made of nucleic acids
-unicellular organism
-stores food reserves as glycogen granules and oil droplets
103
what are viruses?
-a cellular, non-living particle
-smaller than bacteria (20-300 nanometers)
-has nucleic acids (DNA, RNA) only multiply inside living host cells
-nucliec acid enclosed in protien coat called CAPSID
-surrounded by lipid envelope
-have attatchment protiens essential to allow virus to identify and attatch host cells
104
what are capsules?
mucilaginous slime protecting bacterium from other cells
and help groups of bacteria stick together)
105
what are circular dna?
posses genetic information for replication of bacteria cells
106
what are plasmids?
-posses genes that can aid survival of bacteria in adverse conditions
-are vectors in genetic engineering
107
what is active transport?
movemant of moleculs from low concentration region to high concentration refion using ATP and intrinsic protiens
-(not passive) use metablic energy in ATP form
-(move against concentration gradient)
-selective procces (specific substances)
-uses lots of ATP
-more than one molecule can move in same direction (or different) by active transport)
108
what is the procces for direct active transport?
-1) ions outside cell bind to (specifc) receptor sites on carrier protiens where chemical is at low concentration gradient
-2) inside cell, ATP binds to protein ,where ATP hydrolysis, producing ADP molecule & phosphate
-3) phosphate binds to carrier protien and changes shape of carrier protein, so protein opens to opposite side of membrane [transporting moleculs accros side of membrane]
-4) releases molecule into cell and phospate group molecule into cell. causing protien to revert to original shape
(phospate molecule recombines with ADP to form ATP during respiration)
109
what is an interpolation?
determining value from existing values on given data
110
what is co-transport? (for glucose)
-sodium ions actively transported out epithelical cell by sodium-potassium pump (protien carrier moleculs)
--which will maintain a higher concentration of sodium ions in lumen than inside epithelical cells
--- so sodium ions will diffuse into epithelial cells down concentration gradient through (co-transport protien) on cell surface membrane. which also carrys amino acid moleculs/ glucose into cell
---- so glucoe pass into membrsne by faccilitated diffusion
(sodium conc. grad power glucose movemant)
111
what factors help in co-transport?
-microvilli: epithelial cells lining ileum. (finger-like projection 0.6 micrometers in length)
= large surface area for insertion of carrier protiens
-more protien channel and carrier protiens increase active transport accross membrane
112
how is glucose absorbed?
-carbohydrates & protiens digested continously
-as usually greater concentration of glucose & amino acid in ilieum than blood. glucose moves down conc. gradient into blood thats constantly curculated by heart. which is used up during respiration
(also increaed movemant by facilitated fiffusion accross epithelical cell-surface)
cause concentration of either side of epithelial to be equal
also supported by co-transport
113
what is mitosis?
produce two duaghter cell that have same number of chromosomes as parent cells and eachother
nuclei identical
-goes through four stages
•prophase
•metaphase
•anaphase
•Telophase
114
what takes place before mitosis?
the interphase, which involves the replication of DNA
then the two copies of identical DNA from the parent cell form a chromid which joins to a place called the centromere
115
what occurs in the prophase?
-the chromosomes became visible, long threads. (Chromosomes condense!!)
-the centrioles (in animals) move to opposite ends, where the development of spindle fibres that span from centrioles form, which collectivly are called Spindle Apparatus
-the nucleolus dissapears and nuclear envelop breaks down. cause chromosomes free in cytoplams
chromosomes drawn to equater of cell by spindle fibres attatching to centromere
116
what occurs in the metaphase?
-microtubules from centrioles (poles) attatched to centromere.
-chromosomes pulled along spindle apparatus and arrange themselves accross eqauter of celll
117
what occurs durind the anaphase?
centromere divide into two
(spindle fibres[have mitochondria gathered around them] pull chromatids on chromosomes apart)
-causing chromatids to move to opposite poles of cell
(if spindle destroyed by chemicals, chromosomes remain at equater)
118
what occurs during the telophase?
chromosomes reach poles, becaming longer & thinner. leaving only widely spread chromatin
-spindle fibres disintergrate, nulcear wnevelope and nucleolus re-form
-and the cytoplasm divides by mitosis
119
how does cell division occur in prokaryotic cells?
by binary fission
120
what is binary fission?
-circular DNA molecule replicates, attatching copies to cell membrane
-plasmids replicate
-cell membrane grows between two DNA moleculs and pinch inwards, sividing cytoplasm into two
-cell walls thwn form between two DNA moleculs, dividing original cell into two identical daughter cells. with copy of circular DNA and variable copies of plasmids
121
how do viruses replicate?
they replicate by attatching to host cell with surface attatchment protiens injecting nucleic acid into host cell. genetic information injected provides 'instructions' for host cells metabolic procceses.
consequently producing voris organeles that are assembled inti viruses
122
what procces are involved in the cell cycle?
1,interphase (cell synthessis organelles to function, synthesis DNA and check DNA)
2, nuclear division (mitosis/meiosis)
3, cytokenisis: division of cytoplasm too produce two new cells
123
what is cancer?
caused by growth disorder of cells
-uncontrolled growth and division of cells
-makes tumours form
124
what are tumours? and types?
groups of abnormall cells constantly expanding in size
-malignant tumours: grow rapidly, less compact, more life threatining
-benign tumours: grow slowly, more compact, less life threatining
125
where are cancer cells mostly found in thehuman body?(8)
-lungs
-prostate gland
-breast
-ovaries
-large intestine
-stomach
-oesophagus
-pancreas
126
what is mitosis used for?
[growth]- increase size of tissue. all cells grown are geneticly identical
[repair]- if cells damaged/ die cells are replaced with identical structure and function to previous ones
[repoduction] single-celled organisms divide by mitosis give two new organisms
127
how is the rate of mitosis affected?
-by enviroment and growth factors
128
what two genes control mitosis ?
oncogenes
tumour suppresing genes
129
what are mutant cells?
caused from uncontrolled mitosis, are structuraly and functionaly different, but most die ! although... some survive to form tumours
130
what method is used to treat cancer?
chemotherapy
131
what does chemeotherapy do to the cancer?
kills fast dividing cells by blocking part of cell cyle
-prevents dna replication, inhabits metaphase stage kf mitosis and hinders spindle formation
AS CANCER CELLS HAVE FAST RATE OF DIVISION
-(can be damaging to normal cells that are rapidly dividing , like root hair cells)
132
what does a marker gene do?
makes cells more visible to see from the glow. allowing scientist to know to what extent what substances is and is not in cell
133
What is immunity?
Organism ability to resist infection by protecting against disease causing microorganisms.
(Or against toxins produced that invade body )
134
What are antigens?
• Part of organism that’s recognised as non-self by immune system & stimulate immune system response
• protein
• part of cell surface membrane/ walls of invading cells
• triggers production of antibodies part of body’s defence system
135
What are lymphocytes?
• part of specific responses (slower & grant long term immunity)
• produced by stem cells in bone marrow
(are a type of white blood cell)
• two types:
-B lymphocytes. B cells
-T lymphocytes. T cells
136
What are T lymphocytes?
Mature in thymus gland.
Associate with cell-mediated immunity
-respond to cells from other individuals of same species as they are genetically identical. So have different antigen on membrane compared to antigens on organism
[[distinguish invader cells from normal cells]]
137
How do T lymphocytes distinguish invader cells from normal cells?
• phagocytes engulf & hydrolyse pathogen which present some pathogens antigen on cell-surface membrane
•body cells invaded by virus cells present vital antigen on cell surface membrane
• transplanted cells from individuals of some species have different antigen on cell surface membrane
• cancer cells are different from normal body cells & present antigen on cell surface membrane
138
What are antigen presenting cells?
Display non-self antigen on surface membrane
139
What is the process of cell mediated immunity?
1) pathogen invade body cell or taken in by phagocytes
2) phagocytes place antigen from pathogen onto cell surface membrane
3) receptors on T lymphocytes for exactly onto antigen
4) T lymphocytes divide rapidly by mitosis and form clones of genetically
Identical cells
5) clone T cells adapt for certain functions to stop pathogens
140
What are 4 adaption if the cloned T cells in the last stage of cell mediated division?
-Develop into memory cells to enable rapid response to future infection by same pathogen
-stimulate phagocytes to engulf pathogen
- stimulate B cell, to divide & secrete antibodies
- activate cytotoxic T lymphocytes
141
How do cytotoxic T lymphocytes kill infected cells?
-produce protein (perforin) to make holes in cell surface membrane.
Making cell membrane freely permeable to all substances, so cell dies
142
Why are cytotoxic T cells effective against viruses?
is effective against viruses as they use cells as hosts, so it will prevent virus multiplying by killing cell
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What is the mitosis index and how do you find it?
-it is the number of cells undergoing mitosis to number of total cells
-[so number of cells at each stage of mitosis is proportional to time each cell spends]
It is found from snapshots of process in microscope at one moment in time
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What is an infection?
Interaction between pathogen and body’s defense mechanisms
145
What is immunity?
Killing pathogen before it causes any harm
(Varied upon health status)
146
What are the different defense mechanisms in the body?
Non specific immediate response :
• immediate defense( skin)
• phagocytosis, inflammation/antimicrobial chemicals(innate immune response)
Specific slow response (specific immune response)
• T lymphocytes
• B lymphocytes
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How do cells recognize other cells? And Why does it allow for easy recognition?
The proteins are distinguishable from having large variety and exclusively specific tertiary structure on self molecules
Allowing lymphocytes and phagocytes to identify pathogen, non self material, toxins and abnormal body cells in body
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What are the preventative measures used to maintain and organ transplant?
-matching organ closely to recipient (has similar genetics)
-use immunosuppressant drug
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How do lymphocytes recognize cells belonging to the body?
They are millions of lymphocytes constantly colliding with other cells in fetus stage. Usually it’s own body material. So the receptors that exactly fit in body cell will die. Leaving remaining lymphocytes responding to only non self material
-lymphocytes in bone marrow will undergo programmed death (apoptosis) before maturation when encountering self-antigen. So these lymphocytes will disappear in the blood
150
What are phagocytes?
Large particles engulfed by cells in vesicles formed from cell surface membrane on phagocyte
Are a defense against pathogen
Can move from blood into other tissues
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What is the process of phagocytes?
Phagocytes attracted by chemical products of pathogen/abnormal cell along concentration gradient
Receptors on cell surface membrane attach to chemicals on pathogen surface
Phagosome forms, with lysosomes moving to phagosome to fuse with it and engulf pathogen .
Lysozymes within lysosomes destroy ingested bacteria by hydrolysis of cell wall
So soluble products from hydrolysis are absorbed into cytoplasm of phagocyte
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What is the fixed position occupied by a gene on a DNA molecule/ chromosomes
Locus
153
What are B lymphocytes?
-mature in bone marrow
-B cells
-associate with humoral immunity
(Antibodies in blood plasma)
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What is humoral immunity?
-produces specific antibody to respond one specific antigen
1. Antibody on surface which shape makes it compulsory to specific antigen
2, antigen is attached to antibody
3. Antigen enters B cells by endocytes to then became processed antigen (present on B cell surface)
4. T helper cell binds to processed antigen and stimulate B cell to divide by mitosis to form (clones specific to non self antigen) / colonial selection
5 produce monoclonal antibodies
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What are two monoclonal antibodies each B cell clone can form?
Plasma cells:
-secrete antibodies into blood plasma
-can make 2000 antibodies every second
-short lived
-immediate response to body
[primary immune response]
Memory Cells:
-live longer than plasma cells
-circulate in blood & tissue fluid
-when encounter same antigen: divide rapidly into plasma & memory cells
-give long term immunity
-more antibodies produced than in primary immune response
-prevent harm taking place to cells
[secondary immune response]
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What are antibodies and how are they structured?
• proteins
• have specific binding site
(binds to antigen to form antigen-antibody complex)
• synthesized by B cells
• Contains: (two identical antigen binding sites, 2 heavy polypeptide chains, 2light polypeptide chains)
• has an variable region located on antigen binding site that is different on antibodies and an constant region that remains the same on all antibody’s, that also binds to receptors on cells
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What is the function of antibodies?
To prepare antigen for destruction
• agglutination: forms antibody clumps that attach to bacteria/infected cells so it is easier for phagocytes to locate them (as there less spread out)
•Neutralization: antibody blocks antigen binding site
Which stimulate phagocytes to engulf cells that are attached to them
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What are monoclonal antibodies?
Antibodies that are isolated & cloned
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What are the functions of monoclonal antibodies?
To target specific substances in cells given methods:
-monoclonal antibody therapy
-indirect monoclonal antibody therapy
-medical diagnosis
-pregnancy testing
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What is monoclonal therapy?
-involves monoclonal antibodies being produced, which are specific to antigen on diseased cells
-are given to patient & attach receptors on diseased cell
-by attaching to surface of specific cells, it blocks chemical signals being produced by cell (so can stop growth/ infection of cell. EXP cancer)
161
What is indirect monoclonal antibody therapy?
-attach radioactive/ cytotoxic drug to monoclonal antibody to kill cell
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How can monoclonal antibody be used for medical diagnosis?
-interact with specific cells antigen. Making it possible to obtain an measure of specific cell level in blood.
Which is able to detect early warnings of needing to further test
163
How can monoclonal antibodies be used for pregnancy tests?
Can be identified if human chorionic gonadotrophin ,in urine , binds To monoclonal antibodies on test strip of home pregnancy test kits. The HCG-antibody-colour complex moves along strip until trapped by different antibodies to create colored line
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What are the ethical concerns with using antibodies?
-production involves mice, which produce cancer cells =cancer in mice
-deaths involved when using it as treatment for multiple sclerosis
(People must be able to have informed consent)
- testing drugs safety causes dangers, potential death risk for volunteers
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What is passive immunity?
Antibodies from outside source introduced into body (not produced)
So antibodies aren’t replaced, there is no lasting immunity from no direct contact
EXP::: anti-venom
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What is active immunity?
Stimulate production of antibody’s by individuals own immune system
-requires direct contacts
-is longer lasting
Two types: natural and artificial
Natural is infected with disease in normal conditions
Artificial involves vaccination (immunization) to induce immune response without suffering disease
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What are vaccinations?
They introduce disease antigen into body by infection/mouth to stimulate immune response against disease
• vaccines contain one/multiple types of antigen from pathogen
It helps produce memory cells that provide more immediate response to future infections to stop them causing harm
[prevents contraction of disease]
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What is contained in an successful vaccination program?
- an economically available vaccine In sufficient quantities to immunize majority of people
- vaccines have few side affects that aren’t to badly discouraging
-are able to produce, store, & transport vaccines
-administration of vaccines at appropriate time with trained professional and quality facilities
- vaccinating majority of people to create herd immunity
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What is herd immunity?
where large proportion of population are vaccinated to make it difficult for pathogen to spread. Making it highly unlikely an vulnerable individual will contact with infected individual
-they are best carried out one at an time
170
Why might an individual not get a vaccine?
• the are I’ll
• have a compromised immune system
• are a child whose immune system isn’t yet fully functional
171
What are the difficulties with eradicating an disease?
•vaccines failing to induce immunity in certain individuals
• immunity levels not high enough to resist infection causing harm
•{antigenic variability}
antigen on pathogen changes, so immune system can’t recognize it
=[no antibodies ]=[short lived immunity]
• lots of varied specific pathogen
•pathogen conceal themselves in cell or place out of reach from immune system
•individual has religious, ethical or medical reasons to not take it
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What ethics must you consider when producing an vaccination?
-use of animals
-the side effects risk it cause in long
term
-safety vaccine trails and test carried out
-trying vaccine without knowing health risk in areas of desperation for vaccine
-concept of compulsory vaccination
- vaccines continuing when almost eradicated
-the balance between health risk & advantages to controlling disease
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What is HIV?
Human immunodeficiency virus
Causes acquired immune deficiency syndrome(AIDS)
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What is the structure of human immunodeficiency virus?
-has lipid envelope
-attachment protein
-capsid
-two single strands of RNA
-has enzyme called (reverse transcriptase) that catalyzes DNA from RNA
-has matrix
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What group does human immunodeficiency virus belong too?
Retrovirus group
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How is human immunodeficiency virus replicated?
Uses genetic material to instruct host cell biochemical mechanisms to produce components required to make new HIV
1) HIV enters blood stream & circulates blood
2) attachment protein binds to CD4 protein on cell (T-helper cell)
3) protein capsid fuses with cell surface membrane, invading cell with RNa
4) reverse transcriptase converts virus RNA into DNA
5) Virus DNA moves into helper T cells nucleus , into cell DNA
6) HIV DNA creates mRNA in nuclease, which contains instructions to make new viral protein & RNA for new HIV
7) MRNA, passes through nuclear pores & use cell protein synthesis to make HIV particles
8) HIV particles break from cell with piece of cell surface membrane surrounding them, that’s forms into a lipid envelope
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Why is it hard to immediately diagnose a patient with HIV?
The virus isn’t known to be in the body Untill a few years later , as the virus goes into dormancy
178
How does human immunodeficiency virus cause symptoms of acquired immune deficiency syndrome?
-causes reduction in T-helper cells (as low as 200mm)
-so less able to produce antibody/cytotoxic T cells from less cell mediated division = more susceptible to disease
-memory cells gets infected/ destroyed
Creates symptoms
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What are the symptoms of acquired immune deficiency syndrome?
Infection in lungs, intestine, brain, eyes. Weight loss, diahria
(This is due to infections from other pathogens caused by HIV
180
What is the ELISA test?
ELISA: enzyme linked immunosorbent assay
Detects presence & quantity of protein in sample
Is extremely sensitive as it detects small amount of molecules
181
What is the procedure for the ELISA test?
-1) apply sample to surface where antigen in sample will attach to
-2) wash surface to remove unattached antigen
-3) add capture antibody specific to antigen trying to detect and bind to it
-4) wash to remove excess antibody
-5) add second antibody that binds with first antibody which has enzymes attached
-6) add colorless substrate of enzyme . Enzyme acts on substrate to change it into a colored product
-7) antigen present depending of intensity of color present
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How do antibiotics function?
antibodies inhibit enzymes required for synthesis and assembly of peptide cross links in bacteria cell wall. (Not a protien cell wall, but murein= sugers & amino acids)
Weakening the wall, causing the murein (in cell wall) to be easily stretched and unable to resist expansion from the osmotic pressure
Causing water to enter by osmosis = cell burst & die
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Why are antibiotic ineffective against viral diseases?
Viruses use host cells to carry out metabolic activities, so they don’t have a metabolic pathway to be disrupted
-virus has a protein coat , so antibiotics can’t work
- too small for antibiotics to reach
