2 - Cells And Immune System Flashcards

Question

Why do you have to be carful not to get any airbubbles under you cover slip when using a microscope

Answer 1

They will obstruct a view of the specimen

Answer 2

Starch grain in plant cells

Answer 3

To break up the plasma membrane and release the organelles into the solution

Answer 4

To separate any large cell debris or tissue debris (like connective tissue, from the other organelles)

Answer 5

Nuclei Mitochondria Lysosomes Endoplasmic reticulum Ribosomes

Answer 6

After nuclei but before mitrocondria

Answer 7

Pencil No shading / colouring (only draw the lines you can see) Each field of view (circular diagram) should be about 3rd of a page in size If the cells you are viewing are similar / repeatable it’s useful to draw about 4-5 only

Answer 8

Magnification Name of specimen Date of observation

Answer 9

Stage micrometer Eye piece graticule

Answer 10

A precise rule on a slide

Answer 11

1) calibrate - focus the stage micrometer under a low pressure - this must be done for each magnification (objective lens) 2) work our how many eye peice divisions equal every stage division 3) remove the stage micrometer + place slide containing cells under microscope + count the number of eyepiece divisions under one microscope

Answer 12

Transmission electron microscopes Use electromagnets to focus a beam of electrons, which is then transmitted through the specimen Denser parts of the specimen absorb more more electrons, which makes them look darker on the image you end up with.

Answer 13

High resolution image You can see internal structures and organelles like chloroplasts

Answer 14

They can only be used on thin specimens

Answer 15

Scanning electron microscopes Scan a beam of electrons across the specimen. This knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image The image you end up with show the surface of the specimen and they can be 3D

Answer 16

Can be used on thick specimens

Answer 17

Lower resolution image than TEMS

Answer 18

Scanning Transmission

Answer 19

Vacuum Non living - smallest sample Thin Complex staining / preparation (have to be trained to use) Image contains ‘artefacts’

Answer 20

SEM - 3D TEM - 2d

Answer 21

Photomicrograph

Answer 22

- electron beams may destroy sample - preparation difficulties lead to revolution problems - photomicrograph is in ‘false colour’

Answer 23

A network of fibres necessary for the shape and stability of the cell - microfilaments - microtubules - intermediate fibres

Answer 24

- embedded proteins - involved in signalling + communication between cells - others act as antigens for ‘self’ and foreign recognition

Answer 25

Plants - cellulose Fungi - chitin

Answer 26

A complex carbohydrate - freely permeable. It gives shape to cell + allows the cells content to push against it making it rigid It acts as a defence mechanism protecting against invading pathogens

Answer 27

Membrane lined sac filled with cell sap Large + permanent Maintaining turgor against the cell wall

Answer 28

The tonoplast It’s selectively permeable ( some molecules can pass through but some can’t)

Answer 29

Carry out photosynthesis

Answer 30

Vary in shape but are typically disk shape 2-10um long and 1um in diameter

Answer 31

The chloroplast envelope The grana The stroma

Answer 32

Double plasma membrane surrounding the organelle- highly selective in what is allowed to enter and leave

Answer 33

Stacks of up to 100 disc like structures called thylakoids - some thylakoids have tubular extensions that join up with other thylakoids in adjacent grana -

Answer 34

Where the first stage of photosynthesis (light absorption) takes place

Answer 35

Chlorophyll

Answer 36

A fluid filled Matrix Within the stroma are a number of other structures (eg, starch grains)

Answer 37

Second stage of photosynthesis (Synthesis of sugars)

Answer 38

-Granal membrane - large surface membrane for attachment of chlorophyll, electron carriers and enzymes that carry out the first stage of photosynthesis - these chemicals are attached to the membrane in a highly ordered way. - the fluid of the stroma possesses all the enzymes needed to make sugars in stage 2 of photosynthesis. - chloroplasts contain DNA + ribosomes so can quickly + easily manufacture some proteins needed for photosynthesis

Answer 39

Large organelle surrounded by a nuclear envelope (double membrane), which contain many pores. The nucleus contains chromosomes (which are made form protein-bound linear DNA) And another structure called nucleoles

Answer 40

- controls cell activity (by controlling transcription of DNA) DNA contains instructions to make proteins. - pores allows substances to move between the nucleus and the cytoplasm, the nucleolus makes ribosomes

Answer 41

Usually oval shape - double membrane, inner in is folded to form Cristae. Inside is the matrix, which contains enzymes involved in respiration

Answer 42

The site of aerobic respiration, where ATP is produced. Found in large numbers in cells that are very active and require a lot of energy

Answer 43

A group of fluid filled, membrane bound flatterend sacs. Vesicles are oftern seen at the edge of sacs

Answer 44

It processes and packages new lipids and proteins. It also makes lysosomes

Answer 45

A small fluid filled sac in the cytoplasm, surrounded by a membrane and produced by the Golgi apparatus

Answer 46

Stores lipids and proteins made by the Golgi apparatus and transports them out of the cell (via the cell surface membrane)

Answer 47

A round organelle surrounded by a membrane, with no clear internal structure. It’d a type of Golgi vesicle

Answer 48

Contains digestive enzymes called lysozymes. These are kept separate form the cytoplasm by the surrounding membrane, and can be used to digest invading cells or to break down work out components of the cell.

Answer 49

A system of membrane enclosing a fluid filled space. The surface is covered with ribosomes

Answer 50

Folds and processed proteins that have been made at the ribosomes

Answer 51

Similar to RER - but no ribosomes

Answer 52

Synthesises and processes lipids

Answer 53

The site where proteins are made

Answer 54

Very small organelle thar either floats freely on the cytoplasm or is attached to the RER. It’s made of proteins and RNA. It’s not surrounded by a membrane

Answer 55

Small protein tubes if microtubules

Answer 56

Form fibres in cell division known as spindles which separate chromosomes

Answer 57

The process by which cells become specialised for differnt functions

Answer 58

Different genes are switched on and off in each of the specialised cells

Answer 59

A collection of cells (not necessarily identical ones) that preforms a specific function Eg. Epithelial tissue, muscles, nervous, connective

Answer 60

A combination of tissue that are coordinated to preform a variety of functions

Answer 61

Large (70s)

Answer 62

In the nucleus on linear chromosomes

Answer 63

Contained within the cytoplasm held on circular DNA

Answer 64

Peptidoglycan

Answer 65

Eukaryotic

Answer 66

Eukaryotic

Answer 67

Prokaryotic

Answer 68

Eukaryotic

Answer 69

Eukaryotic

Answer 70

Prokaryotic

Answer 71

Prokaryotes

Answer 72

They have nucleic acids but not confined to a nucleus with a nuclear membrane They don’t have mitrochondia and have smaller ribosomes Many have flagellum

Answer 73

0.1 - 1.0 um

Answer 74

Muriel (polysacccharide + peptides)

Answer 75

Oils and glycogen droplets

Answer 76

replicated only inside living cells of other organisms

Answer 77

Generic material (DNA + RNA)on a protein coat ( capsid), some have an envelope. Have glycoprotein receptor spikes on the envelopes

Answer 78

Attach to surface of the host cell they’re infecting

Answer 79

Help it to attach to host cells

Answer 80

Using materials from living cells

Answer 81

20 - 300nm in size

Answer 82

DNA or RNA

Answer 83

Encased in capsid, which may have attachment proteins (protein coat) some have a lipid envelope

Answer 84

Plasmodesmata (Channels for exchanging substances with adjacent cells)

Answer 85

To store excess sugars

Answer 86

Plant cells They have the same organelles including cell wall app and chloroplasts

Answer 87

Plant cells

Answer 88

- their cells walls are made of chitin not cellulose - they don’t have chloroplasts because they don’t photosynthesise

Answer 89

1) the walls of the small intestines have lots of finger like projections called villi, these increase surface area for absorption 2) the epithelial cells on the surface of the villi have folds in their cell- surface membrane, called microvilli. These inc the surface area even more 3) they have lots of mitochondria to provide energy for the transportation of digested food molecules into the cells

Answer 90

Lipids and proteins

Answer 91

Supports the cell and prevents it from changing shape.

Answer 92

A polymer called murein Murein is a glycoprotein

Answer 93

A protein with a carbohydrate attached to it

Answer 94

Helps to protect bacteria from attach by cells of the immune system

Answer 95

Small loops of DNA They arnt part of the main circular DNA molecule. Plasmids contain genes for things like antibiotic resistance, and can be passed between prokaryotes. Plasmids are not always present in prokaryotic cells. Some prokaryotic cells have several

Answer 96

Floats free in the cytoplasm It’s circular DNA, presents as one long coiled up strand It’s not attached to any histone proteins

Answer 97

It’s a long, hair like structure that rotates to make the prokaryotic cell move. Ot all prokaryotes have a flagellum some have more than one

Answer 98

They are not cells

Answer 99

Nucleus acids surrounded by proteins - there not alive

Answer 100

Plasma membrane Cytoplasm Ribosomes

Answer 101

They invade and reproduce inside cells of other organisms,s These are known as host cells

Answer 102

Contains a core of genetic material - either DNA or RNA The protein coat around the core is called the capsid Attachment proteins stick out fro, the edge of the capsid, these let the virus cling on to a host cell

Answer 103

By binary fission

Answer 104

1) the circular DNA and plasmids replicate. The main DNA loop is only replicated once but plasmids can be replicated loads of times 2) the cell gets bigger and the DNA loop move to opposite poles of the cell 3) the cytoplasm begins to divide( amd re cell walls begin to from) 4) the cytoplasm divides and two daughter cells are produced. Each daughter cell has one copy of the circular DNA, but can have a variable number of copies of the plasmids

Answer 105

Viruses use their attachment proteins to bind to complementary receptor proteins on the surface of host cells Differnt viruses have differnt attachment proteins and therefore require differnt receptor proteins on host cells. As a result some viruses can only infect one type of cell ( others can infect lots of differnt cells) Because they are not allibe viruses don’t undergo cell division. Instead they inject their DNA or RNA into host cell - thus hijacked cell they uses Ito own ‘machinery’ to do the viruses work and replicate the viral partials

Answer 106

Growth ( from zygote to embryo to human) Differentiation ( cells become specialised from stem cells + genes start to tell cells what to do ) Repair ( to repair and replace damages tissue)

Answer 107

Viruses are non living so they attach to their host cell with attachment proteins on their surface They inject their nucleic acids into the host cell The genetic information on injected boreal nucleic acid provided instruction for the host cell to start producing viral components eg. Enzymes, nucleic acid

Answer 108

1) a virus enters a cell 2) substances in the cell begin to strip off the viruses outer coat of proteins 3). Nucleic acids in the virus is released 4) nucleic acid get into cells chemical manufacturing system 5) the cell ‘ignors’ it’s own chemical needs + switched to making new viruses 6) the cell is sometimes destroyed in the process - many of the new viruses are released to infect other cells

Answer 109

Every 24 hours

Answer 110

The division of the nucleus to make an exact cope of the DNA in a parent cell

Answer 111

Most of the time Apart from extremely rare cases of mutations

Answer 112

Interphase

Answer 113

chromosomes become shorter and fatter each one consisting of a pair of identical chromatids joined at the centromere Tiny bundles of proteins called centrioles start moving to opposite ends of the cell forming a network of protein fibres across it called spindle. Nucleolus shrinks and eventually disappears Nuclear envelope breaks down and chromosomes lie free in the cytoplasm

Answer 114

Chromosomes arrange themselves on the equator of the spindle but not in homologous pairs Chromosomes appear attached to the spindle at their centromeres

Answer 115

Centromere splits into two each centromere having its own chromatid Spindle fibres contract and pull the chromatids apart centromere first - this makes chromatids appear v-shaped Chromatids now become chromosomes with their centromere leading

Answer 116

Chromatids reach the opposite poles of the cell at the centrioles - they uncoil and become long and thin again. They are now called chromosomes again Nuclear envelope + nucleolus reform - so now two nuclei Spindle fibres degenerate Chromosomes develop into thread lines structure of chromatin Centrioles replicate Cytokinesis follows this phase Cytoplasm divides (cytokinesis) and there are no two genetically identical daughter cells

Answer 117

Prophase Metaphase Anaphase Telophase

Answer 118

3 separate growth staged G1 S G2

Answer 119

Cell grows and new organelles and proteins are mad e

Answer 120

Cell replicated its DNA ready to divide by mitosis

Answer 121

Cell keeps growing and proteins needed for cell division are made

Answer 122

The cell carries out normal functions, but also prepares to divide . The cells DNA is unravelled and replicated to double its genetic content. The organelles are also replicated so it has spare ones and it’s ATP content is increase ( atp provides the energy needed for cell division)

Answer 123

The cell can grow out of control The cells keep pm dividing to make more and more cells wich form a tumour Cancer is a tumour that invades surrounding tissue

Answer 124

By disrupting the cell cycle This kills the tumour cells

Answer 125

The treatment doesn’t distinguish between tumour cells and normal cells They kill normal body cells that are diving. However tumour cells divide more frequently than normal so the treatment is more likely to kill tumour cells.

Answer 126

Chemotherapy prevents the synthesis of enzymes needed for DNA replication. If these arnt produced, the cell is unable to enter the synthesis phase(s) disrupting the cell cycle and forcing the cell to kill itself

Answer 127

Radiation and some drugs damage DNA. At several points in the cell cycle the DNA in the cell is checked for damage. If damage is detected the cell will kill itself - preventing further tumour growth

Answer 128

1) cut 1cm from the top form a growing root. 2) prepare a boiling tube containing 1M hcl acid and put it in a water bath at 60°C 3) transfer the root tip into the boiling tub and incubate for 5 mins 4) using a pipette rinse the root tip with cold water and leave to dry on a paper towel

Answer 129

That’s where the growth occurs so it’s where mitosis takes place

Answer 130

1) place root tip on microscope slide and cut 2mm from the very top. Get rid of the rest 2) use a mounted needle to break the top open and spread the cells out thinly 3( add a few drops of stain and leave for a few min 4) place a cover slip over the cells and push down firmly to squash the tissue. 5) now you can see mitosis under an optical microscope

Answer 131

Makes the chromosomes easier to see. Toluidide blue O, ethano-orcein, feulgen

Answer 132

It will make the tissue thinner and allow light to pass through. But you can’t smear rhe cover slip sideways as you will damage the chromosomes

Answer 133

1) start by clipping the solid onto the stage 2) select lowest powered objective lense 3) use coarse adjustment knob to bring the stage up to just below the objective lense 4) look down the eyepiece (which contains the ocular lense), use coarse adjustment knob to move stage downward away from the objective lens until the image is in focus 5) adjust focus with th e fine adjustment knob, until you get a clear image of what’s on the slide 6) you can then swap to an higher powered objective lense if you need greater magnification

Answer 134

The proportion of cells undergoing mitosis

Answer 135

Number of cells with visible chromosomes ____________________________________________ Total number of cells observed

Answer 136

A transparent ruler with numbers but no units Onto the eyepiece

Answer 137

A microscope slide with an accurate scale with units and is used to work out the value of division on the eyepiece graticule at a particular magnification On the stag e

Answer 138

Things that you can see down the microscope that arnt part of the cell or specimen that your looking at Eg, dust , airbubbles and fingerprints, inaccuracies caused by squashing and staining your sample

Answer 139

In electron micrograph because the specimens need lots of preparation.

Answer 140

By repeatedly preparing specimens in differnt ways. If it can be seen in one preparation but not another it if most likely and aryifact

Answer 141

The tendency of a gas/liquid to spread out from a high conc. to a low conc. till it reaches equilibrium (Net movement of particles from high to low conc.)

Answer 142

F It’s passive

Answer 143

Passive Motion is random and constant Particles bounce of each other + the vessel All particles will distribute themselves evenly as a result of diffusion

Answer 144

Diffusion is proportional to the difference in conc between two regions (the conc gradient) It’s incorrect to say diffusion is proportional to conc

Answer 145

Temperature Conc. gradient Stirring / moving Surface area (eg, alveoli / villi) Distance / thickness (short diffusion pathway) Size of molecule ( Small diffuse fastest)

Answer 146

Lipids They use transport proteins and transport water soluble substances that are insoluble in lipids

Answer 147

Large polar molecules. Eg. Glucose and amino acids Charged ions

Answer 148

Passive But molecules use proteins instead of passive between the phospholipids

Answer 149

Carrier proteins Channel proteins

Answer 150

Pores in membrane Many only let 1 type of molecule through There water filled hydrophilic channels

Answer 151

Molecules fit in at membrane Proteins change shape to pass molecules through

Answer 152

Cell surface membrane

Answer 153

The barrier between the cell and its environment controlling which substances enter and leave the cell. There partially permeable.

Answer 154

They let some molecules through but not others

Answer 155

By diffusion Osmosis Active transport

Answer 156

They act as a barrier between the organelle and the cytoplasm They are also partially permeable

Answer 157

Phospholipid molecules form a continuous double layer (bilayer) The bilayer is fluid because the phospholipids are constantly moving Cholesterol molecules are present within the bilayer Protein scattered through the bilayer like tiles in a mosaic, these include channel proteins and carrier proteins which allow large molecules and ions to pass through the membrane. Receptor proteins on the cell surface membrane. Allow the cell to detect chemicals release from other cells. The chemicals signal to the cell to respond in some way. some proteins are able to move sideways through the bilayer, while others are fixed in position .

Answer 158

Glycol proteins

Answer 159

Glycolipids

Answer 160

Large molecules and ions

Answer 161

Phospholipid head is hydrophilic (attracts water)

Answer 162

Hydrophobic (repels water).

Answer 163

Into a bilayer Head face out towards water on either side of membrane

Answer 164

It acts as a barrier to these dissolves substances As the centre of the bilayer is hydrophobic

Answer 165

No In all except bacterial cell membranes

Answer 166

Fit between the phospholipids

Answer 167

They bind to the hydrophobic tail of the phospholipids , causing them to pack more closley together This restricts movement of the phospholipids, making the membrane less fluid and more rigid It helps maintain the shape of animal cells, this is particle important for cells that Arnt supported by other cells (eg, red blood cells)

Answer 168

Temp Solvent conc

Answer 169

They don’t have much energy, so they can’t move very much They are very closley packed together and the memebrane is rigid But channel proteins and carrier proteins in the memebrane deform, increasing the permeability of the membrane ice crystals may form and pierce the membrane making it highly permeable when it thaws

Answer 170

The phospholipid can move around and aren’t packed tightly together. The membrane is partially permeable. As the temperature increases the phospholipids move more because they have more energy - this increases the permeability of the memebrane

Answer 171

The solvent dissolves the lipids in the cell membrane causing it to lose its structure

Answer 172

Yes But the net movement will be to an area of lower concentration

Answer 173

The path from an area of higher concentration to an area of lower conc. Particles diffuse down a concentration gradient

Answer 174

Yes, as long as they can move freely through the membrane

Answer 175

Simple diffusion

Answer 176

There so big it would diffuse very slowly through the phospholipid belayer

Answer 177

They would diffuse slowly, as Ther're water soluble and the centre of the bilayer is hydrophobic

Answer 178

Through carrier proteins or channel proteins

Answer 179

Particles use channel proteins and carrier proteins to move down a concentration gradient I from a higher to a lower concentration

Answer 180

Move large molecules across membranes, down their conc. Gradient

Answer 181

No, different carrier proteins facilitate different molecule

Answer 182

1) a large molecule attached to a carrier protein in the membrane 2) then the protein changes shape 3) this releases the molecule on the opposite sides of the membrane

Answer 183

Charged particles

Answer 184

Pores in the membrane

Answer 185

Conc, gradient Thickness of exchange surface Surface area

Answer 186

The higher the faster the rate, as diffusion takes place the difference in conc. Between the two sides of the membrane decreases until it reaches an equilibrium, this means that diffusion slows down over time

Answer 187

The thinner the exchange surface the faster the rate of diffusion

Answer 188

The larger the surface area the faster the rate of diffusion

Answer 189

Microvilli

Answer 190

Projections formed by the cell-surface membrane by folding up on itself

Answer 191

By about 600 times

Answer 192

The concentration gradient The number of channel or carrier proteins

Answer 193

Special channel proteins that allow the facilitated diffusion of water through cell membranes they allow cells to reabsorb a lot oj water in the kidneys that would otherwise be excreted by the body, about 180 liters need re-absorbing every day.

Answer 194

As its relatively small

Answer 195

Movement of molecules or ions into or out of a cell from a region of low concentration to a region of high concentration using ATP and carrier molecules.

Answer 196

As materials move against the conc. gradient carrier proteins act as pumps involved in the process It is very selective- and only avows certain substances across

Answer 197

By using ATP directly to move molecules By using a conc. Gradient which is already set up by direct active transport (co - transport)

Answer 198

- Molecules binds to receptors or channel or carrier proteins - on the inside ATP binds to proteins causing split to ADP +pi. This makes the protein molecule change shape and open on me opposite side of the membrane - - molecule is released on the other side of the membrane - p molecule released from protein and recombines with ADP to make ATP - this causes the protein to revert to its original shape

Answer 199

Hydrolysis

Answer 200

Enzymes, hormones and Who cells are two large to fit through carrier proteins so there movea in and out of cells by bulk transport

Answer 201

??.???””? Check (Taken in) This is bulk transport into cells by eg. Phagocytosis and pinocytosis The cell membrane invaginates forming vesicles these are then moved into the cytoplasmfor further processing

Answer 202

Reverse of endocytosis with vesicles being formed by the Golgi apparatus and released outside cells

Answer 203

Cytoskeleton Engulf materials Th fusion of vesicles with cell membranes

Answer 204

Muscle cels _ helps them contract to allow movement

Answer 205

Goblet ceus- secretes mucus

Answer 206

Phagocyte - ATP used to change shape to engulf pathogens

Answer 207

Root hair cells - carrier proteins to take up molecules in the soil against conc. Gradient

Answer 208

Exocytosis Endocytosis Single molecule transport Co-transport

Answer 209

In living respiring cells As active transport links to respiration

Answer 210

Temp. Oxygen conc.

Answer 211

- The rate of AT is affected by temp and oxygen conc. These both affect the rate of respiration and therefore the production of ATP Many cells known to carry out a lot of active transport contain large number of mitochondria Poisons which stop respiration or prevents ATPase from working also stop active transport. Eg. Cyanide inhibits ATP production so it stops active transport. However if ATP is added artificially transport starts again

Answer 212

Carrier proteins

Answer 213

1) active transport usually moves solutes from a low to a high concentration (In facilitated diffusion, they always move from a high to a low concentration) 2) active transport requires energy - facilitated diffusion does not

Answer 214

1) ATP is a common source of energy in the cell. It’s produced by respiration 2) ATP undergoes a hydrolysis reaction, splitting into ADP and Pi. This releases energy so that the solutes can be transported

Answer 215

Carrier protein

Answer 216

1) they bind two molecules at a time 2) the concentration gradient of one of the molecules is used to move one other molecule against its own concentration gradient.

Answer 217

No. Molecules and ions move against their concentration gradient so a decreasing concentration gradient doesn't affect the rate of active transport

Answer 218

1) the speed of individual carrier proteins - the faster they work the faster the rate of active transport 2) the number of carrier proteins present-the more proteins there are, the faster the rate of active transport 3) the rate of respiration in the cell and the availability of ATP. If respiration is inhibited, active transport can't take place.

Answer 219

By co-transportation In the ileum the concentration of the glucose is too low for glucose to diffuse out of the blood

Answer 220

1) sodium ions are actively transported out of the ileum epithelial cells into the blood, by the sodium potassium pump. This creates a concentration gradient., there’s now a higher concentration of sodium ions in the lumen of the ilium, then outside the cell 2) this causes sodium ions to diffuse from the lumen of the ilium into the epithelial cells down their concentration gradient. They do this via the sodium glucose co-transporter proteins. 3) The co-transporter carries glucose into the cells with the sodium. As a result, the concentration of glucose inside the cell increases. 4) glucose diffuses out of the cell into the blood down its concentration gradient through a protein channel by facilitated diffusion

Answer 221

The passage of water from a region where it has high water potential ( dilute) to lower water potential (concentrated) over a partially permeable membrane.

Answer 222

Lower the water potential

Answer 223

Animal cells have solutes in their cytoplasm. If placed in pure water - water would move in causing cells to burst (Eg, haemolysis in red blood cells)

Answer 224

Animal cells are bathed in a liquid which has the same water potential (Eg. Blood plasma in humans)

Answer 225

Potential o water molecules to diffuse out of or into a solution

Answer 226

Pure water

Answer 227

1) the water potential gradient 2) the thickness ofthe exchange surface 3) the surface area of the exchange surface

Answer 228

The higher the water potential gradient the faster the rate of osmosis. As osmosis takes place the differnce in water potential on either side of the mebrane decreases, so the rate of osmosis levels of

Answer 229

The thinner the exchange surface rhe faster the rate of osmosis

Answer 230

The larger the surface area, the faster the rate of osmosis

Answer 231

- Fill in later

Answer 232

1) label 6 boiling tubes 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 mol dm-3 2) use the 1.0moldm-3sucrose solution and water to make up 20cm3 of each concentration (using a pipette) 3) stand the boiling tubes donating the sucrose solution in a test tube rack at a constant temperature 4) using a potato chip cutter. Cut 6 chips from one potato tuber, remove any peel, using a ruler, scalpel and tile cut all chips to the same length. Blot chips dry with a paper towel. ( rll and dab each end) 5) weigh each potatoes chip - record initial mass 6) transfer potato to boiling tube and time 20 mins, blot chips dry then re weigh+ record the final mass 7) calculate change in mass and then calculate percentage change in mass

Answer 233

The vacuoles swells - its a turgid cell

Answer 234

Vacuole shrinks Flaccid cell

Answer 235

Contains more solutes and therefore has a lower water potential than a cell suspended in the solution

Answer 236

Contains the same amount of solutes and therefore has the same water potential as a cell suspended in the solution

Answer 237

Contains less solutes and therefore has a higher water potential than a cell suspended in the solution

Answer 238

Water has moved out the cell by osmosis down a water potential gradient through a partially permeable membrane Hypertonic solution as water moves out of cells as there is a lower water potential out of the cell. This causes the Tonoplast to pull away from the membrane through plasmolysis

Answer 239

Villi + micro villi - inc rate of absorption by inc. SA Thin epithelial calls as walls - short diffusion pathway Thick capillary network - maintains conc, gradient (blood capillaries absorb glucose and amino acids)

Answer 240

Tiny lymphatic vessel

Answer 241

Fatty acids Glycerol

Answer 242

- well supplied with blood vessels - blood can carry away absorbed molecules maintains a concentration gradient - thin walls- short diffusion pathway -villi can move helps maintain diffusion gradient - they inc overall SA - villi contain muscle with contract regularly mixing products of digestion. So always glucose rich food next to the epithelial cells of the villi

Answer 243

Microvilli

Answer 244

Some glucose is taken up by active transport , so all glucose can be taken up by blood

Answer 245

Diffusion can only make both sides of epithelium equal So not all available glucose is absorbed - so some glucose would pass the body

Answer 246

(indirect active transport) Sodium leaves rhe cell while potassium enter the cell ( for every 2 potassium is 3 sodium) This is controlled by ATP

Answer 247

Symport Sodium ions enter the cell down there diffusion gradient With a glucose / amino acid (not down a conc, gradient)

Answer 248

Facilitated diffusion Diffuse down a conc gradient

Answer 249

Measure of the reduction in water potential due to the presents of solute molecules

Answer 250

Hydrostatic pressure to which water is subjected. Usually but not always positive (Sometimes called turgor)

Answer 251

Hypertonic solution, Water leaves the cell, and as sell wall is rigid rhe cell memebrane shrinks away from the cell wall. This process is termed

Answer 252

Hypotonic Water enters cell - cytoplasm takes on water, putting pressure on the cell membrane . Swell A pressure potential is generated when sufficient water has been taken up to cause the cell components to press against the cell wall

Answer 253

The gradient in water potential + transpiration pull, cohesion and root pressure

Answer 254

Cools the plant + maintain adequate mineral uptake

Answer 255

Water lost from the air spaces by evaporation through stomata is replaced by water from the mesophyll cells The constant loss of water to the air creates a lower water potential in the leaf cells that in the cells further away from the evaporation sight , water is pulled through a plant along a dec. gradient in water potential

Answer 256

The transpiration is assisted by the special cohesive properties of water. Water molecules cling to each other as they are pulled through the plant and they adhere to the walls of the xylem. This creates one unbroken collet of water though the plant , the upward pull on the cohesive sap creates tension . This facilitated water uptake and movement through a plant

Answer 257

Water entering the soil creates root pressure Weak push effectfor the water upward movement through a plant

Answer 258

Prokaryote Corkscrew flagellum damages channel proteins so water leaves cell

Answer 259

Dehydration and diarrhoea

Answer 260

A disorder of the intestines where watery feared are produced frequently

Answer 261

Damage to epithelial cells lining the intestines Loss of micro villi due to toxins Excessive secretion of water due to toxins in the intestines eg, cholera toxin

Answer 262

- vital to rehydrate - water alone is not enough as water is not being absorbed by the intestines. Water in cases is being lost be cells - some ions ( electrolytes) are also required to replace those lost by epithelial cells - oral rehydration therapy

Answer 263

Using one carrier proteins in cell surface membrane there are more than one carrier in the CSM that absorb sodium ions. So they use these alternative pathways As sodium ions are absorbed, the water potential inc the cell falls and water enters the cell by osmosis

Answer 264

Water to rehydrate the tissue Sodium ions to replace those lost from epithelial cells ( making optimum use of the sodium glucose carrier proteins) Glucose - to provide energy and stimulate the uptake of sodium ions from the intestines Potassium - to stimulate appetite and replace lost K+ ions Other electrolytes - chloride and citrate ions to help balance electrolytes in all cells

Answer 265

Boiled water mixed. With packets of electrolyte powdered Does t require a trained person

Answer 266

Molecules that can trigger an immune response when detected by the body

Answer 267

On the surface of cells

Answer 268

Pathogens Abnormal body cells ( eg, cancer or pathogen infected cells, which have abnormal antigens on their surface Toxins Cells from other individuals of the same species (eg, organ transplant)

Answer 269

A type of white blood cell that carries out phagocytosis

Answer 270

In the blood amd in tissues

Answer 271

1) a phagocyte recognises the foreign antigens on a pathogen 2) the cytoplasm of the phagocyte moves round the pathogen , engulfing it 3)The pathogen is now contained in a phagocytic vacuole (a bubble) in the cytoplasm of the phagocyte. 4) A lysosome (an organelle that contain enzymes called lysozymes) fuses with the phagocytic vacuole. The lysozymes break down the pathogen. 5) The phagocyte then presents the pathogen's antigens — it sticks the antigens on its surface to activate other immune system cells.

Answer 272

T-lymphocytes

Answer 273

It has receptor proteins on its surface that bind to complementary antigens presented to it by the phagocytes This activates the T-cell Differnt types of Tcells respond in differnt ways. For example, helper T-cells (TH cells) release chemical signals that activate and stimulate phagocytes and cytotoxic T-cells (Tc cells) which kills abnormal and foreign cells. TH cells also activates B-cells, which secrete antibodies

Answer 274

a type of white blood cell There covered with antibodies Each B-cell has a differnt shaped antibody on its membrane , so differnt one bind to differnt shaped antigens

Answer 275

Proteins that bind antigens to form an antigen-antibody complex

Answer 276

It binds to it This together with substances released form helper T-cells, activates the a cell. Thus process is called cola l selection Thus activated B-cell divides into plasma cells

Answer 277

Yes they’re clones

Answer 278

They secrete lots of antibodies specific to the antigen. These are called monoclonal antibodies They bind to the antigen on the surface of the pathogen to form lots of antigen-antibody complexes

Answer 279

2 Become clumped together - called agglutination

Answer 280

Phagocytes then bind to the antibodies and phagocytes many pathogens at once. Thus process leads to the destruction of pathogens carrying this antigen in the body

Answer 281

It’s variable region, which form rhe antigen binding site

Answer 282

A unique tertiary structure ( due to the different amino acid sequences) that’s complementary to one specific antigen.

Answer 283

The cellular response and humoral response

Answer 284

The Tcells and other immune system cells that they interact with, Eg, phagocytes, form cellular response

Answer 285

B-cells, clonal selection and the production of monoclonal antibodies form the humoral response

Answer 286

In the fetus, lymphocytes collide exclusively with body own cells as infection is rare in the fetus because it’s protected by the mother/placenta some sites will have receptors that fit those body own cells. These either die or are suppressed remaining lymphocytes only fits foreign material. An adult lymphocytes produced in bone marrow, initially only encounter self antigens, any lymphocytes that show an immune response to these self antigens, undergo programs cell death (apoptosis) Before they can differentiate into mature lymphocytes No clones of these anti-self lymphocytes will appear in the blood. Only those that might respond to non-antigens.

Answer 287

Immunity is the ability of organisms to resist infection by protecting against disease - causing microorganisms or their toxins that invade their bodies- it involves the recognition of foreign material (antigens)

Answer 288

Lymphocytes

Answer 289

Long term immunity

Answer 290

Antigen is any part of an organism or substance that is recognised as non-self (foreign) by the immune system and stimulates an immune response

Answer 291

Antigens are usually proteins that are part of the cell surface memebrane of cell wall of an invading cell. The presence of antigens trigger production of antibodies

Answer 292

- b and t are both lymphocytes - both are produced by stem cells in bone marrow - responsible for specific immune response which provides long term community

Answer 293

- b cells mature in the bone marrow however T cells pasture in thymus gland - b cells are associated it’s humoral immunity ( that is imunity involving antibodies that are present in body fluids or ‘humour’ such as blood plasma’ However Tcells are associated with cells mediated immunity ( thus us imunity involving body cells)

Answer 294

B cells Antibody’s are proteins which specific binding sites synthesised by B cells ( when body is infected by non self material , a b cell produces a specific antibody )

Answer 295

Each antibody has two identical binding slides. They are complimentary to a speciifc antigen. Antibodies are made up of four polypeptide chains, the chains of one pair along and heavy andare called heavy chains, while the chains of the other pair are shorter, and known as light chains Each antibody has a specific binding site that fits very precisely onto a specific antigen to form an antigen antibody complex The binding site is different on different antibodies and is therefore called the variable region Each binding site consists of a sequence of amino acids that form a specific 3-D shape that binds directly to a specific antigen The rest of the antibody is a constant region to the receptors on cell, such as b cells

Answer 296

Ribosomes - site of protein synthesis Mitrcohcodira- atp which can be sued in protein synthesis RER- fold the protein made in the ribosomes so antibodies take up the correct 3D tertiary structure

Answer 297

Phago- to eat Cyte - hallow as cell or container

Answer 298

extension of rhe cytoplasm

Answer 299

Ability to take up extra cellular particles

Answer 300

Causes blood vessels to become permeable so they can leave the blood

Answer 301

The process by which white blood cells engulf and subsequently digest pathogenic microorganisms.

Answer 302

Chemical products called chemiattractrants

Answer 303

Phagocytes to migrate toward the pathogen along a concentration Gradient Called chemotaxis

Answer 304

Cell surface membrane of the phagocytes has several protein receptors that are able to bind to the complementary antigens present om the surface of the pathogen

Answer 305

The phagocytes call membrane extent outwards around the site of attachment and surrounds the material, effectively engulfing it. The pathogen is now enclosed in a mebrane bound sac (vesicle) called phago some

Answer 306

The phagosome moves towards rhe cell interior and fuses with a lysosome. Thus fusion releases lysosomal enzymes onto the injected pathogen The enzyme digest the pathogen by the process of hydrolysis

Answer 307

By hydrolysis of their cell walls

Answer 308

Absorbed into the cytoplasm of the phagocyte

Answer 309

Primary response

Answer 310

Slow becuase there arnt many B-cells that can make the antibodies needed to bind to it

Answer 311

B-cells make antibodies needed to bind to it, eventually the body will produce enough of the right antibodies to overcome the infection. Meanwhile the infected person will show symptoms of the disease. After being exposed to an antigen, both t and b cells produce memory cells. These memory cells remain in the body for a long time. The person is now immune ( and has the ability to respond quickly ro a second infection

Answer 312

Remember specific antigens and will recognise a second time in a row

Answer 313

Record specific antibodies need to bind the antigen

Answer 314

Is the same pathogen enters the body again the immune system will produce a quicker stronger immune response Colonal selection happens faster. Memory B-cells are activated and divide into plasma cells that produce the right antibodies to the antigen. Memory Tcells are activated and divide into the correct type of Tcells to kill the cell carrying the antigen

Answer 315

Antibodies cause agglutination if bacteria cells, this means that the binding other the specific antibody to the complementary antigen on the bacterial cells cause clumps if bacteria cells to form - thus clumping toughest make its easier for the phagocytes to locate the bacteria as they are less spread out within the body The antibody’s act as markers to stimulate the phagocytes to engulf the bacteria cells to which they are attracted

Answer 316

Process of specific b cells undergoing mitosis

Answer 317

Then takes antigen from pathogen and puts it on its surface (antigen presenting cell) helper T cells bind to antigen B cells Stimulates mitosis

Answer 318

There are millions of differnt B lymphocytes in the body Each has a specific shape of receptor (actually a membrane-bound antibody) on its cell surface membrane. When a foreign antigen enters the blood or tissue fluid, there will be one B ceil with a receptor/antibody that is complementary to that of the antigen. The antibody on that specific, B-cell, therefore bind to the antigen to form an antigen antibody complex. This binding cause the antigen to enter the specific cell by the process of endocytosis. The antigen is then presented on the cell surface membrane of the cell. We say it has been processed. help T cells then bind to the processed antigens. This activates specific B cell, causing it to divide rapidly by the process of mitosis, the result is the large clone of the cells that are genetically identical the clone of cells, then differentiate into one of two cell types, the majority becomes plasma cells. These secrete soluble antibodies that are the correct shape to bind to the foreign antigen. Although they only live for a few days each can make approximately 2000 antibodies a second they responsible for the immediate defence of the body against infection should they count to the same foreign material at a later date they can divide very rapidly into plasma cells and yet more memory cells and increased amount of antibodies secreted at a faster rate other cells differentiate into memory cells. These remain in the body circulating in the blood and tissue fluid for a long time. This secondary immune response shows that the antigen is destroyed before symptoms of disease develop.

Answer 319

Own cells that have been infected by non self material ( from a differnt species ) And Other individuals from the same species becuase genetically differnt ( and so have differnt antigens on their CSM)

Answer 320

Phagocytes that have engulfed and hydrolysed a pathogen prevent some pathogens antigens on their own CSM Body cells invade by a virus present some of the viral antigens on they own CSM Transplanted cells from individuals of the same species have differnt antigens on their CSM Cancer cells are differnt from normal body cells and present antigens on thru CSM

Answer 321

Antigen presenting cells as they can present antigens of other cells on their own CSM

Answer 322

Antigens that are presented on a body cell (Rather than antigens in the body fluid)

Answer 323

Cell mediated immunity

Answer 324

A single antigen

Answer 325

1) pathogens invade body cells or are taken in by phagocytes 2) the phagocyte phase places antigens form the pathogen on its CSM 3) receptors on a specific helper T-cell fit exactly onto there antigens 4) thus attachment activated the T cells to divide By mitosis and form a clone of genetically identical cells

Answer 326

- develop into memory cells that enable a rapid response to future infection by the same pathogen - stimulate phagocytes to engulf pathogens by phagocytosis - stimulated B cells to divide and secrete their antibody s - activate cytotoxic T cells

Answer 327

Produces a protein called perforin that makes holes in the CSM. These holes mean cell memebrane becomes freely permeable to all substances and the cell dies.

Answer 328

Kill abnormal cells and body cells that are infected by pathogens

Answer 329

As viruses replicate in cells (as viruses use living cells)

Answer 330

It’s a virus So it uses it genetic material to instruct the host cells biochemical mechanisms to produce the components required to make HIV

Answer 331

• Following infection HIV enters the bloodstream • A protein on the HIV readily binds to a protein called CD4. While this protein occurs on a number of different cells, HIV most frequently attaches to helper T cells • The protein capsid fuses with the cell-surface membrane. The RNA and enzymes of HIV enter the helper T cells • The HIV reverse transcriptase converts the virus's RNA into DNA. The newly made DNA is moved into the helper T cells nucleus where it is inserted into the cell's DNA. • The HIV DNA in the nucleus creates messenger RNA using the cells enzymes. Thus mRNA contains the instruction for making new viral proteins and the RNA to go into the new HIV • The mRNA passes out of the nucleus through a nuclear pore and uses the cells protein synthesis mechanisms to make HIV particles. • The HIV partides break away from the helperT cell with a piece of its cell surface membrane surrounding them which forms their lipid envelope.

Answer 332

HIV positive

Answer 333

When leading to aids many years later

Answer 334

The human immunodeficiency virus specifically attacks helper T cells. HIV causes AIDS by killing or interfering with the normal functioning of helper T cells. An uninfected person normally has berneen 800 and 1200 helper T cells in each mm3 of blood. In a person suflering from AIDS this number can be as low as 200 mm. helper T cells are important in cell mediated immunity. Without a sufficient number of helper T cells, the immune system cannot stimulate B cells to produce antibodies or the cytotoxic T cells that kill cells infected by pathogens. Memory cells may also become infected and destroyed. As a result, the body Is unable to produce an adequate immune response and becomes susceptible to other infections and cancers. Many AIDS sufferers develop infections of the lungs, intestines, brain and eyes, as well as experiencing weight loss and diarrhoea. It is these secondary, diseases that ultimately cause death.

Answer 335

800 - 12000 in each mm3 of blood

Answer 336

As low as 200mm-3

Answer 337

Human immunodeficiency virus

Answer 338

Enzyme linked immunosorbant assay

Answer 339

Detects the presence of a protein in a Sample and the quantity

Answer 340

1) apply the sample to a surface, for example a slide, it which all the antigens in the sample will attach 2) wash the surface several times to remove any unattached antigens 3) add the antibody that is specific to the antigen we are trying to detect and leave the two to bind together 4) wash rhe surface to remover excess antibody’s 5) add a second antibody that binds with the first antibody . Thus secondary antibody has an enzyme attached to it 6) add the colourless substrate of the enzyme. The enzyme acts on the substrate to change ut to o a coloured product 7) the amount of the antigen present is relative to the intensity of the colour

Answer 341

HIV and the pathogens of disease including tuberculosis and hepatitis ( ELISA is useful as it measures quantity which is imporstant in drug and allergen tests)

Answer 342

Passive immunity is produced by the introduction of antibodies into individuals from an outside source. No direct contact with the pathogen or its antigen is necessary to induce immunity.

Answer 343

Immediately

Answer 344

No as the antibodies are not be produced by the individuals themselves, the antibodies are not replaced when there broken down, no memory cells are formed

Answer 345

Examples of passive immunity include anti-venom given to the victims of snake bites and the immunity acquired by the fetus when antibodies pass across the placenta from the mother.

Answer 346

produced by stimulating the production of antibodies by the individuals' own immune system. Direct contact with the pathogen or its antigen is necessary.

Answer 347

takes time

Answer 348

Natural Artificial

Answer 349

results from an individual becoming infected with a disease under normal circumstances. The body produces its own antibodies and may continue to do so for many years.

Answer 350

forms the basis of vaccination (immunisation). It involves inducing an immune response in an individual, without them suffering the symptoms of the disease.

Answer 351

appropriate disease antigens into the body, either by injection or by mouth. The intention is to stimulate an immune response against a particular disease.

Answer 352

contains one or more types of antigen from the pathogen. These antigens stimulate the immune response

Answer 353

only a small amount of antigen has been introduced,

Answer 354

Memory cells These remain in the blood and allow a greater, and more immediate, response to a future infection with the pathogen.

Answer 355

The result is that there is a rapid production of antibodies and the new infection is rapidly overcome before it can cause any harm and with few, if any, symptoms.

Answer 356

economically available in sufficient quantities to immunise most of the vulnerable population. few side-effects, if any, from vaccination. Unpleasant side-effects may discourage individuals in the population from being vaccinated. • Means of producing, storing and transporting the vaccine must be available. This usually involves technologically advanced equipment, hygienic conditions and refrigerated transport. • There must be the means of administering the vaccine properly at the appropriate time. This involves training staff with appropriate skills at different centres throughout the population. • It must be possible to vaccinate the vast majority of the vulnerable population to produce herd immunity.

Answer 357

Herd immunity arises when a sufficiently large proportion of the population has been vaccinated to make it difficult for a pathogen to spread within that population. Where the vast majority of the population is immune, it is highly improbable that a susceptible individual will come in contact with an infected person.

Answer 358

Herd immunity is important because it is never possible to vaccinate everyone in a large population.

Answer 359

For example, babies and very young children are not vaccinated because their immune system is not yet fully functional. It could also be dangerous to vaccinate those who are ill or have compromised immune systems.

Answer 360

To achieve herd immunity, vaccination is best carried out at one time. This means that, for a certain period, there are very few individuals in the population with the disease and the transmission of the pathogen is interrupted.

Answer 361

Vaccination fails to induce immunity in certain individuals, for example people with defective immune systems. • Individuals may develop the disease immediately after vaccination but before their immunity levels are high enough to prevent it. These individuals may harbour the pathogen and reinfect others. • The pathogen may mutate frequently, so that its antigens change suddenly rather than gradually. This means that vaccines suddenly become ineffective because the new antigens on the pathogen are no longer recognised by the immune system. As a result the immune system does not produce the antibodies to destroy the pathogen. This antigenic variability happens with the influenza virus, which changes its antigens frequently. Immunity is therefore short-lived and individuals may develop repeated bouts of influenza during their lifetime. There Amy be so many varieties of z particular pathogen that it Is almost impossible to develop a vaccine that is effective against all. Cerain pathogens ‘hide’ from the bodys immune system. either by concealing themselves inside cells or by living in places out of reach such as in the intesines, for example, the cholera • Individuals may have objection to vaccination for religious, ethical or medical reasons

Answer 362

• The production of exsisiting vaccines, and the development of new ones, often involves the use of animals. How acceptable is this? • Vaccines have side-effects that may sometimes cause long-term harm. How can the risk of side-effects be balanced against the risk of developing a disease that causes even greater harm? • On whom should vaccines be tested? How should such trials be carried out? To what extent should individuals be asked to accept risk in the interests of the public health? • Is it acceptable to trial a new vaccine with unknown health risks only in a country where the targeted disease is common, on the basis that the population there has most to gain if it proves successful? • To be fully effective the majority, and preferably all, of the population should be vaccinated. Is it right, in the interests of everyone's health, that vaccination should be compulsory? If so, should this be at any time, or just when there is a potential epidemic? Can people opt out? If so, on what grounds: religious belief, medical circumstances, personal belief? • Should expensive vaccination programmes continue when a disease is almost eradicated,

Answer 363

Memory cells

Answer 364

Either free or attached to a dead or weakened (attenuated) pathogen

Answer 365

that it could be broken down by enzymes in gut or the molecules of the vaccine may be too large to be absorbed into the blood

Answer 366

To make sure that memory cells are produced

Answer 367

Primary response

Answer 368

When you're infected a second time with the same pathogen (which has the same antigens on its surace they activate the secondary response and you don't get ill.

Answer 369

When pathogens can change their surface antigens

Answer 370

The memory cells produced for the first infection, will not recognise the different antigens. So the immune system has to carry out the primary response again Yes , as the primary response takes time to get rid of the infection

Answer 371

The influenza (flu) vaccine changes every year. That's because the antigens on the surface of the influenza virus change regularly, forming new strains of the virus. 2) Memory cells produced from vaccination with one strain of the flu will not recognise other strains with different antigens. The strains are immunologically distinct. 3) Every year there are different strains of the influenza virus circulating in the population, so a different vaccine has to be made 4) New vaccines are developed and one is chosen every year that is the most effective against the recently circulating influenza viruses. 5)governments and health authorities the implement a program of vaccination using the most suitable vaccine

Answer 372

this is when a baby becomes immune due to the antibodies it receives from its mother, through the placenta and in breast milk.

Answer 373

this is when you become immune after being injected with antibodies from someone else.

Answer 374

Antibodies produced form a single group of genetically identical B-cells ( plasma cells). This means they are identical in structure.

Answer 375

Their binding sites have a unique tertiary structure.

Answer 376

Different cells in the body have different surface antigens. 2) Cancer cells have antigens called tumour markers that are not found on normal body cells. 3) Monoclonal antibodies can be made that will bind to the tumour markers. 4) You can also attach anti-cancer drugs to the antibodies. 5) When the antibodies come into contact with the cancer cells they will bind to the tumour markers. 6) This means the drug will only accumulate in the body where there are cancer cells. 7) So, the side effects of an antibody-based drug are lower than other drugs because they accumulate near specific cells.

Answer 377

HCG Human chorionic gonadotropin

Answer 378

In the urine of pregnant women

Answer 379

1) The application area contains antibodies for hCG bound to a coloured bead (blue). 2) When urine is applied to the application area any hCG will bind to the antibody on the beads, forming an antigen-antibody complex. 3) The urine moves up the stick to the test strip, carrying any hCG beads with it. 4) The test strip contains antibodies to hCG that are stuck in place (immobilised). 5) If there is hCG present the test strip turns blue because the immobilised antibody binds to any CG — concentrating the hCG-antibody complex with the blue beads attached.if no HCG present the beads will pass through the test area without binding to anything and so it won’t go blue

Answer 380

Pathogenic infections Allergies

Answer 381

Uses a single antibody that is complementary to the antigen you are testing fro

Answer 382

Uses 2 antibodies

Answer 383

Acquired immune deficiency syndrome

Answer 384

Genetic material (RNA) and some proteins ( including the enzymes reverse transcriptase, which is needed for virus replication )

Answer 385

Envelope Membrane stolen form the cell membranes of a previous host cell

Answer 386

copies of an attachment proteins that help HIV attach to the host helper T-cell

Answer 387

Helper T-cells of the host

Answer 388

The infected person won’t experience any symptoms As the HIV replication drops to a lower level

Answer 389

Minor infections of mucous membranes, and recurring respiratory infections

Answer 390

The number of immune system cells decrease further Patients become susceptible to more serious infection including chronic diarrhoea, severe bacterial infections and tuberculosis

Answer 391

patients have a very low number of immune system cells and can develop a range of serious infects such as toxoplasmolysis of the brain and candidiasis of the respiratory system Its these serios infection that kill aids patients not HIV itself

Answer 392

Existing infection Strain of HIV they are infected with Age

Answer 393

By interfering with their metabolic reactions They target the bacterial enzyme and ribosomes used in these reactions

Answer 394

Antibiotics kill bacteria by interfering with their metabolic reactions. They target the bacterial enzymes and ribosomes used in these reactions. 2) Bacterial enzymes and ribosomes are different from human enzymes and ribosomes. Antibiotics are designed to only target the bacterial ones so they don't damage human cells. 3) Viruses don't have their own enzymes and ribosomes — they use the ones in the host's cells. So because human viruses use human enzymes and ribosomes to replicate, antibiotics can't inhibit them because they don't target human processes.

Answer 395

The Few virus specific enzymes that exist

Answer 396

HIV uses reverse transcriptase to replicate. Human cells don't use this enzyme so drugs can be designed to inhibit it without affecting the host cell. These drugs are called reverse-transcriptase inhibitors.

Answer 397

Antiviral drugs

Answer 398

Reducing the spread HIV can be spread via unprotected sexual intercourse, through infected bodily fluids (e.g. like blood from sharing contaminated needles) and from a HIV-positive mother to her fetus. Not all babies from HIV-positive mothers are born infected with HIV and taking antiviral drugs during pregnancy can reduce the chance of the baby being HIV-positive.

Answer 399

Differnt parts of the antigen that can be recognised as foreign by the immnne system and can stimulate an immune response

Answer 400

A microorganism that can potentially cause disease

Answer 401

Term given to describe the way in which B lymphocytes produce antibodies in response to infection

Answer 402

Tea lymphocytes respond to an antigen presenting cell

Answer 403

Histamines

Answer 404

Mixture of differnt antibodies

Answer 405

Antibodies of a single type that are isolated and cloned

Answer 406

One antigen may interfere with another Expensive process so cheaper to only Produce one antibody

Answer 407

To separate a chemical from a mixture Immunoassay - to estimate the quantity of a substance in a mixture (pregnancy test) Cancer treatment Transplant surgery

Answer 408

To deliver cytotoxic drugs to cancer cells, cancer cells have antigens on surface that are not found on healthier cells

Answer 409

Can be used to block t-cells that will cause rejection of a transplanted organ

Answer 410

Polyclonal antibodies

Answer 411

Humanised So human immune system will accept the antibodies and not recognise them as foreign

Answer 412

1) inject foreign material into mouse 2) B-cells of mouse make polyclonal antibodies 3) extract b cells from the spleen 4) mix b cells with cells from cancer tumour in vitro 5) the detergent, breaks the cell surface membrane, allowing both cells to fuse 6) if few cells are separated, using a microscope and cultured to form a clone of cells 7) Each cell is tested any producing the required antibody, grown on a large scale 8 humanised

Answer 413

Tumour cells divide rapidly, which makes the process more efficient

Answer 414

Deliberately inducing cancer to mice Transgenic mice are used to eliminate the humanisation procedure. Is genetic engineering ethical Death association with the use of monooinal antibodies in the treatment of multiple sclerosis Saftey if feasting new medicine ( drug trials)

Answer 415

The vaccine is administered It contains a weakens, dead, dilute or heat attenuated version of the disease The immnuse system identifies these foreign sustances Once antigens are identified, b cells produce proteins that circulate in the blood, these proteins are called antibodies Memory cells produced in response to the antigen are available to fight of the disease if exposed later on

Answer 416

The MMR vaccine and autism

Answer 417

Very small sample size of 12 children- which increased the likelihood of the results being due to chance The study may have been biased because one of the scientists was trying to gain evidence for a lawsuit against the MMR vaccine manufacturer Studies carries out by differnt scientists found no links between autism and the MMR vaccine

Answer 418

2005 Japanese study Looked into medical records of 30,000 children born between 1988 and 1996, and counted number of children that developed autism before the age of seven The mmr jab was first introduced in Japan in 1989 and was stopped in 1993. During this time the Mmr vaccine was administered to children at 12 month

Answer 419

Use data Describe the increases and decreases

Answer 420

There is no link

Answer 421

The sample size was larger so the results are less likely to be due to chance