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bio paper 1 w/out practicals, Cells - Coggle Diagram
bio paper 1
w/out practicals
cell biology
Eukaryotic cells
All living things are made of cells.
Cells are either eukaryotic or prokaryotic
Prokaryotic cells
non living eg bacteria
can fit into a eukaryotic cell
has a cell membrane, cytoplasm and cell wall
does NOT contain chloroplasts or mitochondria
has singular circular strand of DNA that floats freely in cytoplasm
may also contain one or more small rings of dna called plasmids
Microscopy
2 types - electrons and light.
light - use light and lens to form an image of a specimen and magnify it. Lets us see individual cells and larger subcellular structures like nuclei.
Electron- uses electrons rather than light.
higher resolution and magnification
and can see internal structures eg r
Magnification = image size / real size (AIM)
How to use light microscope
Clip the slide on the stage
Select the lowest power objective lens
Use the coarse adjustment job to move the stage up to below the objective lens
Look down the eyepiece, use the coarse adjustment knob to move the stage downwards until the image is roughly in focus
Adjust the focus with the fine adjustment knob until u get a clear image
DRAW OBSERVATIONS
-neatly with a pencil
clear unbroken lines
no colouring or shading
draw in proportion
title and label it with structures and magnification
Cell differentiation
differentiation - the process by which a cell changes to become specialised for its job, as a cell changes, they develop different sub cellular structures and turn into different types of cells. this allows them to carry out specific functions.
differentiation occurs when an organism develops. in animals, it’s lost at an early stage, whereas plants can differentiate throughout their whole life. cells that differentiate in mature animals are mainly used for repairing and replacing cells eg skin or blood
sperm cells - specialised for reproduction. long tail and streamline head to help it swim, a lot of mitochondria in the cell to provide energy needed. also carries enzymes in its head to digest through the egg cell membrane
nerve cells - specialised for rapid signalling
axon is long, enabling impulses to be carried along long distances. have lots of extensions from the cell body ( dendrites) means branched connections can form with any other nerve cell
nerve endings have many mitochondria which supply the energy to make specialised transmitter chemicals called neurotransmitters. these allow the impulses to be passed from one cell to another
muscle cells - specialised to contract quickly to move bones (striated muscle) or to squeeze ( smooth muscle ) causing movement. special proteins (myosin and actin) slide over each other, causing muscles to contract. lots of mitochondria to produce energy from respiration for contraction
they can store a chemical called glycogen that is used in respiration and mitochondria.
root hair cells - specialised to take up water by osmosis and mineral ions by active transport from the soil as they are found in the tips of roots. have large SA due to root hairs, meaning more water can move in. large permanent vacuole affects the speed of movement of water from soil to cell. mitochondria to produce energy from respiration for the active transport of mineral ions into the root hair cells
xylem: transports water around the plant, one way (up). dead. hollow ends to make a tube for water and mineral ions to travel through. thick cell wells (lignin) to support the plant. transpiration
phloem: transports dissolved sugars, glucose and amino acids around the plant. translocation. cells close to the phloem provide energy to transport substances. contains pores
mitosis
cells divide so organisms can grow and repair themselves, cells which have divided by mitosis are genetically identical to the parent cell.
STEPS
cell grows and increases the number of mitochondria and ribosomes
DNA replicates to make 2 copies of each chromosome
the DNA lines up down the centre of cell
4, one set of dna lines up down the centre of cell
5, nucleus divides
cytoplasm and cell membranes divide and two indentical cells are formed
stem cells
stem cell is an undifferentiated cell which can become another type of cell.
two types in humans
embryonic
: from the womb
advantages: can become mist other types of cell. used to treat disease eg diabetes and paralysis, not rejected
disadvantages: can cause transfer of viruses, ethical issues ( religious objections, potential life)
-
adult stem cells
: can form some other types of cells eg blood cell from bone marrow, not rejected by body.
can cause transfer of viruses, can differentiate into fewer types of cells than embryos
plant stem cells
meristem tissue: can differentiate into any other type of plant cell at any point in plants life, can clone rare plants to stop going extinct or special features eg resistance to disease
cell transportation
diffusion
-spreading out of particles from an era of high conc to an area of low conc.such as gas exchange, urea diffuses from cells into the blood plasma where it is taken to the kidney
factors that speed up rate of diffusion
big difference in conc ( large conc gradient)
warm temp
large SA of membrane
only short distance for substance to diffuse
osmosis
diffusion of water particles from an area of high to low conc through a partially permeable membrane
active transport
moves substances from a low to high conc gradient, needs energy from respiration
absorb mineral ions which are low conc in soil, needed for healthy plant growth
sugar absorbed from a low conc in smell intestine, into the blood which has a higher sugar conc, sugar molecules used for cell respiration
exchange substances
gas exchange in lungs
transfer oxygen and remove waste carbon dioxide
alveoli are the site of gas exchange
to maximise this, they have an enormous SA, moist lining for dissolving gases, thin walls and good blood supply
villi in the small intestines
-increased SA so digested food is absorbed quivkly into the blood
single layer of surface cells
good blood supply
structure of leaves
carbon dioxide diffuses in to the air spaces within the leaf then diffuses into the cells where photosynthesis occurs
underneath of leaf is exchange surface, contains stomata’s which carbon dioxide diffuses in through
oxygen and water vapour diffuse out through the stomata (water vapour is also lost from all over the leaf surface via evaporation)
size of stomata is controlled by guard cells. these close the stomata if the plant is losing water faster than it’s being replaced by the roots. without these guard cells the plant will wilt.
the flattened shape of the leaf increases the area of this exchange surface so that its more effective.
the walls of the cells inside the leaf form another exchange surface. the air spaces inside the leaf increase the area of this surface so there’s more chance for carbon dioxide to get into the cells
gills
gills are the gas exchange in fish
water (containing oxygen) enters the fish through its mouth and passes out through the gills. as this happens oxygen diffuses from the water into the blood in the gills and carbon dioxide diffuses from the blood into the water
each gill is made of lots of thin plates called gill filaments which give a big SA for exchange of gases
the gill filaments are covered in lots of tiny structures called lamellae which increase SA
the lamellae have lots of blood capillaries to speed up diffusion
they also have a thin surface layer of cell to minimise the distance the gas has to diffuse
blood flows thought the lamellaes in one direction and water flows over in the opposite direction. this maintains a large concentration gradient between the water and blood
the conc of oxygen in the water is always higher than in the blood, so as much oxygen as possible diffuses from water in to blood
organisation
cell organisation
cells are the basic building blocks that make up all living organisms. specialised cells form tissues, which form organs, which form organ systems
similar cells are organised into tissues
muscular tissue which contracts to move
glandular tissue which makes and secretes chemicals like enzymes and hormones
epithelial tissue, which covers some parts of the body eg the inside of the gut
tissues are organised into organs
-muscular tissue, which moves the stomach wall to churn food
glandular tissue, which makes digestive jucies
epithelial tissue , which covers the outside and inside of stomach
organs are organised into organ systems
organ system us a group of organs working together to perform a particular function
eg the digestive system breaks down and absorbs food.
enzymes
enzymes are biological catalysts which speed up reactions without being used up
work in specific conditions - temp and pH
lock and key method - active site to make substrate into products, breaks them down so they’re easier to absorb
if not at right temp or Ph they denature
digestive enzymes break down molecules such as starch, proteins and fats since they are too big to pass through the walls of the digestive system.
starch - amylase - maltose and other sugars
amylase made in salivary glands, pancreas and small intestine
proteins - protease - amino acids
protease made in stomach (pepsin) pancreas and small intestine
lipids - lipase - glycerol and fatty acids
lipase is in pancreas and small intestine
bile
bile is produced in the liver, stored in gallbladder before it’s released into small intestine
hcl acid in stomach is too acidic for small intestine. bile is an alkali so it neutralises the acid so the enzymes can work the best.
it also emulsifies fats (globules) into tiny droplets. this gives a bigger SA for lipase to work on which makes digestion faster
the lungs
lungs are in th thorax (top part of body)
seperated from lower part of the body by the diaphragm
protected by the rib cage, surrounded by pleural membranes
trachea —> bronchi —> bronchioles —> alveoli
alveoli carry out gas exchange in the body - lungs contain millions of alveoli surrounded by a network of capillaries.
blood passing next to the alveoli has just returned to the lungs from the rest of the body, so it contains lots of carbon dioxide and little oxygen. oxygen diffuses out of the alveolus (high conc) into the blood (low conc). carbon dioxide diffuses out of the blood to be breathed out.
when th blood reaches body cells oxygen is released from thr RBC and diffuses into the body cells
at the same time, carbon dioxide diffuses out of the body cells into the blood, then carried back to the lungs
breathe per min = no. of breaths / no. of mins
the heart
double circulatory system
right ventricle pumps deoxygenated blood to the lungs to take in oxygen. blood then returns to the heart
left ventricle pumps oxygenated blood around the body. the blood gives up its oxygen at the body cells and deoxygenated blood returns to the heart to be pumped to the lungs again.
heart is a pumping organ (muscle) that keeps the blood flowing around the body. the walls are mostly muscle tissue.
the heart has valves to make sure that blood flows in the right direction - they prevent it flowing backwards
order from L to R
vena cava, pulmonary artery, aorta, pulmonary vein
heart is always flipped
blood flows into the two atria from the vena cava ( right atrium ) and the pulmonary vein ( left atrium )
the atria contract, pushing blood into the ventricles
the ventricles contract, forcing the blood into the pulmonary artery and aorta, and out of the heart
blood then flows to the organs through arteries, and returns through veins
the atria fill again and the whole cycle starts over
the heart also needs its own supply of oxygenated blood. arteries called coronary arteries branch off the aorta and surround the heart, making sure it gets all the oxygenated blood it needs.
heart has pacemaker
resting heart rate is controlled by a group of cells in right atrium wall that act as a pace maker. these cells produce a small electrical impulse which spreads to the surrounding muscle cells, causing them to contract
an artificial pace maker is often used to control the heartbeat if natural pacemaker cells don’t work properly, eg if they have irregular heartbeat. it’s a little device that’s implanted under the skin from the groin and have a wire going to the heart. it produces an electric current to keep the heart beating regularly
blood vessels
ARTERIES - carry blood AWAY from the heart under pressure.
heart pumps the blood out at high pressure so the artery walls are strong and elastic
walls are thick compared to the size of the hole down the middle ( the lumen )
they contain thick layers of muscle to make them strong, and elastic fibres allow them to stretch and spring back.
CAPILLARIES - involved in exchange of materials at the tissues
very small
arteries branch into capillaries
they carry blood really close to every cell in the body to exchange substances with them
they have permeable walls so substances can diffuse in and out
they supply food and oxygen, and take away waste like co2
one cell thick, increasing the rate of diffusion by decreasing the distance
veins - carry blood to the heart
capillaries eventually join to form veins. the blood is at lower pressure in the veins so the walls don’t need to be as thick as artery walls
bigger lumen than arteries to help the blood flow despite the low pressure
valves to prevent backflow
circulatory system - blood
red blood cells
carry oxygen from lungs to cells in body
biconcave disc - large SA to absorb oxygen
don’t have a nucleus so it can carry more oxygen
red pigment called haemoglobin
haemoglobin binds to oxygen to form oxyhemoglobin in the lungs. in body tissues the opposite happens - oxyhemoglobin splits up and oxygen diffuses into the cells.
white blood cells
defend against infection
change shape in order to perform phagocytosis
others produce antibodies to fight microorganisms as well as anti toxins to neutralise any toxins produced by microorganisms
do have a nucleus
platelets
clot blood
small fragments of cells that have no nucleus
clot wounds to stop blood pouring out and stop micro organisms getting in.
lack of platelets can cause excessive bleeding and bruising
plasma
liquid that carries everything in the blood
pale straw colour
carries:
RBC and WBC and Platelets
nutrients like glucose and amino acids. these are the soluble products of digestion which are absorbed from the gut and taken to the cells of the body
carbon dioxide from organs to lungs
urea from liver to kidneys
hormones
proteins
antibodies and anti toxins
cardiovascular disease
stents keep arteries open
CHD is when the coronary arteries that supply the blood to the muscle of the heart get blocked by layers of fatty material building up. this causes the arteries to become narrow, so blood flow is restricted and there will be a lack of oxygen to heart muscle, resulting in a heart attack.
stents are tubes that are inserted inside arteries. they keep them open, making sure blood can pass through to the heart muscles. this keeps the heart beating and the person alive.
stents are a way of lowering the risk of a heart attack in people the coronary heart disease. they are effective for a long time and the recovery from the surgery is relatively quick
on the downside, there is a risk of complications during the operation and a risk of infection from surgery. there is also a risk of patients developing a blood clot near the stent (thrombosis)
statins reduce cholesterol in the blood
cholesterol is an essential lipid that your body produces and needs to function properly. however, too much of a certain type of cholesterol ( bad - LDL ) can cause health problems
too much LDL can cause fatty deposits to form inside arteries, which can lead to CHD.
statins are drugs that can reduce the amount of LDL cholesterol present in the bloodstream. this slows down the rate of fatty deposits forming
advantages of statins
reduce the risk of strokes, chd and heart attacks
increase the beneficial cholesterol (HDL)
may prevent other diseases from occuring
disadvantages of statins
statins are a long term drug that must be taken regularly - can forget to take them
negative side effects
effect isn’t instant - takes time
artificial hearts are mechanical devices that pump blood
used when donor organs aren’t available
temporary fix to keep a person alive until a donor heart can be found or to let someone rest and recover. or can be used as a permanent fix
main advantage of artificial hearts is that they are less likely to be rejected by the body’s immune system as plastics or metals are used.
surgery to fit this can lead to bleeding and an infection. the heart also doesn’t work as well as natural healthy ones. blood doesn’t flow as smoothly which causes blood clots and lead to strokes. patients has to take drugs to thin their blood and make sure this doesn’t happen which can cause bleeding if they’re hurt.
faulty heart valves
replaced with mechanical or biological valves
damaged by heart attacks, infection or old age
damage may cause valve tissue to stiffen, so it won’t open properly. or a valve may become leaky, allowing blood to flow in bothers directions rather than just toward. this means that blood doesn’t circulate as effectively.
replacing the valve is damage is severe. replacement valves are either taken from humans, mammals (cows and pigs) or man made.
less drastic procedure than a heart transplant. still problems with blood clots tho
artificial blood can keep you alive
heart still pumps remaining red blood cells around as long as the volume of blood can be topped up.
artificial blood is a substitute, eg saline which is a salt solution used to replace the lost volume of blood. it’s safe if no air bubbles get into the blood and can keep people alive even if they loose 2/3 of blood cells. this may give patients more time to reproduce new blood cells. if not, patient would need blood transfusion.
health and disease
health is the state of physical and mental wellbeing. diseases are responsible for ill health.
diseases can be communicable or non-communicable
communicable diseases are spread from person to person or animals to people. they are caused by pathogens like bacteria, viruses, parasites or fungi. they are contagious/infectious.
non-communicable diseases cannot spread, last long time and get worse slowly. eg asthma, cancer and chd.
different types of diseases can interact
people who have problems with their immune system have an increased chance of suffering with communicable diseases like the flu because their body cannot defend itself
cancer can be triggered by infection by certain viruses. for example, infection with some types of HIV can cause long term infections in the liver where the virus lives in the cells. this can lead to an increased chance of developing liver cancer. HPV can cause cervical cancer in women.
immune system reactions in the body caused by an infection by a pathogen can sometimes trigger allergic reactions such as skin rashes or worsen the symptoms of asthma.
mental health problems can affect life expectancy
other factors can affect your health
good and balanced diet or not
stress
life situation - easy access to medicine, prevention of illness, healthy food, condoms etc
risk factors for non communicable diseases
life style
environment- pollution, asbestos
smoking - damages walls of arteries and the cells in the linings of the lungs
obesity and type 2 diabetes
drinking too much alcohol and liver disease+ brain functioning
smoking and drinking when pregnant
cancer from exposure to carcinogenics eg radiation
risk factors don’t always directly cause disease
cancer
cancer is caused by uncontrolled cell growth and division, forming a tumour.
2 types of tumours
benign - tumour grows until there’s no more room and stays in one place (usually within a membrane) rather than invading other tissues in the body.
malignant - tumour spreads to neighbouring tissues and grows. cells break off and spread to other parts of the body by travelling in the blood stream, they invade healthy cells and form secondary tumours - they are dangerous and cancerous
risk factors can increase the chance of some cancers
assosiated with lifestyle - smoking, obesity, uv exposure and viral infection.
also associated with genetics - faulty genes inherited like mutations can increase cancer
plant organisation
organised into tissues and organs
1) epidermal tissue covers the plant
2) palisade mesophyll tissue - in the leaf where most photosynthesis occurs
3) spongy mesophyll tissue - in the leaf containing big air spaces to allow gases to diffuse in and out of cells
4) xylem and phloem transport water, mineral ions and food
5) meristem tissue found in growing tips of shoots and roots and is able to differentiate into different types of plant cell.
leaf is an organ made up of several types of tissue
epidermal tissue is covered with a waxy cuticle which helps reduce water lost by evaporation
upper epidermis is transparent so light can pass through to the palisade layer
palisade layer has lots of chloroplasts meaning they are by the top of the leaf here they can get most the light
xylem and phloem form a network of vascular bundles. they also help support the plant
tissue of leaves are adapted for efficient gas exchange, eg the lower epidermis is full of holes called stomata which let co2 diffuse directly into the leaf. the opening and closing of stomata is controlled by guard cells in response to environmental conditions. the air spaces in spongy mesophyll increase rate of diffusion
transpiration and translocation
phloem tubes transport food
made of elongated living cells with small pores in end of walls to allow cell sap to flow through
transport food substances (mainly dissolved sugars) made in the leaves to the rest of the plant for immediate use or storage
transport goes in both directions
process is called translocation
xylem tubes take water up
made of dead cells joined end to end with no walls between them and a hole down the middle, they are strengthened by lignin.
they carry water and mineral ions from the roots to the stem and leaves.
movement of water from the roots, through the xylem and out the leaves is called the transpiration stream
transpiration is the loss of water from the plant
transpiration is caused by the evaporation and diffusion of water from a plants surface. happens mostly at the leaves.
this evaporation creates a slight shortage of water in the leaf, and so more water is drawn up from the rest of the plant through the xylem vessels to replace it.
this means more water is drawn up from roots, and so there’s a constant transpiration stream of water,
transpiration and the stomata
transpiration rate is effected by 4 main things
light intensity - brighter the light, greater the rate. stomata close as it gets darker so little water can escape
temperature - warmer it is, faster it happens. particles have more energy to evaporate and diffuse out the stomata
air flow - better the air flow the greater the rate. if it’s poor, the water vapour surrounds the leaf and doesn’t move away. this means there’s a high conc of water particles outside the leaf as well as inside of it, so diffusion doesn’t happen as quickly
humidity - the drier the air the faster it happens
guard cells are adapted to open and close stomata
kidney shape which opens and closes the stomata in a leaf
when the plant has lots of water the guard cells fill with it and go plump and turgid. this makes the stomata open so gases can be exchanged for photosynthesis.
when the plant is short of water, the guard cells lose water and become flaccid, making the stomata close. this helps to stop too much water escaping.
thin outer walls and thickened inner walls to make open and closing work
sensitive to light and close at night
found more on the underside of leaves - cooler and in the shade so less water is lost
infection and response
communicable disease
pathogens are microorganisms that enter the body and cause disease. they cause communicable (infectious) diseases in plants and animals.
pathogens are spread in many ways
water - dirty water
air - breathed in through droplets
direct contact - touching contaminated surfaces
reduce or prevent spread
being hygienic eg washing hands
destroying vectors
isolating infected individuals
vaccination
bacteria are small living cells which reproduce rapidly inside your body. they make you feel ill by producing toxins that damage your cells and tissues
two bacterial diseases
salmonella causes food poisoning. symptoms are fever, stomach cramps, vomitting and diarrhoea. symptoms are caused by toxins that bacteria produce. can get from contaminated food. most poultry in the uk is given vaccination against salmonella
gonorrhoea is an STD. passed on by sexual contact, caused by bacteria (duh). symptom is pain when urinating, thick yellow/green discharge from penis or vag. used to be treated with penicillin but strain has become resistant. prevention methods are antibiotics and condoms
viruses are not cells but they reproduce rapidly inside of your cells. they replicate themselves using the cells machinery to produce many copies, causing the cell to eventually burst, releasing all the new viruses. the cell damage is what makes you ill.
three main viral diseases
measles. spread by droplets from an infected persons sneeze or cough. develop a red skin rash and a fever. can sometimes lead to pneumonia or inflammation of the brain and can be fatal. most people are vaccinated (MMR) when young.
HIV is a virus spread by sexual contact or by exchanging bodily fluids such as blood by sharing needles. initially causes flu like symptoms for a few weeks, then will be dormant for several years. during this time, HIV can be controlled with antiretroviral drugs. these stop the virus replicating. the virus attacks the immune system cells, making it unable to cope with other infections or cancers. this is know as AIDS, or late stage HIV.
TMV is a virus that affects plants like tomato’s. it causes a mosaic pattern on the leaves and become discoloured, the discolouration meaning photosynthesis can’t occur, so the virus effects growth.
protists are single celled eukaryotics
some are parasites which live on or inside other organisms and can cause them damage. they are often transferred to the organism by a vector - a vector is an organism which carries the disease but isn’t actually infected itself.
malaria is caused by protists
part of malarias life cycle takes place inside the mosquito. mosquitos are vectors - they pick up the malaria protist when they feed on an infected animal.
infects by inserting protist into animals blood vessels
causes repeating episodes of a fever, can be fatal
spread can be stopped by stopping breeding of mosquitos
can be prevented by mosquito nets or insecticides
fungi
some are single celled, others have a body which is made up of hyphae. these can grow and penetrate human skin and the surface of plants causing disease
hyphae can produce spores
fungal disease
rose black spot is a fungus that causes black or purple spots to develop on leaves of rose plants. the leaves then turn yellow and drop off.
less photosynthesis can happen so the plant doesn’t grow very well.
-spreads by water or wind
gardeners treat disease using fungicides and stripping the plant of affected leaves. these leaves then need to be destroyed so that the fungus can’t spread to other rose plants.
fighting disease
defence systems
skin is a barrier to pathogens and secretes anti microbial substances which kill pathogens.
hair and mucus in your nose trap particles that could contain pathogens
trachea and bronchi secrete mucus to trap pathogens. are lined with cilia (hair like structures) which waft up mucus to the back of throat where it can be swallowed,
stomach produces hcl acid. this kills pathogens that make it far from the mouth.
immune system
white blood cells engulf foreign cells and digest thru a process called phagocytosis
every invading pathogen has unique molecules called antigens on the surface.
when some types of wbc come across a foreign antigen, they will produce proteins called antibodies to lock into the invading cells so that they can be found and destroyed by other wbc.
the antibodies produced are specific to that type of antigen - they won’t lock onto any others.
anribodies are then produced rapidly and carried around the body to find similise bacteria or viruses.
if the person is infected with the same pathogen again the wbc will rapidly produce the antibodies to kill it - the person is naturally immune to that pathogen and won’t get ill.
produce antitoxins by counteracting toxins produced by bacteria.
vaccination
protect from future infections
involve injecting small amounts of dead or inactive pathogens. these carry antigens which cause your body to produce antibodies to attack them.
if live version of the pathogen appears the wbc can rapidly mass produce antibodies to kill of the pathogen.
Pros : control lots of disease, can prevent epidemics
cons: don’t always work eg not giving immunity, can have bad reaction.
drugs
some drugs relief symptoms, others cure the problem.
painkillers relieve pain rather than curing disease, reducing symptoms
antibiotics kill or prevent the growth of the bacteria causing the problem without killing your own body cells. different antibiotics kill different types of bacteria, so it’s important to be treated w the right one
but antibiotics don’t destroy viruses. viruses reproduce using your body cells which makes it difficult to develop drugs that destroy just the virus without killing the body’s cells.
use of antibiotics has greatly reduced the no of deaths from communicable diseases caused by bacteria.
bacteria can mutate and become resistant to an antibiotic. if you have an infection, some of the bacteria might be resistant to antibiotics. they will survive and reproduce. this resistant strain can cause a serious infection that can’t be treated by antibiotics. to slow down the rate of development of resistant strains, it’s important for doctors to avoid over-prescribing antibiotics.
many drugs come from plants
plants produce a variety of chemicals to defend themselves against pests and pathogens. some of these chemicals can be used as drugs to treat human diseases or relieve symptoms.
aspirin - willow, painkiller
digitalis - foxgloves, heart conditions
or microorganisms
penicillin - penicillium on a pétri dish aka mould.
developing drugs
three main stages
1) preclinical testing - human cells and tissues used
2) live animals eg mouse’s. test efficacy and toxicity to find best dosage
3) tested on healthy human volunteers in clinical trial. making sure it has no negative side effects. low dosage is given and is gradually increased
if results are good, it is tested on people with the disease/illness. the optimum dose is found - most effective and few side effects.
to test how well it works, two groups randomly assigned, one is given the drug, another a placebo. this is so the doctor can see actual difference the drug makes.
clinical trials are blind - ( double blind trial ) the patients in the study don’t know whether they get the drug or the placebo, the doctors usually don’t either to increase validity and so they aren’t subconsciously influenced by their knowledge.
then gets peer reviewed
monoclonal antibodies - triple only?
monoclonal antibodies are identical antibodies.
produced by B-lymphocytes - a type of wbc
produced from clones of a single wbc. antibodies are identical and will only target one specific protein antigen.
lymphocytes don’t divide very easily so they fuse a mouse b-lymphocyte to a tumour cell ( they reproduce / divide rapidly and can grown easily) to create a hybridoma
hybridoma cells can be cloned to get lots of identical cells. these cells all reproduce the same antibodies (monoclonal antibodies). these can be collected and purified
you can make them bind to whatever u want as they only bind to a specific molecule.
pregnancy tests
a hormone called HCG is found in the urine of women when they are pregnant. pregnancy testing sticks detect this hormone by:
the bit of the stick you urinate on has antibodies to the hormone with blue beads attached. the test strip has more antibodies to the hormone stuck onto it.
-if you are pregnant the hormone binds to the antibodies on the blue beads. the urine moves up the stick, carrying the hormone and the beads. the bead and hormone bind to the antibodies on the strip. so the blue beads get stuck and turn it blue.
treating disease
different cells in the body have different antigens on their cell surface. so you can make monoclonal antibodies that will bind to specific cells in the body,
cancer cells have antigens on their cell membranes that aren’t found on normal body cells. they are called tumour markers.
in the lab, you can make monoclonal antibodies that bind to these tumour markers.
an anticancer drug can be attached to these monoclonal antibodies.
the antibodies are given thru a drip.
these target specific cells because they only bind to the cancer tumour markers. the drugs kill the cancer cells.
research
used to bind to hormones and other chemicals in the blood to measure their levels.
test blood samples in labs for certain pathogens
locate specific molecules on a cell or tissue: monoclonal antibodies are made to bind to specific pathogen / molecule, fluoresent dye is used. if it’s present, it can be detected using the dye.
advantages:
cancer treatment
disadvantages
more side effects than expected
plant disease and defence
minerals
nitrates needed for protein making = growth, a lack of nintrates = stunted growth
magnesium make chlorophyll, lack of magnesium = chlorisis and yellow leaves
plants get infected by disease but also animals.
eg aphids (ladybugs are their predator)
sympons of disease in plant
stunted growth
spots on leaves
patches of decay
abnormal growths
malformed stems or leaves
discolouration
infestation of pests are easy to spot - you see them on plants
identify plant disease by
gardening manual / website
take plant to lab
testing kits using monoclonal antibodies
defences
physical:
waxy cuticle provides barrier
cell wall made of cellulose forms physical barrier if pathogens make it past waxy cuticle
layers of dead cells around stems eg bark
chemical:
produce antibacterial chemicals eg mint plant and witch hazel
produce poisons which deter herbivores eg tobacco plants, foxgloves and deadly nightshade.
mechanical defences:
thorns and hairs stop touching and eating it
droop or curl - knock off insects and move away
mimic other organisms, tricking organisms into not eating them.
bioenergetics
photosynthesis and limiting factors
endothermic reaction
plants use glucose in 5 main ways
respiration
making cellulose for strong plant cell walls
making amino acids - combined w nitrate ions to make amino acids which are then made into proteins
stored as oils or fats (lipids) in seeds
stored as starch in roots, stems and leaves, ready for use when photosynthesis isn’t or can’t happen. starch is insoluble which makes it better for storing than glucose. a cell with lots of glucose would draw loads of water in and swell up.
rate of photosynthesis is affected by light intensity, concentration of CO2 and temp.
these factors have a combined effect on the rate of photosynthesis but which factor depends on the environmental conditions.
night = light
winter = temp
warm and bright = co2
chlorophyll can also be a limiting factor - affected by disease, environmental stress or lack of nutrients.
light increases until it reaches a certain point - meaning there is other limiting factors, same with co2 and temp
enzume denaturing still applies for temp + other reactions get damaged (45 degrees optimum)
graphs plato
inverse square law
light intensity is proportional to 1/ (distance)^2
you can artificially create ideal conditions for farming
GREENHOUSE
traps suns heat, makes sure temp doesnt become limting
-use a heater to keep it ideal temp
shades and ventilation to cool things down
artificial light supply
paraffin heater to heat greenhouse + as a by product carbon dioxide
keeping plants enclosed protects from pests and disease
farmers can add fertilisers to soil to provide minerals for healthy plants
costs money to set up but crops grow much faster and harvested more often, which can then be sold,
respiration and metabolism
respiration is a process of transferring energy from glucose which goes on in every cell. it is exothermic
three examples of how its used
to build up larger molecules from smaller ones
allow muscles to contract
keep body temp steady in colder surroundings in mammals and birds
metabolism is the sum of all chemical reactions in an organism
many reactions are linked together to form bigger reactions
eg
small glucose molecules joined together in reactions to form starch, glycogen and cellulose.
lipid molecules are each made from 1 molecule of glycerol and 3 fatty acids
gluclose is combined w nitrate ions to form amino acids which then make proteins.
other metabolism reactions where larger molecules are broken into smaller ones eg
glucose broken down in respiration.
excess protein is broken down in a reaction to produce urea.
aerobic respiration
needs plenty of oxygen
most efficient way to transfer energy from glucose
glucose + oxygen —> carbon dioxide + water
anaerobic respiration
incomplete breakdown of glucose making lactic acid
glucose —> lactic acid
doesnt transfer as much energy as aerobic respiration as glucose isn’t fully oxidised
in plants and yeast it is different- produce ethanol and carbon dioxide instead of lactic acid
glucose —> carbon dioxide + ethanol
anaerobic respiration in yeast is fermentation
exercise
muscles need energy from respiration to contract. when you exercise your muscles contract more so you need more energy. this comes from increased respiration, meaning your cells need more oxygen. your breathing rate and breath volume increases to get more oxygen into the blood and your heart rate increases to get this oxygenated blood around the body faster, removing co2 at the same time,
when you do vigorous excercise, your body can’t supply oxygen to your muscles quick enough so they start respiring anaerobically causing build up of lactic acid in muscles
anaerobic respiration leads to oxygen debt - amount of extra oxygen your body needs to react with the build up of lactic acid and remove it from the cells. oxygen reacts w lactic acid to form harmless co2 and water. this means you breath heavy even after stopping exercise to get more oxygen into the blood to repay your oxygen debt.
blood that enters muscles also transports lactic acid to the liver, converting it back into glucose.
Cells
