cell organisation Flashcards
what are large multicellular organisms made up of?
organ systems
what is a specialised cell?
a cell made to carry out a particular function
what is differentiation?
the process where cells become specialised for a particular job. It occurs during the development of multicellular organisms
what do specialised cells form?
tissues which form organs which form organ systems
what do large multicellular organisms have inside them?
different systems for exchanging and transporting materials
what is a tissue?
a group of similar cells that work together to carry out a particular function it can include more than one type of cell
what are examples of tissues in mammals?
muscular tissue, which contracts to move whatever it’s attached to
glandular tissue, which makes and secretes chemicals like enzymes and hormones
epithelial tissue, which covers some parts of the body e.g. inside gut
what is an organ?
a group of different tissues that work together to perform a certain function
what tissues is the stomach made up of?
muscular tissue, moves stomach wall to churn up food
glandular tissue, makes digestive juices to digest food
epithelial tissue, covers the outside and inside of the stomach
what is an organ system?
a group of organs working together to perform a particular function
what is an example of an organ system?
digestive system, breaks down and absorbs food
made up of:
glands(pancreas and salivary glands) which produce digestive juices
stomach and small intestine, which digest food
liver, which produces bile
small intestine, absorbs soluble food molecules
large intestine,absorbs water from undigested food, leaving feeces
what do organ systems work together to make?
entire organisms
what are enzymes
catalysts produced by living things
how could you usually make a reaction happen more quickly
raising the temperature, this would speed rate of useful reactions but also bad ones, there is also a limit to how far you can raise the temperature inside a living creature without damaging its cells
what do living things produce as biological catalysts
enzymes which reduce the need for high temperatures and we only have enzymes to speed up useful reactions in the body
what is a catalyst?
a substance which increases the speed of reaction, without being changed or used up
what are enzymes made up of
they are all large proteins and all proteins are made up of chains of amino acids these chains are folded into unique shapes, which enzymes need to do their jobs
why do enzymes have special shapes?
so they can catalyse a reaction
what do chemical reactions usually involve?
things being split apart or joined together
what does every enzyme have?
an active site with a unique shape that fits onto the substance involved into a reaction
how many reactions do enzymes usually catalyse
one specific reaction
why do enzymes only catalyse one specific reaction?
because for the enzyme to work the substrate has to fit into its active site, if the substrate doesn’t match the enzymes active site then the enzyme will reaction won’t be catalysed
what is the induced fit model?
the active site changes shape a little as the substrate binds to it to get a tighter fit
what is lock and key
how enzymes active site and substrate fit perfectly with eachother
what does changing the temperature do in an enzymic reaction
changes rate of an enzyme-catalysed reaction
what happens if the reaction gets too hot in an increased temperature enzyme reaction
some of the bonds holding the enzyme together can break this changes the shape of the enzyme active site so the substrate won’t fit anymore the enzyme is said to be denatured.
what is the temperature called that enzymes work their best at
optimum temperature
how does ph affect enzymes?
if it’s too high or too low the ph interferes with the bonds holding the enzyme together this again changes shape of active site and denatured the enzyme
what is the usual optimum ph enzymes work best at?
neutral ph 7, but not always e.g.pepsin is a enzyme used to break down proteins in the stomach it works best at ph2 meaning it’s best suited in acidic conditions
how can you test how ph affects amylase activity?
- drop of iodine into each well of spotting tile
- place bunsen on heat proof mat, and tripod and gauze over bunsen. put a beaker of water on top and heat till 35 degrees (use thermometer)
- use a syringe to add 1cm3 of amylase solution and 1cm3 of a buffer solution with ph of 5 to a boiling tube, put tube into water beaker for 5 minutes
- use different syringe to add 5 cm3 of starch solution into the boiling tube. immediately mix contents and start stop watch
- use continuous sampling to record how long it takes for amylase to break down all starch, to do so use dropping pipette to take a fresh sample from boiling tube every 30 seconds and put drop into well when iodine remains browns orange starch is no longer present
- repeat with buffer solutions of different ph to see how ph affects the time taken for starch to be broken down
7.control variables each time (concentration and volume of amylase solution to make it a fair test.
how do you calculate rate of reaction?
rate=1000/time
if an experiment changes overtime you can calculate the rate of reaction by dividing amount that it has changed by by time taken
how are enzymes used in digestion produced
produced by cells and then realeased into the gut to mix with food
what are big molecules and how are they broken down?
starch, proteins and fats are BIG molecules, too big to pass through walls of the digestive system, so digestive enzymes break these BIG molecules down into smaller ones like sugars (glucose and maltose), amino acids, glycerol and fatty acids. these smaller soluble molecules can pass easily though walls of digestive system allowing them to be absorbed into the bloodstream
what do carbohydrases do?
convert carbohydrates into simple sugars, amylase is an example if carbohydrase it breaks down starch into maltose
amylase is made in three places 1.salivary glands, 2.pancreas, 3.small intestine
what do proteases do?
convert proteins into amino acids
made in three places
1.stomach ( it’s called pepsin there), 2.pancreas, 3. small intestine
what do lipases do?
convert lipids into glycerol and fatty acids they are made in two places
1.pancreas, 2.small intestine
how does the body use the products of digestion
can be used to make new carbohydrates, proteins and lipids . some of the glucose made is used in repriration
what is bile?
it neutralises the stomach acid and emulsifies fats. produced in the liver and stored in the gall bladder before being released into the small intestine.
how does bile work with hydrochloric acid?
hydrochloric acid in the stomach makes the oh too acidic for enzymes in the small intestine to work properly. bile is an alkaline it neutralises the acid to make conditions alkaline the enzymes in the small intestine work best in alkaline comditions
what does bile do to fats?
it emulsifies them (breaks them into tiny fat droplets, much bigger surface area of fat for the enzyme lipase to work on which makes digestion faster.
what catalyses the breakdown of food
enzymes. they are used in the digestive system and produced by specialised cells in glands and the gut lining, different enzymes catalyse the breakdown of different food molecules.
what is the function of the salivary glands?
produce amylase enzymes in the saliva
what is the long tube called comeing down from the tongue?
gullet (oesophagus)
what is the function of the liver?
where bile is produced which neutralises stomach acid and emulsifies fats
what is the function of the gall bladder?
where bile is stored before being released into the small intestine
what is the function of the large intestine?
where excess water is absorbed from the food
what does the liver look like?
near the gullet largest organ in digestive system
what does the gall bladder look like?
small organ on top of liver next to stomach
what is the function of the stomach?
1.it pummels the food with its muscular walls
2. it produces the protease enzyme, pepsin
3. produces hydrochloric acid for 2 reasons:
to kill bacteria
to give the right ph for the protease enzyme to work (ph2)
what does the pancreas look like
i between size of liver and gall bladder just below stomach
what is the function of the pancreas?
produces protease, amylase and lipase enzymes. it releases these into the small intestine
what is the function of the small intestine?
produces protease, amylase and lipase enzymes to complet digestion. this is also where the digested food is absorbed out of the digestive system into the blood.
what is the function of the rectum?
where feeces(made up of mainly indigestible food) are stored before leaving through the anus
how do you prepare food for food tests?
get a piece of food and break it up with a pestle and mortar, transfer it into a beaker and add some distilled water, give mixture a stir with a glass rod to dissolve some food and then filter solution to get rid of solid bits of food
how do you test for sugars?
using the benedict’s test
you can test for reducing sugars not non reducing sugars using this test.
1.prepare food sample and transfer 5 cm3 to a test tube
2.prepare a water bath so that it’s set to 75 degrees c
3.add some benedict’s solution to the test tube about 10 drops using pipette
4. place test tube in the water bath using a test tube holder and leave for 5 mins pointing tube away from you
5.if contains sugar solution will turn from blue-green to yellow or brick-red depending on how much sugar it contains
how do you test for starch?
1.make food sample and transfer 5 cm3 into test tube
2. add a few drops of iodine and gently shake if it contains starch the solution will change from orange-brown to blue-black
how do you test for proteins?
using the biuret test.
1. prepare a food sample and add about 2 cm3 into a test tube
2.add 2 cm3 of biuret solution to the sample and mix contents of the tube by gently shaking
3. if it contains protein the sample will change from blue to purple
how do you test for lipids?
use sudan III solution
1.prepare an unfiltered food sample of 5 cm3 into a test tube
2.use a pipette and add 3 drops of sudan III solution to the test tube and gently shake
3. if the food contains lipids the top layer of the test tube will be bright red
what is the function of the lungs?
you need oxygen in your bloodstream to supply your cells for respiration. you also need to remove carbon dioxide from your bloodstream this all happens when your lungs breathe air in and out
where are the lungs?
in the thorax
what is the thorax?
the top part of your body, it’s separated from the lower part of the body by the diaphragm
what are the lungs?
big pink sponges that are protected by the rib cage they are surrounded by the pleural membranes.
what happens to the air we breathe in?
goes through the trachea, this splits into two tubes called the bronchi (each one is a bronchus), one going into each lung, the bronchi split into progressively smaller tubes called bronchioles these finally end at small bags called alveoli where gas exchange takes place
what is the function of alveoli?
to carry out gas exchange.
how do the alveoli carry out their function?
1.the lungs contain millions of little air sacs called alveoli, surrounded by a network of blood capillaries. this is where gas exchange happens
2.the 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 very little oxygen.oxygen diffuses out the alveoli’s into the blood and carbon dioxide diffuses out the blood into the alveolus to be breathed out.
what happens after diffusion has taken place during gas exchange?
when blood reached body cells oxygen is released from the red blood cells and diffuses into the body cells, at the same time carbon dioxide diffuses out of the body cells into the blood it’s then carried back to the lungs.
how can you calculate breathing rate/ breaths per minute?
breaths per minute= number of breaths/number of minutes
can you label lungs?
add:
oesophagus
trachea
bronchiole
bronchus
alveoli
diaphragm
intercostal muscle
rib
heart
pleural membranes
what does the circulatory system do?
carries food and oxygen to every cell in the body, and also is a waste collection service and carries waste products to where they can be removed by the body
what is the circulatory system made up of?
heart, blood vessels and blood, humans have a double circulatory system - two circuits joined together
what happens in the first circuit of the double circulatory system?
the right ventricle pumps deoxygenated blood to the lungs to take in oxygen. the blood then returns it to the heart
what happens in the second circuit of the double circulatory system ?
the left ventricle pumps oxygenated blood around all the other organs of the body. the blood gives up its oxygen at the body cells and the deoxygenated blood returns to the heart to be pumped out to the lungs again
why does the heart contract?
to pump blood around the body
what is the heart?
the heart is a pumping organ that keeps the blood flowing around the body, the walls of the heart are mostly made up of muscle tissue, the heart has valves to make sure blood flows in the right direction-they prevent it flowing backwards.
how does the heart use its four chambers to pump blood around?
1.blood flows into the atria from the vena cava and the pulmonary vein
2.the atria contract, pushing the blood into the ventricles
3.the ventricles contract,forcing the blood into the pulmonary artery and the aorta and out of the heart
4.the blood then flows to the organs through arteries, and returns through veins
5.the atria fill again and the cycle restarts
can you label a heart?
add:
pulmonary artery
vena cava
aorta
pulmonary vein
right atrium
left atrium
4 valves
right ventricle
left ventricle
how does the heart get oxygenated blood?
it needs its own supply of oxygenated blood, arteries called coronary arteries branch off the aorta and surrounding the heart, making sure it gets all the oxygenated blood it needs
what is a pacemaker
the heart had a pacemaker, your resting heart rate is controlled by a group of cells in the right atrium wall that act as a pacemaker, these cells produce small electrical impulses which spread to the surrounding muscle cells, causing them to contract.
what is an artificial pace maker?
it is often used to control the heartbeat. if the natural pacemaker cells don’t work properly (e.g. if the patient has an irregular heartbeat). it’s a little device that is implanted under the skin and has a wire going to the heart. it produces an electrical current to keep the heart beating regularly
what are blood vessels
three different types:
arteries-these carry the blood away from the heart
capillaries-these are involved in the exchange of materials at the tissues
veins-these carry the blood to the heart
how do arteries carry blood under pressure?
1.the heart pumps the blood out at a high pressure so the artery walls are strong and elastic
2.the walls are thick compared to the size of the hole down the middle
3.they contain thick layers of muscle to make them strong and elastic fibres to allow them to stretch and spring back
what are the characteristics of capillaries?
thin wall-only one cell thick
very small lumen
nucleus of cell
what are capillaries?
- arteries branch into capillaries
2.capillaries are tiny can’t see them
3.they carry the blood really close to every cell in the body to exchange substances with them
4.they have permeable walls, so substances can diffuse in and out
5.they supply food and oxygen and take away waste like co2
6.their walls are usually only one cell thick this increases the rate of didfusion by decreasing the distance over which it occurs
how do veins take blood back to the heart?
1.capillaries eventually join up to form veins, the blood is at a lower pressure in the veins so the walls don’t need to be as thick as artery walls
2.they have a bigger lumen than arteries to help the blood flow despite the lower pressure
3.they also have valves to help keep the blood flowing in the right direction
what are characteristics of veins?
large lumen
elastic fibres and smooth muscle
valves
how can you calculate rate of blood flow?
rate of blood flow= volume of blood/number of minutes
what is the function of red blood cells?
carry oxygen from lungs to all cells in the body
what are the characteristics of a red blood cell that help it carry out his function?
biconcave disc shape, large surface area to absorb oxygen
no nucleus so more room to carry oxygen
red pigment called haemoglobin
how does haemoglobin work in the body?
binds to oxygen to become oxyhaemoglobin. in the body tissues, the reverse happens - oxyhaemoglobin splits into oxygen and haemoglobin to release oxygen into the cells
what is the function of white blood cells?
defend against infection
what are the characteristics of white blood cells to help them carry out their function?
some can change shape to gobble up unwelcome microorganisms, in a process called phagocytosis
others produce antibodies to fight microorganisms, as well as antitoxins to neutralise any toxins produced by the microorganisms
they have a nucleus
what is the function of platelets?
help blood clot
how are platelets adapted to carry out their function?
no nucleus, small fragments of cells
help blood clot wounds- to stop bleeding out and microorganisms getting in
lack of platelets cause excessive bleeding and bruising
what is plasma?
the liquid that carries everything in blood
how are plasma adapted to carry out their function?
pale straw-coloured liquid which carries:
red and white blood cells and platelets
nutrients like glucose and amino acids (soluble products of digestion which are absorbed by gut and taken into bodies cells
carbon dioxide from organs to lungs
urea from liver to kidneys
hormones
proteins
antibodies and antitoxins
what is cardiovascular disease?
diseases of the heart or blood vessels, e.g. coronary heart disease
what do stents do?
tubes inserted into the arteries that keep them open, making sure blood can pass through to the heart muscles and keep the heart beating, they lower risk of heart attack for people with CHD, they are effective for long time and quick surgery recovery
what are the risks of stents?
complications during the operation and a risk of infection. could also develop a blood clot near the stent called thrombosis
what is coronary heart disease?
coronary heart disease is when coronary arteries that supply blood to the muscle of the heart get blocked by layers of fatty material build up, arteries become narrow, so blood flow is restricted
what are statins?
chesterol is an essential lipid your body produces and needs to function, too much of a certain type of cholesterol (LDL) causes health problems
having too much of this in blood stream can cause fatty deposits to form inside arteries leading to CHD
statins are drugs that reduce the amount of LDL cholesterol present in the bloodstream, slows rate of fatty deposits forming
what are the advantages of statins?
1.can reduce stroak risk, CHD and heart attacks by reducing LDL cholesterol
2.statins inc the amount of HDL (good) cholesterol in bloodstream which removes LDL from bloodstream
3.some studies suggest they may prevent other diseases
what are the disadvantages of statins?
1.long-term drug should be taken regularly, could forget to take
2.negative side effects, headaches, liver damage, kidney failure, memory loss
3.not instant effect takes time to kick in
tell me about artificial hearts?
mechanical devices that pump blood for a person whose own heart has failed, temp fix to keep person alive until donor is found or help a person recover and give their heart time to rest and heal, in some cases they are permanent
main advantage they are less likely to be rejected by immune system than donor heart because made from metal/plastics so body doesn’t recognise them as foreign and attack in same way as living tissue
surgery could lead to bleeding and infection, also don’t work aswell as healthy hearts parts could wear out or electrical motor could fail, blood clots and stroakes could happen as blood doesn’t flow as smoothly has to take blood thinners which could cause bleeding problems
what is a mechanical and biological valve?
valves in heart can be damaged/weakened by heart attacks, infection or old age
valve tissue could stiffen so won’t open properly or could become leaky, blood flows in both directions rather than just forward so doesn’t circulate as effectively as normal
you can replace valves by taking from humans or other mammals (biological) or can be man made (mechanical)
replacing valves a lot less drastic than a whole heart transplant but still major surgery to fit new valve and blood clots can still occur
what is artificial blood?
heart can pump remaining red blood cells round to get oxygen to organs as long as blood volume can be topped up if someone looses lots of blood
artificial blood is a blood sub e.g. saline replacing lost volume of blood, if no air bubbles get into blood it can keep people alive if not blood transfusion is needed.
ideally artificial blood replacement function of lost red blood cells so no need for blood transfusion
what is a communicable disease?
can spread from person to person or between animals and people, can be caused by things like bacteria, viruses, parasites and fungi. sometimes described as contagious or infectious diseases. e.g. measles and malaria
what is a non-communicable disease?
those that cannot spread between people or between animals and people, they generally last for a long time and get worse slowly
. e.g. asthma, cancer and CHD
what are examples of diseases that interact?
- people with immune system problems have an increased chance of suffering from communicable diseases like influenza, because their body is less likely to be able to defend itself against pathogens that cause disease.
- some types of cancer can be triggered by infection by certain viruses, e.g. infection with some types of hepatitis virus can cause long-term infection in the liver, where the virus lives in the cells meaning increased chance of dveloping liver cancer or infection with HPV , can cause cervical cancer in women
- immune systems reactions in the body caused by infection by a pathogen can sometimes trigger allergic reactions like skin rashes or worsen asthma symptoms
- mental health issues like depression triggered when someone is suffering from severe physical health problems particularly if the effect every day activities or life expectancy
what other factors can affect your health?
- good balanced diet, that gives everything you need and right amounts poor diet affects physical/mental health
- stress constantly leads to health issues
- life situation, have easy access to medicines? access to things to prevent illness like buying healthy foods or condoms
what risk factors increase your chance of getting a disease?
- lifestyle like how much exercise they do, they can also be in the presence of certain sub stances in the environment like air pollution or substances in your body (asbestos fibres - used in building until realisation that fibres can build up in body and cause cancer in later life
- many non-communicable diseases are caused by several different risk factors interacting with eachother rather than just one alone
- lifestyle factors have different impacts locally , nationally and globally
what risk factors can cause a disease directly?
- smoking proven to cause cardiovascular disease, lung disease and lung cancer, damages walls of arteries and the cells in the lining of the lungs
- obesity causes type 2 diabetes by making body less sensitive or resistant to insulin struggles to control concentration of glucose in the blood
- drinking too much causes liver disease and affect brain function causing brain to loose volume
- smoking when pregnant causes health problems for unborn baby and also alcohol
- cancer be causes by direct exposure to certain substances or radiation things that cause cancer are known as carcinogens e.g. ionising radiation
what is the cost of non-communicable diseases?
- tens of millions of people round the world die from non-communicable diseases every year, they may have lower quality of life or shorter lifespan effecting sufferers and their loved ones
- financial cost to NHS researching and treating diseases is huge families may have to move or adapt their home to help family member with disease which can be costly can effect family as income is reduced, this can also effect countrys economy
what is cancer?
uncontrolled cell growth and division
what is a benign tumour?
tumour grows until no more room, stays in one place (usually within a membrane) rather than invading other tissues in the body, not normally dangerous and tumour isnt cancerous
what is a malignant tumour?
tumour grows and spreads to neighbouring healthy tissues, cells can break off and spread to other parts of the body by travelling in the bloodstream, malignant cells invade healthy tissues elsewhere in body and for secondary tumours. Malignant tumours are dangerous and can be fatal - they are cancers
what risk factors can increase the chance of some cancers? LIFESTYLE
- smoking- linked to lung cancer, but also mouth, bowel, stomach and cervical cancer
- obesity- linked to bowel, liver, and kidney cancer, second biggest preventable cause of cancer after smoking
- UV exposure- people often exposed to UV radiation from sun have increases chance of developing skin cancer, sunny climates, sun beds and people outside a lot are at higher risk
- viral infection- infection with some viruses shown to increase chances of developing some cancers, e.g. hapatitis B and hapatitus C viruses can icrease risk of developing liver cancer can spread through unprotected sex or shared needles usually depends on lifestyle.
what risk factors can increase the chance of some cancers? GENETICS
- inherit faulty genes make you more susceptible to cancer
2, mutations in the BRCA genes linked to increased risk of developing breast or ovarian cancer
what are examples of plant tissues?
epidermal tissue - covers whole plant
palisade mesophyll tissue - where most photosynthesis happens
spongy mesophyll tissue - in the leaf containing big air spaces to allow gasses to diffuse in and out of cells
xylem and phloem - transport water, mineral ions and food around plant (through roots stems & leaves)
meristem tissue - found at growing tips of shoots and roots and able to differentiate into lots of different types of plant cell allowing the plant to grow
what are plants made up of?
organs like stems, roots and leaves plant organs work together to make organ systenms which perform various tasks that a plant needs to carry out to survive and grow
what is the function of the waxy cuticle?
helps reduce water loss by evaporation
why is the upper epidermis transparent?
so light can pass through to the palisade layer
what does the palisade layer have lots of?
chloroplasts where phtosynthesis takes place these are at the top of the leaf where they can get most light
what do the xylem and phloem do?
form network of vascular bundles, deliver water & other nutrients to entire leaf and help support the structure
what do xylem and phloem take away?
glucose made by photosynthesis
what are the tissues of the leaf adapted for?
gas exchange e.g. lower epidermis full of stomata
what are stomata?
little holes in lower epidermis that allow CO2 to diffuse into leaf
-found usually on under side cooler and shaded less water lost than if on upper surface
what is a guard cell?
opens and closes stomata in response to environmental conditions, air space in spongy mesophyll increase rate of diffusion of gasses adapted for gas exchange
-kidney shape to open & close
-when plant has lots water guard cells plump/turgid makes stomata open
-when short of water they lose water & are flaccid makes stomata close
-thin outer walls and thick inner walls to help opening and closing work
-light sensetive close at night to save water
what does PHLOEM do?
make columbs of elongated living cells with small holes in end walls to allow cell sap to flow through. transport food substances made in leaf to rest of plant for immediate use or storage. trasport goes both directions. CALLED TRANSLOCATION
what does XYLEM do?
made of dead cells joined end to end with no end walls between and hole down middle. strengthened with lignin. carry water & mineral ions from roots to stem/leaves. movement of water from roots through xylem & out of leaves, CALLED TRANSPIRATION STREAM
what is transpiration?
caused by evaporation & diffusion of water from plants surface. mostly happens at leaves. evaporation creates slight shortage of water in leaf, so more water drawn up from rest of plant through xylem to replace it. therefore more water drawn up from roots so constant transpiration stream of water through plant. side effect of how leaves adapted for photosynthesis
what is transpiration rate affected by?
light intensity - brighter light=greater transpiration rate, stomata close in dark as photosynthesis cant happen so little water escapes.
temperature - warmer=faster transpiration, water particles have more energy to evaporate/diffuse out stomata
air flow - better air flow=greater transpiration rate, if poor water vapour surrounds leaf & doesnt move away, diffusion is slow. if not water vapour swept away maintaining low concentration of water in air out of leaf
humidity - drier air around leaf=faster transpiration, similar to air flow, if humid lots of water in air so concentration gradient not big
how do you estimate rate of transpiration?
measuring uptake of water by plant, because you can assume water uptake by plant is directly related to water loss by leaves.
set up aparatus and record starting position of air bubble, start stopwatch and record distance moved by bubble per unit per time.
keep conditions constant e.g. temp and humidity
