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Biology

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leah turner

on 19 April 2014

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Transcript of Biology

genes and enzymes.
Life processes.
organ systems.
Biology
Genetic engeneering.
Uses enzymes to cut and paste genes.
A useful gene is cut out of one organisms chromazome using enzymes
enzymes are then usedto cut another gene from another organisms chromozome and then the useful one is inserted
this produced genetically modified organisms
human genes can be used to make gm bactirea.
Genetic engeneering can benifit humans.
Uses for gm organisms...
Reducing vitamin a deficiency
beta-carotine is used to make vitimin a
without vitamin a people can go blind. Golden rice is a variety of GM rice it contains two genes from other organisms that alow the rice to produce beta-carotine
Producing human insulin
The human insulin gene can be inserted into bacteria to produce human insulin
this can help treat diabetes
Increasing crop yield
Gm crops have their genes modified e.g so they're resistant to herbacides.
Contravertial topic.
people say that there will be a problem with the amount of plants that grow around the crops that wildlife needs will die reducing farmland biodivercity, people are also worried they may develop alergies to the food that the crops produce,
there is also the risk the the transplanted genes could get into the natural environment, so weeds could be herbaside resistant.
Mitosis.
to grow and replair your bodys cells need to devide and produce new cells,
Mitosis makes new cells for groth and repair, human body cells are diploid meaning they have two vertions of each chromosome. one from the persons mother and one from the father, when a cell devides it makes two identicle daughter cells.each with the same amount of cells as the origional cell.
Mitosis.
When a cell gets a signal that it needs to devide it first copies the chromosomes so they make an x shape each arm being exactly identicle to the arm oposite the chrimosomes line up in the center of the cell and the cell fibres pull them apart, the two arms of each chromosomes go to oposite ends of the cell and membranes form around each of the sets forming the new cells then the cytplasm devides.
mitosis is in asexual reproduction.
The offsping has exactly the same genes as the parent an example is strawberry plants the form runners this way, there is so genetic variation.
Meiosis.
gametes have half the number of chromosomes, sex cells are gametesin sexual reproduction gametes combine to form a new cell which will grow to become a new organism.
Gametes are hiploid which means they have one copy of each chromosome. this sis so that when two gametes combine in fertalisation the resulting cell (the zygote) has the right number of chromosomes, these are them diploid cells
Meiosis
to make a cell that has half the right amount of chromosomes they use meiosis, meiosis only happens in the reproductive organs. meiosis is when a cell devides to make four hiploid nuclei who dont have identicle chromosomes.
Meosis devitions.
Devition 1
the same as mitosis the cells chromosomes copy themselves so that one of each arm is the exact copy or the other arm, they line up at the center of the cell and then are pulled apart so each new cell has only one copy of each chromosome. some of each chromosome goes into each cell making a mix of mother and father dna creating variation in the offsping.
Division 2
in the second division the chromosomes line up in the center of each of the cells and are pulled apart by the cell fibers
then you get four gametes cells each with a single set of chromosomes in it.
Cloning mamals
Cloned mammals can be made by adult cell cloning.
Cloneing is a type of aesexual reproduction, it produces cells that are genetically identicle to an origonal cell.
Adult cell cloneing ...
removing a nucious from an unfurtalised egg cell (enucliated) a nuclius is then taken from a body cell e.g. skin cell this is a diploid nucious containing the right amount of chromosomes
the diploid cell is put into the empty egg cell then stimulated so it divides like a normal embio would through mitosis to grow then once its a group of cells its implanted into a adult female to grow into a genetically identicle copy.
Cloning uses and issues.
Cloning mammals can help with organ shortages and transplants. the study on animal clones could help the understanding of embryos and on aging and aging disorders. cloning could also help endagered species.
Reduced gene pool this means there are fewer alliles
If a species are closely related and a new desese is introduced it more likely to wipe out the entire population. because there is no resistance against the desease.
They might not live as long because dolly was cloned from an older sheep she got lung desease and artheritis which are more common in older animals.
Clones are often born with genetic defects and it takes alot of attempts to clone an animal.
stem cells
cells devide to make you grow they also differenciate to do different jobs.
Embrionic stem cells can turn into any cells.
The fertalised egg cell can devide by mitosis and create a bundle of cells called an embrio of the new organism, to start with they are all the same called embrionic stem cells, these are able to devide into either more stem cells or into new cells e.g. blood cells this prosses is called diferetiation this is how the recognisable human starts to form organs and a working body, in most animal cells the ability to differentate is lost early on but plant cells never lose the ability adults usually only have this ability in places like bone marrow but theyre not as versitile.
Stem cells may be able to cure deseases.
Sickle cell enemia can be cured by a bone marrow transplant that then creates new blood cells from the stem cells in the bone marrow. scientists have tried taking stem cells early on in embryos and in certain conditions they create specialized cells. it might even be possible to replace stem cells that dont work so that people can recover from a desease.
But theres alot of ethical concerns with this reaserch to be done so people can get stem cells to help.
Some people dont think its right to experiment on embios cus each one is a pottential human life and scientists should find new sorces for stem cells. although other people think that the potential lives to be saved are more important than the potetial lives from the embrios.
Respiration is releasing energy out of organic molicules like glucose.
All living things use respiration to get energy from food. ITS THE PROCESS OF BREAKING DOWN GLUCOSE TO RELEASE ENERGY WHICH GOES ON IN EVERY LIVING CELL!
Aerobic respiration needs plenty of oxygen.
Aerobic just means with air its the most efficient way to release energy from
Glucose + oxygen ---> carbon dioxide + water (+ energy)
Raw materials and waste diffuse in and out of cells
The circulatory system carries glucose, oxygen and CO2 around the body in the blood. The glucose needed for respiration comes from the breakdown of food in the digestive system, oxygen comes from air breathed into the lungs. CO2 is breathed out. the smallest blood vessels in the body are capilleries All cells in the body have these nearby to supply them with glucose and oxygen and then take away the waste carbon dioxide. these move between the cells and capillaries through diffusion. Diffusion is movement of particles from a higher concentration to a lower concentration.
When cells respire they use up oxygen and glucose so the concentration is low and more is diffused into the cell from the high concentration in the capillaries. and the same when they respire co2 is produces so this diffuses into the capillaries from the cell. the bigger the difference in concentration the faster the difusion.
Respiration and excersise
muscles need energy from respiration to contract when you excersise muscles contract more frequently than normal so there is more energy needed. this energy comes from increased respiration so more oxygen is needed in the cells to do this your breathing increases to take in more oxygen and your heart rate increases to pump more blood around the body to get to the cells as it it used up in respiration, because of this the rate of diffusion increases aswell, when you do vigerous excersise that needs alot more energy quicker you respire anaerobically CARDIAC OUTPUT = HEART RATE X STROKE VOLUME. cardiac output is the volume of blood that is pumped around the body in one minuite.
Anaerobic respiration does not use any oxygen.
Anaerobic just means without air,
Glucose ---> lactic acid (+ Energy)
This doesn't release as much energy as aerobic respiration but its quicker, but it produces a build up of lactic acid in the muscles and can give you cramp the advantage is is that you can keep going for a little longer but after you stop excersising you have an oxygen dept meaning you need to repay the oxygen that didnt get to the muscles in time this is called excess post excersise oxygen consumption (EPOC) meaning you have to keep breathing hard afterwards.
Photosynthesis.
Photosynthesis is the process that produces food/glucose in plants, photosynthesis happens in the leaves of green plants. Photosynthesis happens in chloroplasts, they contain chlorphyll which obsorbs the energy from the sunlight and used it in the reaction:
Carbon Dioxide + Water ---> glucose + oxygen.
Leaves are adapted for efficient photosynthesis.
Leaves are broad with a large surface area so they are exposed to sunlight they contain lots of chlorophyll and chloroplasts to absorb light, they have stoma which allow gases like CO2 and O2 in and out and are also used in transpiration.
Limiting factors of photosynthesis.
Light mainly but also CO2 and the temperature. At night theres no light in the winter theres no warmth and if its bright and sunny it limits the amount of CO2
The rate of photosynthesis.
Not enough light slows down the rate of photosynthesis
Light provides the energy needed for photosynthesis. As light increases so will the rate at a steady increase but only to a point. but if your using the distance from lamp then it wont work it has to be light intensity.
carbon dioxide also effect it.
the same as light intencity it will increase gradually and then even out on a graph
Temperature.
if the tempriture is the limiting fator then its because its too low. the enzymes that are needed for photosynthesis work slow in low temperatures, but if its too hot then the enzymes will denature and wont work at all. this is usualy around 45 degrees.
Osmosis is water molecules evening up.
OSMOSIS IS THE MOVEMENT OF WATER MOLECULES ACROSS A PARTIALLY PERMIABLE MEMBRANE FROM A REGION OF HIGH WATER CONCENTRATION TO A REGION OF LOW WATER CONCENTRATION.
A
partially permeable membrane
is just a membrane with really small holes in it so only small molecules like water can pass through it. the water molecules can pass both ways through the membrane during osmosis this is because they move about randomly. but because there is more molecules on one side there is a steady net flow of water into the region with fewer water molecules this means if there is a stronger sugar solution it will get diluted like the water is evening out.
Water uptake and loss in plants.
Root hairs take in water by osmosis.
the cells on a plant root grow into long hairs which stick out into the soil each branch will be covered in millions of these little hairs giving it a large surface area so it can bring up more water from the soil.
The higher concentration of water in the soil means water enters the root hair cells by osmosis.
Root hairs take in minerals using active transport.
the concerntration of minerals in the soil is usualy low and high in the root hair cell the proses for the minerals to be taken into the root hair cell is called active transport, it works by using energy from respiration o help the plant pull in the minerals from the soil against the concentration gradient. this is essential for growth.
xylem moves substances from the root to the rest of the plant.

Phloem transports sugars from the leaves to growing and storage tissue.
Transpiration is the loss of water from the plant.
Transpiration is caused by evaporation and diffusion from inside the leaves.
This creates a shortage of water so more water is drawn up through xylem vessels in the plant to replace the evaporated water.
this means more water is needed to be drawn up from the soil by the roots meaning there is a kind of cycle.
This is a side effect of the way photosynthesis works as it needs stoma to get gasses in and out of the leaves because there is a higher concentration of water inside the leaves it is diffused to the outside through the stoma and is then evaporated.
However this is useful in supplying the plant water for photosynthesis.
Distribution of organism.
Organisms live in different places, a habitat is the area something lives the study of distribution is the study of how common an organsm is found.
pooters
pitfall traps
sweep nests
pond nests.
Evedence for evolution
A fossil is any trace of an animal or plant that lived a long time ago they can be formed by ...
gradual replacement - things like teeth and bone don't decay and are gradually replaced by minerals that form rock like substance shaped like the organs teeth or bone.
casts and impressions - if an animal is buried in a soft material like clay then the animal will make an imprint like a cast of what it looks like as the clay hardens around it.
presevation - in places where microbes cant work there is no decay because of glaciers (too cold) or in amber (no oxygen or moisture)
Fossils tell us what the creature looked like how long ago they existed from what rock layers the fossil is collected from. and how they have evolved. but the fossil record is incompleate this is because not all plants and animals form fossils most of them just decay
most body parts just decay like soft body tissue and we also havent found all the ones that have formed.
The pentiadactyl limb
This is a limb with 5 digits
Quite a lot of animals have this limb and they all have a similar structure but normally used for different functions, this proves that all of these species have formed from the same ancestor.
growth and development.
growth is an increase in size or mass.
you can measure growth in size ... height length width or circumference
wet mass
... organisms contain a lot of water the growth is how much its gained or lost
Dry mass ... dry mass is the mass of an organism that doesnt contain water but it can only be measured after the organism is dead so it has dried out.
Cell division differentiation and elongation.
cell differentiation - the proses a cell goes through to be specialised for a job
cell devision - mitosis
elongation - where a plant cell expands making the cell bigger and so making the plant grow this is only in plants
growth in animals is through devision which happens at a fast rate at the start of an animals life so the ability to differentate is lost later on the only devision is then used to repair rather than to grow.
plants grow continuously through theyre life so they can always differentiate to develop new parts this is through cell elongation rather than devision which is usualy at the end of the roots and shoots.
Cell organisation and the circulatory system.
Tissues - e.g. muscle tissue is a similar group of cells that work together to carry out a particular function.
Organs - e.g. the heart is a group of different tissues that work together to perform a particular function
Organ systems - e.g. the ciscularory system is a group of organs that work together to perform a particular function.
The heart.
The hearts 4 main chambers are
right atrium, right ventricle, left atrium and left ventricle
and its 4 main blood vessels are called the
vena cava pulmonary artery aorta and the pulmonary vein
.
1. the right atrium gets
deoxadised
blood from the body through the vena cava
2. The deoxadised blood moves through the right ventricle which pumps it to the lungs through the pulmonary artery.
3. the left artium then receives
oxygenated
blood from the lungs through the pulmonary vein.
4. it then moves through the left ventricle and out the aorta to be pumped around the body to supply oxygen to the cells off the body.
the left ventricle has a thicker wall because it needs more muscle to pump blood all the way around the body in comparison to the right ventricle which only goes to the lungs.
The valves are between each section and are there to prevent backflow of the blood.
The blood
Red blood cells.
Red blood cells are used to carry oxygen around the body. they have a
biconcave disc
shape to have a large surface area to absorb oxygen. they contain haemoglobin which contains a lot of iron
in the lungs heamoglobin combines with oxygen (making it oxyhaemoglobin) this is then reverced when the blood gets to the cells to release the oxygen.
Red blood cells dont have a nucleus alowing more room in the cell for haemoglobin. a lack of iron in someones diet can lead to a type of anaemia because the cells cant carry enough oxygen.
The more red blood cells you have the
more oxygen can get around your body, at high
altitudes people produce more blood cells to
make up for the lack of oxygen.
White blood cells.
They are used to protect from disease, they change shape to take in any unwanted micro organism
They make
antibodies
to fight microorganisms as well as
antitoxins
to neutralise any toxins produced by the microorganisms, if you have a low white blood cell count this increases the risk of infection whereas a high count means you have an infection or even leukaemia.
Platelets
help blood clot, they are small fragments of cells and they help make a clot at a wound to stop all your blood pouring out and stop more microorganisms getting in a lack of these could lead to excessive bleeding and bruising.
Plasma is the liquid that carries everything in the blood.
it keeps the blood fluid and transports everything, red white and platelets
Also nutrience like
glucose
and
amino acids
these are absorbed from the gut and taken to body cells
carbon dioxide
which is a waste product formed in every cell which needs to be taken to the lungs to be removed.
urea
- a waste product formed in the liver, the blood transports it to the kidneys where its removed.
Hormones
- transported from glans to target organs
Antibodies and antitoxins
that are produced by white blood cells.
Blood vessels.
Arteries - they carry the blood away from the heart.
capillaries - these are involved in the exchange of materials with the tissues
Veins - these carry the blood TO the heart.
Arteries.
These carry the blood under high pressure so the artery walls are strong and elastic. the lumen is small compared to the thickness of the wall this is because they contain layers of muscle to make them strong.
Capilleries
Arteries branch into capillaries which are really small like too small to see small, they carry the blood really close to the cells to exchange substances with them through diffusion, because they have permiable walls, they supply food to cells and take away waste products. The walls are about 1 cell thick making it easier for substances to diffuse because there is less distance to travel.
Veins take the blood back to the heart.
Capillaries then eventually join to veins which take the blood back to the heart, the blood isnt at a higher pressure so they dont need to have as thick walls as arteries they have bigger lumin to make the blood flow easier dispite the low pressure, they also have valves which keep the blood flowing the right direction.
The digestive system
digestion is the breakdown of food into soluble products, which are then absorbed into the body, the food is broken down by digestive enzymes and mechanically by chewing.
the breakdown of food is catylised by enzymes.
starch proteins and fats are big molicules which cant pass throught the digestive system.
sugars amino acids glycerol and fatty acids are much smaller and can pass through without a problem.

Digestive enzymes.
Carbohydrases -
e.g.
amylais
digest starch sugars
protease
- e.g.
pepsin digests
proteins and amino acids
Lipase
- digests fat and fatty acids and
glycerol.
Places in the digestive system
Mouth - food is moistened with saliva that contains amylase enzymes which breaks down starch, food is chewed to form a
bolus
before being swallowed
Oesophagus - the tube running from the mouth to the stomach, it moves the bolus down using contracting muscles that push it along this is
peristalsis
Stomach - the stomach pummels the food with its muscular walls while also producing pepsin which is a protease enzyme aswell as hydrochloric acid to kill bacteria and to give the protease enzymes the right environment to work its best (pH2 - acidic.
Liver - where
bile
is produced. Bile is used to neutralise stomach acid and
emulsify fats.
Gall bladder - where bile is stored before being released into the small intestine
pancreas - makes protease amylase and lipase enzymes to be realeased into the small intestine.
Small intestine - produces protease lipase and amylase to compleate digestion this is also where food is obsorbed into the rest of the body out of the digestive system.
large intestine - where excess water is absorbed from the food.
Digestive enzymes.
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