Mitosis examples

5.15 - Genetically modified Plants

1. Maize is damaged by the larvae of the European cork borer which can lead up to a 20% loss of crop yield.
2. The bacteria BT has a chromosome which has a gene that can produce "bt toxin" which can kill the cork borer larvae.
3. The first step is to take restriction enzymes to the gene of BT and chop the gene out so that you have the BT gene for the toxin.
4. Then it has to be transferred to the cells of the maize plant. This isn't easy but the technique involved nowadays is a gene gun. 
5. The gene gun takes tiny particles of gold coated with the BT gene and fired at high velocity at the plant cell. This introduces the BT gene to the interior of the plant cell. Therefore the maize cells have the BT gene.
6. When the genes are switched on they will emit the toxin  that can kill the larvae. This gives maize resistance to the damage caused by cork borers

5.14 - Humulin

• A culture of this bacteria will be injected into the fermenter
• It will be necessary to provide this culture:
• Nutrients
• Controlled temperature and pH
• Gases inside the fermenter
• Providing the perfect temperature, pH, gases and the right nutrients will insure optimal growth of the bacteria.
• The population will therefore increase and the bacteria will manufacture the protein Insulin.
• The bacteria inside the fermenter will  manufacture insulin from the nutrient provided (amino acids).
• It will then be necessary to remove the product and carry out purification
• It needs to be purified for human consumption. The ways to purify the insulin is called downstream processing
• The genetically engineered human insulin is called humulin

5.13b - Hosting Recombinant DNA

• Once the recombinant DNA (human gene and bacterial plasmid) is made it is necessary to transfer it to the host cell.
• In this case we will use the virus which consists of nucleic acid (DNA or RNA) and the protein shell (capsid)
• The first thing to do is to remove the nucleic acid from the virus because we only need the capsid.
• The plasmids are then taken up by the virus. The virus acts as the vector of the recombinant DNA
• It is going to help us transfer the DNA into our host cell. The reason we have chosen the virus because that type of virus is known as a phage. What it does is infect bacterial cells. 
• The virus is able to attach to the cell membrane of the bacteria and insert the recombinant DNA into our host cell.
• At the end of this process we have a bacterial cell which now contains the recombinant DNA including the human gene for insulin.

5.13a - Recombinant DNA

The plasmids are found in bacterial cells. They are a ring of DNA and are small and dont carry many genes

A virus has a protein shell (capsid) and inside there'll be a nucleic acid (DNA or RNA). The virus has no other cellular components (such as cytoplasm nucleus)

Human chromosomes consists of DNA. But we will only look at one gene which codes for the protein insulin which is a hormone that controls blood sugar levels.

1. The restriction enzyme is selected that can cut out the gene responsible for insulin.
2. Once the gene is cut we would cut the plasmid with the same restriction enzyme.
3. This would leave the plasmid with the ring structure broken.
4. The next stage is to introduce the human insulin gene into the cut plasmid (the plasmid is composed of DNA, just like the human gene)
5. The plasmid will then be left with the human gene inserted inside of it.
6. It is then necessary to complete the process by applying a 2nd enzyme (DNA ligase) which will join the DNA
7. This combination of the human gene and plasmid DNA is known as recombinant DNA

5.11- Breeding animals

Understand that animals with desired characteristics can be developed by selective breeding.

Example: Cow
Desired: Milk yield

• The earliest farmers noticed that some cows make around 50ml of milk each time they are milk and a few others make 150ml of milk but most of them make 100ml. 
• The farmer will take all the milk but choose to breed only the ones that make 150ml milk
• In the next generation a few cows produce 100ml, 200ml and the majority produce 150ml.
• Of course the farmer take all the milk and select the cows that produce the most milk for breeding
• Perhaps in the next generation the cows will produce 150 to 250 ml of milk.
• The farmers are therefore developing the desired characteristics by selective breeding.
• For this to work the milk yield must be genetic

5.10 Breeding Plants

Understand plants with desired characteristics can be developed by selective breeding.


The number of rice grains is in the control of genes, the farmer wants to improve the number of rice grain per plant (increase the yield). He notices some plants have 6 grains per stem and others have 8 or 10 grains per stem. The farmers decision is to harvest the plants with 6 & 8 grains per plant and use the other grains (10 grains per stem) for planting.

He notices the next generation of rice the grains increased to 8,10 and 12 grains per stem. Therefore he harvest the 8 and 10 grain stems and selects the 12 grain ones for breeding and planting.
In this way the number of grains of rice will gradually increase = yield increases. This is an example of selective breeding

5.9 - Fish Farming

5.9 explain the methods which are used to farm large numbers of fish to provide a source of protein, including maintenance of water quality, control of intraspecific and interspecific predation, control of disease, removal of waste products, quality and frequency of feeding and the use of selective breeding.

Fish are an attractive product for farmers since they have low fat and high protein. Also they are efficient at turning their nutrient into fish mass.

• Fish farming allows us to control the quality of water (we want it to be clean)
• We can control predators
• We can reduce pests and other forms of disease

By controlling all these factors we contribute to an increase in the yield of fish. However where you have a high density of fish there is a higher chance of the transmission of diseases. That is why some fish farmers use antibiotics, this is a concern to human health.
The abundance of fish within a farm makes pests common which leads to farmers using pesticides which is also a concern to human health

5.8 - Fermenter

5.8 interpret and label a diagram of an industrial fermenter and explain the need to provide suitable conditions in the fermenter, including aseptic precautions, nutrients, optimum temperature and pH, oxygenation and agitation, for the growth of microorganisms

The industrial fermenter is the reaction vessel in which fermentation occurs. It is usually made of metals such as steel or copper.

• The fermenter has a steel jacket outside and another steel jacket inside and in between the 2 there is water. (This is a cooling jacket because once the fermentation gets going it produces heat and this will cool down the reaction so it happens at optimal conditions)
• The fermenter will need to be cleaned therefore there is inlet where steam goes in to sterilize the fermenter (between fermentations)
• Within a fermenter there will be a heating plate to raise the temperature. The heating plate and cooling jacket are used to control the temperature so that it can provide the optimum temperature for fermentation
• So the fermentation can occur there is a tap (pipework) to insert nutrients because they act as the food for the micro-organisms.
• There is also a temperature probe to monitor the temperature. This will tell us to deploy either the heater or cooling jacket.
• The reaction also needs the addition of micro-organisms through another tap
• There will also be a pH probe to effect the pH to keep the optimum conditions for fermentation to occur 
• Also there needs to be a way to stir the reaction therefore we add a motor to a mechanism that agitates the mixture preventing to clump together.
• At the end of the reaction there needs to be a way to drain off the product, this would then go on to a process called "downstream processing" which involves purification.

The idea of a fermenter is to control the optimum growth conditions for the micro-organism so that it can produce the product we are looking for.

5.7 Bacteria in the Production of Yoghurt

5.7 understand the role of bacteria (Lactobacillus) in the production of yoghurt

• Milk comes from the cow
• Treat the milk to remove pathogens (Pasteurisation)
• Milk sugars are converted to lactic acid (by incubating the milk at 45/6 oC and adding lactobacillus
• The lactobacillus produces the enzymes that break down the milk sugars to produce lactic acid
• The acid will result in a lower pH (acidic condition) which causes milk proteins to solidify.
• This is what we call yoghurt

5.5 - Yeast the Production of Beer

5.5 understand the role of yeast in the production of beer

Beer is largely ethanol, an alcohol molecule which is produced from glucose. Glucose is broken down to ethanol and carbon dioxide (anaerobic respiration).

Glucose--------[[Yeast]]---------> Ethanol + Carbon dioxode
Yeast supplies the enzymes to bring about this conversion.

The ethanol is the alcohol in beer. It can be flavoured by adding plants such as hops. The glucose comes from starch which is converted into maltose and then into glucose:
Starch -----[[Amylase]]----->Maltose----[[Maltase]]---->Glucose

Strach comes from sources such as barley seeds, wheat seeds and even rice. The starch is broken down through the germination of seeds, known as Malting.

5.4b - Biological control

5.4 understand the reasons for pest control and the advantages and disadvantages of using pesticides and biological control with crop plants

Biological control:

Is when and alien specie is introduced from another country to eat the pest.

An example of this is in Australia when the prickly pear cactus (pest) of north america was first introduced into gardens and escaped into the countryside and flourished under the Australian climate system. The cactus spread all over Australia into a good deal of agricultural land and it was necessary to get rid of it since there was no natural herbivore of the cactus. Therefore and alien specie was introduced for another country (a moth). This moth was introduced and had no competitors so they started to remove the prickly pear cactus.

Advantages:

• No toxic chemicals involved
• Less impact on man and wildlife   

Disadvantage:

• Not 100% effective
• Difficult to control (Danger that the introduced alien specie starts feeding on native species causing native species to diminish)
• Difficult to match predator to the prey (cant find predatory herbivores to remove the pest)

5.4a - Pesticides

5.4 understand the reasons for pest control and the advantages and disadvantages of using pesticides and biological control with crop plants


Pests use crops as their food source which reduces the productivity of the farm ( = -crop yield) and this has a financial impact on the farmer because he is producing less. Therefore farmers use pesticides.
Pesticides are chemicals designed to kill pests. There are both advantages and disadvantages of using pesticides.


Adv:

• Pesticides are easy to obtain
• It is also easy to apply to crops
• It is extremely effective and kill pests

Dis:

• It is toxic and can kill other plants and animals and can also harm humans
• Bio-accumulation is when the pesticides build up through the food chain causing problems to animals in higher trophic levels
• Mutation happens and the pests often become resistant against a pesticide so it will have to be applied at a higher level or find an alternative pesticide which can be even more dangerous

5.3 - Fertilisers

5.3 understand the use of fertiliser to increase crop yield


Fertilisers are used to promote the growth of plants.
Fertilisers usually consist of nitrates and phosphates
Nitrates: Forms proteins which is used to repair the plant cells
Phosphates: Are present in the membrane and DNA of plants


There are 2 kinds of fertilizers, organic and inorganic fertilisers.
The main difference is that organic fertilizers are just animal waste while inorganic ones are artificial and man made.

5.2- Crop Yield

5.2 understand the effects on crop yield of increased carbon dioxide and increased temperature in glasshouses

Relates to:

Rate of photosynthesis: CO2 + H2O ----------> C6H12O6 + O2

Increase in carbon dioxide means that the rate of photosynthesis will increase, which results in an increase in crop yield up to a point where it reaches  the optimum point of the rate of photosynthesis

The results of an increase of temperature is similar except that once the rate of photosynthesis reaches its optimum temperature the enzymes will denature, decreasing the rate of photosynthesis and therefore decreasing the total crop yield.

Increasing temperature in a greenhouse has other effects such as avoiding frost damage and keeping a constant temperature. Both of these also increase total crop yield.

5.1 - Glasshouses

5.1 describe how glasshouses and polythene tunnels can be used to increase the yield of certain crops


Glasshouses are used to to make the conditions ideal for a plant to grow.
Eg:

• Light enters the glasshouse and is absorbed by substances in the glasshouse such as soil and plants.
• The plants re-emit the light energy as heat and the average temperature in the glasshouse increases
• The trapped warm air is better for the plants because it is nearer to the plants optimum temperature which means the enzymes in the plants react faster and produce more
• Glasshouses also prevent things such as insects and animals to come and eat the plants. Not only that but it also protects the plants from natural things like wind, snow and changes in temperature
• Also since it is a closed area it prevents water vapour to escape therefore the plants wont dry out

Polythene tunnels work the same way as a glasshouse, heating up the environment making it more ideal for the plant to grow however it provides less protection for the plants. Polythene tunnels are more common because they are a lot cheaper/ affordable and can be set up more easily

Endocrine system

                                            Endocrine glands --------> Target -------------------> Effects
1. ADH                                 Pituitary                               Collecting duct              Inc amt of H2O in blood
2. Adrenaline                         Adrenal                               Heart                            Inc Heart rate
3.Insulin                                 Pancreas                             Liver                             Store glucose
4. Glycogen                           Pancreas                             Liver                             Put sugar into blood
5. Testosterone                      Testes                                Testes (sperm)               Sperm cell mature

2.89 - Hormones

2.89 understand the sources, roles and effects of the following hormones: ADH, adrenaline, insulin, testosterone, progesterone and oestrogen.


Adrenaline: is produced by adrenal glands (above the kidney) and is released in times of excitement, fear or stress. Adrenaline helps prepare the body for action in the following ways:

• Glycogen is converted to glucose in the liver, so more glucose reaches the muscles as a source of energy for the rapid contractions needed for sudden action
• Increases heart rate so that more glucose and oxygen are delivered to the muscles for energy release
• The bronchioles widen so that more air reaches the lungs
• Blood vessels to the brain widen so that more glucose and oxygen is delivered to these organs
• Blood vessels to the gut and other organs narrows allowing blood to be diverted to more life-saving organs
• Hairs are raised

ADH: is made in a gland in your brain and controls the level of water in your body.


Insulin: The pancreas makes insulin. The insulin tells the liver to take glucose out of your blood so it is changed into glycogen in the liver . Insulin lowers blood glucose(sugar)  levels back to normal


Testosterone & Oestrogen are hormones that bring about the changes to our bodies that occur at puberty
Testosterone is the male hormone and brings out these changes in boys:

• the testes start making sperms
• hair starts to grow on the face and body
• The voice deepens
• the muscles develop

Oestrogen is the female hormone and brings out these changes in girls:

• The ovaries start to release eggs
• hair starts to grow on parts of the body
• the breasts develop
• the hips widen
• periods start

2.88 - Skin

2.88 describe the role of the skin in temperature regulation, with reference to sweating vasoconstriction and vasodilation


Stimuli: Body temp
Receptor/coordinator: Hypothalamus
Effector: Skin
Response:

Vasoconstriction (when its cold):

• Blood vessels at you skin surface close up. they cut down the flow of blood to the surface so less heat is lost by radiation
• Sweat glands stop making sweat
• Shivering: Your muscles start to contract quickly, this produces extra heat that warms your body

Vasodilation (when its hot):

• Blood vessels at your skin surface widen. They allow more blood to flow to the surface so more heat is lost by radiation
• Sweat glands in your skin make sweat. the sweat evaporates and cools you down

2.87 - Eye response/focus

2.87 understand the function of the eye in focusing near and distant objects, and in responding to changes in light intensity

• Most of the bending of the light rays is done by the curved cornea but the lens can also bend the light rays but only slightly (focus)
• The shape of the lens is controlled by the ciliary muscles
• If you are looking at a distant object:
• The ciliary muscles relax
• This tightens the ligaments
• therefore the lens is pulled into a thin shape
• The distant object focuses on the retina
• If you are looking at a close object:
  • The ciliary muscles contract
  • This slackens the ligaments
  • therefore the lens becomes thicker
  • The near object focuses on the retina

2.86- Structure and function of the eye

2.86 describe the structure and function of the eye as a receptor

2.85 Reflex Arc

2.85 describe the structure and functioning of a simple reflex arc illustrated by the withdrawalof a finger from a hot object

Stimulus --> Receptor --> coordinator --> effector --> response
(Hot surface) --> (heat sensor) --> CNS --> (Muscle) --> (remove finger)

2.84 Electrical impulses

understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses

• The receptors detect a stimuli
• The receptors then send a message along the sensory neuron to the spinal cord
• electrical impulses (signals) are sent through the nerves to the central nervous system
• These impulses pass really quickly through the axons
• The quicker the electricity goes to the CNS the quicker you react therefore the axon is surrounded by fat to insulate the axon so that the electricity flows quicker
• The brain then detects that there is something going on
• electrical signals are sent down the motor neurons to the effectof

2.83 Central nervous system

recall that the central nervous system consists of the brain and spinal cord and is linked to sense organs by nerves

Receptor --> coordinator --> effector

• The central nervous system is made up of your brain and spinal cord which are made of delicate nervous tissue. The brain is protected by the skull and the spine by the backbone
• The central nervous system controls your actions and it is connected to different parts of the body by nerves.
• These nerves that connect the CNS to the body are made up of nerve cells or neurons
• Sense organs are our receptors and they send messages to the CNS telling it what has happened. These messages are sent along the sensory neurons
• Muscles and glands are our effectors and the CNS sends them a message that tells the muscles what to do. The messages are sent along the motor neurons

2.82 - Communications

describe how responses can be controlled by nervous or by hormonal communication and understand the differences between the two 

Ways of connecting the coordinator to the effector:

1)

• -The yellow part on the left is the cell body and it is embedded inside the spine and it would connect to the effector (muscle)
• -The electrical impulse (nerve impulse) is carried along the nerve (orange structure) from the cell body to the synaptic knob where it connects to the muscle. (it can be up to a meter long)
• - In mammals the axon is surrounded but the "schwann cell", these contain a lot of fat and creates the "mylin sheath". This increases the speed of nerve conduction.

2)

• Endocrine system involves the endocrine gland which produces a chemical called a hormone (protein, steroids). eg: Adrenal gland
• The hormone is secreted into the blood (Adrenaline) 
• It travels through the blood stream to the organ it affects called the target tissue.
• Hormones can have multiple targets (multiple effects)

Differences:

Nerves are fast and use electrical impulses.

Hormones are slow and use chemicals

2.77a - Thermoregulation

Homeostasis: Conditions are kept the same
Homeothermic: Temperature is kept the same

Mammals (Homeothermic): when the environmental temperature changes their body temperate stays the same. They keep their body at the optimum temperature

2.76 - Sensitivity

Organism respond to changes in their environment eg:
-Light
-Temp
-Pressure
-Chemical
For these changes organisms require Receptors and Effectors (Muscles, Glands) to respond to the changes.
The response ensures that the organism is able to survive changes in the environment