Genetically Modified Plants

Example:

Maize is damaged by larvae of European cork borer --> 20% loss of crop yield.

This can be solved with that existence of Bacterium BT. In the chromosome of BT there is a gene, and when it is switched on it produces BT toxin which can kill cork borer larvae. 

We have to get the Bt toxin into maize to protect it from European cork borer.

1. Take restriction enzyme to the gene of Bt Bacterium and chop this gene out so that we will get the Bt gene for the toxin. 
2.  Transfer it to the cell of the maize plant. The technique currently being used involved 'gene gon'. --> taking tiny particles of gold coated in Bt genes. They are then fired at high velocity at the plant cell, introducing the Bt gene to the interior of the plant cell. 
3. So the plant cell gets the gene and the maize cell have the Bt gene which make it toxin when switched on --> kill larvae. 
4. This gives the maize resistance to damage caused by the cork borer.

credits to Michelle Huang

5.14 Humulin

The bacterial cell containing the recombinant DNA with the human genes (in this case the production of insulin) can be injected into a fermenter.

In this fermentor chamber we need to consider:

• -Nutrient  - (Used to manufacture insulin protein) 
•  Temperature - (Optimal temperature for bacteria growth ->Increase in population where the bacteria will then switch on the gene for insulin and manufacture protein insulin. )
•  pH
•  Gases 

It will then be necessary to remove the product and carry out purification ( downstream processing)

Genetically engineered human insulin is called Humulin.

5.13 Recombinant DNA

Recombinant DNA

Plasmids are find in bacterial cells and are a ring of DNA and are particularly small carrying little DNA.

Viruses have a protein shell called a capsid and inside there would be a Nucleic acid (of which contains either DNA or RNA).


The human chromosome is made of DNA and in our example, we will talk about the gene which codes for the production of the protein, insulin (hormone controlling blood sugar levels).

1. The restriction enzyme would be selected to cut the DNA, leaving us with the gene of insulin separately.
2. Having cut the gene, the plasmid will also be cut with the same restriction enzyme.
3. This leaves the plasmid ring structure broken, the human insulin gene is then inserted into the plasmid.
4. This will leave our plasmid with the human gene inserted and is then necessary to apply ligase enzyme which will join the DNA.
5. This combination of the human gene, and the plasmid is known as recombinant DNA.

Hosting Recombinant DNA 

1. After the recombinant DNA is formed, it is necessary to find a host cell for it. In this instance, we will use the virus to achieve this.
2. We have to remove the nucleic acid from the virus, leaving us with the capsid of the virus alone.
3. The plasmids are taken up by the virus and the virus will act as a vector of the recombinant DNA.
4. It will help us transfer that DNA to our host cell, the virus known as a phage infects bacterial cells, and so the virus is able to attach to the cell membrane of the bacteria and insert the recombinant DNA into our host cell.
5. At the end of this process, we will have a bacteria containing the recombinant DNA including the human DNA for insulin

Credits to daniel lo

5.12 Restriction and Ligase Enzymes

A restriction enzyme is able to cut DNA at particular location. Location is identified by the base sequence of DNA molecule - very important tool in biotechnology and genetic engineer. 

A DNA Ligase is able to join the two DNA together. 

5.11 Breeding Animals

Example of Breeding animals : cows


 The desired outcome for the cow is the milk yield.

1.  The earliest farmers would realise a few cows would be producing 50 ml of milk, while some produces 150 ml of milk - roughly  most of the cows would be producing 100 ml of milk.
2. The farmer will then collect all the milk and he will only choose cows which produce 150 ml milk as the breeding cows. 
3. In the next generation we find that a few cows are producing 100 ml, a few cows are producing 200 ml and the majority of cows will be producing 150 ml of milk.

He will then repeat the same method selecting the cows which produce 200 ml milk as the breeding cow. And in the next generation there would be a few cows producing 150 ml of milk, a few producing 250 ml of milk and the majority producing 200 ml of milk.

So as we progressively select, we change the desired characteristic. We are able to develop the desired characteristic by selective breeding. 

5.10 Breeding Plants

• The number of rice grain per rice is under the control of genes - The farmer wants to increase the number of rice grain per plant to increase the yield. 
• Some plants have 6 grains per stem, while others have 8 and 10 grains per stem 
• The farmer's decision is to harvest the grains with 6 and 8 grains, but will use those with 10 grains for planting. 

In the next generation of rice, the grains increase to 8-10-12 . The farmer will then harvest those with 8 and 10 grains, but selective those with 12 grains for planting and breeding.

In this way, the number of grains of rice which are found on  these plants gradually increases. This causes the increase in yield. 

This is an example of selective breeding.

5.9 Fish Farming

Fish contains high proteins and also low fat. They are also efficient at turning the nutrients into fish mass.
Fish farming will result in increasing the yield of the fish by controlling these factors:

• allow us to control the quality of water 
• controlling the amount of predators 
• controlling the pests 
• controlling diseases

- However the higher the density of fish, the higher the chance that disease will spread. Farmers control this by use of antibiotics and pesticides to keep away pathogen carrying pests . These antibiotics are concerns to human health. 

- Abundance of fish also makes pest and requires farmers to use pesticides which are also concern to the human health.

5.8 Fermenter

The fermenter is to keep the optimum growth conditions for the conditions so it will provide the product we demand. 

• Aseptic Precautions  = this prevents pathogens and unwanted bacteria from contaminating the substrates and products
• Optimum temperature = enzymes produced by the microorganism function best at this temperature, so to produce more yield, this temperature is controlled
• pH Levels = enzymes also function best at a certain pH, so this is similarly controlled by the fermenter
• Oxygenation = Oxygen is needed in the reaction since it is aerobic
• Agitation = this ensures that the microorganisms are distributed evenly throughout the fermenter, and prevents clusters of them from forming; also ensures even temperature and nutrient concentration

credits to Nik

5.7 Yoghurt

1.  The milk is obtain from the cow through process called milk production
2.  Milk goes through process where they remove pathogens such as TB bacillus. This process is called pasteurization where this heat treatment kills off any pathogens in the milk. 
3.  Milk sugar then converted to lactic acid - From incubating the milk to about 45-46 degree centigrade with the addition of lactobacillus
4.  Lactobacillus produces the enzyme that breaks down the milk sugar lactose to produce lactic acid.
5.  The lactic acid result in a lower ph making the milk protein to solidify and this solidification of the milk product is what we call yoghurt. 

5.5 Beer Production

Understand the role of yeast in the production of beer

Beer-- composed largely ethanol, which is a kind of alcohol

Equation = Glucose --Yeast/Enzyme--> Ethanol + Carbon Dioxide 

This reaction is in the form of anaerobic respiration which is carried out by yeast, which is a kind of microorganism able to supply the enzyme, to bring about this convert ion.

Ethanol is often flavored by the addition of plants such as hops. 

Glucose comes from starch in a two step process: 

1. Starch -----> Maltose 

Enzyme: amylase

Source: Barley seeds, wheat seed, rice

Starch is broken down through amylase through the germination of the seed, which is the stage called malting. 

2. Maltose -----> Glucose

Enzyme: Maltase

Credits to Michelle Huang

5.4 Pesticide and Biological Control

 Large fields of crops of the same type are called Monoculture. 

Monocultures tend to be really susceptible to pests which uses the crops as their own food source. 

This reduces the productivity of the farm which reduces the amount of crop yield making a financial impact on the farmer as less is produced.

To overcome this, one of the solutions is to use pesticides  - chemicals used to kill the pests

Advantage of using Pesticides:

• Chemicals are easy to obtain
• Easy to apply
• Very effective

Disadvantage

• Many of the chemicals are toxic which can damage other plants and animals, other than the pests and may be harmful to humans as well.
• Bio accumulation -  where the pesticides build up through the food chain causing problems for animals in the higher trophic levels. 
• Mutation in the pest often lead to resistance - the pesticide will need to be applied at a higher level, ->the pests have complete resistance to the pesticide and so the farmers have to find an alternative pesticide.

Biological Control:

• A great example of this is Australia where the prickly pear cactus ( of North America) was first introduced into gardens and escaped into the countryside and flourished under the Australian climate system. 
• The cactus started to cover a good deal of agricultural land and was necessary to get rid of it
•  But there was no natural herbivore of the cactus so an alien specie (non-native specie) was introduced from another country which was a moth (Cactoblastis) which feeds on the cactus. 
• This moth was introduced and had no competitors so they started to remove the prickly pear cactus.
• This control of pests by herbivore is called Biological control.

Advantages

• No toxic is involved
• Less image on the human /wildlife

Disadvantages

• Not 100% completely effective 
• Often difficult to control -  often a danger that the alien specie would start preying on native species  causing native specie population to diminish
• Difficult to match a predator to the prey which can effectively remove the pest
• Takes time

5.3 Fertilisers

The use of fertiliser to increase crop yield


We can increase the growth of plants in farming by the application of fertilizers to the soil which are forms of nitrate and phosphate, or combination of both.

These compounds go down into the soil and are taken up from the root structure and move in the transpiration stream up to the leave and used in the leaf for the constructions.

Examples : Nitrate will go and forms proteins, Phosphate will go forms DNA and membrane structure 

They are 2 fertilizers:

Organic: 

• Are produced from animal waste from farm - take form from cow's feaces collected by the farmers
•  Through the process of decomposition and fermentation and form a substance known as slurry. 
• This gives crop plant a supply of nitrate and phosphate to promote growth. 

Artificial :

• Take the forms of chemicals :Potassium nitrate and Ammonium nitrate
• Apply to the field, they will go into solution in the soil water. 
• This will release nitrate and promote growth in the same way as it would do at the compound. 

5.2 Crop Yield

The rate of photosynthesis
                                            light/ enzyme
Carbon dioxide + water  ----------------------->  Glucose + Oxygen
            CO2   + H20     ------------------------>C6H1206 + O2


1. Increase of concentration of carbon dioxide
If we increase the concentration of carbon dioxide ->the rate of photosynthesis will increase --> increasing in crop yield up to a point where it reaches the optimum point of the rate of photosynthesis.  That point will give you the highest yield of product. 

Increase in temperature

• If we increase the temperature then we increase the kinetic energy. 
• This causes the particles to collide into each other more frequently 
• Resulting higher chance for them to collide in correct orientation with greater temperature  ->higher rate of reaction. 

However as the rate of photosynthesis reaches the optimum ->the rate of photosynthesis starts to slow down, as some enzymes denature which decreases total crop yield.

Another effect on temperature is that it avoid frost damage and provide constant temperature  

5.1 Glasshouses and Polythene Tunnels

Glasshouse (or greenhouse) constructed as a simple house structure but all surfaces are made of glass in which it allows light to penetrate through to the interior.


How the glasshouse works

•  Solar radiation - the initial source of energy (in the form of light)
•  Light can be able to penetrates through the glass into the internal surfaces and is absorbed by surfaces inside the glasshouse - this could be the soil, wooden surface and plants themselves
• These surfaces then reemit this energy as heat where it warms the air ,  raising its average kinetic energy which in other words temperature increases

How warm air in the glass house increase the crops yield? 

• The higher temperature leads to closer, or optimum temperature for enzyme reaction such as photosynthesis. This is when enzymes work most efficiently allowing the fastest rate of reaction so more product is being produced.
• This  provide constant temperature throughout the year -> making constant production 
• Prevention of loss of water vapor  - they have a constant supply of water making the crops don't dried out
•  Avoid frost damage to seedlings in the spring time 
•  Glasshouses are often warmed by the burning of fossil fuels  -> making an increase of carbon dioxide level ->increase concentration of substrate for photosynthesis- --> increase product of photosynthesis
• Ethene may form through  incomplete combustion and as the product which can help stimulate fruit ripening, particularly with the tomato.

The polythene tunnels, 

usually a framework with polythene over the surface which also allows light to penetrate through to the interior.The advantage of polythene tunnels is because of the cheaper costs but also more adjustable and movable .The disadvantages of polythene tunnels provide less shelter for the plants and may be less effective which may have an effect of the output.

2.89 Hormones

Adrenaline - It is produced by the adrenal glands which a re located above each kidney.
Adrenaline is released during times of excitement
Adrenaline helps the body prepare for action in the following ways :

• Glycogen is converted to glucose where it reaches the muscles as a source of energy for the rapid contractions for sudden action
• Heart rate increases so the more glucose and O2 are delivered to the muscle
• Bronchioles widen so more air is reaches the lungs
• Blood vessels are widen so more glucose and 02 can delivered to organs

ADH - It is produced by the pituitary glands . Their target is to controls the level of the water in your body, it controls the amount of water re-absorption in the collecting duct. 


Insulin  -Is produced in the pancreas. It lowers blood sugar by changing it to glycogen. It control blood sugar level.


Glucagen - it is also produced in the pancreas where it increase the blood sugar level.

Testosterone - It is produced in the testes in males only. This develops male features during puberty. Brings about the changes to our bodies. 

Progesterone and Oestrogen - it is produce in the ovaries ( female only). There control the menstrual cycle and develop female features during puberty. 

2.88 Skin response

There are many different types of sensors on the skin such as pain sensors, touch sensors, pressure sensors and temperature sensors which we will focus on.

Our body keeps our body temperature constant at about 37 Degrees Celsius and thermoregulates in order to keep the body temperature in this range. This is also known as homeostasis.

If the surrounding temperature is too cold:

• Vasoconstriction happens as capillary narrows which decreases the flow of heat to the skin
• We stop sweating as we lose heat in this process as well
• We shiver to increase heat production in the muscles
• Hair erects in order to trap a warm layer of air and to avoid heat from escaping.

If the surrounding temperature is too hot:

• Vasodilation happens where the capillary is widened which carries more blood to the surface which heat can be transferred out.
• Sweating occurs which decreases body temperature

credits to Daniel

2.87 Eye response

Seeing things
Light enters your eye through the cornea, it passes through the lens and is focused on the retina.
In the retina there are cells which are sensitive to light called rods and cones.
When light stimulates them they send impulses to the brain along to the optic nerve. Your brain interprets these impulses to make a picture.


Focusing
Most of the bending of the light rays is done by the curved cornea but lens can bend the light rays slightly.
The shape of the lens is controlled by the ciliary muscles.


Looking at distance object:

• the ciliary muscles relax
• the suspensory ligaments tightens 
• The lens is pulled into a thin shape
• The distance object is focused on the retina

Looking at near object:

• the ciliary muscle contract
• this slackens the suspensory ligaments
• the elastic lens goes fatter
• The near objects is focused on the retina.

2.86 Structure and Function of the eye

The eyes respond to light rays and they give us our sense of sight.

• Each eye lies in a socket in the skull - it is moved by the action of 3 pairs of eye muscles ( Circular, Radiel and Ciliary muscle) 
• At the front of the eye is the cornea where the light enters from here. 
• It then passes through the pupil which is surrounded by the iris and through the lens and is focused on the retina.

2.85 Reflex

• Reflex is the simplex type of response. It is very quick and is involuntary (automatically happen without you being able to consciously controlling it). 
• Reflex reactions are often for self-protection, such as blinking, sneezing, or pulling your hand away from a hot object. 

• stimulus --> receptor --> sensory neurone --> relay neurone in CNS --> motor neurone --> effector --> response

• The small nerve called relay nerve in the spinal cord directly connects sensory nerve to the motor nerve so the response can take place. 
• They know which relay nerve to target because it is encoded within our DNA.

Example :The reflex arc for touching hot object:

Stimulus (pain sensor responding to heat) --> sensory neuron --> spinal cord --> relay neuron --> motor neuron --> effector (muscles) --> response (pulling your hand away from the heat source)

(credits to Michelle)

2.84 Electrical Impulses

• The messages that nerves carry are called the nerve impulses and they are electrical signals.
• They pass along quickly along the axon of the neuron.
• Some axons have a fatty sheath around them which insulates the axon and allows the impulse to travel faster along the axon.

Diagram showing how it works:

(credits to Daniel)

2.83 Central Nervous System

• The nervous system controls your action and coordinates different parts of the body.
• The central nervous system consist of the brain and the spinal cord where they are both made of delicate nervous tissue .They are both protected where the brain is protected inside the skull and the spinal cord is protected inside your backbone.
• The peripheral nerves connects organs to the central nervous system. Each nerves is made up or nerve cels or neurones. 
• Sense organs are our receptors where they send messages to the central nervous system and are sent along the sensory neurons. 
• When the central nervous system sends messages telling effectors what to do, the message is sent along the motor neuron. 

2.82 Communication

1. Nervous system

• The cell body of the nerve would be embedded to the spine
• On the other end (synaptic knob) of the nerve would be connected to the effector which in this case is the muscle fibers
• The electrical impulse or the nerve impulse is carried inside the walls from the cell body to the synaptic knot where it connects to the muscles through the axon which can be as long as one meter and only one cell wide.
• In mammals, the axon can be surrounded by another kind of cell known as the schwann cell - contains a great deal of fats and formed a myelin sheath, which helps increase the speed of nerve conduction and is one way of connecting the coordinator to the effector.

2. Hormone - Endocrine system

• Endocrine gland produces chemical known as hormone which can be proteins or steroids. 
• Example adrenal gland which produces adrenaline. The hormone is secreted into the blood and travels through the stream and arrive at target tissue/ organ that will have an effect on.
• Hormones can have multiple target and brings about multiple effects.

Difference between Nerves and Hormones:

• Nerves transfer impulses much faster than hormone does
• Nerve impulses re sent through neurons whereas hormones are sent through blood.
• Nerve impulses enables body to response to external environment and the hormones enable body to respond to internal environment

2.77a Thermoregulation

Homeostasis - Conditions are kept at the same or constant throughout

Homeothermic - Temperature are kept the same or constant

Organisms such as mammal keeps their body temperature constant despite changes in the temperature of the environment. These organisms are called homeothermic organisms. 

Mammals always keep their body temperature constant because enzymes have a point of temperature which is called optimum temperature (maximum) . They would try to keep their body temperature as close to the optimum temperature as possible. 

credits to michelle

2.76 Sensitivity

Sensitivity is the characteristic in which organism respond to changes in their environment.


The different types of stimuli are:
- Light                     - Temperature         -Pressure          - Chemical


To detect the changes in the environment, organisms are required to have receptors 
The response is produced by effectors which are muscles or glands. 


It is the response that ensures the organism is able to survive the changes in the environment.