CB4- Natural Selection and Genetic Modification

• When bacteria evolve to become able to survive exposure to antibiotics, they have developed:

  Antibiotic Resistance
• Formation of Antibiotic Resistance

  A population of bacteria infects somebody, that person then takes antibiotics to kill the bacteria . Yet, some bacteria have a random mutation that makes them less susceptible or resistant to the antibiotic than others. The antibiotics kill all the bacteria except those that are resistant . The resistance strains of bacteria now have more resources to grow and multiply . More mutations may arise , leading to greater resistance

  There is now a strain of bacteria that can't be killed by antibiotics , which we call antibiotic resistance
• To reduce the rise and spread of antibiotic resistance we should decrease the use of antibiotics
• Antibiotics only kill bacteria , therefore, are not effective in treating viral diseases
• To reduce the rise and spread of antibiotic resistance doctors shouldn't need to prescribe antibiotics for mild bacterial infections as our bodies can generally fight mild bacterial infections themselves
• It is important to take the full course so that they can kill all of the bacteria
• Reasons for antibiotic resistance being common

  Doctors often prescribe antibiotics in cases where they aren't necessary

  Many people don't take the full course of antibiotics , so not all the bacteria are killed

  Huge amounts of antibiotics are given to farm animals in order to make them grow faster
• Antibiotic Resistance Problems

  If more bacteria are resistant to antibiotics, we won't be able to treat those infections , this means more people will die of bacterial infections 
• Darwin's Theory of Evolution

  Variation within a species arises . There is competition for food / space / mates within it . The better adapted members of the species will survive the ' Survival of the Fittest '. These survivors pass on the beneficial genes to their offspring . The beneficial characteristic become more common
• Fossil Evidence

  Ardi ( 4.4mil years ago ) -

  About 1.2m tall and 50kg

  Very long arms and big toes ( able to climb trees )

  Leg bones suggest she was able to walk upright

  Skull volume= $350cm^3$
• Fossil Evidence II

  Lucy ( 3.2mill years ago )-

  1.07m tall

  Probably walked upright

  Toe bones were arranged like humans but more curved

  Skull Volume: 400cm
• Fossil Evidence III- Leakey's Discoveries

  Homo Habilis ( 2.4-1.4mil years ago )-

  Quite short with long arms and can walk upright

  Skull volume = $500-600cm^3$
• Fossil Evidence IV

  Homo Erectus ( 1.8-0.5mil years ago )-

  1.79m tall

  Strongly built

  Skull volume = $850cm^3$
• Stone tools

  Scientists can work out the ages of layers of rock , therefore , can assume the stone tool is the same age of the rock

  Used for cutting u meat , fighting or skinning an animal
• Classification


  The organism of living things into groups according to their similarities

  COULD BE BASED ON: Physical traits , Behavior , DNA etc
• Linnaeus's system of classification

  Kingdom

  Phylum

  Class

  Order

  Family

  Genus

  Species
• 5 Kingdoms: Animal

  CHARACTERISTICS:

  Multicellular with cells arranged as tissues and organs

  Cells have nuclei

  No cell walls

  EXAMPLES: Humans
• 5 Kingdoms: Plants

  CHARACTERISTICS:

  Multicellular with cells arranged as tissues and organs

  Have chloroplasts for photosynthesis and have cellulose cell walls

  Cells have nuclei

  EXAMPLES: Roses
• 5 Kingdoms: Fungi

  CHARACTERISTICS:

  Multicellular , apart from yeast

  Live in/on the dead matter on which they feed

  Cells have nuclei

  Cell walls contain chitin

  EXAMPLE: Mushrooms
• 5 Kingdoms: Protists/Protozoan 


  CHARATERISTICS:

  Mostly unicellular , few multicellular

  Cells have nuclei

  Some have cell walls made of different substances

  EXAMPLES: Amoeba
• 5 Kingdoms: Prokaryotes 


  CHARACTERISTICS:

  Unicellular

  Do not have nuclei

  Flexible cell wall

  EXAMPLE: Bacteria
• The Development of Genetic Analysis

  All organisms apart from prokaryotes have unused sections of DNA in their genes . Most of a gene is used to make a protein , but the unused sections don't help , therefore, all organisms were divided into three domains
• Three domains

  Archaea - cells with no nucleus , genes contain unused sections of DNA

  Bacteria - cells with no nucleus , no unused sections in genes

  Eukarya - cells with a nucleus , unused sections in genes
• Breed 


  The variety within a species of animals
• Variety 


  the variety within a species of plants
• Artificial Selection

  when humans choose certain organisms because they have useful characteristics
• Selective breeding

  They select the better adapted animals and used them to breed . By repeating this over and over again , they end up with offspring with the better genes
• Plants and animals are often selectively bred for:

  Diseases resistance

  Increased yield

  Drought resistance

  Fast growth
• Genetic Engineering

  Involves changing the DNA of one organism ( its genome ), by inserting genes from another , creating genetically modified organisms

  ---> faster process yet expensive
• Golden Rice

  Is a GMO w two genes inserted into its genome . One from a daffodil and a bacterium allowing rice to produce carotene in its grains

  This makes more vitamin A with a lack of it causing blindness
• Other important GMOS

  Disease Resistant

  Increasing growth and growth rate

  Human-like Organs

  Antibiotics etc
• Vector 


  Any DNA molecule used to carry new DNA into another cell
• Selective Breeding Risks

  Certain alleles are selected so others can become rare or disappear therefore, alleles that might be useful in the future might not be available

  If a change in condition affects one organisms , it will affect others

  Animal welfare concern

  There will be a lack of variation
• Genetic Engineering Issues

  Seeds are expensive

  People might think it is bad for your health

  If growing own crops , more time , less yield