Gene Technology

Question 1

What is selective breeding

Answer 1

Artificial selection- humans choose which characteristics (+alleles) will be passed onto offspring, not nature

Question 2

What is the method for selective breeding

Answer 2

-desired characteristics are identified
-individuals with the desired characteristics are bred together
-choose offspring that also have the desired characteristic
-only the offspring exhibiting the desired characteristics are bred together again
-this is repeated over several generations until the desired trait is fully developed

Question 3

What is an example of a desired characteristics

Answer 3

A dog being loyal and intelligent

Question 4

What are the advantages of selective breeding in animals

Answer 4

-you can remove undesirable characteristics from the genotype of a breed
-specific traits can be chosen to make a breed more useful
-higher yields= higher profit
-animal conservation, individuals around the world can be bred to increase genetic diversity

Question 5

What are the disadvantages of selective breeding in animals

Answer 5

-animal welfare issues, the needs of humans come before the needs of animals
-animals may be bred with health issues, genetic deformities are more likely expressed
-it takes a long time (many generations) to produce many individuals with the desired characteristic
-it is down to chance which alleles are passed on to offspring, may not work
-if a population is genetically similar then they are more vulnerable to being killed by a pathogen

Question 6

How can selective breeding be used in plants

Answer 6

By the same process, plant breeders can produce varieties of garden plants (e.g roses) and crop plants (e.g wheat) which grow more quickly, give a higher yield of grain and are more resistant to disease

Question 7

What are two ways natural selection differs from selective breeding

Answer 7

-selective breeding is artificial and done by humans
-natural selection takes longer than selective breeding

Question 8

What is an example of a desired characteristic developed by selective breeding in a crop plant

Answer 8

-wheat
-short stems and many large seeds

Question 9

What is recombinant DNA

Answer 9

Making a new combination of DNA bases by combining DNA from 2 species

Question 10

What is a transgenic organism

Answer 10

An organism which contains genetic material from a different species/organism

Question 11

What are restriction enzymes

Answer 11

Enzymes which cut DNA molecules at specific points. They can be used to cut out specific genes from a molecule of DNA

Question 12

What is DNA ligase

Answer 12

Enzymes which join the cut ends of DNA molecules

Question 13

What is a vector

Answer 13

A structure which can be used to transfer genes in genetic engineering e.g plasmid and viruses

Question 14

Define transgenic

Answer 14

The transfer of genetic material from one species to another different species

Question 15

What are plasmids

Answer 15

Smaller pieces of circular DNA

Question 16

How can large amounts of human insulin be manufactured from genetically modified bacteria

Answer 16

-plasmids are isolated from a bacterium
-the plasmids are opened with a specific restriction enzyme (cut a specific DNA sequence)
-the gene to be transferred is cut from the donor DNA (human) using the same restriction enzyme. This gene has the instructions to make insulin
-the opened up plasmids and the isolated genes are mixed with a DNA ligase enzyme to create recombinant plasmids
-some bacteria will take up the plasmids containing the gene
-the bacteria that have taken up the plasmid now contain the gene from the donor cell
-this bacteria is then put into a fermenter so that it can multiply into a huge population
-these bacteria now make human insulin

Question 17

How can viruses be used as vectors

Answer 17

• a useful gene can be inserted into the DNA of a virus, the virus injects it into the bacteria and the bacteria will make the desired product by following the instructions in the gene

Question 18

How do restriction enzymes work

Answer 18

-each restriction enzyme recognises a certain base sequence in a DNA strand
-when it ecnocunters that sequence it will cut the DNA molecules
-it will only cut the DNA molecule if it can see the base sequence on both strands
-if the restriction enzymes make a straight cut, the fragments of dna produced have blunt ends
-other restrictive enzymes make a staggered cute meaning the DNA fragments have sticky ends because fragments of dna with exposed bases are more easily joined by ligase enzymes

Question 19

What is genetic engineering/modification

Answer 19

-it is the artificial modification of the genetic material in a living organism. It produces an organism with a unique set of genes
-in genetic engineering genes can be swapped across species (as DNA is universal) creating a transgenic organism
-it is not the same as cloning

Question 20

What are the benefits of genetic modification

Answer 20

-can grow crops in countries where they wouldn’t normally grow e.g drought tolerant plants
-less food waste, GM crops can be made with longer shelf lives, taste better, bigger etc
-food is cheaper/ more economically viable so can feed more people
-can make medicine that is difficult to make in a lab
-faster than selective

Question 21

What are the concerns of genetic modification

Answer 21

-not natural, mixing genes from different species interferes with natural selection
-unforeseen circumstances
-might be animal welfare issue which harm animals
-ethical issues
-might take years to develop and is initially expensive to set up

Question 22

What are the advantages of genetic modification in plants

Answer 22

-increasing crop yield
-can make resistant crops e.g drought, disease, pest
-health benefits e.g vitamin production

Question 23

What are the disadvantages of genetic modification in plants

Answer 23

-can affect the number of weeds and flowers that usually live around crops reducing biodiversity
-not even is convinced that GM crops are safe, people may develop allergies
-transplanted genes may get out into the natural environment e.g weeds becoming superweeds

Question 24

What is micropropagation

Answer 24

A process in which very small pieces of plant (tissues) are grown using nutrient media. They are initially grown in petri dishes on nutrient agar- they are grown in vitro (outside a living organism)

Question 25

What is the process of micropropagation in which explants are grown in vitro

Answer 25

-explants are cut from the parent plant using sterilised tools -explants are sterilised by soaking in a disinfectant and rinsing in sterile water. This removes pathogens and bacteria/fungi that might compete for resources e.g minerals -sterilised explants are transferred to a sterile Petri dish containing sterile nutrient agar The explants grow (mitosis) and divide into small masses of cells called a callus -each callus is transferred to a fresh growth medium that contains a range of plants growth regulators causing the callus to develop roots, stems and leaves forming a plantlet -plantlets can be transferred to individual potting trays and develop into plants

Question 26

What are the advantages of micropropagation

Answer 26

-large numbers of genetically identical plants can be produced rapidly -plants can be produced at any time of year in controlled conditions indoors -large numbers of plants can be stored easily and then developed as required

Question 27

Why are plants produced by cuttings and micropropagation genetic clones of the parent plants

Answer 27

-the new plants have the same DNA as they are cut from the same plants -therefore when the plant grows and makes new cells via mitosis, genetic clones of the first plants will be made which have exactly the same DNA

Question 28

Define cloning

Answer 28

The use of various techniques to produce genetically identical individuals

Question 29

What are the three cloning techniques

Answer 29

-clone plants using cuttings (asexual technique) -clone plants using micropropagation (asexual technique) -clone animals using somatic cell nuclear transfer

Question 30

What is somatic cell nuclear transfer

Answer 30

Removing the nucleus from a displaced body cell and placing it in an enucleated egg cell. This the grows into an embryo which is implanted into the uterus of a surrogate sheep.

Question 31

Who do we use as an example to show the stages of production of cloned mammals

Answer 31

Dolly the sheep

Question 32

What are the stages in the process of cloning mammals such as dolly the sheep (8)

Answer 32

-an egg is taken from the ovary of sheep A -a diploid body cell e.g udder is taken from sheep B -the nucleus is removed from the egg of sheep A, it become enucleated -the enucleated egg from sheep A and the body cell from sheep B are fused together with electricity -now an egg has been made which contains the DNA from sheep B -the cell divides by mitosis until an embryo forms -the embryo is implanted into the uterus of a surrogate sheep -a sheep with the DNA of sheep B is born. She is a clone of sheep B. This is dolly

Question 33

What are the applications of clonings

Answer 33

-production of animals which have a protein in their milk which could be used to treat a medical condition e.g blood clotting factors -testing of new drugs as the animals are genetically identical they should all react in a similar way -build up populations of endangered plants or animals

Question 34

What are the drawbacks of cloning

Answer 34

-reproductive cloning is very inefficient -a variety of organ defects have been seen -premature aging -ethical issues - conflict with religious and societal views -unforeseen consequences e.g medical problems in offspring

Question 35

How can cloned animals be used to make human proteins

Answer 35

-animals such as sheep can be genetically modified to produce several human proteins -the sheep would be called transgenic -these genetically modified sheep secrete the protein in their milk -cloning more sheep like this would allow more production of this protein

Question 36

Why are stem cells important in multicellular plants and animals

Answer 36

-stem cells are unspecialised cells but they can divide by mitosis many times to produce daughter cells -later it can differentiate into specialised cells -specialised cells are important as they can carry out particular functions -this is especially important in the formation of tissue high are groups of similar specialised cells carrying out a particular function -stem cells are particularly important in embryos as they are the source of all specialised cells in the development of an individual -stem cells are more common in adult plants that in adult animals -this makes it much easier to grow new plants by micropropagation techniques because more stem cells with be presente

Question 37

How can stem cells be used in medicine

Answer 37

-stem cells can be collected from embryos and used to create new tissues in the laboratory that could be used to treat a variety of diseases and disorders -embryonic stem cells can be grown in the laboratory in a Petri dish (in vitro) -when they have grown into colonies they can be split up and exposed to different conditions which encourage certain genes to switch on and off -in this way, embryonic stem cells can be grown into different tissue types which can be inserted into an adult -inside the adult, the cells continue to grow and repair the adult organs from within -this can be mixed with gene therapy where a faulty gene can be edited (by cutting with restriction enzymes and a working gene can be inserted using ligase)

Question 38

What are the advantages of using stem cells in medicine

Answer 38

-they have the greatest potential to treat human diseases -an embryo at such an early stage of development can be seen as a ball of indentical, undifferentiated cells bearing no resemblance to a human being -as long as a person gives consent sources of stem cells such as bone marrow raises no real ethical issues

Question 39

What are the disadvantages of using stem cells in medicine

Answer 39

-only allowed in the UK under licensed and specified conditions -presents ethical issues whether a human embryo less than 14 days old should be afforded the same respect as a fetus or adult person -even if reproductive cloning remains illegal in the uk, the information gained could be used to clone humans elsewhere -it is wrong to allow human suffering when there is a possibility of alleviating it -it is wrong to destroy spare embryos that could be used in research