B14 Flashcards
what is an allele
different form of the same gene
what is phenotype
the physical appearance caused by inherited information
what is variation
difference in characteristics in or between species
what are the genes of a female gamete
xx
what are the genes in a male gamete
xy
where does genetic variation arise from
mutations
how does a new phenotype occur
mutations happen continuosly in the body during cell division. However most mutations do not alter the phenotype. Most influence the phenotype but do not determine the phenotype
how can a phenotype be influenced
- differences in the genes of organisms caused by mutations and sexual reproduction
- differences in the environmental conditions organisms live in
- or both
how are identical twins born
a feertillised egg splits in to and grow independently which means the twins have the same DNA so the differences have to some from the environment
what are some phenotype variation caused by genes
- eye colour
- natural hair colour
- nose shape
- blood type
- ear lobe shape
what are some phenotype variation caused by the environment
- hair lenght
- accents
- tatoos
- scars
what are some factors affected by genes and the environment
- weight
- skin colour
- being athletic
how are non-identical twins formed
when 2 sperm fertilise 2 seperate eggs at the same time
what is the theory of evolution
- 3 billion years ago simple life organisms evolved by natural selection causing variation
what is evolution
a change in inherited characteristics of a population over time through natural selection
when is a new species formed
when population of one species has become so different in phenotype they can no longer breed to produce fertile offspring
what is a species
a group of similar organisms which can reproduce to have fertile offspring
what is natural selection
when a species shows variation causing it to be better adapted at surving allowing to breed more successfully and pass on its genes
are mutation always negative
no some could be positive or not positive at all and fatal
what factors can cause mutations
- x-rays
- UV light
- Radiation
- Chemicals
what is selective breeding
when humans breed plants and animals to get desired characteristics
does selective breeding fertil offspring
no, it produces infertile offspring
what are the steps in selective breeding
1- parents with desired characteristics are choosen from a population
2- they are bred together
3- from teh offspring thoose with desirable characteristics are bred
4- this happens over many generations untill all the offspring show desired characteristics
what are cons of selective breeding
- health problems
- body growing soo fast that the legs can not support the large bodies
- reduction in the gene pool
- organisms can have harmful gene defects cause of the reduced gene pool
- organisms are vulnerable to new diseases
what are plants selectively bred for
- higher yield
- disease resistance
- drought resistance
- more flowers
what are animals selectively bred for
- higher yield
- more muscle
- fast growth
- quality of stuff produced by the animal
what is a gene pool
- the combination of all the different genes in a population
what is genetic engineering
involves changing the genetic material in an organism by cutting out the desirable gene from one organism and transferring it to another
what are teh modern uses of gentic engineering
- producing insulin
- crops resistance to diseases
- crops producing a higher yield
- finding out where genes are expressed in the body
what does GE stand for
genetic engineering
what does GM stand for
genetic modification
gimme the steps of genetic engineering
1- a restriction enzyme is used to cut out a piece of DNA from the organism
2- bacteria containing plasmid DNA
3- Plasmid is taken out and opened up using restriction enzymes
4- the insulin gene is inserted to the bacterial plasmid
5- the plasmid is inserted back into the bacteria
6- the bacterial cell divides to produce more bacteria with insulin gene
what is the ligase enzyme used for
joining ends of DNA togetehr
what is Lysozyme used for
used to break open the bacterial cell so that the plasmid can be removed
what are the advantages of using GM crops
- improved growth rate
- better quality crops
- higher yield
- drought resistant
- disease resistant
what are the disadvantage sof GM crops
- insects can become disease resistant if they eat too much pesticide forming plants
- effect on human health is unknown
- genes from GM plants may spred to the wildlife
- GM plants are mostly infertile
what is a clone
an organims produced by asexual reproduction which is genetically identical to the parent
what are the 2 ways plants can be cloned
- tissue culture
- plant cuttings
what are the 2 ways animals can be cloned
- embryo transplant
- adult cell cloning
how does tissue cultures work
- a small piece of tissue is taken from a plant
- it is then grown on agar jelly containing the right nutrients and hormones for the plant to grow
what are the pros of tissue cultures
- can be used to preserve plants
- can produce hundreds of clones of plants
what are the disadvantages of using tissue cultures
- ## it is expensive
how does plant cuttings work
- a part of the plant is removed and dipped in plant growth hormones powder
- placed into moist soil
- if the conditions are suitable then the plant will grow
what are the advantages of using plant cuttings
- easy
- cheap
- simple
what are the disadvantages of using plant cuttings
- right conditions are needed which at times can not be met
how does embryo transplant work
- a cow becomes pregnant
- the emrbyo is removed before cells can become specialised
- embryo is split and grown in a labratory till the calf is ready to be placed back into the uterus of a host cow
what are the advantages of embryo transplant
- can produce 3x times more calves than through normal reproduction
- farmers can sell the embryos worldwide
what are the disadvantages of embryo transplants
- it is expensive
- ## some say it is unethical
how does adult cell cloning work
- a skin cell from sheep A is taken and the nucleus is removed
- unfertilised agg cell from sheep B is taken and the nucleus is removed
- nucleus from sheep A is take ]n and placed into nucleus-less egg cell from sheep B
- an electric shock stimulates egg cell to divide and from an embryo
- embryo is placed into adult female sheep C
- a clone of sheep A is formed
what are the advantages of using adult cell cloning
- can help animals be saved from extinction
- could be used to produce large numbers of clones
- can be medically used to collect to substances secreted by animals
- this technique can be used to clone human babies which can give hope to infertile couples
what are the disadvantages of using adult cell cloning
- leads to plants and animals having identical genes so leads to a lower gene pool
