B13 Flashcards
Why are you different to your family members
Nature and nurture
What is nature genetic variation
You have a unique set of genes that give you your own set of characteristics
What is nurture environment
Environment determine how much your genes are used
Example of nurture environment
May have gene to be tall but do not have enough food when you are growing you will not reach full potential of tall genes
How can you study differences in genetically identical plants
Put them in different growing conditions
Any difference of identical twins is due to
environment ( have same genes)
Any difference of non identical twins / same sex sibilings
genes ( experience same environment if together)
Genetic studies with humans look at
Identical twins brought up together
“ separately
Non identical twins brought up together
Same sex, non twin siblings brought up together
How does survival of the fittest work
organism had mutation so an allele is produced which makes the organism better suited to the environment outcompeting its neighbours, surviving , reproducing and pass on their alleles to their offspring ( which hopefully allow offspring to do the same)
How does variation occur in a population
Difference in genes due to meiosis and sexual reproduction
What is mutation
Change in DNA code
when does Mutations occur
DNA is replicated during cell division
During gamete formation —> phenotype of offspring and introduce new variants into the species
3 kinds of change mutation can cause
No change
Drastic change that limits survival
Change enhances survival -> better suited to the environment or environmental change ( RARE)
Who formed theory of evolution by natural selection
Charles Darwin
What did theory of evolution by natural selection state
All living things evolved from simple life forms that first developed 3 billions years ago
How is new species formed
Members of species change enough that they can no longer interbred
evolution of oysters
oyster fishermen noticed oysters in their catch
all oyster beds almost empty
few oysters had mutations that made them resistant to the disease (had mutation already - disease did not cause the mutation to occur)
oysters survived and reproduced
oyster beds full again with disease resistant strain of oysters
isseus with evolutionary changes
fast or slow depending on length of life cycle
selective breeding
procedure used in agriculture to produce offspring that possess the beneficial characteristics of both parents
how does selective breeding work
animals or plants with desirable traits selected from a population which are used as breeding stock
farmer/breeder then selects from the offspring of this breeding stock the ones with the most desirable traits and breed these
continues for generations until offspring show desired traits
examples of selected traits
disease resistance in crops or garden plants eg TMV resistant rose plant
animals that produce more milk and meat
domestic dogs or farm animals with a gentle nature
plants with large, highly coloured , heavily scented flowers
results of selective breeding
fields of wheats with large heavy heads
placi diary cows that produce litres of milk a day
dogs that are gentle enough to be around kids
NOTE: ALL totally different to the ancestors they were bred from
issues with selective breeding
reduce the gene pool (number of alleles ) in a population —> reduce variation within a population and variation within alleles —> changing environment eg new disease or climate change means population not able to cope with change and die off eg bananas = clones
problem of inbreeding —> low allele variation —> vulnerability to genetic diseases and to genetic defects
what is genetic engineering
involves changing the genetic material of an organism
