INHERITANCE, VARIATION AND EVOLUTION #2 Flashcards
what are the two factors that influence some of our characteristics
genes and environment
natural selection
start with variation is present in the population due to mutations
the change in conditions (in the question) causes the (mutation) to become an advantage
this means the individuals with the mutation are more likely to survive, breed and pass on the allele for that characteristic to their offspring
the offspring inherit the characteristic
the change in condition must be sustained over multiple generations
what is selective breeding
selective breeding is a process where humans breed plants and animals for desired characteristics
what type of features is selective breeding used for to acquire
disease resistance in food crops or garden plants
animals that produce more meat or milk
domestic dogs and farm animals with a gentle nature
large flowers
the process of selective breeding
from existing stock select the ones that have the characteristics you are after
breed them with each other
select the best of the offspring and breed them together
continue this process over several generations, eventually all the offspring will have the characteristics
limitations of selective breeding
selective breeding greatly reduces the number of alleles in the population
there is less variation between individuals in the population
what is genetic engineering
is to transfer a gene responsible for a desirable characteristic from one organism into another organism so that it also has that characteristic
process of genetic engineering
a useful gene is cut from the chromosome of an organism using enzymes and is inserted into a vector
the gene is then inserted into the chromosome of another organism
this gives it its desirable characteristic
how can insulin be made so that patients do not have to use pig insulin
the gene for insulin production is cut from human dna using enzymes
a bacterial plasmid is cut open with enzymes and the human gene inserted
the plasmids are transferred to bacterial cells which then produce the insulin by protein synthesis
how are gm crops useful
they have had their genes modified to improve the size
quality of fruit
or to make them resistant to disease
problem with genetic engineering
maybe changing the organisms genes might accidently create unplanned problems which could get passed on to future generations
cons for gm crops
may not be safe for human health
transplanted genes can get out into the natural environment
pros for gm crops
certain characteristics can increase the yield
people living in developing countries lack nutrients, gm crops could be engineered to contain the nutrients missing.
what are clones
clones are individuals that are identical to their parents
how to clone plants
tissue culture- take small groups of cells from part of a plant and growing them under special conditions
a mass of identical plant cells form called a callus
each callus cell can be grown into a new plant
name a quick and cheap way of cloning plants
tissue culture
two ways of cloning animals
embryo transplant and adult cell cloning
what happens in embryonic cloning
an embryo is divided into several individual cells
each cell grows into an individual embryo in the lab
transfer embryos into their host mothers, which have been given hormones to get them ready for pregnancy
identical cloned calves are born
in adult cell cloning…….
you remove the nucleus from an unfertilised egg cell,
take the nucleus from a skin cell and insert it into an empty egg cell
give the cell an electric shock so it starts to divide to form an embryo
insert the embryo into a host mother to develop
benefits of adult cell cloning
save animals from extinction
risks of adult cell cloning
limits the variation in a population
ethical reasons
benefits of genetic engineering in medicine and agriculture
medical drugs have been produced
gm crops have been developed that they are resistant to herbicides or to insects
other gm crops grow well in hot places in the world
can improve the growth rate of plants and animals
disadvantages of genetic engineering in medicine and agriculture
insects that are not pests may be affected by gm crops
in the long terms insects may become resistant to pesticides
worry about the effect of eating gm crops on human health
ethical reasons
what two factors cause variation between organisms of the same type
genes
the environment
in adult cell cloning which cell provides the nucleus for the clone
a skin cell from the adult being cloned
how are new genes formed
by mutation
what class of chemicals is used to stimulate the cells in tissue culture
hormones
for natural selection questions what should you remember
mutation of gene—-advantage to survival——-breed——pass on genes
lamaraks theory
his theory stated that characteristics that develop during an organisms lifetime can be passed on to the next generation
darwins theory
theory of natural selection when he went to an island
he noticed that organisms of a particular species show a wide range of variation for a particular characteristic
he also observed that reproduction always gives more offspring than the environment can support
he concluded that those with characteristics best suited for their environment are more likely to survive and breed successfully
Darwin did not know about genes
why did people object darwins theory of evolution
it challenged the creationist theory that god created the earth and all living things on it
many scientists were not convinced because they still did not think there was sufficient evidence for the theory
Darwin theory could not be explained without the knowledge of genetics and variation which was discovered 50 years after darwins death
what is speciation
where the populations become so different that successful interbreeding is no longer possible
what is genetic variation
the wide range of alleles that control the characteristics in a population
what is isolation
where two populations of a species become separated
how can populations become isolated
islands can break away from mainland new rivers can form mountain ranges can separate populations and climate
what are fossils
fossils are the remains of organisms from millions of years ago that can be found in rocks
how can fossils be formed
from the hard parts of animals that do not decay easily
from parts of organisms that have not decayed because some conditions for decay are absent
parts of organisms being replaced by other materials
name a hard part of an animal that will not decay easily
bones
what is extinction
means that a species that once existed has completely died out
what can cause extinction
a new disease can kill all members of a species
a new predator may be introduced to an area that kills and eats all species
a catastrophic event can happen like a volcanic eruption
why might a species die out if the climate changes
climate change may make it too cold or hot or too wet or too dry for a species and reduce its food supply
why do some pathogens spread rapidly
people are not immune to it
there is no effective treatment
what do mutations of pathogens produce
new strains that are resistant to antibiotics
how does antibiotic resistant bacteria become resistant
mutations of pathogens new strains which are resistant to antibiotics
antibiotics kill the individual pathogens that have not developed resistance
the resistant pathogens survive and reproduce and a whole population of a resistant strain develops
how do you slow down the rate of development of resistant strains
antibiotics should not be used for mild infections and patients should always complete each course of antibiotics
what are the three domains called
archaea, bacteria and eukaryota
what is archaea
they are primitive forms of bacteria, including extremophiles that can live in extreme conditions
what kingdom does the domain archaea have
archaebacteria
what kingdom does the domain bacteria have
eubacteria
what is eukaryota
all have cells that contain a nucleus enclosing the genetic material
what kingdoms do eukaryota have
Protista
fungi
plants
animals
why are there no fossils of early life forms
early organisms had soft bodies so any fossils would’ve been destroyed by geological activity
MRSA Is a bacterium resistant to many antibiotic how can the spread be reduced in hospitals
doctors and nurses should wash hands to kill microorganisms
isolate patients to reduce spread of bacteria
make sure visitors wash their hands before and after they leave the hospital to maintain high amount of hygiene
suggest three factors that can change in a habitat area causing problems for the organisms living there
the climate might change hot colder wetter drier
a new predator might move into the area
a new competitor for the food supply might move into the area
what is the main difference between lamaraks theory of evolution and darwins theory
Lamarck suggested that characteristics that developed during the lifetime of the organism could be passed on, Darwin said that organisms with the best characteristic survived to breed and the offspring inherited the characteristic
what are evolution trees
they show the relationship between different groups of organisms
what is geographical isolation give an example
two populations of organisms become separated and live in two different regions for example either side of a river
what are the stages of speciation
isolation of two groups
there is genetic variation in the two populations
alleles are selected that give an advantage
interbreeding is no longer possible because the populations have diverged
therefore a new species has formed
types of genetic testing
antenatal testing
neonatal testing
pre- implantation genetic diagnosis
antenatal testing
Antenatal testing is used to analyse an individual’s DNA or chromosomes before they are born. This testing is offered to couples who may have an increased risk of producing a baby with an inherited disorder, but it can’t detect all the risks of inherited disorders.
neonatal testing
involves analysing a sample of blood that is taken from pricking a baby’s heel. It detects genetic disorders in order to treat them early.
Pre-implantation genetic diagnosis (PGD)
is used on embryos before implantation. Fertility drugs stimulate the release of several eggs.The eggs are collected and fertilised in a Petri dish. This is known as in vitro fertilisation (IVF). Once the embryos have reached the eight-cell stage, one cell is removed.
