inheritance, variation, evolution Flashcards
asexual reproduction
- 1 parent
- no fusion of gamets
- production of genetically identical offspring
- mitosis
gamets are
sex cells
sexual reproduction
- fusion of male and female gametes
- mix of genetic information
- meiosis
animal gametes
sperm + egg
flowering plants gametes
pollen + egg
meiosis
- copies of genetic information made
- Cell divides twice to form four gametes
- > single set of chromosomes (haploid)
- all gametes are genetically different
genome of an organism
The entire genetic material of that organism
uses of genome
- search for genes linked to disorders
- scientists understand cause of inherited disorders (how to treat)
- investigate how humans may have changed our time
characteristic of genome are controlled by…
a single gene
alleles
different forms
blue eyes, brown hair
genotype
combination of alleles present in a gene
BB
phenotype
how the alleles are expressed
blue eyes
alleles can be either
- dominant
- recessive
homozygous
two alleles are the same
BB,bb
heterozygous
alleles are different
Bb
dominant
captial letter
recessive
lowercase letter
monohybrid inheritance
1 gene involved
polydactyl
extra finger or toe
->causes by dominant allele
cystic fibrosis
disorder of cell membrane
->caused by a recessive allele
females
XX
males
XY
offspring inherits
- 1 sex chromosome from mother (X)
- 1 sex chromosome form father(X/Y)
variation may be due to the differences:
- the genes that individuals have inherited (genetics)
- conditions in which individuals have developed (environment)
mutations create
new alleles
evolution
gradual change in the inherited characteristics of population over time
evolution can lead to
the formation of new species
natural selection
-states that all species have evolved from simple life forms that first developed more than 3 billion years ago
who thought of natural selection?
charles darwin
natural selection occurs because:
- within a species more individuals are born than can survive
- differences in their genes
- individuals with characteristics best suited to environment (more likely to survive)
- > more likely to survive
evidence for evolution
- when theory was published, mechanism of inheritance and variation was not known
- now shown that characteristics are passed on from 1 generation to the next by genes
fossils
remains of organisms from hundreds of thousands of years ago found in rock
fossils formed:
- from the hard parts of animals that do not decay easily
- from parts of organisms that have not decayed, because conditions needed were absent
- when parts of the organisms are replaced by other materials they decay
- footprints
scientists use fossils…
to look at how organisms have gradually changed over long periods of time
problems of fossils
- earth forms of life were soft bodied
- > left few traces behind
- what traces there were may have been destroyed my geological activity
development of antibiotic resistant strains of bacteria
-bacteria can evolve rapidly
-when reproduce mutations occur
-bacteria might be resistant, antibiotics not killed
-bacteria survive + reproduce
—> resistant strain develops
steps of selective breeding (artificial selection)
1) chose parents that best show desired characteristics
2) breed together
3) from offspring chose those with desired characteristics
4) continue over many generations
selective breeding:
the process by which humans breed plants + animals with particular, desirable characteristics
selective breeding characteristics:
- disease resistance in food crops
- animals that produce more meat/milk
- domestic dogs with gentle nature
- large or unusual flowers
selective breeding can lead to
inbreeding
- probe to disease
- inherited defects
genetic engineering involves
changing the characteristics of an organisms by introducing a gene from another organism
genetics engineering is
a more recent way of bringing about changes in organisms
in genetic engineering
1) enzymes are used to isolate desired gene
2) gene is inserted into a vector (bacterial plasmid / virus)
3) the vector is used to insert the genes into the required cell
fungi and bacteria cells are
genetically engineered to produce useful substances
main system way to remember
kid prefer chips over fancy green salads
main system
kingdom phylum class order family genus species
new models of classification proposed because:
- microscopes improved (know more about cells)
- biochemical processes became better understood
for evidence there is a
three domain system
in tds organisms are divided into:
- archaea
- bacteria
- eukaryota
archaea
- primitive bacteria
- living in extreme environments
bacteria
true bacteria
eukaryota
nucleus
protists, fungi, plants + animals
extinction is caused by
- changes in environment
- new predators
- new diseases
- new,more successful competitors
- single catastrophic event (volcanic eruption)
evolutionary trees
method used by scientists to show how they think organisms are related
