B6 Flashcards
Process of meiosis
1) Chromosomes in diploid cell are copied
2) Similar chromosomes pair up and genes are swapped between them.
3) Cell divides to produce 2 diploid cells.
4) These cells divide again to produce 4 haploid cells (gametes)
Asexual Reproduction
Plants can reproduce both sexually and asexually.
- Asexual reproduction happens via mitosis; daughter cells are identical - clones (no fusion of gametes)
Advantages of asexual reproduction
- population can rapidly increase
- only one organism needed for reproduction
Disadvantages of asexual reproduction
-no genetic diversity
-difficulty to adapt to environments
Sexual reproduction advantage
-Can become better adapted to environment.
Description of DNA
DNA is a double helix polymer that stores genetic code.
DNA Key Terms
Phenotype; expression of genotype in physical characteristics
Genotype; specific genetic code
Gene; portion of DNA that codes for a protein (by mapping these it allows us to find out the causes of disorders).
Genome; entire genetic make-up of any organism
What is an allele?
Different versions of the same gene
- Dominant alleles are expressed over recessive alleles
- For a recessive allele to be presents in the phenotype, there must be no dominant allele. (E.G, ‘bb’)
What is a homozygous allele?
2 alleles that are the same
E.G, ‘bb’, ‘BB’
What is a heterozygous allele?
2 alleles that are different
E.g, ‘Bb’
Polydactyly and CF
-Polydactyly is caused by a dominant allele
-Cystic Fibrosis is caused by a recessive gene
What is Darwin’s theory of evolution?
Random mutations results in mutation, some organisms are better adapted - those better adapted are more likely to survive.
What is Lamarck’s theory of evolution?
mutations/adaptations are a result of environment affecting characteristics inherited by offspring and so it cannot be random.
Antibiotic resistant bacteria
used as evidence for Darwinian evolution; if not all bacteria are killed, those most resistant will reproduce.
What is selective breeding?
Breeding organisms that have desired characteristics to produce offspring in which the characteristics are more pronounced.
What is genetic engineering?
The insertion of a gene into an organism’s genome so it synthesises a specific protein to achieve a desired characteristic.
Process of GE
1) Desired gene is cut using enzymes
2) Gene inserted into a vector (bacteria/plasmid)
3) Vector inserts gene into cells of another organism early in development
4) Organism develops with desired characteristic due to every cell synthesising that specific protein.
Classification System in order
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Types of domain
Archaea (found in extreme conditions - extremophiles)
Bacteria
Eukaryote
Binomial Names
Genus + Species
