B6 - Inheritance, Variation & Evolution Flashcards
What is meiosis?
The process in which gametes (sex cells) are made - genetically different from parent cells
What are the stages of meiosis?
- Chromosomes in diploid cell (23 pairs) copied
- Similar chromosomes pair up and genes are swapped between them
- The cell then divides to make two diploid cells
- Those cells divide again along with the chromosomes to make 4 haploid cells (gametes)
What is asexual reproduction?
It happens by mitosis.
The the daughter / child / offspring’s cells will be identical (cloned)
Advantage - only one parent is needed
What is the genome?
The entire genetic code in an organism.
What is DNA and a gene?
DNA: double helix polymer - stores genetic code
Gene: portion of DNA that codes for a protein - mapping these allows us to identify causes of disorders
What is a genotype and a phenotype?
Genotype: an organism’s specific genetic code
Phenotype: how the code is expressed in physical characteristics
What are alleles?
Different versions of the same gene
What are dominant and recessive alleles?
Dominant - expressed even when genotype contains a recessive allele
Recessive - must both be the same recessive allele in order for it to be expressed in the phenotype
What do homozygous and heterozygous mean?
Homozygous - Two alleles for a particular gene (characteristic) are the same (e.g. BB or bb)
Heterozygous - Two alleles for a particular gene (characteristic) are different (e.g Bb)
What are inherited disorders?
- Passed down from parents to offspring
- Caused by mutations in alleles - a mutation change in DNA
- Non-communicable (not caused by a pathogen)
- Can be caused by dominant or recessive alleles
What is Polydactyly?
- A person with extra fingers and/or toes
- Caused by a dominant allele - PP or Pp
What is Cystic Fibrosis?
- Disorder of the cell membranes
- Abnormally thick mucus is produced - cough or low energy/weight
- Caused by a recessive allele (f) parents must be a carrier of this allele
What is Darwin’s theory of evolution?
- Random mutations result in variation
Some organism’s better adapted to the environment
These compete (survival of the fittest)
Those better adapted are more likely to survive - over time these desirable characteristics are more pronounced
What is Larmack’s theory of evolution?
- Mutations/adaptations are a result of environment affecting characteristics inherited by offspring; not random
What is a species?
An organism is the same species if they can produce fertile offspring
What is selective breeding?
Breeding organism’s that have desired characteristics to produce offspring in which they 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
Describe the process of genetic engineering.
- Desired gene is cut from another organism’s DNA using enzymes
- Gene is inserted into a vector (e.g a bacteria plasmid or virus)
- Vector inserts gene into cells of another organism early in development
- Organism develops with desired characteristic due to every cell synthesising that specific protein
What are fossils?
The decayed remains of organisms (or evidence of their existence)
- Fossils that look like bones are bones that have been replaced with minerals
- Some fossils can still have soft organic tissue if the conditions for decay aren’t present
- Hardened footprints in mud are fossils (as are other traces of organism’s left behind)
What is the order of classification?
Kingdom
Phylum
Class
Order
Family
Genus
Species
Could remember with:
King Philip Came Over For Good Soup
What is the binomial name for an organism?
Genus + Species
What does Domain consist of?
It’s the level above Kingdom.
- Archaea (primitive bacteria, extremophiles)
- Bacteria (true bacteria)
- Eukaryota (everything else - DNA contained in nucleus)
