Inheritance Flashcards
Definition of gene
Sequence of DNA that occupies a specific locus on a chromosome and codes for a polypeptide
Definition of allele
A varied nucleotide sequence for a particular gene
What is monohybrid inheritance?
Inheritance of a single gene
Test cross
Individual has phenotype of dominant characteristic but genotype is unknown
Crossed with an individual that is homozygous recessive
What is co dominance
Both alleles are expressed individually
Blood groups
Incomplete dominance
Phenotype is a intermediate between two parent phenotypes
What is independent assortment?
Maternal and paternal chromosomes mix with each other in any combination at metaphase 1 of meiosis
What is dihybrid inheritance?
Simultaneous inheritance of two unlinked genes
What is the null hypothesis for the chi test?
There is no difference between the observed and expected results
Any deviation is due to chance
What is a hermaphrodite?
Flowers make both pollen and ovules
Monoecious plants
Separate male and female flowers on the same plant
Dioecious plants
Separate male and female individuals
Factors controlling whether an individual is male or female
- Temperature
- Sequential hermaphroditism
- can become hermaphrodite and fertilise itself
- hierarchy
- ploidy level
- chromosome structure
Definition of mutation
A change in quantity or structure of the DNA of an organism
When is the cell cycle do mutations occur?
DNA replication in s phase
What increases the rate of mutations?
- ionising radiation
- mutagenic chemicals
4 ways mutations occur
- gene or point mutation
- chromosome mutation
- anueploidy
- polyploidy
What is a gene point mutation?
DNA polymerase changes the base sequence
How can gene point mutations occur?
- addition
- duplication
- subtraction
- substitution
What is non disjunction
Faulty spindle can result in chromosomes not being shared equally between daughter cells. One receives 2 copies of a chromosome while the other receives none.
What is polyploidy?
Have more than 2 complete sets of chromosomes
How does polyploidy arise?
- chromosomes move to same pole
- 2 diploid gametes fuse
- endomitosis- replication of chromosomes not followed by cytokinesis
Why is polyploidy more common in plants?
- reproduce asexually
- hermaphrodite
What is epigenetics?
Changes to gene expression but not the DNA nucleotide sequence
