B9. Inheritance Flashcards
Define ‘inheritance’.
The transmission of genetic information from generation to generation.
Define ‘chromosome’.
A thread of DNA, made up of a string of genes.
Define ‘gene’.
A length of DNA that is the unit of heredity and codes for a specific protein; a gene may be copied and passed on to the next generation.
Define ‘haploid nucleus’.
A nucleus containing a single set of unpaired chromosomes.
Define ‘diploid nucleus’.
A nucleus containing two sets of chromosomes.
Define ‘allele’.
Any of two or more alternative forms of a gene.
Describe the inheritance of sex in humans (XX and XY chromosomes).
- Of the 23 pairs of chromosomes present in each human cell, one pair is the sex chromosome
- These determine the sex of the individual
- Males have XY, and females have XX.
Define ‘mitosis’.
Nuclear division giving rise to genetically identical cells in which the chromosome number is maintained by the exact duplication of chromosomes.
State the roles of mitosis.
- Helps in growth
- Repairs damaged tissues
- Replaces worn out cells
- Asexual reproduction
Define ‘meiosis’.
As a reduction in which the chromosome number is halved from diploid to haploid.
What are the results of meiosis?
Gametes
Genetic variation so the cells produced are not all genetically identical
Genotype
the genetic makeup of an organism in terms of the alleles present
Phenotype
the physical or other features of an organism due to both its genotype and its environment
Homozygous
having two identical alleles of a particular gene
Heterozygous
having two different alleles of a particular gene
