III: 3 - Inheritance Flashcards
3.1 Chromosomes 3.2 Mitosis 3.3 Meiosis 3.4 Monohybrid inheritance 3.5 Variation 3.6 Selection 3.7 Genetic engineering
Define
genetics
Genetics is the study of inheritance
Define
inheritance
The transmission of genetic information (DNA/genes) from generation to generation.
Define
chromosome
A thread of DNA, made up of a string of genes
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.
Allele
Any of two or more alternative forms or variety of a gene
Haploid nucleus
A nucleus containing a single set of unpaired chromosomes, e.g. in sperm cells and egg cells.
Diploid nucleus
A nucleus containing two sets of chromosomes, e.g. in body cells.
How is sex inherited in humans?
The 23rd pair of chromosomes in humans is responsible for sex. Females have an XX chromosome pair, whilst males have XY.
The egg cell always carries an X chromosome, whilst the sperm will carry either X or Y. Therefore, it is the sperm that affects which sex the offspring will be.
Define
mitosis
Nuclear division giving rise to genetically identical cells in which the chromosome number is maintained by the exact duplication of chromosomes
What is the role/significance of mitosis?
- Growth
- Repair of damaged tissues
- Replacement of worn out cells
- Asexual reproduction.
Define
meiosis
Reduction division in which the chromosome number is halved from diploid to haploid
What is the role/significance of meiosis?
- Produces gametes
- Results in genetic variation so the cells produced are not all genetically identical
- Keeps chromosome number in a species that undergoes sexual reproduction
What are the differences between mitosis and meiosis?
Define
monohybrid inheritance
and
monohybrid cross
Monohybrid inheritance is the inheritance of a single characteristic for which two alleles are inherited.
A monohybrid cross is the study of the inheritance of one characteristic.
Genotype
Refers to the genetic makeup of an organism in terms of the alleles present, e.g. Tt or GG.