Modes of reproduction Flashcards
Define asexual reproduction
Asexual reproduction is the process resulting in the production of genetically identical offspring from one parent without the fusion of gametes
What are some disadvantages of asexual reproduction
- No genetic variation in offspring, species cannot adapt to changing environment
What are some advantages of asexual reproduction
- Only 1 parent required
- Fusion of gametes not required
- Relatively faster
- All beneficial qualities passed onto offspring
What is the Cell Theory
The Cell Theory states that all news cells are derived from pre-existing cells through the process of cell division
Why does DNA replication take place
Ensures that the daughter cell receives the same amount of DNA as the parent cell
Define mitosis
Mitosis is a part of cell division which produces 2 genetically identical daughter cells so the chromosome number is maintained
Describe the process of mitosis
Prophase
- Chromatin condense, coil and shorten to form chromosomes
Metaphase
- Chromosomes line up at the equator of spindle
Anaphase
- Each centromere splits
- Spindle fibres pull chromatids apart to opposite poles of cell
Telophase
- Chromosomes decondense to form chromatin
Define cytokinesis
Cytokinesis is a process that occurs right after mitosis, where cytoplasm is divided to produce 2 completely separated daughter cells
Describe cytokinesis in animal cells
- Cleavage or furrow appears between the 2 nuclei
- Deepens until 2 separated daughter cells are formed
How is mitosis important in repair
Replace old cells and tissues lost by normal processes of wear and tear
Describe cytokinesis in plant cells
- Cell plate forms by fusion of vesicles from Golgi apparatus
Why is mitosis important
Mitosis maintains the genetic stability of an organism by maintaining identical chromosomal numbers, exact genetic information and diploid set of chromosomes throughout generations
How is mitosis important in growth
Increase number of cells within organism
Define haploid cells
Haploid cells are cells that only have 1 set of chromosomes
(Gametes)
How is mitosis important in asexual reproduction
Allow for reproduction without the fusion of gametes
Why is the production of genetically identical cells important
New cells need to carry out the same function as old cells to be able to replace them properly
Define diploid cells
Diploid cells are cells that have 2 sets of chromosomes
(Somatic body cells)
Define homologous chromosomes
Homologous chromosomes are a pair of chromosomes that have identical structural features, with one chromosome inherited from each parent
How are homologous chromosomes identical
- Same length
- Same size
- Same shape
- Same centromere position
Define an allele
An allele is an alternative form of a gene which occupies the same location on a pair of homologous chromosomes
Define meiosis
Meiosis is part of cell division that produces genetically dissimilar cells containing half the number of chromosomes as the parent cell, hence is used to form gametes
Why is the chromosome number halved during meiosis
Homologous chromosomes are separated
What is reduction division
Reduction division is when homologous chromosomes are split, resulting in the production of gamete cells with half the number of chromosomes as the parent cell
Why is meiosis important
- Produces haploid gametes that are genetically dissimilar
What does mitosis result in
2 genetically identical daughter cells with the same number of chromosomes as parent cell
What does meiosis result in
4 genetically dissimilar daughter cells with half the number of chromosomes as parent cell
Where does mitosis occur
All somatic body cells
Where does meiosis occur
Reproductive organs
