Modes of Reproduction Flashcards
Define asexual reproduction
Is the process resulting in the production of genetically identical offspring from one parent without the fusion of gametes
Advantages of asexual reproduction
- Only one parent required
- Fusion of gametes not required
- Beneficial qualities passed on
- Faster than sexual repro
What is the disadvantage of asexual reproduction
- No genetic variation in offspring, species not well adapted to changes in the environment
Define mitosis
Mitosis is a part of cell division which produces two daughter cells that are genetically identical to each other, chromosome number is maintained
Name the order of phases in mitosis
Prophase, metaphase, anaphase, telophase
Define cytokinesis
The division of the cytoplasm to produce two completely separated daughter cells
Describe cytokinesis in animal cells
Cleavage or furrow appears between two nuclei in cytoplasm, deepens until parent cell pinches into two daughter cells, each with complete nucleus and share of organelles
Describe cytokinesis in plant cells
A cell plate forms by the fusion of vesicles produced by the Golgi apparatus.
State the importance of mitosis
To maintain genetic stability of an organism, meaning two daughter cells formed are genetically identical and contain same number of chromosomes as the parental cell
What is maintained in mitosis to be exactly the same
Identical chromosome numbers, exact genetic information and diploid set of chromosomes
How does mitosis help growth
Increase in number of cells within the organism (e.g. development of fertilised egg)
How does mitosis help repair the organism
Regeneration and replacement of cells and tissues lost in normal processes of wear and tear, aging, damage and disease
How does mitosis help in asexual reproduction
Reproduction of an organism without production of gametes
Why must cells be genetically identical
So that they can carry out the same function. New cells that replace damaged cells must be exact copies of original cells for tissue to function properly
Define haploid
Haploid cells have only one set of chromosomes, where number of chromosomes is represented by n, normally gametes/sex cells
Define diploid cells
Those with two sets of chromosomes in the nucleus, number of chromosomes in diploid cell represented by 2n
What are somatic cells
Human somatic cells are all body cells except gametes, dividing by mitosis. 46 chromosomes arranged into 23 pairs of homologous chromosomes, one from mother one from father
Define sexual reproduction
Sexual reproduction is the process involving the fusion of the haploid nuclei of the male and female gametes to form a zygote.
Advantages of sexual reproduction
May inherit beneficial qualities, genetic variation
Disadvantages of sexual reproduction
Two parents are usually needed, fusion of gametes needed, slower
Similarities between asexual and sexual reproduction
Both processes pass on genetic materials to the offsprings, produce new offspring
Define homologous chromosomes
A pair of chromosomes having identical structural features
What are some similarities between homologous chromosomes
Same length, size and shape
Same centromere position
Genes for same biological features at corresponding location on the chromosome, thus determine same traits, but may have different alleles
What is allele
Allele is alternative form of gene which occupies same location on a pair of homologous chromosomes
Define meiosis
A part of cell division that produces genetically dissimilar cells containing half the number of chromosomes as the parent cell
Why is chromosome number halved due to separation of homologous chromosomes
To maintain the constancy of number of chromosomes from generation to generation, as when nucleus of two gametes fuse the diploid number for the species will be recovered
State importance of meiosis
Produces haploid genes and produces gametes that are genetically dissimilar
How does meiosis produce haploid gametes
During meiosis, each pair of homologous chromosomes in parent nucleus separates to form daughter cells, each daughter cell receives one copy, when two gametes fuse diploid number is restored and maintained
Why does meiosis produce gametes that are genetically dissimilar
Greater genetic variation, better species is adapted to changes in environment. increases likelihood that at least some individuals would possess desirable traits to adapt to new environment
