Inheritance (Cell Division) Flashcards
What are the two types of cell division?
Mitosis
Meiosis
What cells are the result of mitosis?
Two genetically identical diploid cells
The cells are genetically identical to the parent cell and eachother
What is the process of mitosis?
Each chromosome in the nucleus of the diploid parent cell copies itself exactly (forms x shaped chromosomes)
The chromosomes line up in the centre of the cell, where cell fibres pull them apart
The cell divides, forming two exact copies of the original cell
What is mitosis used for?
Growth
Repair
Cloning
Asexual reproduction
What cells are the result of meiosis?
Four genetically different haploid cells
They are genetically different because they have a random one of the two alleles possesed by the individual for each gene
What is the process of meiosis?
Each chromosome in the nucleus of the diploid parent cell copies itself exactly (forms x shaped chromosomes)
The maternal and paternal pairs line up along the centre of the cell, recombination occurs and then cell fibres will pull the pairs apart
This leads to the cell dividing once, forming two diploid cells with one of each recombinant pair of chromosomes
The two cells then each divide once without copying their chromosomes, forming a total of four haploid cells
What is meiosis used for?
It is used for the production of gametes (sperm, egg, pollen)
It produces variation by forming new combinations of maternal and paternal chromosomes
How does random fertilisation lead to genetic variation?
In meiosis, every haploid cell (gamete) produced will be genetically unique as it will have a unique combination of maternal and paternal chromosomes (so a unique combination of alleles)
Because of this, each gamete (egg, sperm) will be genetically different in an organism so the random fusion of any of these gametes will result in a genetically different zygote, leading to genetic variation
What is the other way variation in organisms can occur other than genetic and what are examples?
Environmental
For example, diet causes you to gain weight, an accident can cause scarring, trees in the shade will grow taller than normal in order to reach the light
What’s the difference between continuous and discontinuous features?
Continuous feautres, like height, are when there are very small degrees of differences and variation is seen on a spectrum
Discontinuous features, like blood group, are when there are no inbetweens
In human cells, what is the diploid number of chromosomes?
46 chromosomes (23 pairs)
In human cells, what is the haploid number of chromosomes?
23 chromosomes
