Which processes lead to most genetic variation in sexually reproducing organisms?
Meiosis: Meiosis is the process of cell division that happens in the gametes or sex cells during sexual reproduction. Meiosis ensures the introduction of genetic variation. In Meiosis, the cell divides twice in such a way that four cells are formed from one parent cell.
How are sister chromatids and homologous chromosomes different from each other?
Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication.
What is a major difference between mitosis and meiosis I in a diploid organism?
What is a major difference between mitosis and meiosis I in a diploid organism? Sister chromatids separate in mitosis, while homologous pairs of chromosomes separate in meiosis I. A student is looking through his light microscope (~450 X) at a squashed and stained onion root tip.
How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 2n 8 )?
How many possible gamete combinations are there for an organism that has a diploid number of 8? 24 = 2 X 2 X 2 x 2 = 16 different combinations. 12. Homologous chromosomes a.
What are the 3 types of genetic variation?
For a given population, there are three sources of variation: mutation, recombination, and immigration of genes.
What are the 5 sources of genetic variation?
- random mating between organisms.
- random fertilization.
- crossing over (or recombination) between chromatids of homologous chromosomes during meiosis.
Is a sister chromatid a chromosome?
The two copies of a chromosome are called sister chromatids. As long as the sister chromatids are connected at the centromere, they are still considered to be one chromosome. However, as soon as they are pulled apart during cell division, each is considered a separate chromosome.
Are sister chromatids made only of DNA?
A sister chromatid refers to the identical copies (chromatids) formed by the DNA replication of a chromosome, with both copies joined together by a common centromere. In other words, a sister chromatid may also be said to be ‘one-half’ of the duplicated chromosome.
What is the difference between homologous and nonhomologous chromosomes?
Main Difference – Homologous vs Non-homologous Chromosomes
Homologous chromosomes refer to the chromosomes in the same pair while non-homologous chromosomes refer to the chromosomes in different pairs.
What is the major difference between mitosis and meiosis I?
Mitosis results in two identical daughter cells, whereas meiosis results in four sex cells.
Which of the following do the two chromosomes of the pair have in common?
If we choose one of these pairs, suck as pair 14, which of the following do the two chromosomes of the pair have in common? Length, centromere position, staining pattern, and traits coded for by their genes.
When can Nondisjunction occur choose the best answer?
When can nondisjunction occur? Choose the best answer. Nondisjunction errors can occur in meiosis I, when homologous chromosomes fail to separate, or in either mitosis or meiosis II, when sister chromatids fail to separate. You just studied 33 terms!
How do you calculate chromosomes?
The number of chromosomes does not correlate with the apparent complexity of an animal or a plant: in humans, for example, the diploid number is 2n = 46 (that is, 23 pairs), compared with 2n = 78, or 39 pairs, in the dog and 2n = 36 (18) in the common earthworm.
How many different chromosome combinations are possible?
There are 8,324,608 possible combinations of 23 chromosome pairs. As a result, two gametes virtually never have exactly the same combination of chromosomes. Each chromosome contains dozens to thousands of different genes.
How does crossing over increase variation in genes?
The chromosomes cross over at points called chiasma. At each chiasma, the chromosomes break and rejoin, trading some of their genes. This recombination results in genetic variation.