Table of Contents
How many ways can you line up in metaphase?
There are two possible ways pairs of homologs (also known as tetrads) can line up on the metaphase plate during Metaphase I. This possible number of alignments equals 2n, where n is the number of chromosomes per set.
What aligned during metaphase?
During metaphase, the cell’s chromosomes align themselves in the middle of the cell through a type of cellular “tug of war.” The chromosomes, which have been replicated and remain joined at a central point called the centromere, are called sister chromatids.
How do you calculate the number of possible combinations of a chromosome?
The possible combinations are equal to 2n, where n is the haploid number. For the organism in Figure 9-18, n = 2, so the number of chromosome combinations is 22, or 4. For a human, n = 23, so there are 223, or about 8 million, possible chromosome combinations!.
How do you find all possible gametes from a parental genotype?
Simply place a 2 above each heterozygous gene pair and a one above each homozygous gene pair. Then multiply the numbers together to obtain the total number of different possible gametes.
How many possible genetic combinations are there?
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 many possible gamete types of drakes can be generated through the process of crossing over alone?
from an original cell that contains a diploid number of 46 (2n=46)? 3. How many possible gamete types can be generated through the process of crossing over alone? Mitosis (begins with a single cell) Meiosis (begins with a single cell) # chromosomes in parent cells 46 46 # DNA replications 1 1 # nuclear divisions 1 2.
How many possible genetic combinations can arise from meiosis?
= 256 different combinations.4 days ago.
What are the 4 stages of the cell cycle?
In eukaryotes, the cell cycle consists of four discrete phases: G1, S, G2, and M. The S or synthesis phase is when DNA replication occurs, and the M or mitosis phase is when the cell actually divides. The other two phases — G1 and G2, the so-called gap phases — are less dramatic but equally important.
Why is karyotyping done in metaphase only?
Karyotype is done at metaphase because metaphase is the only stage in cell cycle when the chromosomes are unduplicated and line up along the equatorial plate of the spindle. The chromosomes are easier to see when they are elongated and uncondensed.
How are chromosomes arranged during metaphase and anaphase?
In metaphase (a), the microtubules of the spindle (white) have attached and the chromosomes have lined up on the metaphase plate. During anaphase (b), the sister chromatids are pulled apart and move toward opposite poles of the cell. Following prometaphase, metaphase begins.
What 3 things happen in metaphase?
In metaphase, the mitotic spindle is fully developed, centrosomes are at opposite poles of the cell, and chromosomes are lined up at the metaphase plate.
How many possible combinations of maternal and paternal chromosomes are there?
The total possible number of different gametes is 2n, where n equals the number of chromosomes in a set. In this example, there are four possible genetic combinations for the gametes. With n = 23 in human cells, there are over 8 million possible combinations of paternal and maternal chromosomes.
How many different combinations are possible between human maternal and paternal chromosomes?
Exactly two maternal and two paternal chromosomes always move to each of the two poles. The first to move influences all the others. They align and assort independently to form any of 16 different combinations.
What are the possible chromosome combinations in the two daughter cells?
Humans have 23 pairs of chromosomes. That means that one person could produce 223 different gametes. In addition, when you calculate the possible combinations that emerge from the pairing of an egg and a sperm, the result is (223)2 possible combinations.
What gamete possibilities could come from this parent’s genotype AaBb?
There are four possible combinations of gametes for the AaBb parent. Half of the gametes get a dominant A and a dominant B allele; the other half of the gametes get a recessive a and a recessive b allele. Both parents produce 25% each of AB, Ab, aB, and ab.
How many genotypes are possible with 4 alleles?
4 alleles there are 1 + 2 + 3 + 4 = 10 genotypes.
What are the possible gametes an individual with genotype AA can produce?
An individual with the genotype Aa can make two types of gametes: A and a. Since this is a random process, the individual will, on average, make equal numbers of each gamete. (Frequency of 1/2 for each gamete).
How many combinations are possible with 4 DNA base pairs?
256 That is correct. In a tetranucleotide block where the nucleotides can appear more than once and the order is random, there can be 256 possible combinations.
How many combinations are possible with 8 DNA base pairs?
For 8 base pairs, there are 48=65536 possible combinations.
How many unique humans are possible?
The number is essentially infinite. Using an estimate of mutation frequency of around 2 x 10^-8 per base pair per replication event, we get 60 novel mutations in every living human being. There are 7 billion humans, so we know that some 420 billion different variants are possible.
How many possible gametes can be formed following meiosis excluding crossing over events from an original cell that contains a diploid number of 16?
, where n = number of different chromosomes. b. Using that formula, how many chromosomal combinations can result from meiosis when the diploid number is 16? = 256 different combinations.
What would happen if crossing over did not happen?
If crossing over did not occur during meiosis, there would be less genetic variation within a species. Also the species could die out due to disease and any immunity gained will die with the individual.
How does independent assortment during metaphase I help to produce diverse gametes?
The law of independent assortment states that the random orientation of homologous chromosome pairs during metaphase I allow for the production of gametes with many different assortments of homologous chromosomes.
What is the difference between metaphase in mitosis and metaphase 1 in meiosis?
In metaphase 1 the pairs of chromosomes referred to as bivalents are totally condensed. Moreover the in metaphase 1 of meiosis there is no centromere division whereas in metaphase of mitosis it does. They align on the metaphase plate in between the poles.
How many Tetrads align at the metaphase plate of meiosis I?
The orientation of each tetrad is independent of the orientation of the other 22 tetrads. This event—the random (or independent) assortment of homologous chromosomes at the metaphase plate—is the second mechanism that introduces variation into the gametes or spores.
Why do siblings look different meiosis?
After all, kids get their genes from the same parents. But brothers and sisters don’t look exactly alike because everyone (including parents) actually has two copies of most of their genes. And these copies can be different. Parents pass one of their two copies of each of their genes to their kids.
