# How many possible gamete combinations are there for an organism that has a diploid number of 8?

Table of Contents

## How many possible gamete combinations are there for an organism that has a diploid number of 8?

16 different combinations

## How many different chromosomal combinations can result from meiosis in a species that has a diploid 2N number of 8 assume no crossing over occurs?

Sixteen different combinations

## How do you calculate the number of possible chromosome combinations?

If you know the haploid number for an organism, you can calculate the number of possible combinations in the gametes. 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.

## How many different combinations are possible in the gametes of an organism whose haploid number is 3?

At meiosis I, homologous pairs are separated irrespective of the maternal or paternal origin of the chromosome. This leads to variation in the combinations of chromosomes found in the haploid cells at the end of meiosis II. With three pairs of chromosomes, there are 23 = 8 combinations.

## How does a gamete end up with an extra chromosome?

When a sperm fertilizes an egg, the union leads to a baby with 46 chromosomes. But if meiosis doesn’t happen normally, a baby may have an extra chromosome (trisomy), or have a missing chromosome (monosomy). These problems can cause pregnancy loss. Or they can cause health problems in a child.

## Is there a way to prevent chromosomal abnormalities?

There is no treatment that will prevent embryos from having chromosome abnormalities. The older a woman gets, the higher the chances that an embryo will have an abnormal number of chromosomes. This is why women have a higher miscarriage rate as they get older.

## What increases the risk of chromosomal abnormalities?

Several factors increase the risk of having a baby with a chromosomal abnormality: Woman’s age: The risk of having a baby with Down syndrome increases with a woman’s age—steeply after age 35. Family history: Having a family history (including the couple’s children) of a chromosomal abnormality increases the risk.

## What causes the most common chromosomal abnormality called trisomy 21?

Also known as Down syndrome, trisomy 21 is a genetic condition caused by an extra chromosome. Most babies inherit 23 chromosomes from each parent, for a total of 46 chromosomes. Babies with Down syndrome however, end up with three chromosomes at position 21, instead of the usual pair.