# Genetics Overview

## Key Questions

Meiosis is the formation of gametes, and gametes contain the genetic information that parents pass to offspring. Additionally, meiosis creates genetic variation.

#### Explanation:

In meiosis, sperm and eggs are formed through spermatogenesis and oogenesis respectively by taking oocytes and spermatocytes(diploids, or having two copies of the same chromosome, one from mom and one from dad) (in more detail at the bottom) splits them up, so you end up with 4 gametes that each have one sister chromatid. These chromatids are just condensed DNA and are our genes.

This increases genetic variation and leads to evolutionary adaptability because it allows the child to have both the mom and the dad's genes without having 92 chromosomes (in the case of humans).

In Meiosis I, the cell goes through similar steps as mitosis, except the chromatids are pulled apart in anaphase I, an entire chromosome is pulled apart. This creates two cells. Finally, those 2 cells have their chromatids pulled apart in meiosis II, resulting in 4 sperm with genetic differences ready to create a baby. In terms of eggs, 4 are created but only 1 survives because the egg splits unevenly so that the one egg that survives has the most amount of nutrients for the baby.

Genetics use probability to predict inheritance

#### Explanation:

We can use the basics of probability to determine the likelihood an offspring will express a trait. One way to do this is using punnet squares, where the genotype for each parent is placed on the left side and the top of the square, as seen below.

We would then fill in the remaining squares by taking one allele/contribution from the corresponding row and the second allele/contribution from the corresponding column. We will end up with two letters in each of the cells that are empty in the above example.

This would be our result:

We have four squares and four options. However, because all four of our options are the same (YG), the chance of having an offspring with the YG phenotype is 100%.

Here is another example of a genetics probability question on Socratic.

It is the study of inheritable characteristics that are given an identity by genes in an organism.

#### Explanation:

Genetics in simple terms is the study of genes, hereditary characteristics, and heritable variations in organisms.

Genetics tries to unravel how genes are responsible for encoding the traits we observe in an organism.

There are three different levels of genetics

1. Transmissible genetics which is basically studying how the hereditary traits are passed from parent. here we study the traits transmission at a singular organism level.

2. Molecular genetics which study the chemical nature of the gene itself and look at how the gene encode the genetic information which is replicated and then used by the organism in the form of protein. here we can even look at same gene across different species, individuals and types of organism. (example can include comparing human and yeast RNA Polymerase structure)

3. Population genetics studies the makeup of the population in one species with large number of individuals to study the variations in the species or gene pool. it also gives us the idea on how a species is evolved from its ancestors.

Note:
These there levels are not obsolete there can be different types of categories like fly genetics (based on organism) where scientist study about fruit fly genetics which can be divided in the above three categories.

Sometimes genetics is divided using structure in different specialized field of genes like chromosomal genetics, where you study about genetics about the chromosomes.