Genetics Terminology, DNA Structure, Punnett Squares, and Cell Division: A Comprehensive Overview

WORKSHEET
1.1 Define Genetics Terminology.
Some of the genetics terminology are:
1) Gene : DNA segments carry all the genetic information. This information is called
genes, Gene is a sequence of DNA bases. These bases are adenine, guanine, cytosine,
thymine. It decides the order of amino acids (Lodish et al., 2013).
2) Carcinogen: Any substance which has the potential of causing cancer
3) Allele: Allele is a different form of gene. When the copies of gene is different, they
are known as alleles.
4) Chromosome: Chromosome is the thread like structure that contains the DNA
molecules and situated inside the nucleus.
5) RNA: RNA is single stranded nucleic acid made up of nucleotides and does the
function of translation, transcription and decoding to produce proteins.
1.2 Explain the Structure of DNA.
Source: (Berry & Crowley, 2013)
DNA carry genetic information. This information are known as genes. DNA consists of
nucleotides. Nucleotide consists of four parts. A nitrogen base, a phosphate group, a sugar
molecule group. In addition, a nitrogen base. Further, there are four types of nitrogen bases.
These are adenine, Thymine, cytosine , guanine. the order of these nitrogen bases. Human
DNA consists of 3 billion nitrogen bases (Prusiner, 2013). Nucleotides are attached closely
together and forms 2 long strands forming a double helix structure also known as ladder
structure. Like in a ladder, the two sides are phosphates and sugar molecules while bases are
considered the rungs. Adenine to thymine and cytosine binds to guanine.
1.3 Predict outcomes using Punnett Squares

Punnet square is a simple graphical way to represent all the possible outcomes of genotypes
during the breeding. The gentic composition should be known. These outcpmes are
represented in a tabular form. The boxes of the punnet square simply stands for the entire
alternative that could occur if we mate in between each of the different gametes.
Monohybrid cross is a cross that simply looking at one trait. Consider if we are crossing
purple flowers (PP) that are homozygous with that of the homozygous white flowers (pp), PP
is the dominant trait whereas pp is the recessive trait, so the only possible outcome here is 1:1
ratio.
Source: (Cheetham, 2013)
In case of heterozygous, what we get is 1: 2: 1 genotype ratio and 3: 1 phenotype ratio
Source: (Cheetham, 2013)
In case of , incomplete dominance, we get a 1: 2:1 of the same ratio for both phenotypic and
genotypic ratio.

Source: (Cheetham, 2013)
During the dihybrid cross when we look at the parent, that is RrYy × RrYy,
The four gametes that could be produced with this parent are RY, Ry, rY, ry
9:3:3:1 is what we get in this dihybrid cross where
1) 9 are the phenotypes of round and yellow seeds,
2) 3 of the phenotypes are round and green
3) 3 of the phenotypes are yellow and wrinkled
4) The one is left alone.
These are all the possible outcomes of punnet square by taking an example
2.2 Explain the various cycle of mitosis and meiosis
Mitosis is the division of the cell in which the mother cell is divided into two daughter cells
that are genetically identical. Mitosis can also be defined as the division process in which the
DNA of the cell's nucleus is split equally into two sets of chromosomes. Various stages of
mitosis are:
Source: (Su, Singer & Srinivasan, 2015)
1. Prophase: In early prophase, some structures are break down while others are build
up by the cell. In addition, it sets the stage for division of the chromosomes. In late
prophase, the mitotic spindle begins to capture and organize the chromosomes.
2. Metaphase: In metaphase, the spindle has captured all the chromosomes and lined
them up at the middle of the cell. Now it is ready for division.