6452 Aiou solved Assignment 2 spring 2023

Course: Biology-II (6452)                  Semester: Spring, 2023

Level: B.Ed. (2.5/4-Year)

Assignment no 2

Question 1: Chargaff’s Rules, DNA Structure, and Diagram

Question: What is Chargaff’s rules? Write the structure of DNA. Also draw the structure of DNA.

Answer:

Chargaff’s Rules: Chargaff’s rules, proposed by Erwin Chargaff, are fundamental principles governing the base composition of DNA:

1. The amount of adenine (A) is equal to thymine (T), and the amount of cytosine (C) is equal to guanine (G). This principle is known as base pairing complementarity.
2. The ratio of purines (A+G) to pyrimidines (C+T) is approximately 1:1.

DNA Structure: DNA (deoxyribonucleic acid) is a double-stranded molecule with a unique structure. It consists of:

• Phosphate Backbone: Alternating sugar (deoxyribose) and phosphate molecules form the backbone of each strand.
• Base Pairs: Adenine (A) pairs with thymine (T) through two hydrogen bonds, while cytosine (C) pairs with guanine (G) through three hydrogen bonds.

DNA Structure Diagram: (DNA structure diagram goes here)

Question 2: Chromosomal Aberrations and Changes in Chromosome Number

Question: What do you know about chromosomal aberration? Changes in the number of chromosomes.

Answer:

Chromosomal Aberration: Chromosomal aberrations are structural changes in chromosomes that can result in genetic disorders. They can involve deletions, duplications, inversions, and translocations. These abnormalities may lead to improper gene expression, disrupted cell division, and a range of phenotypic effects.

Changes in Chromosome Number: Changes in chromosome number are known as aneuploidy. They involve the loss or gain of individual chromosomes. Examples include:

• Trisomy: An extra chromosome is present, e.g., Down syndrome (trisomy 21).
• Monosomy: A chromosome is missing, which is often lethal.

Question 3: Colour Blindness and Its Types

Question: What is color blindness? Describe types of color blindness and their effects.

Answer:

Color Blindness: Color blindness, also known as color vision deficiency, is a genetic condition that affects a person’s ability to perceive certain colors accurately. It results from the absence or dysfunction of specific photoreceptor cells in the retina.

Types of Color Blindness:

1. Protanomaly: Reduced sensitivity to red light. Red and green colors appear less distinct.
2. Deuteranomaly: Reduced sensitivity to green light. Red and green colors may appear similar.
3. Tritanomaly: Reduced sensitivity to blue light. Blue and yellow colors may be difficult to differentiate.
4. Monochromacy: Complete absence of functioning cones, leading to total color blindness.
5. Anomalous Trichromacy: Altered sensitivity of one of the cone types, resulting in difficulties in distinguishing certain colors.

Effects of color blindness vary depending on the type and severity. It can impact daily activities and professions that require accurate color discrimination.

Question 4: Basic Genetic Engineering Techniques

Question: What are basic genetic engineering techniques?

Answer:

Basic genetic engineering techniques involve manipulating an organism’s DNA to achieve desired outcomes. Some techniques include:

1. Restriction Enzymes: These enzymes cut DNA at specific recognition sites, enabling DNA manipulation.
2. DNA Cloning: DNA fragments are inserted into plasmids and then replicated in host cells.
3. Polymerase Chain Reaction (PCR): Amplifies specific DNA segments for analysis or cloning.
4. Gel Electrophoresis: Separates DNA fragments based on size using an electric field.
5. Recombinant DNA: Combines DNA from different sources, forming recombinant molecules.

These techniques underpin advances in biotechnology and genetic research.

Question 5: Life Cycle of Conifers

Question: Give a description of the life cycle of cones.

Answer:

Conifers, a group of seed-producing plants, exhibit a life cycle characterized by alternation of generations:

1. Sporophyte Generation: The dominant phase, consisting of mature trees. Conifer trees produce cones on specialized branches.
2. Cone Formation: Cones are reproductive structures that contain male and female reproductive organs. Male cones release pollen, containing sperm cells.
3. Pollen Dispersal: Wind carries pollen to female cones, enabling fertilization.
4. Fertilization: Sperm cells from pollen fertilize egg cells within female cones.
5. Zygote Formation: Fertilized egg cells form zygotes, which develop into embryos.
6. Seed Development: Zygotes develop into seeds within the female cones.
7. Seed Dispersal: Seeds are released from cones and dispersed by wind or animals.
8. Germination: Seeds that land in suitable conditions germinate, giving rise to new sporophytes.