Question

BIU A A E 8. A DNA molecule has two strands (double helix) – how many of its strands are/is used during replication and transcription? 9. What is the difference between transcription and translation occurring in Prokaryotes and eukaryotes? 10. What is the relation between mRNA and genetic code? 11. Using genetic code table-list the corresponding aminoacids for triplet code: CAG, GAG, CAC, AUA, GUA, GCA and UGA, UAA and UAG 12. How many start and stop codons are there? 13. If the DNA single strand is AATTGGCCCGTAT, the what will be the complementary second strand of DNA? second 14. If the DNA single strand is AATTGGCCCGTAT, the what complementary RNA strand will be synthesized? Chapter # 4 Genetics 15. What is phenotype - give examples 16. What is genotype- give examples 17. What is an allele? 18. What is the difference between an allele and a chromosome 19. Who was Gregor Mendel- why he is regarded as Father of Genetics 20. Why did Mendel choose pea plants to understand how traits are inherited or passes on from one generation to the other? acer o 06 A

Answer 1

ANSWER

Part 8

During replication, both strands of DNA are used as template to synthesize new complementary strands. Template strands are known as parent strands while new strands are called as daughter strands. In contrast to replication, only one DNA strand is used to synthesize the RNA and the process is known as transcription. This strand is known as template or non-coding strand while the other strand (which is not utilized during transcription) is known as coding strand as it has exact sequences like RNA strand except for uracil that is absent in DNA strand.

Part 9

In prokaryotes, both transcription and translation take place in cytoplasm because of the absence of nucleus. However, in eukaryotes, transcription takes place in nucleus and translation occurs in cytoplasm.

In prokaryotes, transcription and translation happen at the same time. This means while transcription is still occurring, protein synthesis also initiates along with it. But in eukaryotes, both the processes occur at different places (transcription in nucleus and translation in cytoplasm). So, transcription and translation never take place simultaneously.

Prokaryotic RNA does not undergo any modications but eukaryotic RNA undergoes several post-transcriptional modifications including 5'- capping, intron splicing, 3'-polyadenylation.

Part 10

Messeanger RNA or mRNA is made up of nucleotide sequences that are used to synthesize amino acid chain which forms a polypeptide. These nucleotide sequences are read by transfer RNA (t-RNA) in the form of codons, a three-letter nucleotide sequence. Codons are also known as triplets and each codon or triplet encodes a particular amino acid during translation. However, more than two codons can also encode a particular amino acid.

Part 11

11. CAG GAG CAC AUA GUA G CA UGA UAA UAG 1 - Gen- Geu His-Ile-Val - Ala Brop codons

Part 12

There are three stop codons present, which are UGA, UAA and UAG. These are known as universal stop codons.

Part 13

13- 13 s' АРТТе са се сетят | | | | | ттен ссссссөтө 5' complementary DNA strand 3'

Part 14

19 5 99 TT е су се сетят UŲ AAÇÇGGGCAUA complementary RNA strand д! 5'

Part 15

Phenotype is an observable traits of an organism which arise as a combination of genotype and the surrounding environment. Example- Skin color, hair color, height, weight.

Part 16

The combination of certain alleles which determine the phenotype of an organism is known as genotype. Example- Genotype for hair color would be BB (Black), Bb (Brown) and bb (blonde).

Part 17

Allele is a variant of a gene. In other words, it is an alternative gene form which exists on the same chromosomes. Mutation and natural selection are the key forces which lead to the formation of different alleles of the same gene in an organism or a population.

Part 18

The major difference between chromosome and allele is that, the chromosome is a segment of DNA which contains several genes. These genes have further different forms of alleles which are present on the particular loci on the chromosomes.

Part 19

Gregor Mendel was a monk and a scientist and is popularly known as 'Father of Genetics'. He made outstanding discoveries regarding inheritance pattern of several traits. From his pea plant experiments, he concluded genes are present in the form of pairs and they are inherited from parents to offspring and to subsequent generations. Mendel was the first one who unfolded the idea behind dominant and recessive traits and how they express in the organism. Because of this, he is regarded as father of genetics.

Part 20.

Mendel chose pea plants because

1. These plants have a short life cycle, thus, several generations were easy to observe in a short time.

2. Pea plants exhibit bisexual traits i.e. they are hermaphrodite.

3. They can self-pollinate and produce pure breed.

4. Their traits can be easily identified such as round and wrinkled seeds, purple and white flowers, yellow and green seeds.