Biology

Molecular Biology and Genetics

985 Questions

Molecular biology and genetics explore the structure and function of DNA, RNA, genetic mutations, and heredity. Understanding these building blocks of life is essential for most biology examinations. Review these practice questions to test your molecular genetics knowledge.

DNA structure and basesGenetic mutationsNucleic acids compositionDNA sequencing and replication

Molecular Biology and Genetics Questions

Multiple choice zoology mutation dna fingerprinting human genome project and dna fingerprinting instruments in biotechnology

Microsatellite sequences are repeat units with base pairs

  1. 1 - 6

  2. 5 - 30

  3. 11 - 60

  4. 20 - 120
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Microsatellites are polymorphic repeating units of 1–6 base pairs in length, found in human DNA. Microsatellites can be amplified for identification by PCR and can be used as molecular markers. Microsatellite analysis (MSA) is a PCR analysis of DNA in exfoliated urine cells.

So, the correct answer is '1-6.'

Multiple choice botany breeding and biotechnology branches of biotechnology gene cloning biotechnology and genetic engineering

Biologically functional gene coding for tyrosine tRNA of E.coil, synthesized by Khorana in 1979, had

  1. 333 nucleotide pairs

  2. 312 nucleotide pairs

  3. 77 nucleotide pairs

  4. 207 nucleotide pairs
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

H. G. Khorana and co-workers synthesized the gene for $E$.$coli$ tyrosine tRNA precursor. The tyrosine tRNA precursor has 126 nucleotides. A complete sequence of dsDNA coding for tyrosine tRNA precursor of E. coli was synthesized. Twenty six small oligonucleotide DNA segments that produced a complete tRNA precursor were synthesized. These oligonucleotides were then arranged into six dsDNA segments. Each ds DNA segment had single stranded ends to facilitate their joining to produce complete gene of 126 base pairs for tyrosine tRNA precursor of E. coli. He then synthesized biologically functional gene coding for tyrosine t-RNA of E.coil. It was 207 base pairs long with 51 bp long promoter region, a 126 bp long precursor region of tRNA, a 25 bp long DNA in which 16 base pairs contained restriction site for EcoRI. Option D is the correct answer.

Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

Which out of the following statements is incorrect?

  1. Genetic code is ambiguous.

  2. Genetic code is degenerate.

  3. Genetic code is universal.

  4. Genetic code is non-overlapping.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since there are 64 triplet codons and only 20 amino acids, genetic code is non-ambiguous. Non-ambiguous code means that there is no ambiguity about a particular code. One codon specifies only one amino acid and not any other except GUG which normally codes for valine but in certain conditions it also codes for N-formyl methionine as initiation codon.

Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

Choose the correct answer from the alternatives given, Human genome consists of approximately

  1. $3 \, \times \, 10^9$ bp
  2. $6 \, \times \, 10^9$ bp

  3. 20,000 + 25,000 bp
  4. $2.2 \, \times \, 10^4$ bp
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The human genome contains 23 chromosomes. The DNA in the haploid set contains 3 billion base pairs.
So, the correct answer is '($3\, \times \,10^9$ bp)'
Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

The genome of Caenorhabditis elgans consists of

  1. 3 billion base pairs and 30,000 genes

  2. 180 million base pairs and 13,000 genes

  3. 4.7 million base pairs and 4,000 genes

  4. 97 million base pairs and 18,000 genes

  5. 12 million base pairs and 6,000 genes
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The genome of the nematode Caenorhabditis elegans is known to consist of approximately 97 million base pairs and contains about 18,000 genes.

Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

Nucleotide pairs present in human genes vary between

  1. 100 - 1000

  2. 500 - 5000

  3. 2000 - 2,000,000

  4. 10,000 - 10,000,000
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The human genome consists of 50,000 to 100,000 genes located on 23 pairs of chromosomes. One chromosome in each pair is inherited from the mother, the other from the father. Each chromosome contains a long molecule of DNA, the chemical of which genes are made. Genes are of differing length, ranging in size from roughly 2,000 to as many as 2,000,000 base pairs. 

So, the correct answer is '2000-2,000,000.'

Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

Total number of base pairs found in human genome is?

  1. $3.5$ million
  2. $35000$
  3. $35$ billion
  4. $3.1$ billion
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The human genome of Homo sapiens is stored on 23 chromosome pairs. 22 of these are autosomal chromosome pairs, while the remaining pair is sex-determining. The haploid human genome occupies a total of just over 3 billion DNA base pairs that means 6 billion base pairs per diploid cell.
So, the correct answer is '3.1 billion'.
Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

The commonly used hosts in HGP ________________.

  1. Bacteria and yeast

  2. Bacteria and fungi

  3. Protozoa and bacteria

  4. Plants and fungi
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the Human Genome Project, DNA fragments were cloned into vectors and propagated in host organisms to be sequenced. Bacteria (using BACs) and yeast (using YACs) were the primary hosts used for this purpose.

Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

Select the wrong statement.

  1. The human genome contains $3164.7$ million nucleotide bases
  2. Less than $10\%$ of the genome codes for protein

  3. Repeated sequences make up very large portion of the human genome
  4. Chromosome $1$ has most genes $(2968)$ and Y has the fewest $(231)$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A human being has an estimated 30,000 genes located on 46 chromosomes (23 pairs). These genes are known, collectively, as the human genome, with a total of about 3 billion DNA base pairs. Thus, option A is correct.

Each chromosome contains hundreds to thousands of genes, which carry the instructions for making proteins. Each of the estimated 30,000 genes in the human genome makes an average of three proteins. Protein-coding sequences (specifically, coding exons) constitute less than 1.5% of the human genome. Aside from genes (exons and introns) and known regulatory sequences (8–20%), the human genome contains regions of noncoding DNA. More than 90 percent of the genome is noncoding DNA, sometimes called "junk" DNA, that has no known function. Therefore, option B seems correct.

Repeated Sequences (also known as repetitive elements or repeats) are patterns of DNA or RNA that occur in multiple copies (in arrays of tandemly repeated sequence or dispersed repeats) throughout the genome. They have been recognized as a potential source of genetic variation and regulation, with over two-thirds of a sequence consisting of repetitive elements in humans. Thus, Option C is correct.

Chromosome 1 is the largest human chromosome, representing approximately 8 percent of the total DNA in cells. Two copies of chromosome 1, one copy inherited from each parent, form one of the pairs, containing around 2000 genes that provide instructions for making different proteins.
The Y chromosome is one of the two sex chromosomes in humans (the other is the X chromosome). The Y chromosome (found in males) represents almost 2 percent of the total DNA in cells. It likely contains 60-70 genes that provide instructions for making proteins, involved in male sex determination and development. Therefore, Option D although correct shows wrong numbers.

Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

The total number of nitrogenous bases in human genom is estimated to be about

  1. 3.5 million

  2. 35 thousand

  3. 35 million

  4. 3.3 billion
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Human genome has around 21,000 genes in its 3.3 billion base pairs haploid genome. The haploid DNA content of a cell is called as C-value. The C-value paradox is concerned with presence of excessive amounts of DNA in eukaryotic cells and the difference of C-value between eukaryotic species having similar complexity. Presence of large amount of base pairs is explained on the basis of large amount of structural DNA and junk DNA in chromosomes. Thus, correct answer is '3.3 billion'.