DNA

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Biology › DNA

Questions 1 - 10
1

How can synteny help with understanding chromosomes?

It can indicate conserved regions

It can indicate crossover events

It can indicate recombination events

It can indicate hybridization

It can indicate recessive neofunctionalization

Explanation

Synteny is the conservation of order of genes. Being able to see conserved blocks in genes when comparing two chromosomes of the same species, it indicates that at some time in evolutionary history, these blocks originated from a hypothetical common ancestor. Genes that are highly conserved among species are usually vital to the organism's viability. For example, the genes required for glycolysis to occur are required in almost all organisms.

2

Which of the following replication proteins is used to unwind the DNA double helix?

Helicase

Primase

DNA polymerase

DNA ligase

Explanation

DNA helicase unwinds the double helix, separating the two strands so they may be replicated by DNA polymerase.

Primase adds an RNA primer to help initiate DNA replication. DNA ligase is responsible for joining Okazaki fragments on the lagging strand during replication.

3

A genome is best described as which of the following?

The entire set of DNA found within all chromosomes

The free floating DNA found outside the nucleus

The DNA specifically found in bacterial cells

A mapping unit for DNA

A computer system for storing DNA information

Explanation

Based on the definition of genome, it is the entire set of DNA found within all the chromosomes an organism contains. The human genome is contained on 23 pairs of chromosomes, which code for about 25,000 genes.

4

How can synteny help with understanding chromosomes?

It can indicate conserved regions

It can indicate crossover events

It can indicate recombination events

It can indicate hybridization

It can indicate recessive neofunctionalization

Explanation

Synteny is the conservation of order of genes. Being able to see conserved blocks in genes when comparing two chromosomes of the same species, it indicates that at some time in evolutionary history, these blocks originated from a hypothetical common ancestor. Genes that are highly conserved among species are usually vital to the organism's viability. For example, the genes required for glycolysis to occur are required in almost all organisms.

5

Which of the following RNA molecules is responsible for carrying the code that will be read at the ribosome in order to create a protein?

mRNA

tRNA

rRNA

snRNA

Explanation

Messenger RNA, or mRNA, is the RNA strand that is transcribed from the gene found on DNA. It is responsible for being read by a ribosome in order to create a protein.

Ribosomal RNA (rRNA) forms a structural component of the ribosomes. Transfer RNA (tRNA) carries amino acid residues and provides an anticodon to add the amino acids to the growing protein at the ribosome. Small nuclear RNA (snRNA) are found in the nucleus and help regulate transcription and maintain telomere length.

6

Which of the following is not correct regarding eukaryotic DNA?

DNA is found in the nucleus, cytoplasm, and ribosomes.

Deoxyribose is the sugar that composes DNA.

DNA runs antiparallel in a 5' to 3' direction.

DNA's bases include adenine, guanine, thymine, and cytosine.

DNA is self-replicating.

Explanation

All of the responses are correct except that eukaryotic DNA is found in the nucleus, cytoplasm, and ribosomes. In eukaryotes, DNA is only found in the nucleus, mitochondria, and only sometimes free floating in the cytoplasm. DNA is not found in ribosomes. RNA on the other hand, is found in the nucleus, cytoplasm, and ribosomes. Note that since prokaryotes lack membrane-bound organelles, their DNA is free-floating in the cytoplasm.

7

How can synteny help with understanding chromosomes?

It can indicate conserved regions

It can indicate crossover events

It can indicate recombination events

It can indicate hybridization

It can indicate recessive neofunctionalization

Explanation

Synteny is the conservation of order of genes. Being able to see conserved blocks in genes when comparing two chromosomes of the same species, it indicates that at some time in evolutionary history, these blocks originated from a hypothetical common ancestor. Genes that are highly conserved among species are usually vital to the organism's viability. For example, the genes required for glycolysis to occur are required in almost all organisms.

8

A genome is best described as which of the following?

The entire set of DNA found within all chromosomes

The free floating DNA found outside the nucleus

The DNA specifically found in bacterial cells

A mapping unit for DNA

A computer system for storing DNA information

Explanation

Based on the definition of genome, it is the entire set of DNA found within all the chromosomes an organism contains. The human genome is contained on 23 pairs of chromosomes, which code for about 25,000 genes.

9

Which of the following replication proteins is used to unwind the DNA double helix?

Helicase

Primase

DNA polymerase

DNA ligase

Explanation

DNA helicase unwinds the double helix, separating the two strands so they may be replicated by DNA polymerase.

Primase adds an RNA primer to help initiate DNA replication. DNA ligase is responsible for joining Okazaki fragments on the lagging strand during replication.

10

Which of the following is not correct regarding eukaryotic DNA?

DNA is found in the nucleus, cytoplasm, and ribosomes.

Deoxyribose is the sugar that composes DNA.

DNA runs antiparallel in a 5' to 3' direction.

DNA's bases include adenine, guanine, thymine, and cytosine.

DNA is self-replicating.

Explanation

All of the responses are correct except that eukaryotic DNA is found in the nucleus, cytoplasm, and ribosomes. In eukaryotes, DNA is only found in the nucleus, mitochondria, and only sometimes free floating in the cytoplasm. DNA is not found in ribosomes. RNA on the other hand, is found in the nucleus, cytoplasm, and ribosomes. Note that since prokaryotes lack membrane-bound organelles, their DNA is free-floating in the cytoplasm.

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