Chapter 22 Self-test questions

. Which of the following does NOT contain phosphate?

A nucleoside.

A nucleotide.

DNA.

RNA.

. Which of the following is a purine?

Adenine.

Thymine.

Uracil.

Cytosine.

. Which of the following statements is correct, according to Chargaff's rules?

All DNA molecules contain the same proportions of A, C, G and T.

Single-stranded RNA molecules contain the same amount of A and U.

In double-stranded DNA, the amount of T equals the amount of C.

In double-stranded DNA, the amount of G equals the amount of C.

. Which of the following statements about DNA structure is correct?

Stacked base pairs of DNA interact by van der Waals interactions.

The A form of DNA is the form usually found in cells.

The diameter of the DNA double helix (B form) is 10 nm.

The DNA double helix is left handed.

. Approximately what proportion of the human genome is made up of repetitive DNA sequences?

1%

15%

50%

90%

. Which of the following statements about the human genome is correct?

About 1.6% of the genome encodes protein sequences.

All non-protein coding sequences in the genome are believed to be 'junk' DNA with no function.

Introns are the sections of protein-coding genes that actually encode amino acid sequences.

The human genome is believed to contain approximately 50,000 protein coding genes.

. Which of the following is true of histones?

Histones are acidic proteins.

Histones are found in animal chromatin but in not in plant cells.

The amino acid sequences of histone proteins are very similar in different organisms.

All histones form part of the nucleosome core particles in chromatin.

. Double-stranded DNA molecules that are AT-rich DNA melt at a lower temperature than GC-rich DNA–true or false?

True.

False.

. If a DNA sequence is written: CATTAAG, you can assume that the 'C' is the 5' end and the 'G' is the 3' end.

True.

False.

. The DNA in a eukaryotic chromosome is many times longer than the chromosome itself. How many times longer is the DNA in a human chromosome than the length of the chromosome?

10 x

100 x

10,000 x

1,000 x

. Which of the following statements is correct? Please select all that apply.

The enzyme that retroviruses and retrotransposons use to synthesise DNA is known as reverse transcriptase.

Transposons occur only in eukaryotes.

Transposons are responsible for most of the repetitive DNA in human cells.

Transposons have no known direct function but they may have benefits in evolution.

. A large part of the human genome has in the past been regarded as 'junk' DNA. Which of the following statements about 'junk' DNA is correct according to our current understanding? Please select all that apply.

About 1.6% of the human genome has no known function and has been described as 'junk' DNA.

Bacteria have no junk DNA.

There are no genes in junk DNA.

MicroRNA genes do not code for proteins.

. Which of the following statements about split genes is correct? Please select all that apply.

The coding sequence in human genes is interrupted by spacer sequences called exons.

Human genes can be split by up to 500 spacer sequences.

Most genes in bacteria are not split.

The biggest human gene is bigger than the E. coli genome.

Chapter 22 Self-test questions

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