MA 2

In humans, it appears that the 20,000 functional genes occupy less than ______ of the human genome.

2%

LINES and SINES are repetitive sequences that make up about _________ percent of the human genome.

35%

Which of these statements about heterochromatin are TRUE? Heterochromatin remains relatively condensed (tightly coiled) during the cell cycle. Heterochromatin has relatively few genes. Heterochromatin is found in the telomeres and centromere.

All

Which of the following are examples of heterochromatin? Select all that apply. centromeric DNA telomeric DNA repetitive DNA

All. (Repetitive DNA is often associated with heterochromatin. At the centromere, these heterochromatic repetitive sequences facilitate binding of spindle fibers during segregation of homologous chromosomes and sister chromatids. Telomeric repetitive sequences are involved in the maintenance of the chromosome's structural integrity.)

n E. coli, the genetic material is composed of

Circular, double-stranded DNA

What is the first order of chromatin packing?

Coiling around nucleosomes (The first order of chromatin packing occurs when DNA coils around nucleosomes, whereby DNA is reduced to about one‑third its original length)

Chromatin is made of

DNA and proteins

Viral chromosomes exist in a variety of conformations and can be made up of

DNA or RNA

euchromatin vs heterochromatin

Euchromatin: many genes expressed, less chromatin condensation Heterochromatin: condensed chromatin, few expressed genes (Chromatin exists in different states of compaction and relaxation that regulate access to DNA by regulatory proteins. Heterochromatic regions of chromosomes are relatively inaccessible to transcriptional proteins either transiently (in the case of facultative heterochromatin) or nearly always (in the case of constitutive heterochromatin). In contrast, in euchromatic chromosome regions, transcriptional proteins and enzymes are more easily able to gain access to DNA.)

T/F: Each human contains an identical set of VNTRs.

False

T/F: Viral genomes are always linear, double-stranded DNA.

False

T/F: TATAGCGTAGCTAGCT repeated in tandem over and over is a gene sequence that codes for a protein.

False (The majority of repetitive DNA serves no known function)

T/F: The second order of chromatin packing occurs when nucleosomes coil together to form a fiber that is 300 nm in diameter.

False (The second order of chromatin packing occurs when nucleosomes coil together to form a solenoid fiber that is 30 nm in diameter.)

A sequence of about 300 base pairs is found at different locations on many different chromosomes in the genome. The sequence shows up about 550,000 times in the genome. This illustrates a:

SINE (Sequence is not in tandem because it is not next to each other over and over, instead it is found in many places in the genome. Thus it is eaither a SINE or LINE. Sequences less than 500 base pairs are considered SINES.)

What makes up the protein component of a nucleosome core?

Two tetramers of histone proteins. (One tetramer is composed of two units each of histones H2A and H2B, and the other is composed of two units each of histones H3 and H4.)

Living organisms are categorized into two major groups based on the presence or absence of a nucleus. What group is defined by the presence of a nucleus?

eukaryotic organism

Which of the following have circular chromosomes made of double-stranded DNA? mitochondria chloroplasts prokaryotes eukaryotic nuclear chromosomes

mitochondria chloroplasts prokaryotes

CGCGCGCGCGCGCGCGCGCGCGCGCGCG represents a sequence we wouldl categorize as a:

short-tandem repeat (STR)

All EXCEPT which of the following are examples of repetitive DNA? variable number tandem repeat (VNTR) DNA telomerase gene DNA SINE DNA telomere DNA

telomerase gene DNA (The DNA sequence constituting the gene for telomerase is euchromatin and is relatively unique.)