M3 L2 Chromosome Structure

The macromolecular complex of DNA, histones, and nonhistone chromosomal proteins is called

chromatin

Humans cells each contain almost _____ of DNA that is packaged up into a nucleus ~ 10 µm in diameter. Packing this much DNA into the nucleus is analogous to stuffing ____ of spaghetti into a ____

-2 meters -10,000 miles - basketball

In eukaryotic cells, the genome is divided into linear segments of ____ and packaged into structures called _____

-DNA -Chromosomes

coding information for genes

-One gene's sense strand can be another gene's anti-sense strand. -Only one of the two strands of DNA contains coding info to make RNA. -The coding strand has the same nucleotide sequence as the resulting RNA (excepting for T and U).

Interphase cells are characterized by____ chromosomes that are _____ within the nucleus.

-less condensed -organized in discrete regions

The chromosomes we typically see in images are isolated from ____ cells These chromosomes are in the most highly condensed form. But most of the time, cells are in the______ part of the cell cycle. During this phase, the chromosomes are ______ and less densely packed.

-mitotic -interphase -still organized within the nucleus

The ____ interaction between DNA and nucleosome core octamer is primarily mediated by______ This occurs because the surface of the octamer contains a lot of_____ amino acid side chains and the ____ of DNA have_____

-noncovalent -electrostatic attractions -basic -sugar-phosphate backbones -a negative charge

T/F Prokaryotes and eukaryotes use the same mechanisms to package up their DNA.

FALSE

T/F 5' and 3' UTRs are transcribed into RNA, but not translated into protein. Therefore, they are considered to be nonfunctional parts of a gene.

FALSE 5' and 3' UTRs are functional because they contain regulatory information for mRNA processing and translation.

T/F Introns are spliced out of DNA before a gene is transcribed to RNA and therefore do not contribute to the final protein sequence.

FALSE Introns are transcribed to RNA but spliced out of the RNA molecule before translation. Therefore, introns do not contribute to the final protein sequence.

T/F All functional DNA sequences inside a cell code for protein products.

FALSE not all functional DNA sequences code for protein. Some sequences encode only RNA molecules (tRNA, rRNA, other non-coding RNA molecules). Other DNA sequences bind to specific regulatory proteins (like transcription factors, for example). Other DNA sequences are sites where specific chromosomal protein structures are built (for example, centromeric and telomeric DNA).

T/F Gene sequences correspond exactly to the respective protein sequences produced from them.

FALSE this statement is false for two reasons. First, genes often contain intron sequences. Second, genes always contain nucleotides flanking the protein-coding sequences that are required for the regulation of transcription and translation.

What type of macromolecule helps package DNA in eukaryotic chromosomes?

proteins

T/F Each eukaryotic chromosome must contain the following DNA sequence elements: multiple origins of replication, two telomeres, and one centrosome. These are examples of functional DNA sequences that do not code for RNAs or proteins

true

The octameric histone core is composed of four different histone proteins, assembled in a stepwise manner. Once the core octamer has been formed, DNA wraps around it to form a nucleosome core particle. Which of the following histone proteins does NOT form part of the octameric core?

H1

The classic "beads-on-a-string" structure is the most decondensed chromatin structure possible. Which component of chromatin is important for bundling up the beads-on-a-string into the more compact 30 nm fiber?

H1 linker histones