What terms describes the dna–protein complexes that look like beads on a string?

The "beads on a string" in the chromatin are DNA-protein complexes called Nucleosome.

Explanation:

The Nucleosome has got the following components:

1. Each nucleosome is about 11 nanometre in diameter.

2. It comprises of the following regions: (i) a core and (ii) a linker.

3. The core region of the nucleosome has about 146 base pairs of DNA that forms 1.67 rotations around a histone protein octamer forming the core particle.

4. Each histone octamer is made up of four types of core histone proteins, H2A, H2B, H3 and H4 respectively. Each of these proteins are present in two copies per nucleosome.

5. The core histone-DNA  particles are linked to each other by an approximately, 80 base-pair long DNA, called the linker DNA.

6.The linker DNA region of the nucleosome binds to another histone protein called the H1 histone. The H1 histone is responsible for condensing or decondensing the chromatin, depending upon whether that region of the DNA is necessary for transcription or replication, by decreasing or increasing the length of the linker region of the DNA respectively.

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blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.