Abeka Biology Quiz 36 (2024)

FAQs

What term refers to the two-spiral structure of the DNA molecule? ›

​Double Helix

Double helix, as related to genomics, is a term used to describe the physical structure of DNA. A DNA molecule is made up of two linked strands that wind around each other to resemble a twisted ladder in a helix-like shape.

Each nucleosome is made of DNA wrapped around eight histone proteins that function like a spool and are called a histone octamer. Each histone octamer is composed of two copies each of the histone proteins H2A, H2B, H3, and H4.

Within a molecule of DNA, pairs of bases are chemically bonded together by hydrogen bonds. These bonds hold the two strands of the molecule together. Bases pair up with each other in a consistent way, and this process is called complementary base pairing, or Watson-Crick base pairing.

The swim bladder is a gas-filled organ that fish use to adjust their buoyancy in water.

Deoxyribonucleic acid (abbreviated DNA) is the molecule that carries genetic information for the development and functioning of an organism. DNA is made of two linked strands that wind around each other to resemble a twisted ladder — a shape known as a double helix.

To maximize the efficiency of base-pair packing, the two sugar-phosphate backbones wind around each other to form a double helix, with one complete turn every ten base pairs (Figure 4-5).

DNA molecules first wrap around the histone proteins forming beads on string structure called nucleosomes. Nucleosomes further coil and condense/gather to form fibrous material which is called chromatin.

In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.

Whereas eukaryotes wrap their DNA around proteins called histones to help package the DNA into smaller spaces, most prokaryotes do not have histones (with the exception of those species in the domain Archaea). Thus, one way prokaryotes compress their DNA into smaller spaces is through supercoiling (Figure 1).

What type of chemical bond joins the bases of complementary DNA strands? ›

The two strands are held together by hydrogen bonds between pairs of bases: adenine pairs with thymine, and cytosine pairs with guanine.

Gene-silencing RNA molecules recognize specific genetic sequences through complementary base-pairing. These RNA molecules can shut down portions of the genome, turning off protein production. RNA does this by recruiting proteins to modify histones (or the epigenome).

Fish, crustaceans, and many other aquatic animals need to exchange oxygen and carbon dioxide in the water in order to survive. They are able to do this with specialized structures called gills.

A lateral line is a sense organ of microscopic pores used to detect movement and vibration in the surrounding water. Located just under the skin, the lateral line consists of sensory receptors called neuromasts. When the cilia in the neuromasts vibrate, the fish can feel.

Cartilaginous fish, such as sharks and rays, do not have swim bladders. Some of them can control their depth only by swimming (using dynamic lift); others store fats or oils with density less than that of seawater to produce a neutral or near neutral buoyancy, which does not change with depth.

The double helix is a description of the molecular shape of a double-stranded DNA molecule. In 1953, Francis Crick and James Watson first described the molecular structure of DNA, which they called a "double helix," in the journal Nature.

The structure of DNA is a double helix. In other words, it is a double stranded molecule that twists like a spiral staircase.

The term used to describe the relationship between the two strands in a DNA double helix is (D.) complementary. The two DNA strands are complementary because the sequence of nucleotides on one strand determines the sequence on the opposite strand through base pairing rules (A with T and G with C).

The entire structure is called a nucleosome, each of which includes an octamer of histone proteins and 146 to 147 base pairs of DNA. [2][3] The millions of nucleosomes tightly coil the continuous DNA strand into chromatin which is further condensed into the chromosome classically visualized during cell division.