Table of Contents
What is the simple structure of DNA?
The DNA molecule consists of two strands that wind around one another to form a shape known as a double helix. Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups. Attached to each sugar is one of four bases–adenine (A), cytosine (C), guanine (G), and thymine (T).
What is the structure of a DNA molecule?
Double Helix Double helix is the description of the structure of a DNA molecule. A DNA molecule consists of two strands that wind around each other like a twisted ladder. Each strand has a backbone made of alternating groups of sugar (deoxyribose) and phosphate groups.
What is DNA simple?
The molecule inside cells that contains the genetic information responsible for the development and function of an organism. DNA molecules allow this information to be passed from one generation to the next.
What is the size of A DNA molecule?
about 2 inches reference quote length The World Book Encyclopedia . Chicago, World Book, 1999. On the average, a single human chromosome consists of DNA molecule that is about 2 inches long. 2 , 3 m.
What is the appearance of the DNA molecule?
Mandira P. A molecule of DNA looks like a spiral staircase. The steps of the stair represents paired bases attached by hydrogen bonds.
How many strands of DNA are in A cell?
Each chromosome is formed by 2 strands of DNA tied by hydrogen bonds to each other making the classic DNA double helix (double-stranded DNA). So, in total there are 46*2=92 strands of DNA in each diploid human cell!.
Where is topoisomerase located?
Topoisomerase is also found in the mitochondria of cells. The mitochondria generate ATP as well as playing a role in programmed cell death and aging. The mitochondrial DNA of animal cells is a circular, double-stranded DNA that requires the activity of topoisomerase to be replicated.
What are the steps of replication of DNA in a cell?
DNA replication steps. There are three main steps to DNA replication: initiation, elongation, and termination. In order to fit within a cell’s nucleus, DNA is packed into tightly coiled structures called chromatin, which loosens prior to replication, allowing the cell replication machinery to access the DNA strands.
What is a replication bubble?
A replication bubble is an unwound and open region of a DNA helix where DNA replication occurs. Helicase unwinds only a small section of the DNA at a time in a place called the origin of replication. In eukaryotes, there are several origins of replication on each chromosome.
What is a DNA strand?
This mitochondrial DNA is more like bacterial DNA—a single long, circular piece of DNA made up of two strands of DNA. A DNA strand is a long, thin molecule—averaging only about two nanometers (or two billionths of a meter) in width.
What is DNA ks3?
DNA stands for deoxyribonucleic acid. It is a chemical made up of two long molecules, arranged in a spiral. We refer to this as the double-helix structure. DNA carries genetic information. It has all the instructions that a living organism needs to grow, reproduce and function.
How many atoms are in a DNA molecule?
Everything except subatomic particles is made out of atoms. DNA is composed of five different atoms (in various combinations): C — Carbon. H — Hydrogen.
How is DNA is formed?
DNA is made of chemical building blocks called nucleotides. These building blocks are made of three parts: a phosphate group, a sugar group and one of four types of nitrogen bases. To form a strand of DNA, nucleotides are linked into chains, with the phosphate and sugar groups alternating.
How much DNA is in a single cell?
How much DNA does a human cell contain? A human cell contains about 6 pg of DNA.
Why is DNA helical in structure?
The helical structure of DNA arises because of the specific interactions between bases and the non-specific hydrophobic effects described earlier. Within the helix, the two complementary DNA chains form what is called an antiparallel helix, where strands have opposite 5′ to 3′ polarity.
Which of the following is part of a DNA molecule?
DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C).
Why is DNA an acid?
DNA or RNA are called nucleic acids because of the acidic nature of the phosphate group attached to them. The phosphodiester bond can easily lose the proton in the presence of nucleophile group subsequently masking the basic nature of nitrogenous bases.
How many chromosomes does a human have?
In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females.
What is DNA code?
The DNA code contains instructions needed to make the proteins and molecules essential for our growth, development and health. There are 20 different amino acids, which are the building blocks of proteins. Different proteins are made up of different combinations of amino acids.
Is helicase a topoisomerase?
Summary – Helicase vs Topoisomerase Helicase is an enzyme that separates annealed two strands of DNA, RNA or DNA-RNA hybrid by breaking hydrogen bonds between bases. In contrast, topoisomerase is an enzyme that creates single-stranded or double-stranded breaks to relieve stress during supercoiling.
What does helicase enzyme do?
Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.
Is gyrase A topoisomerase?
DNA gyrase is an essential bacterial enzyme that catalyzes the ATP-dependent negative super-coiling of double-stranded closed-circular DNA. Gyrase belongs to a class of enzymes known as topoisomerases that are involved in the control of topological transitions of DNA.
