33 terms

DNA Structure

Flash cards for Honor's Biology on the structure of DNA

Terms in this set (...)

What is DNA?
DNA is the molecule that contains the bases that form the code to produce the specific proteins that the organism needs to help determine its traits.
What does the abbreviation "DNA" mean?
Deoxyribose Nucleic Acid.
Why is DNA called the Blueprint for life?
DNA is called the blueprint for life because it has the instructions for making an organism
Where is DNA found?
DNA is found in the nucleus of each cell that the organism has
What is the difference between where DNA is located in a eukaryote cell vs. a prokaryote cell?
Eukaryotes (e.g., animal cells or plan cells) enclose their DNA in the nuclei. Prokaryotes (e.g., bacteria) do not enclose DNA in nuclei.
What is the role of DNA in heredity?
DNA stores, copies and transmits the genetic information in a cell.
What is the foremost job of DNA?
The foremost job of DNA is to store information. The genetic material stores information needed by every living cell.
When does the cell copy information?
Before a cell divides, it must make a complete copy of every one of its genes.
How does a cell transmit information?
When a cell divides, each daughter cell must receive a complete copy of the genetic information.
What is the impact of the loss of DNA during meiosis?
In meiosis, homologous chromosomes line up and move to separate daughter cells. The loss of any DNA during meiosis might mean a loss of valuable genetic information from one generation to the next.
Why would the storage of genetic information in genes help explain why chromosomes are separated so carefully during mitosis?
In mitosis the two sets of genetic material separate and each daughter cell receives one complete set of chromosomes.The loss of any DNA during mitosis would mean that the daughter cell would not receive a complete of chromosomes and valuable genetic information would not be transmitted from one generation to the next.
What is DNA composed of?
DNAis a nucleic acid made up of nucleotides joined into long strands or chains by covalent bonds.
What are nucleic acids?
Nucleic acids are long, slightly acidic molecules originally identified in cell nuclei.
What are nucleotides?
Nucleotides are made up of three components: a 5-carbon sugar called deoxyribose, a phosphate group and a nitrogenous base.
What is a nitrogenous base?
A nitrogenous base is a base that contains nitrogen.
How many nitrogenous bases does DNA contain?
DNA has four nitrogenous bases.
What are the 4 nitrogenous bases of DNA?
The four nitrogenous bases of DNA are Adenine, Guanine, Cytosine and Thymine.
How do biologists often refer to the 4 nitrogenous bases of DNA?
Biologists often refer to the 4 nitrogenous bases by the first letter of their base names: A, G, C and T.
How are the four nitrogenous bases divided?
The four nitrogen containing bases found in DNA are divided into 2 groups: Purines and Pyrimidines. Two-ringed bases are purines (i.e., A and G); and one-ringed bases are pyrimdines (i.e., C and T).
How are the nucleotides in a strand of DNA joined?
The nucleotides in a strand of DNA are joined by a covalent bond formed between the sugar of one nucleotide and the phosphate group of the next.
What is a covalent bond?
A covalent bond is a type of bond between atoms in which the electrons are shared. Remember these are weak hydrogen bonds.
What is Chargaff's Rule?
Chargaff's Rule is named after Erwin Chargaff, and Austrian-American biochemist who discovered that the percentages of adenine (A) and thymine (T) are almost equal in any sample of DNA; and the percentages of guanine (G) and cytosine (C) are almost equal.
Can the nucleotides be joined together in any order?
Yes, the nucleotides can be joined together in any order.
What does "helix" refer to?
Helix refers to an extended spiral chain of units in a protein, nucleic acid, or other large molecule.
Who are the "Fantastic Four" of DNA structure?
Maurice Wilkins, Rosalind Franklin, James Watson, and Francis Crick.
What process did Rosalind Franklin use to get information about the structure of DNA molecules?
Rosalind Franklin used X-ray diffraction to get information about the structure of the DNA molecule.
How did James Watson and Francis Crick describe the structure of a DNA molecule?
Watson and Crick described the structure of a DNA molecule as a double helix, in which two strands of nucleotide sequences were wound around each other.
Do the two strands of DNA run in the same or opposite directions?
The two strands of DNA run in opposite directions, and are said to be "antiparallel."
Why is the fact that the strands are antiparallel important?
This arrangement enables the nitrogenous bases on both strands to come into contact at the center of the molecule, and it allows each strand of the double helix to carry a sequence of nucleotides, arranged almost like letters in a four-letter alphabet.
What is base pairing?
Base pairing describes the fact that the hydrogen bonding only occurs between certain base pairs of nucleotides, namely, A-T, and G-C.
Why does base pairing explain Chargaff's Rule?
Because if A will only pair with T, then for every A there must be an equal percentage of T's; and if G will only pair with C, then for every G there must be an equal number of C's.
What is the "Genetic Code?"
The sequence of bases is what scientists refer to as the "Genetic code."
What is a "Gene?"
A "Gene" is a segment of DNA that codes for a protein, which in turn codes for a trait (skin tone, eye color..etc), a gene is a stretch of DNA.