Chapter 24-DNA: The Regulation of Life Flashcards
By the mid 1940s, scientists had begun to realize that a mysterious substance in the nucleus of a cell, known as __________________, somehow controlled heredity.
Deoxyribonucleic acid, DNA
Who were the two biochemists who deduced the actual structure of DNA, which revealed that each gene of an organism is the part of the DNA molecule that controls a particular trait?
James D. Watson
Francis H. C. Crick
The discoveries by biochemists James D. Watson and Francis H. C. Crick revealed that each _____________ of an organism is the part of the DNA molecule that controls a particular trait.
Gene
Within your body, every somatic cell contains 46 _________________ in the nucleus, each of which contains one molecule of DNA.
Chromosomes
Ordinarily, short segments of each DNA molecule are coiled on protein “spools” called:
Histones
Groups of eight histones (protein spools) are clustered together to form a:
Nucleosome
The millions of protein “spools” filling the nucleus give the nucleus a grainy texture when viewed under a powerful microscope. Scientists after refer to DNA stored in this manner as:
Chromatin
The bundles of tightly coiled _________ are the chromosomes that are visible during mitosis and meiosis.
DNA
Besides DNA, the other important nucleic acid in the cell is:
Ribonucleic acid, RNA
Both nucleic acids, DNA and RNA, are composed of special molecules called:
Nucleotides
Each DNA molecule consists of two long nucleotide chains that are twisted about one another, giving the molecule the shape of a twisted ladder. Scientists refer to this double-spiral structure as a:
Double helix
What are the four different types of bases that make up the “rungs” in a DNA molecule?
Guanine (G)
Cytosine (C)
Adenine (A)
Thymine (T)
Only one type of __________________ will “fit” another. (thymine+adenine), (guanine+cytosine).
Base (guanine, cytosine, adenine, thymine)
The process in which only one type of base will “fit” another is called:
Base pairing
The structure of an RMA molecule is similar to that of DNA, except the ___________ consists of only one strand instead of two.
RNA
Three of the bases in DNA (guanine, cytosine, and adenine) are identical to those of DNA. However, RNA uses a base called __________________ instead of thymine.
Uracil
What is the process by which DNA makes a copy of itself before cell division called?
Replication
Through what process does the cell copy the information contained in the DNA into messenger RNA (mRNA) molecules?
Transcription
Through what process do mRNA molecules provide the information to the ribosomes to make protein molecules through:
Translation
Scientists have found that many viruses, like the HIV virus, are able to make DNA starting from molecules of RNA in a process called:
Reverse transcription
When a new protein is needed, the DNA coding for that protein is transcribed into a __________________ molecule?
Messenger RNA
Molecules of _______________ collect free amino acid molecules and carry them to ribosomes to be assembled into proteins.
Transfer RNA
What serves as the part of the structure of the ribosomes themselves and is the most abundant type of RNA in the cell?
Ribosomal RNA
What is a consecutive sequence of three nucleotides in the mRNA which translates into one specific amino acid?
Codon
