Biology- Chapter 10 Flashcards
Molecular Biology
The study of heredity at the molecular level
Nucleotides
Both DNA and RNA are nucleic acids, which consist of long chains ( polymers) of chemical units (monomers) called this.
Polynucleotides
Can be very long and may have any sequence of the four different types of nucleotides ( A, C, T, AND G)
Sugar - Phosphate Backbone
The result of repeating pattern of sugar phosphate sugar phosphate, which is known as this. When nucleotides are joined together by covalent bonds between the sugar of one nucleotide and the phosphate of the next.
DNA
DeoxyriboNucleic Acid , with nucleic referring to DNA’s location in the nuclei of eukaryotic cells.
The bases of DNA can be divided into two types:
Thymine (T) and Cytosine (C) : single-ring structures
Adenine (A) and Guanine (G) : are larger, double-ring structures.
RNA contains what instead of Thymine?
It contains Uracil (U), and the R in RNA stands for Ribose
Compare and Contrast the chemical components of DNA and RNA.
Both are polymers of nucleotides ( a sugar + a nitrogenous base + a phosphate group ). In RNA, the sugar is ribose; in DNA, it is deoxyribose. Both RNA and DNA, have the bases A, G, and C, but DNA has T and RNA has U.
Double Helix
The thickness of the helix suggested that it was made up of two polynucleotide strands.
How does complementary base pairing make DNA replication possible ?
When the two strands of the double helix separate, each serves as a template on which nucleotides can be arranged by specific base pairing into new complementary strands.
What enzymes connect nucleotides together during DNA replication?
DNA polymerases
DNA Polymerases
The enzymes that make the covalent bonds between the nucleotides of a new DNA strand.
What are transcription and translation ?
Transcription is the transfer of genetic information from DNA to RNA. Translation is the use of the information in an RNA molecule for the synthesis of a polypeptide.
How many Nucleotides are necessary to code for a polypeptide that is 100 amino acids long?
300
Codons
The genetic instructions for the amino acid sequence of a polypeptide chain are written in DNA and RNA as a series of three-base words.
Transcription
The transfer of genetic information from DNA into an RNA molecule
Translation
the transfer of the information from RNA into a polypeptide
Genetic Code
Is the set of rules that convert a nucleotide sequence in RNA to an amino acid sequence.
RNA Polymerase
RNA nucleotides are linked by the transcription enzyme that is called this.
Terminator
In the third phase, termination, the RNA polymerase reaches a special sequence of bases in the DNA template called this.This signals the end of the gene.
How does RNA polymerase “know” where to start transcribing a gene?
It recognizes the gene’s promoter, a specific nucleotide sequence.
mRNA
In the cells of prokaryotes, which lack nuclei, the RNA transcribed from a gene immediately functions as this, the molecule that is translated into a protein
Cap and Tail
Protect RNA from attack by cellular enzymes and help ribosomes recognize the RNA as mRNA.
Introns
Most genes of plants and animals, it turns out , include such internal noncoding regions, called this.
Exons
The coding regions -the parts of a gene that are expressed
RNA splicing
Before RNA leaves the nucleus, the introns are removed, and the exons are joined to produce an mRNA molecule with a continuous coding sequence.
Why is the final mRNA often shorter than the DNA gene that coded for it?
Because introns are removed from the RNA
tRNA
Transfer RNA: To convert the three letter words (codons) of nucleic acids to the amino acid words of proteins, a cell uses a molecular interpreter called this.
Anticodon
At one end of the folded molecule is a special triplet of bases called this.
Ribosomal RNA
Each subunit is made up of proteins and a considerable amount of yet another kind of RNA, this.
What is an anticodon?
An anticodon is the base triplet of a tRNA molecule that couples the tRNA to a complementary codon in the mRNA. The base pairing of anticodon to codon is a key step in translating mRNA to a polypeptide.
Start Codon
Where translation is to begin on the mRNA
Which of the following does not participate directly in translation: ribosomes, transfer RNA, messenger RNA, DNA?
DNA
Stop codon
Elongation continues until this reaches the ribosomes’s A site.
Transcription is the synthesis of __, using ___ as a template.
mRNA; DNA
Translation is the synthesis of___, with one___ determining each amino acid in the sequence.
Protein (polypeptides); codon
Which organelle coordinates translation?
Ribosomes
Mutation
Any change in the nucleotide sequence of a cell’s DNA
What would happen if a mutation changed a start codon to some other codon?
mRNA transcribed from the mutated gene would be nonfunctional because ribosomes would not initiate translation
What happens when one nucleotide is lost from he middle of a gene?
In the mRNA, the reading of the triplets downstream from the deletion is shifted , leading to a long string of incorrect amino acids in the polypeptide.
Lytic Cycle
Most phages enter a this reproductive cycle. After many copies of the phage are produced within the bacterial cell, the bacterium lyses (breaks open)
Lysogenic Cycle
Some viruses can reproduce through this alternative route. Viral DNA replication occurs without phage production or the death of the cell.
Describe one way some viruses can perpetuate their genes without immediately destroying the cells they infect
Some viruses can insert their DNA into the DNA of the cell they infect ( the lysogenic cycle). The viral DNA is replicated along with the cell’s DNA every time the cell divides.
What are three ways that viruses can get into a plant?
Through lesions caused by injuries, transfer by insects that feed on the plant, and contaminated farming or gardening tools.
Why is infection by herpesvirus permanent?
Because Herpesvirus leaves viral DNA in the nuclei of nerve cells.
AIDS
Acquired ImmunoDeficiency Syndrome
HIV
Human Immunodeficiency Virus
Retrovirus
An RNA virus that reproduces by means of DNA molecule, the reverse of the usual DNA to RNA flow of genetic information.
Reverse transcriptase
AIDS AND HIV carry this, it catalyzes reverse transcription: the synthesis of DNA on an RNA template.
Provirus
The resulting double stranded viral of DNA then enters the cell nucleus and inserts itself in the chromosomal DNA becoming this.
Why is HIV called a retrovirus ?
Because it synthesizes DNA from its RNA genome. This is the reverse (“retro”) of the usual DNA to RNA information flow.
Prions
Cause a number of brain diseases in various animal species.
What makes prions so unusual as pathogens?
Prions, unlike any other infectious agent, have no nucleic acid (DNA and RNA)
