Chapter 20- Molecular Genetics Flashcards
1
Q
Carries all the genetic information for an organism
A
Deoxyribonucleic acid (DNA)
2
Q
Responsible for interpreting the genetic information into proteins that will carry out the essential cellular functions
A
Ribonucleic acid (RNA)
3
Q
What are the two nucleic acids
A
DNA and RNA
4
Q
What are the components of DNA and RNA
A
- 5-carbon sugar
- Phosphate
- 4-heterocyclic amines (nitrogenous bases)
5
Q
The sugar in DNA is ________ and the sugar in RNA is ________
A
2’-deoxyribose; ribose
6
Q
How do 2’-deoxyribose and ribose differ
A
The absence of a hydroxyl group at the carbon-2 position of 2’-deoxyribose
7
Q
The nitrogenous bases of DNA and RNA are divided into
A
2 families: pyrimidines and purines
8
Q
What re the pyrimidine bases in DNA
A
Cytosine and thymine
9
Q
What are the pyrimidines found in RNA
A
Cytosine and uracil
10
Q
What are the major purines of DNA and RNA
A
Adenine and guanine
11
Q
How do pyrimidines and purines differ in RNA and DNA
A
Location of functional groups around the ring
12
Q
How are nucleosides produced?
A
Combination of sugar, either ribose (in RNA) or 2’-deoxyribose (in DNA) with a purine or pyrimidine base
13
Q
What is the covalent bond between the sugar and purine/pyrimidine base called
A
B(beta)-N-glycosidic linkage
14
Q
N- __ of pyrimidines and N- __ of purines participate in glycodidic bonds of nucleosides
A
1; 9
15
Q
The nucleoside formed with ribose and adenine is called ________ and ribose with guanine is called _________ and the nucleoside formed with 2’-deoxyribose and adenine is called ________ and 2’-deoxyribose with guanine is called _________
A
Adenosine; guanosine
2’-deoxyadenosine and 2-deoxyguanosine
16
Q
The ribonucleosides formed with cytosine and thymine are called what
A
Cytidine and uridine
17
Q
The deoxyribonucleosides of cytosine and thymine are called
A
2’- deoxycytidine and thymidine
18
Q
Why is thymidine not called 2’-deoxythymidine
A
It is only found in DNA so does not need prefix to distinguish
19
Q
DNA and RNA are long polymers of __________
A
Nucleotides
20
Q
What does each nucleotide consist of
A
5-carbon sugar, one of five nitrogenous bases, and one or more phosphorylation groups
21
Q
A nucleotide with the sugar ribose is a ________ and one having the sugar 2’-deoxyribose is a ___________
A
Ribonucleotide; deoxyribonucleotide
22
Q
The covalent bond between the sugar and phosphorylation group is a _______ bond
A
Phosphoester
23
Q
The covalent bond between sugar and phosphorylation group is formed by what
A
Condensation reaction between 5’-OH of the sugar and an -OH of the phosphorylation group
24
Q
A single strand of DNA is a polymer of nucleotides bonded to one another by 3’-5’ _________ bonds
A
Phopshodiester
25
What is the backbone of a DNA polymer of nucleotides called and why
sugar phosphate backbone; composed of alternating units of 5 carbon sugar 2’-deoxyribose and phosphorylation groups in phosphodiester linkage
26
What is the linkage of a nitrogenous base to each sugar of DNA/RNA polymer called
N-glycosidic linkage
27
What is an example of a noncovalent attraction that helps maintain the double helix structure of DNA
Hydrogen bonding between nitrogenous bases in the center of the helix
28
In dna: adenine forms 2 hydrogen bonds with ________ and cytosine from 3 hydrogen bonds with __________
Thymine; guanina
29
What is the diameter of the double helix of DNA
2.0 nm
30
T or F: the two strands of DNA are complementary strands because the sequence of bases on one automatically determines the sequence of bases on the other
T
31
The helix of DNA completes one turn every _____ base pairs
10
32
One complete of DNA helix is _______ nanometer
3.4
33
Pieces of DNA that carry genetic instructions, or genes, of an organism
Chromosomes
34
Has one chromosome
Prokaryotes
35
The complete set of genetic information in all the chromosomes of an organism
Genome
36
Organisms with a simple cellular structure in which there is no true nucleus surrounded by a nuclear membrane and there are no true membrane bound organelles
Prokaryotes
37
Organisms that have cells containing a true nucleus enclosed by a nuclear membrane
Eukaryotes
38
Are animals, plants, and fungi eukaryotes or prokaryotes
Eukaryotes
39
Consists of a strand of DNA wrapped around a small disk made up of histone proteins
Nucleosome
40
The complex of DNA and histone proteins is termed ________ and makes up eukaryotic chromosomes
Chromatin
41
What do additional chromosomes on 13, 18, and 21 cause
13= Palau syndrome; 18= Edward syndrome; 21= down syndrome
42
Males with 2 X chromosomes and one Y chromosome
Exhibit Klinfelter syndrome
43
Characteristic of men with and extra Y chromosome and women with 3 X chromosomes
Unusually tall
44
A woman with single X chromosome has
Turner syndrome
45
It is thought that ____% of all miscarriages result from abnormal chromosome number
50%
46
How do RNA molecules differ from DNA molecules
1. RNA usually single stranded
2. Sugar phosphate backbone of RNA consists of ribonucleotides linked by 3’-5’ phosphodieter bonds
3. The nitrogenous base uracil (U) replaces thiamine (T)
47
DNA replication begins are a unique sequence n the circular chromosome known as
Replication origin
48
The point at which the new deoxyribonucleotide is added to the growing daughter strand is called
Replication fork
49
Replication occurs bidirectionally at a rate of about _____ new nucleotides every second
500
50
What is the first step in DNA replication
Separation of the strands of DNA
51
How are the strands of DNA separates
The protein helicase breaks the hydrogen bonds between base pairs
52
In DNA replication, the stress causing supercooling by helicase is relieved by what enzyme
Topoisomerase
53
The enzyme ________ catalyzes the synthesis of a small piece if RNA called an RNA primer that serves to prime the process of DNA replications
Primase
54
The enzyme ___________ reads each parental strand and catalyzes the polymerization of a complementary daughter strand
DNA polymerase III
55
The precurser for DNA replication
Deoxyribonucleotide triphophate
56
Breaks the hydrogen bonds betweeen DNA strands
DNA helicase
57
Excises the RNA primers and fills in with DNA
DNA polymerase I
58
Covalently links the DNA fragments together
DNA ligase
59
What is the central dogma of molecular biology
States that in cells, the flow of genetic information contained in DNA is a one-way street that leads from DNA to RNA to protein
60
The process by which a single strand of DNA serves as a template for the synthesis of an RNA molecule
Transcription
61
Three classes of RNA molecules
Messenger RNA, transfer RNA, ribosomal RNA
62
Carries genetic information for a protein from DNA to the ribosomes. It is cpmplementary RNA copy of a gene of the DNA
Messenger RNA (mRNA)
63
Is a structural and functional component of the ribosomes, which are “platforms” on which protein synthesis occurs
Ribosomal RNA (rRNA)
64
How many types of rRNA in bacterial vs eukaryotes ribosomes?
3 vs 4
65
Translates the genetic code of the mRNA into the primary sequence of amino acids in the protein
Transfer RNA (tRNA)
66
Have a cloverleaf-shapped secondary structure resulting from base pair hydrogen binding
Transfer RNA
67
What is the tertiary structure of tRNA
L-shaped
68
Transcription is catalyzed by
RNA polymerase
69
The first stage of transcription involves binding of RNA polymerase to a specific nucleotide sequence, the __________, at the beginning of the gene
Promoter
70
What are the stages of RNA transcription
1. Initiation
2. Chain elongation
3. Termination
71
The only amino acids that have a single codon
Methionine and tryptophan
72
How many codons in serine and leucine
6
73
A three letter genetic code
Codon
74
The process of protein synthesis is called
Translation
75
Translation is carried out by
Ribosomes
76
Each tRNA is specifically recognized by the active site of an enzyme called
Aminoacyl tRNA synthetase
77
The first stage of protein synthesis
Initiation
78
Proteins that assist in the formation of a translation complex composed of an mRNA molecule and the initiator tRNA
Initiation factors
79
the ribosome has 2 binding tRNA molecules
1. Holds the growing peptide bound to a tRNA molecule
2. Holds the Aminoacyl tRNA carrying the next amino acid to be asses to the peptide chain
1. Peptidyl tRNA binding site (P-site)
2. Aminoacyl tRNA binding site (A-site)
80
The three termination codons with no corresponding tRNA molecules
UAA, UAG, UGA
81
What type of mutation is this:
ATGGACTTC
ATGCACTTC
Point mutation
82
What type of mutation is this
ATGGACTTC
ATGTTC
Deletion mutation
83
What type of mutation is this
ATGGACTTC
ATGCTCGACTTC
Insertion mutation
84
Mutation that cause no change in the proteins
Silent mutation
85
Any chemical that causes a change in the DNA sequence
Mutagen
86
Absorption of UV light by DNA causes adjacent pyrimidine bases to become covalently linked… what is the [product called
Pyrimidine dimer
87
Condition where people are very sensitive to UV light and can develop mul;triple skin cancers usually before the age of 20
Xeroderma pigmentosum
88
Bacterial enzymes that cut the sugar-phosphate backbone of DNA molecules at specified nucleotide sequences
Restriction enzymes aka restriction endonucleases
89
The first restriction endonuclease purified and studied was called
EcoR1
90
Two DNA fragments that are staggered are called sticky ends because
They can reasscoiate with one another by hydrogen bonding
91
To produce multiple copies of a gene it must be joined to a
Cloning vector
92
What is a cloning vector
A piece of DNA having its own replication origin so that it can be replicated inside a host cell
93
What are the two major kinds of cloning vectors
Bacterial virus/phage vectors & plasmid vector
94
Bacterial viruses that have been genetically altered to allow the addition of cloned DNA fragments
Bacterial virus/phage vectors
95
Extra pieces of circular DNA found in most kinds of bacteria
Plasmids
96
The plasmids used in cloning vectors often contain antibiotic resistance genes that are useful in what
Selection of cells containing a plasmid
97
In plasmids, often a gene for resistance to an antibiotic
Selectable marker
98
The gene that codes for the enzyme B-galactosidase
LacZ
99
The DNA “glue” enzyme
Ligase
100
A technique used to identify the presence of a gene on a particular DNA fragment
Hybridization
101
What is an obstacle to gene cloning in eukaryotic cells
Presence of introns bc cloning bacteria lack enzymes to splice out introns
102
How do you perform Polymerase chain reactions
A small mount of DNA is mixed with Taq polymerase, the primer, and the 4 DNA nucleotide triphosphates
103
Why does Taq polymerase not denature when heat is raised to 96 degrees in a thermocycler?
Taq polymerase is very heat stable… comes from bacteria that live in hot springs in Yellowstone national park
104
A technique that provides both DNA sequence information and a method for identifying the DNA sequences next to it on the chromosome
Chromosome walking
105
Brings together the disciplines of computer science, mathematics, statistics, DNA technology, and engineering to devise methods and software tools for organizing, understanding, analyzing and applying the knowledge we gain from these DNA sequences
Bioinformatics
106
Most a,I o acids have several codons causing the genetic code to be called
Degenerate
107
Catalyzes bond formation between the tRNA and the amino acid
Aminoacyl tRNA synthetase
108
Causes peptidyl transferase to hydrolyze the bond between the peptide and the peptidyl tRNA, releasing the completed peptide
Release factor
109
Where does protein synthesis occur
The ribosome
110
Uv light causes formation of
Pyrimidine dimers
111
Refers to the fact that each parental DNA strand serves as the template for the synthesis of a daughter strand. As a result, each of the daughter DNA molecules is made up of one strand of the original parental DNA and one strand of the newly synthesized DNA
Semiconservative DNA replication
112
What enzyme proofreads the newly synthesized strand of DNA and corrects any errors by removing the incorrectly inserted nucleotide and adding the proper one
DNA polymerase III
113
Small ribonucleoprotein complexes that carry out RNA splicing
Spliceosomes
114
Help to recognize intron-exon boundaries and are made up of small nuclear ribonucleoproteins (snRNPs)
Spliceosomes
115
What is the purpose of a poly(A) tail on eukaryotic mRNA
Protects the 3’ end of the mRNA from degradation by exonucleases
