Chapter 6: DNA Flashcards
1
Q
DNA
A
Deoxyribonucleic acid
2
Q
What is a nucleic acid?
A
Molecules that store information
DNA
3
Q
What is the connection between DNA and chromosomes?
A
DNA exists as long fibers called chromosomes, which contain genes.
4
Q
Polymer
A
A large molecule made by repeating a smaller unit
5
Q
What are the polymers in DNA called?
A
Nucleotides
6
Q
How many chromosomes do humans have?
A
46; 23 pairs
7
Q
DNA helicase breaks which type of bond in the DNA molecule?
A
Hydrogen bonds
8
Q
The overall structure of DNA is a…
A
Double helix
9
Q
What does a nucleotide contain?
A
A central five-carbon sugar (deoxyribose in DNA), a negatively charged phosphate, and a base made from one or two rings of nitrogen and carbon.
10
Q
T/F: The sugar and phosphate are identical among all DNA nucleotides
A
True
11
Q
Polynucleotide
A
A polymer made up of many nucleotides covalently bonded together. Contained in one molecule of DNA.
12
Q
T/F: A polynucleotide can contain any combination of the four bases along its length
A
True
13
Q
An A-T base pair is held together by how many hydrogen bonds?
A
2
14
Q
A C-G base pair is held together by how many hydrogen bonds?
A
3
15
Q
DNA Replication
A
The process by which a DNA molecule is copied
16
Q
DNA replication is said to be semi-conservative because…
A
Each new molecule conserves half of the original molecule
17
Q
Describe the first step in DNA replication
A
The double helix is peeled apart by the enzyme helicase. This forms a “replication bubble” where the bases in each separate DNA strand are exposed.
18
Q
Describe the second step in DNA replication
A
DNA polymerase binds the two separate DNA strands together. Using the original strand as a template, DNA polymerase matches the correct bases together.
19
Q
Describe the third step in DNA replication
A
DNA ligase fuses the two individual fragments into a final DNA molecule
20
Q
What are the two types of nucleic acids found in all living cells?
A
DNA and RNA
21
Q
What does RNA stand for?
A
Ribonucleic acid
22
Q
What are the similarities between DNA and RNA?
A
- Both are polymers of nucleotides
- Each consists a sugar
- Both have phosphates
- Both have bases
23
Q
What are the three structural differences between DNA and RNA?
A
- DNA is double stranded; RNA is single stranded
- The sugar is DNA is deoxyribose; the sugar in RNA is ribose
- DNA has Thymine base; RNA has Uracil base
24
Q
How does DNA direct the production of proteins?
A
DNA first produces RNA, which manufactures the production of proteins
25
T/F: DNA produces your appearance
False; DNA produces proteins that are responsible for physical traits
26
How does genetic information flow from DNA to RNA to protein?
Flow of information starts in the DNA in the nucleus; information encodes into RNA that leaves the nucleus; RNA is used to produce proteins using ribosomes in the cytoplasm.
27
Transcription
The synthesis of RNA on a DNA template
28
How does RNA leave the nucleus?
Through an opening in the nuclear envelope called the nuclear pore.
29
Translation
The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule
30
Messenger RNA (mRNA)
A ribonucleic acid that encodes genetic information from DNA and encodes it to ribosomes
31
Codon
A three-nucleotide sequence in mRNA that specifies a particular termination signal; the basic unit of the genetic code
32
In eukaryotic cells, transcription takes place in the...
nucleus
33
Describe the first step on transcription
An enzyme called RNA polymerase binds to a promoter, which is a "start here" signal for the beginning of a gene
34
Describe the second step in transcription
RNA polymerase synthesizes a molecule of RNA; A matches with T, U matches with A, C matches with G, G matches with C
35
Describe the third step in transcription
Introns are removed, eons are joined together (RNA splicing)
36
What is the fourth step of transcription?
mRNA leaves the nucleus
37
Translation takes place in what part of the cell?
Ribosomes within the cytoplasm
38
Ribosomal RNA (rRNA)
The type of nucleic acid that makes ribosomes along with proteins. It is the most abundant type of RNA
39
Transfer RNA (tRNA)
An interpreter in translation. The specific anticodons pick up an amino acid and and conveys the appropriate codon.
40
Anticodon
On a tRNA molecule, a sequence of three nucleotides that is complementary to a codon
41
Triplet code
The correspondence between an mRNA codon and its amino acid
42
What is the specific start codon?
AUG
43
What are the three stop codons?
UAA, UAG, UGA
44
Where are the binding sites for mRNA and tRNA?
In ribosomes
45
Initiation
The first step of translation. An mRNA molecule binds to a small ribosomal subunit. tRNA then binds to the "start" codon
46
Elongation
The second step of translation. The polypeptide grows longer due to the newly made amino acids from tRNA and mRNA. That tRNA molecule then leaves the cell, making room for the next one.
47
Termination
The final step in translation. The ribosome disassembles once it reaches a "stop" codon on an mRNA.
48
What is the first step of gene expression?
Transcription
49
What is NOT a modification to the mRNA?
Promoter binding
50
RNA polymerase is transcribing a segment of DNA that contains the sequence shown below, using the upper strand as template. What will the sequence of this segment of RNA be?
5’GATCTACGTA3’
3’CTAGATGCAT5’
UACGUAGAUC
51
Name the process of PCR in order
1. Start with a sample of double-stranded DNA
2. Heat sample to two DNA strands
3. DNA polymerase duplicates DNA strands
4. Cool sample to allow DNA helices to form
52
Which of the following is FALSE regarding X-Chromosome inactivation?
Inactivated X chromosome happens in the Zygote
53
Which part of a nucleotide molecule in DNA encodes genetic information?
The base
54
Which nucleic acid acts like an enzyme, stabilizing and orienting different molecules to facilitate the formation of bonds between them?
rRNA
55
How is translation initiated?
Two ribosomal subunits bind to the mRNA transcript.
56
PCR is used to copy just a relatively small region of DNA, not the entire genome. How do researchers specifically target the region of interest?
They use two primers, each about 15 to 20 nucleotides long, that flank the region of interest.
57
T/F: Both genetically modified plants and animals make up a significant part of our food supply.
False
58
When is cell-to-cell communication particularly important in regulating gene expression?
During embryonic development
59
Puberty is caused by the release of follicle stimulating hormone and luteinizing hormone from the pituitary gland. These hormones are delivered to the ovary in girls and initiate the monthly release of mature egg cells. This is an example of what mechanism of regulation of gene expression?
A typical signal transduction pathway
60
The small circular molecules of DNA commonly found in bacteria are called...
Plasmids
61
Gel electrophoresis separates DNA fragments according to their...
Length
62
T/F: Standard STR analysis of a DNA sample from a crime scene and DNA from a suspect shows matches at four sites. The suspect is guilty.
False
63
Where does the bond form that binds one strand of DNA to its other strand?
Between the bases
64
Do all cells of the body express the same genes?
No, since they don't all need to make the same proteins
65
T/F: During transcription of a specific gene, only one DNA strand serves as a template for the formation of RNA.
True
66
Which enzyme is responsible for adding complementary DNA bases to an exposed DNA strand?
DNA polymerase
67
After DNA replication...
Each of the two daughter DNA molecules contains one strand from the original DNA molecule and one newly synthesized strand
68
What is the role of primers in the PCR techniques?
To target specific areas of DNA
69
Gene cloning is used to...
Produce large quantities of human proteins
70
Finding a male calico cat is...
Not impossible, but rare. X-chromosome inactivation can sometimes happen in males, but mostly females
71
What is the monomer of the DNA molecule?
Nucleotide
72
Gene regulation
The turning on and off of specific genes within a living organism
73
Gene expression
The process whereby genetic information flows from genes to proteins; the flow of genetic information from the genotype to the phenotype: DNA → RNA → protein.
74
What happens if a chromosome is condensed?
The many genes that it contains are inaccessible and won't be able to produce proteins
75
X-chromosome inactivation
In female mammals, the inactivation of one X-chromosome in a somatic cell. All descendants have the same copy of X-chromosome inactivation
76
Barr body
A dense body formed from a deactivated X chromosome found in the nuclei of female mammalian cells.
77
Transcription factors
A series of proteins that must bind to DNA before transcription can begin
78
Intron
Noncoding regions that are spliced out
79
Exon
Coding regions that are pasted together, forming multiple mRNAs
80
What ways can the RNA transcribed from a gene be altered?
1. A cap and a tail are added
2. Introns are spliced out and eons are pasted together. Several mRNAs can be produced from a single gene
3. microRNAs bind to RNA molecules and prevent them from producing protein
81
Signal transduction pathway
A series of molecular changes that converts a signal received on a target cell’s surface to a specific response inside the cell.
82
What is the usual result of a signal transduction pathway?
Turning off one or more genes. A new protein is made from the signal
83
Development
The growth and specialization of cells and tissues that occur as the cells of a zygote multiply and differentiate to form a multicellular organism. An important example of cell-to-cell signaling
84
Induction
Occurs when one group of cells influences the development of the adjacent group of cells
85
Homeotic genes
Master control genes; helps with the development of an overall structure in an organism
86
Mutation
Any change in the nucleotide sequence of DNA
87
Mutagen
A chemical or physical agent that interacts with DNA and causes a mutation.
88
Carcinogen
Cancer-causing agents
89
Point mutation
A change in a single nucleotide pair of a gene.
90
Silent mutation
Does not change the amino acid produced
91
Missense mutation
Substituting one amino acid for another
92
Nonsense mutation
Changes an amino acid codon into a stop codon, resulting in a shorter defective protein
93
T/F: A codon is three consecutive nucleotides
True
94
Insertion
Mutations that add nucleotides
95
Deletions
Mutations that remove nucleotides
96
Frameshift mutation
When an insertion or deletion throws off a reading frame
97
Sickle-cell disease is caused by...
The replacement of an A with a T at the 17th nucleotide of one of the genes for hemoglobin
98
Tumor
An abnormal mass of cells that forms within otherwise normal tissue.
99
Cancer
A malignant growth or tumor caused by abnormal and uncontrolled cell division.
100
Cell cycle control system
A cyclically operating set of proteins that triggers and coordinates events in the eukaryotic cell cycle.
101
Cell cycle control system
A cyclically operating set of proteins that triggers and coordinates events in the eukaryotic cell cycle.
102
Oncogene
A gene that leads to uncontrolled cell growth
103
Growth factor
A protein secreted by certain body cells that stimulates other cells to divide.
104
Tumor supressor gene
A gene whose product inhibits cell growth
105
Cancer is defined as...
Abnormal growth of the body's own cells
106
Cancer begins within...
A single cell when multiple photo-oncogenes into oncogenes
107
Metastasis
The spread of cancer cells from their site of origin to sites distant in the body
108
Proto-oncogenes
Normal, necessary genes that help regulate cell growth
109
A typical genetic engineering challenge is...
To produce large quantities of a desired human protein
110
Gene cloning
The production of multiple copies of a gene
111
Restriction enzyme
DNA cutting enzymes that only target specific nucleotide sequences
112
Examples of humans manipulating nature
1. Biotechnology
2. DNA technology
3. Genetic engineering
113
Restriction site
A specific DNA sequence recognized by a particular restriction enzyme
114
Sticky ends
The result of restriction enzymes, fragments with single-stranded regions which can join to other pieces of DNA
115
Recombinant DNA
A DNA molecule containing nucleotides from more than one source
116
Genome
An organism's entire set of DNA
117
Genomic library
A collection of cloned DNA fragments that include the organism's entire genome
118
What role does DNA ligase play in the manipulation of DNA?
DNA ligase pastes DNA fragments onto plasmids
119
Nucleic acid probe
A complementary molecule that helps visualize the target DNA
120
Reverse transcriptase
An enzyme that can synthesize DNA molecules from the collection of mRNAs within a cell
121
Complementary DNA (cDNA)
The result of reverse transcriptase; represents just the genes that were producing proteins in the cell at that time. Results in a gene with only exons
122
Genetically modified organisms (GMOs)
Ones that have acquired one or more genes by artificial means
123
Transgenic organism
An organism that contains genes from another organism, typically another species
124
What is the relationship between producing a GMO and plasmids?
Plasmids act as a temporary DNA carrier, allowing genes to be inserted into another
125
Polymerase chain reaction (PCR)
A laboratory technique by which a specific segment of DNA can be targeted and copied quickly and precisely
126
What is the key to PCR?
DNA polymerase, because it synthesizes the new strands of DNA
127
DNA polymerase
An enzyme that synthesizes a new strand of DNA that is complementary to the original
128
Primers
Artificially created, single-stranded DNA that bind to a target sequence
129
DNA profiling
Allows an investigator to determine with certainty whether two samples of DNA came from the same individual
130
Short tandem repeats (STRs)
Sites where a short nucleotide sequence is repeated many times in a row
131
STR analysis
A comparison of the length of STRs
132
Gel electrophoresis
Allows visualization of DNA samples based on length
133
How identical are the genomes of two humans?
99.5%
134
How much of human DNA codes for proteins?
1.5%
135
24% of human DNA...
Consists of sequences that control genes but are not genes themselves
136
59% of human DNA...
Is repetitive
