Biology Ch 10 Flashcards
1
Q
Molecular Biology
A
The study of heredity at the molecular level
2
Q
Frederick Griffith
A
Killed pathogenic bacteria, mixed with living harmless bacteria, and those became pathogenic.
3
Q
Alfred Hershey and Martha Chase
A
Used bacteriophages to show that DNA is the genetic material of T2.
4
Q
Bacteriophages
A
Viruses that infect bacterial cells.
5
Q
Radioactive sulfur detects
A
Proteins (outside)
6
Q
Radioactive Phosphorus detects
A
DNA (inside)
7
Q
Replication cycle of phage T2
A
- A phage attaches itself to a bacterial cell.
- The phage injects its DNA into the bacterium.
- The phage DNA directs the host cell to make more phage DNA and proteins; new phages assemble.
- The cell lyses and releases the new phages.
8
Q
Nucleotides
A
Long chains (polymers) of chemical units (monomers)
9
Q
Polynucleotide
A
A nucleotide polymer (chain)
10
Q
Nucleotide is composed of
A
Nitrogenous base, 5-C Sugar, and Phosphate group.
11
Q
Nucleotides are joined by
A
Sugar-phosphate backbone
12
Q
Nitrogen-containing base
A
Adenine, Cytosine, Thymine, and Guanine
13
Q
Thymine & Cytosine
A
Pyrimidines
14
Q
Adenine & Guanine
A
Purines
15
Q
DNA
A
Deoxyribonucleic Acid
16
Q
Nucleic refers to
A
DNA’s location in the nuclei of eukaryotic cells
17
Q
RNA uses / has
A
Sugar Ribose and Uracil instead of Thymine
18
Q
Rosalind Franklin
A
Was the one who produced an X-ray image of DNA
19
Q
Watson and Crick
A
Realized that DNA consisted of 2 polynucleotide strands wrapped into a double helix.
Won Nobel Prize in 1962
20
Q
Double Helix
A
The sugar-phosphate backbone is on the outside
The nitrogenous bases are perpendicular to the backbone in the interior.
21
Q
A & T forms
A
2 Hydrogen bonds
22
Q
C & G forms
A
3 Hydrogen bonds
23
Q
Semiconservative Model
A
2 DNA stands separate.
Each strand becomes a template for other strands
Each new DNA helix has one old strand with one new strand
24
Q
Replication of a DNA molecule begins at
A
Origins of replication
25
Origins of replication
Short stretches of DNA having a specific sequence of nucleotides.
26
Proteins that initiate DNA replication
Attach to the DNA at the origin of replication & Separate the 2 strands of the double helix
27
Replication then proceeds in both directions creating
replication bubbles
28
DNA replication occurs in
5' to 3' direction
29
Replication is continuous on the
3' to 5' template
30
DNA polymerases
Add nucleotides only to the 3' end of the strand
31
Replication is discontinuous on the
5' to 3' template, forming short Okazaki fragments
32
DNA Ligase
an enzyme that links Okazaki fragments together into a single DNA strand.
33
DNA specifies traits by
Dictating protein synthesis
34
What is the link between genotype and phenotype?
Proteins
35
Molecular chain of command
From DNA in the nucleus to RNA
RNA in the cytoplasm to protein
36
Transcription
The synthesis of RNA under the direction of DNA
37
Translation
The synthesis of proteins under the direction of RNA
38
What provide the instructions for making specific proteins?
Genes
39
The initial one gene - one enzyme hypothesis
Based on studies of inherited metabolic disease
40
The one gene - one enzyme hypothesis
Expanded to include all proteins
41
Many eukaryotic genes code for a set of polypeptides by a process called
Alternative splicing
42
The sequence of nucleotides in DNA provides a
Code for constructing a protein
43
Protein construction requires....
a conversion of a nucleotide sequence to an amino acid sequence
44
Transcription rewrites...
The DNA code into RNA but using the same nucleotide
45
The flow of information from gene to protein is based
Triplet code
46
The genetic instructions for the amino acid sequence of a polypeptide chain are written in....
DNA and RNA as a series of non-overlapping three-base "words" called codons.
47
Translation involves switching from the...
nucleotide "language" to the amino acid "language"
48
Each amino acid is specified by
A codon
49
How many codons are possible?
64
50
Genetic Code
The amino acid translations of each of the nucleotide triplets
51
How many nucleotides specify one amino acid?
3
52
How many codons correspond to amino acids?
61
53
What codes for methionine and signals the start of transcription?
AUG
54
What signal the end of translation?
3 "stop" codons
55
The genetic code is...
Redundant, unambiguous, and nearly universal
56
Redundant
With more than one codon for some amino acids
57
Unambiguous
Any codon for one amino acid does not code for any other amino acid
58
Nearly Universal
The genetic code is shared by organisms from the simplest bacteria to the most complex plants and animals
59
What are 3 stop codons?
UAA, UAG, and UGA
60
What are the 3 steps of transcription?
Initiation, Elongation, and Termination
61
Initiation
RNA synthesis begins after RNA polymerase attaches to the promoter.
62
Elongation
Using the DNA as a template, RNA polymerase adds free RNA nucleotides one at a time.
63
Termination
RNA synthesis ends when RNA polymerase reaches the terminator DNA sequence
64
Messenger RNA (mRNA)
1. encodes amino acid sequences
| 2. conveys genetic messages from DNA to the translation machinery of the cell.
65
In prokaryotes,
mRNA can stay in the same place that it is made in order to convey genetic messages from DNA to the translation machinery of the cell
66
In eukaryotes,
mRNA have to exit the nucleus via nuclear pores to enter the cytoplasm
67
Eukaryotic mRNA has..
introns
68
Introns are
interrupting sequences that separates exons
69
Exons are
The coding regions.
70
Eukaryotic mRNA undergoes....
processing before leaving the nucleus
71
RNA splicing
Removes introns and joins exons to produce a continuous coding sequence.
72
What are added to the ends of the mRNA?
A cap and tail of extra nucleotides
73
Why are cap and tail of extra nucleotides added?
1. to facilitate the export of the mRNA from the nucleus
2. to protect the mRNA from degradation by cellular enzymes
3. to help ribosomes bind to the mRNA
74
T or F
| The cap and tail themselves are not translated into protein
True
75
Transfer RNA (tRNA)
Function as an interpreter, converting the genetic message of mRNA into the language of proteins.
76
tRNA perform as an interpreter by
1. Picking up the appropriate amino acid
| 2. Using anticodon to recognize the appropriate codons in the mRNA
77
Translation occurs on....
The surface of the ribosome
78
Ribosomes coordinate...
1. The functioning of mRNA
2. The functioning of tRNA
3. The synthesis of polypeptides.
79
How many subunits does ribosomes have?
2: small and large
80
Each subunit is composed of...
ribosomal RNAs and proteins
81
When do ribosomal subunits come together?
During translation
82
For what do ribosomes have binding sites for?
for mRNA and tRNA
83
T or F
| The differences between the ribosomes of bacteria and eukaryotes are medically significant
True
84
What drugs are used to combat bacterial infections?
Certain antibiotic drugs that can inactivate bacterial ribosomes while leaving eukaryotic ribosomes unaffected.
85
What are 3 phases of translation?
Initiation, elongation, and termination
86
Initiation brings together...
1. mRNA
2. a tRNA bearing the first amino acid
3. the 2 subunits of a ribosome
87
What establishes where translation begin?
Initiation
88
How many steps does initiation goes through?
2 steps
89
Step 1 for Initiation
An mRNA molecule binds to a small ribosomal subunit, and a special initiator tRNA binds to mRNA at the start codon.
90
The first tRNA has what anticodon?
UAC
91
Step 2 for initiation
A large ribosomal subunit joins the smal subunit, allowing the ribosome to function
92
P site
Where the first tRNA is occupied and it hols the growing polypeptide
93
A site
Available to receive the nest amino-acid-bearing tRNA
94
Each cycle of elongation has....
3 steps
95
1st step of Elongation
The anticodon of an incoming tRNA molecule, carrying its amino acid, pairs with the mRNA codon in the A site of the ribosome.
96
2nd step of Elongation
The polypeptide separates from the tRNA in the P site and attaches by a new peptide bond to the amino acid carried by the tRNA in the A site
97
3rd step of Elongation
The P site tRNA (now lacking an amino acid) leaves the ribosome, and the ribosome translocates (moves) the remaining tRNA (which has the growing polypeptide) from the A site to the P site.
98
Elongation continues until the...
Termination stage of translation
99
During the termination stage of translation...
1. The ribosome reaches a stop codon
2. The completed polypeptide is freed from the last tRNA
3. The ribosome splits back into its separate subunits
100
The flow of genetic information is from...
DNA to RNA to Protein
101
In transcription, the mRNA is...
Synthesized on a DNA template.
102
In eukaryotic cells, transcription occurs in...
the Nucleus, and the mRNA is processed before it travels to the cytoplasm
103
In prokaryotes, transcription occurs in the...
Cytoplasm
104
What are the 4 steps of translation?
1. Amino Acid Attachment
2. Initiation of polypeptide synthesis
3. Elongation
4. Termination
105
Mutation
Any change in the nucleotide sequence of DNA
106
Mutation can involve...
1. Large chromosomal regions
| 2. Or just a single nucleotide pair
107
Mutation can be divided into how many general categories?
2
108
Nucleotide substitutions involve...
The replacement of one nucleotide and its base-pairing partner with another pair of nucleotides.
109
Base substitutions may.....
1. Have no effect at all
2. Change the amino acid coding
3. Change an amino acid into a stop codon
4. Lead to a base substitution that produces an improved protein that enhances the success of the mutant organism and its descendants
110
Silent Mutation
No effect at all
111
Missense Mutation
Changing of amino acid coding that produces a different amino acid
112
Nonsense Mutation
Changing an amino acid into a stop codon
113
Nucleotide insertions or deletions of one or more nucleotides in a gene may....
1. Cause a frameshift mutation
2. Lead to a significant changes in amino acid sequence
3. Produce a nonfunctional polypeptide
114
Frameshift Mutation
Alters the reading frame (triplet grouping) of the genetic message
115
Mutagenesis
The production of mutations
116
Mutations can be caused by....
1. Spontaneous errors that occur during DNA replication or recombination
2. Mutagens
117
Mutages
are high-energy radiation such as X-rays and ultraviolet light and chemicals.
