Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

AP Biology Mr. Maiorana > Chapters 13,14,15 test > Flashcards

Chapters 13,14,15 test Flashcards

(146 cards)

Start Studying
1
Q

What was The major achievement of James Watson and Francis Crick?

A

They made an elegant double-helical model for the 3 dimensional structure of DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What make nucleic acids unique in nature?

A

Their ability to direct their own replication from monomers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What was the key factor in determining the identity of genetic material? why?

A

Choosing the appropriate organisms to study, like bacteria and viruses because they are simpler

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is transformation? Who first used this term in genetics?

A

discovered by Frederick Griffith, transformation is a change in genotype and phenotype due to assimilation of external DNA by a cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are bacteriophages?

A

Called phages for short, these are viruses that infect bacteria that are used to study DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a virus?

A

An organisms that is basically just DNA(or sometimes RNA) enclosed within a protective coat that must infect other cells and take over their metabolic machinery to reproduce

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Who discovered whether viruses used DNA or protein to infect and reprogram other cells and how?

A

Alfred Hershey and Martha Chase. They did this by tagging phage protein with a radioactive isotope of sulfur and tagging phage DNA with radioactive phosphorus. They found that phage DNA entered the the host cells and protein did not

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why was Hershey and chase’s experiment important and what were their conclusions?

A

They concluded that DNA injected by the phage must be the molecule carrying genetic information that makes the cells produce new viral DNA and proteins. Their study was important bc it provided powerful evidence that nucleic acids rather than proteins are hereditary material, at least viruses.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How was Erwin Chargaff significant?

A

He provided further evidence that DNA is the genetic material. He first discovered that the base ratios that compose DNA vary in different species, a diversity that was believed to be absent made DNA a more credible candidate to be genetic material. He also noticed that the number of adenines was close to the number of thymines and the number of guanines almost equaled the number of cytosines. These discoveries resulted in Chargaff’s rules(which are these 2 findings)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What dies antiparallel mean? what part of DNA is this applicable to?

A

Antiparallel means that they run in opposite directions parallel to each other. This sugar phosphates run in the DNA double helix structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why is adenine always paired with thymine and guanine with cytosine?

A

A and G are purines, nitrogenous bases with 2 rings. C and T are pyrimidines, nitrogenous bases with 1 ring. Purines are about twice as wide as pyrimidines, so purine-purine pairs are too wide and pyrimidine-pyrimidine pairs are 2 narrow to account for the uniform 2nm diameter of a double helix. Furthermore, each base has chemical side-groups that can form H bonds with it’s partner only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the model of DNA that Watson and Crick came up with for their hypothesis on DNA replication?

A

The semiconservative model

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the origins of replication?

A

The particular sites where DNA replication begins, these are short patches of DNA having a specific sequence of nucleotides. Proteins that initiate DNA replication attach to the DNA and separate the two strands and opening up a replication bubble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a replication fork?

A

A Y-shaped region where the parental strands of DNA are being unwound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are helicases?

A

Enzymes that untwist he double helix at the replication forks, separating the two parental strands and making them available as template strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are single-strand binding proteins?

A

Proteins that bind to the unpaired parental strands after they separate, keeping them from repairing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is topoisomerase?

A

A enzyme that helps relieve the strain caused by the untwisting if the double helix that causes tighter twisting and strain ahead of the replication fork

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How is DNA replication similar and different bacteria and prokaryotes?

A

Bacteria have one origin of replication, while eukaryotes have multiple to speed of the process. Both of these processes are similar in that replication proceeds in both directions from each origin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a primer?

A

The short stretch of RNA that is the initial nucleotide chain produced during DNA synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is primase? What does it result in?

A

The enzyme that synthesizes a primer by starting a complementary RNA chain from a single RNA nucleotide, adding RNA nucleotides one at a time, using the parental DNA strand as a template. The completed primer is based paired to the template strand and the new DNA strand will start from the 3’ end of the RNA primer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are DNA polymerases?

A

Enzymes that catalyze the synthesis of new DNA by adding nucleotides to a preexisting chain. Most require a primer and a DNA template strand along which complementary DNA nucleotides lines up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are 2 examples of DNA Polymerase?

A

DNA Polymerase III and DNA Polymerase I, they play a major role in DNA replication in E. coli.

III: adds a DNA nucleotide to the RNA primer and then continues adding DNA nucleotides complementary to the parental DNA strand to the growing end of the new DNA strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What consists of each nucleotide added to a growing DNA strand?

A

A sugar attached to a base and 3 phosphate groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is dATP and how is it different from ATP?

A

dATP is the adenine nucleotide used to make DNA. It is different from ATP because its sugar is deoxyribose instead of ribose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What makes the nucleotides used for DNA synthesis chemically reactive?
their triphosphate tails have an unstable cluster of negative charge
26
What exergonic reaction helps drive the polymerization reaction?
As each monomer joins the growing end of a DNA strand, two phosphate groups are lost as a molecule of pyrophosphate then they undergo hydrolysis to become two inorganic molecules of phosphate
27
What does a helix being antiparallel affect replication?
Due to the structure, DNA can only add to the free 3’ end of a primer or growing DNA strand, never to the 5’ end. Thus, the new DNA strand can only elongate in the 5’ to 3’ direction
28
What is the leading strand?
The DNA strand made by the continuous addition of nucleotides to the new complementary strand as the replication fork progresses
29
How many primers are needed for DNA pol III to synthesize the leading strand?
One
30
What is the lagging strand?
The template strand elongating away from the replication fork
31
What are okazaki fragments?
The fragments in which the lagging strand is synthesized discontinuously by.
32
What is different about primers on the leading and lagging strand?
One primer is required on the leading strand, whereas each okazaki fragment must be primed separately on the lagging strand
33
What is the role of DNA pol III and I on lagging strands?
DNA pol III forms the okazaki fragment after the RNA primer. DNA pol I replaces the RNA nucleotides of the adjacent primer with DNA nucleotides
34
What is DNA ligase?
An enzyme that joins the final nucleotide of the replacement DNA from DNA pol I to the first DNA nucleotide of the Okazaki fragment, joining sugar-phosphate backbones of all okazaki fragments into a continuous DNA strand
35
Why is the railroad track representation if DNA inaccurate?
1. The various proteins in DNA replication actually fork a single large complex 2. The DNA replication complex may not move along the DNA, it may actually be vice versa
36
Why is DNA replication so accurate?
During replication, DNA polymerases proofread each nucleotide against its template as soon as it is added to the growing strand. If an error is found, the nucleotide is removed and synthesis is resumed
37
What is mismatch repair?
When enzymes other than DNA polymerase remove and replace incorrectly paired nucleotides that DNA polymerase missed
38
What is nuclease?
A DNA cutting enzyme that cuts out a damaged segment of DNA and the resulting gap is filled with nucleotides, using DNA polymerase and DNA ligase
39
What is nucleotide excision repair?
A DNA repair system involving nuclease and its function
40
What makes a mismatched nucleotide replication permanent?
replication
41
How has mutation effected evolution?
A low mutation rate allows evolution and diversity of species we see today. Some mutations are beneficial and are ultimately responsible for the appearance of new species
42
What is telomerase?
An enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells, restoring them to their original length and compensating for the shortening that occurs in replication
43
How are bacterial and eukaryotic chromosomes different?
Eukaryotic chromosomes consist of one linear DNA molecule associated with a large amount of protein. Bacteria consist mostly of one double stranded circular DNA molecule
44
How is a nucleoid and a nucleus different?
The nucleoid is not surrounded by membrane and the nucleus is
45
What is heterochromatin?
Interphase chromatin that is visible as irregular clumps with a light microscope. This is less accessible to the machinery responsible for transcription
46
What is euchromatin?
Less compacted and more disperse chromatin
47
What are the 4 most common types of histones in eukaryotes and what do they do?
H2A, H2B, H3 and H4. They are critical for DNA packing
48
What is a nucleosome?
(10nm) Unfolded chromosome resembling “beads”, the basic unit of DNA packing. These consist of DNA wrapped twice around a protein core composed of two molecule of each histone type and a histone tail extending from the nucleosome
49
What is a 30-nm fiber?
The next level of packing from nucleosomes/10-nm fibers. A fifth histone, H1, becomes involved at this level. The histone tails of one nucleosome and the DNA linker of another interact, coil, and fold to form a 30nm fiber, this is prevalent in the interphase nucleus
50
What are looped domains?
(300-nm fiber) The next level from 30 nm fibers. The 30nm fibers form loops called looped domains attached to a chromosome scaffold composed of proteins, making up the 300nm fiber
51
What is the metaphase chromosome?
The next level of packing from a 300 nm chromosome. The looped domains coil and foil to form a 700nm chromatid. Particular genes always end up located at the same places
52
What is nucleic acid hybridization?
The base pairing of one strand of nucleic acid to a complementary sequence on another strand
53
What are plasmids?
small circular DNA molecules that replicate separately from the bacterial chromosome
54
What is recombinant DNA?
A DNA molecule formed when segments of DNA from 2 different sources-often different species-are combined in a test tube
55
What is gene cloning?
The production of multiple copies of a single gene
56
What is the most common way to clone DNA in a laboratory?
Using E. coli plasmids to make a recombinant bacterium
57
What are restriction enzymes?
Enzymes that cut DNA molecules at a limited number of specific locations. They protect bacteria by cutting up foreign DNA from other organisms or phages
58
What is a restriction site?
A specific, short DNA sequence that a restriction enzyme recognize where it cuts the DNA
59
How is the DNA of a bacterial cell protected from its own restriction enzymes?
The addition of methyl groups to adenines and cytosines within the sequences recognized by the enzymes
60
What are restriction fragments?
The fragments made when a restriction enzyme cuts DNA. All copies of an identical DNA molecule yield the same fragments
61
What is gel electrophoresis?
A technique used to see restriction fragments. This technique separates a mixture of segments by length.
62
What is a sticky end?
The single stranded end of a restriction fragment that can formed H-bonded base pairs with complementary sticky ends on any other DNA molecules cut by the same enzyme, which are temporary but can be made permanent by DNA ligase
63
What is a cloning vector?
The two DNA molecules joined in gene cloning. A DNA molecule that can carry foreign DNA into a host cell and replicate there. It often is a bacterial plasmid that has ine copy of a restriction site recognized by a particular restriction enzyme selected by the researcher and purchased
64
What is a polymerase chain reaction?
(PCR) A technique used to copy a specific DNA sample quickly
65
What are the parts of a PCR cycle?
1. Denaturation: heat briefly to separate DNA strands 2. Annealing: Cool to allow primers to form H bonds with ends of target sequence 3. Extension: DNA polymerase adds nucleotides to the 3’ end of each primer
66
What is DNA sequencing?
Using the principle of complementary base pairing to determine a gene’s complete nucleotide sequence
67
What link phenotype and genotype?
Proteins
68
What is gene expression?
The process by which DNA directs the synthesis of proteins
69
What is the bridge between DNA and protein synthesis?
nucleic acid RNA, DNA undergoes transcription and translation
70
What is transcription?
The synthesis of RNA using information in the DNA
71
What is messenger RNA?
(mRNA), RNA with a transcript of the gene’s protein building instructions. Comes from a template of DNA in which it gets its sequence from
72
What is translation?
Synthesis of a polypeptide using mRNA. The cell translates the nucleotide sequence of an mRNA molecule into the amino acid sequence of a polypeptide
73
What are the sites of translation?
ribosomes
74
How does the flow of genetic information differ in transcription and translation in bacteria and eukaryotes?
Since bacteria dont have nuclei, their DNA is not separated by nuclear membranes from ribosomes and other protein synthesizing equipment. This allows translation to begin while transcription is still in progress
75
Where does transcription occur?
the nucleus
76
What is pre-mRNA?
RNA in eukaryotic cells that has yet to be modified in mRNA
77
What is a primary transcript?
The initial RNA transcript from any gene, including RNA that is not synthesized into protein
78
What is a triplet code?
the genetic information for a polypeptide chain written in DNA as a series of nonoverlapping, 3 nucleotide words
79
What is the template strand?
The DNA strand that gets transcribed and provides a pattern or template for the sequence of nucleotides in an RNA transcript
80
how are DNA an RNA strands related
they are complementary bc of base pairing, not identical
81
How is mRNA similar and different than the pairs that form during DNA replication?
They have the same base pairs except for U/T and mRNA has ribose instead of deoxyribose
82
What are codons?
mRNA nucleotide triplets, they go in the 5’ to 3’ direction. Can also be DNA triplets in the nontemplate strand. The are complementary to the template strand
83
What are the functions of codons? what does AUG do?
Codons initiate, stop and code for amino acids. AUG codes for an amino acid and serves as a start codon
84
What are reading frames?
Reading the symbols of nucleotides in the correct groupings
85
What is RNA polymerase?
An enzyme that pries two strands of DNA apart and joins together RNA nucleotides complementary to the DNA template strand
86
How are DNA and RNA polymerase different?
Similar: can go in the 5’ to 3’ direction Different: RNA polymerase doesnt need a primwr, DNA polymerase does
87
What is a promoter and a terminator?
A promoter is the DNA sequence where the RNA attaches for transcription. In bacteria, the terminator is the sequence that signals the end of transcription
88
What is a transcription unit?
The stretch of DNA that is transcribed into an RNA molecule
89
What are the stages of transcription?
1. Initiation: After RNA polymerase bonds to the promoter, DNA strands unwind, polymerase initiates RNA synthesis at the start point of template strand 2. Elongation: polymerase moves downstream, unwinding DNA and elongating the RNA transcript 5’ to 3’ , DNA strands reform a double helix after 3. Termination: Eventually, the RNA transcript is released and polymerase detaches from DNA
90
what are transcription factors?
A collection of proteins that mediate the binding of RNA polymerase and the initiation in eukaryotes
91
What is the transcription initiation complex?
The collection of transcription factors and RNA polymerase II bond to the promoter
92
What is a TATA box?
A very important DNA sequence in a promoter
93
What end of the RNA gets nucleotides added to it?
the 3’ end
94
How is termination if transcription different in bacteria and eukaryotes?
Bacteria: Polymerase hits terminator sequence in DNA and detaches Eukaryotes: RNA polymerase II transcribes a polyadenylatiom sequence, then about 10-35 nucleotides downstream from there, proteins cut the transcript from the RNA polymerase releasing pre-mRNA
95
What is RNA processing?
In eukaryotic nuclei, enzymes modify pre-mRNA before the genetic messages are dispatched to the cytoplasm. Both ends of the primary transcript are altered. Sometimes parts of the pre-mRNA are cut out and the remaining parts are spliced together, the results produce and mRNA molecule ready for translation
96
What is a 5’ and a poly-A tail? What functions do they share?
A 5’ cap is a modified form of guanine added to the 5’ end after transcription of the first 20-40 nucleotides. A poly-A tail is 50-250 A nucleotides added to the 3’ end. They both 1. Facilitate transport of mature mRNA from the nucleus 2. Protect mRNA from degradation by hydrolytic enzymes 3. They help ribosomes attach to the 5’ end of the mRNA once in the cytoplasm
97
What is RNA splicing?
Cutting and pasting of regions of RNA
98
What are introns and exons?
Introns: Segments of intervening sequences between coding regions. These are cut out in the nucleus after pre-mRNA is transcribed Exons: Coding regions that are usually expressed
99
What is alternative RNA splicing and why is this used?
Alternative RNA splicing is when different sections of pre-mRNA are treated like introns and exons, therefore many more types of polypeptides can be produced than the number of genes
100
What is a spliceosome and its function?
A large complex of proteins and small RNAs(that catalyze the process) that remove the introns by bonding to several short nucleotide sequences along the intron, including key sequences at the end. The intron is released and rapidly degraded
101
What are ribozymes?
RNA molecules that function as enzymes
102
What is transfer RNA?
(tRNA) The translator that transfers amino acids from the cytoplasmic pool of amino acids to a growing polypeptide of a Ribosome
103
What is an anticodon?
the nucleotide triplet that base-pairs to a specific mRNA codon
104
What is the structure of a tRNA codon?
tRNA is a series of about 80 nucleotides with and anticodon at one and at an amino acid attachment at the other end
105
How is tRNA made in eukaryotes?
It is transcribed from DNA templates in the nucleus, then travels to the cytoplasm
106
how is tRNA similar in bacteria and eukaryotes?
Each tRNA molecule is used repeatedly, picking up its designated amino acid in the cytosol, depositing onto a polypeptide chain then leaves the ribosome to pick up an amino acid
107
What are aminoacyl-tRNA synthetases?
A family of related enzymes responsible for the correct matching of tRNA to amino acids
108
What is wobble?
The flexible base pairing of codons and anticodons
109
What is required for the accurate translation of genetic messages?
1. A tRNA that binds to an mRNA molecule must carry the right amino acid and no other(aminoacyl-tRNA synthetases) 2. Pairing a tRNA anticodon to the right mRNA codon(wobble)
110
What are ribosomes made up of?
A large and small subunit each consisting of proteins and one or more rRNAs
111
How are ribosomes similar and different in bacteria and eukaryotes? Where are ribosomes synthesized in the eukaryotes?
In eukaryotes, the subunits are made and the rRNA genes are transcribed in the nucleus. This is then exported to the cytoplasm. Similarities: Large and small subunits join to form a functioning ribosome only when they attach to an mRNA molecule. Differences: rRNAs are 3 molecules in bacteria and 4 in eukaryotes. Eukaryotic ribosomes are slightly larger
112
What are p sites, a sites and e sites?
P: Holds tRNA carrying the growing polypeptide chain A: holds tRNA carrying the next amino acid to be added to the chain E: the exit site for discharged tRNAs
113
How is initiation of translation similar and different in bacteria and eukaryotes?
Different: In bacteria a small subunit binds to tRNA and mRNA in either order. In eukaryotes, the tRNA binds to the 5’ cap and moves downstream Similar: Start codon signals start of translation
114
Initiation of translation
A small ribosomal subunit binds mRNA to initiator tRNA. This is completed by the attachment of the large ribosomal subunit. Initiation factor protein bring everything together. Initiator tRNA sits in P site, A site is ready for the next tRNA
115
Elongation(translation)
Amino acids are added one by one to the polypeptide chain. Involves elongation factor proteins. rRNA of large ribosomal subunit catalyzes the formation of a peptide bond between amino acids
116
Termination of translation
Final stage, a stop codon reaches the A site of a ribosome, a release factors bonds to the stop codon in the A site breaking the bond between the polypeptide and tRNA in the P site releasing the polypeptide through the exit tunnel
117
Where is GTP required in translation?
Initiation: To form initiation complex Elongation: Codon recognition(increases efficiency and accuracy), translocation Termination: breakdown of translation assembly
118
What happens to a polypeptide after translation?
It undergoes folding, coiling and modifications. Modifications include cleaving, chemical modifications, and combining with other chains
119
What is a signal peptide?
A signal that makes the free ribosome attach to the ER during translation
120
What is a signal-recognition particle?
A protein-RNA complex that recognizes the signal peptide. Escorts the ribosome to ER membrane receptors
121
What are polyribosomes?
Strings of ribosomes that translate a strand of RNA at the same time to produce copies of the same polypeptide quickly
122
What are missense mutations?
Nucleotide substitution point mutations that change one amino acid to another
123
What is a nonsense mutation?
A point mutation that changes a codon for an amino acid into a stop codon. Almost always lead to nonfunctional proteins
124
What is a frameshift mutation?
An insertion or deletion mutation that isnt a multiple of 3. This causes the codons to be improperly grouped
125
What are mutagens?
Physical and chemical agents that interact with DNA in a way that causes mutations
126
What is an operator?
A segment of DNA that acts as a switch, located within the promoter or in between the promoter and enzyme coding genes. It controls the access if RNA polymerase to these genes
127
What is an operon?
The promoter, operator, and genes they control
128
What is a repressor?
A protein that switches on operon off by bonding to the operator and preventing the attachment of RNA polymerase. Can be active or inactive
129
What is a regulatory gene?
The gene that produces a repressor
130
What is a corepressor?
A molecule that cooperates with a repressor to turn an operon off(tryptophan)
131
What are repressible and inducible operons?
Repressible: Usually on but can be repressed when a molecule bonds to a regulatory protein Inducible: Usually off but can be stimulated when a molecule bonds to a regulatory protein
132
What is an inducer?
A molecule that bonds to the repressor and inactivates it
133
What is the difference between positive and negative gene regulation?
Positive: Regulatory protein interacts directly with the genome to switch transcription on, and vice versa for negative
134
What is an activator?
a protein that binds to DNA and stimulates transcription of a gene
135
How do repressors and activators act as on/off switches and volume control?
Repressors determine if a gene transcribes at all and an activator determines the rate at which a gene transcribes
136
What is differential gene expression?
the expression of different genes by cells with the same genome
137
What is a common control point for gene expression in all organisms?
transcription
138
What is DNA methylation?
The process of enzymes methylating DNA bases. Effects are heritabke
139
What is epigenetic inheritance?
Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequenfe
140
What are control elements?
segments of noncoding DNA having particular nucleotide sequences that serve as binding sites for transcription factor proteins
141
What are enhancers?
groupings of distal control elements(binding sites)
142
How can enhancers influence transcription?
Activator proteins bind to the distal control elements. Then a DNA bending protein bends the DNA and brings the activators/enhancers/distal control elements closer to the promoter. The activators bind to mediator proteins and transcription factors, forming an active transcription initiation complex on the promoter
143
How can transcription factors function as repressors?
1. Bind directly to a control element, blocking activator binding or turning off transcription when activators are bound 2. Block the binding of activators to proteins that allow the activators to bind to DNA
144
How do activators and repressors influence transcription indirectly?
by affecting chromatin structure by recruiting proteins
145
In which cells can RNA splicing occur?
Eukaryotic cells
146
Where can nucleotide sequences that determine mRNA lifespan be found?
Most commonly at the 3’ end of the UTR

AP Biology Mr. Maiorana (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions