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UNIT 6 ck12’s 4.1-4.7 Flashcards

1
Q

What does DNA stand for?

A

Deoxyribonucleic acid

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2
Q

What is the primary function of DNA?

A

Contains instructions for all the proteins your body makes

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3
Q

What determines the structure and function of cells?

A

Proteins

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4
Q

What initiates a protein’s structure?

A

The sequence of amino acids

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5
Q

Where is DNA found in eukaryotic cells?

A

In chromosomes within the nucleus

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6
Q

Where are proteins made?

A

At ribosomes in the cytoplasm

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7
Q

What is the role of RNA in the central dogma?

A

Carries information from DNA to ribosomes

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8
Q

What does RNA stand for?

A

Ribonucleic acid

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9
Q

How does RNA exit the nucleus?

A

By squeezing through pores in the nuclear membrane

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10
Q

What is the central dogma of molecular biology?

A

DNA → RNA → Protein

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11
Q

What are the two processes involved in the central dogma?

A

Transcription and translation

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12
Q

Where does transcription occur in eukaryotic cells?

A

In the nucleus

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13
Q

What type of RNA is produced during transcription?

A

Messenger RNA (mRNA)

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14
Q

What happens to mRNA after it leaves the nucleus?

A

It goes to a ribosome in the cytoplasm

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15
Q

What occurs during translation?

A

Reads the genetic code in mRNA and makes a protein

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16
Q

What is DNA?

A

DNA, deoxyribonucleic acid, is the genetic material in your cells

DNA determines your characteristics and is inherited from your parents.

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17
Q

Who made important discoveries about DNA in the 1920s?

A

Frederick Griffith

Griffith contributed significantly to identifying DNA as the genetic material.

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18
Q

What are the two strains of bacteria studied by Griffith?

A

R (rough) strain and S (smooth) strain

These strains exhibited different virulence properties.

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19
Q

What was the outcome when mice were injected with the S strain?

A

The mice died

The S strain is virulent.

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20
Q

What was the outcome when mice were injected with the R strain?

A

The mice did not die

The R strain is non-virulent.

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21
Q

What happened when Griffith injected mice with heat-killed S-strain bacteria?

A

The killed bacteria did not harm the mice

This was expected as the bacteria were non-viable.

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22
Q

What was the surprising result when dead S-strain bacteria were mixed with live R-strain bacteria?

A

The mice died

This indicated a transformation occurred, leading to the conclusion that DNA is the genetic material.

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23
Q

Fill in the blank: DNA is passed on from your _______.

A

[parents]

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24
Q

True or False: The S strain of bacteria is non-virulent.

A

False

The S strain is virulent and causes death in mice.

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25
What significant milestone in molecular biology is associated with DNA?
The identification of DNA as the genetic material ## Footnote This discovery was crucial for understanding genetics.
26
What process did Griffith call when the R strain became deadly?
Transformation ## Footnote Griffith observed that something in the killed S strain was transferred to the harmless R strain, making it deadly.
27
Who led the team that investigated Griffith's findings in the early 1940s?
Oswald Avery ## Footnote Avery's team included scientists Colin MacLeod and Maclyn McCarty.
28
What substances did Avery's team inactivate to test their hypothesis?
Proteins, RNA, and DNA ## Footnote They focused on inactivating these substances in heat-killed S-strain bacteria.
29
What was the outcome when proteins and RNA were inactivated during the experiment?
R-strain still transformed into the deadly S-strain ## Footnote This indicated that proteins and RNA were not the genetic material.
30
What happened when DNA in the S-strain was inactivated?
R-strain did not transform ## Footnote This led to the conclusion that DNA is the genetic material.
31
What conclusion did Avery's team reach about DNA?
DNA is the substance that controls the characteristics of organisms ## Footnote This established DNA as the genetic material.
32
Fill in the blank: Griffith observed that something in the killed S strain was ________ to the previously harmless R strain.
transferred
33
True or False: Avery's experiments ruled out DNA as the genetic material.
False ## Footnote Avery's experiments concluded that DNA is the genetic material.
34
What type of bacteria was mixed with the heat-killed S-strain bacteria in Avery's experiment?
Harmless R-strain bacteria
35
Who conducted experiments to confirm that DNA is the genetic material?
Alfred Hershey and Martha Chase ## Footnote Their experiments were crucial in the acceptance of DNA as genetic material.
36
What type of viruses did Hershey and Chase use in their experiments?
Bacteriophages ## Footnote Bacteriophages are viruses that infect bacteria.
37
What is the composition of bacteriophages?
DNA inside a protein coat ## Footnote This structure is essential for their function as viruses.
38
How do viruses reproduce?
By inserting their genetic material into a cell ## Footnote They utilize the host cell's machinery to replicate.
39
What did Hershey and Chase use to label the DNA and proteins in viruses?
Different radioactive elements ## Footnote This labeling helped to track which molecule was inserted into bacteria.
40
What molecule did Hershey and Chase identify as being inserted into bacteria?
DNA ## Footnote This finding confirmed DNA as the genetic material.
41
True or False: The conclusion that DNA is the genetic material was widely accepted immediately after its proposal.
False ## Footnote It required further research to gain acceptance.
42
What are the four different nitrogen bases of DNA?
Adenine (A), Guanine (G), Cytosine (C), Thymine (T) ## Footnote These bases are crucial for the structure and function of DNA.
43
Who made important discoveries about DNA in the mid 1900s?
Erwin Chargaff ## Footnote Chargaff's work laid the foundation for understanding the composition of DNA.
44
What is Chargaff's contribution to the study of DNA?
He studied DNA from many different species and focused on the nitrogen bases ## Footnote Chargaff's findings helped establish key principles in molecular biology.
45
True or False: Chargaff was primarily interested in the structure of proteins.
False ## Footnote Chargaff focused on the nitrogen bases of DNA, not proteins.
46
Fill in the blank: Chargaff studied DNA from many different _______.
species ## Footnote This diversity in study contributed to his significant findings.
47
Who are credited with discovering the double helix shape of DNA?
James Watson and Francis Crick ## Footnote They built upon the work of other scientists, including Rosalind Franklin.
48
What is the shape of DNA as discovered by Watson and Crick?
Double helix ## Footnote It is often described as resembling a twisted ladder.
49
What technique did Rosalind Franklin and other scientists use to study DNA's structure?
X-rays ## Footnote This technique helped them learn more about the physical structure of DNA.
50
What contribution did Rosalind Franklin make to the discovery of DNA's structure?
X-ray crystallography photos ## Footnote These photos provided crucial evidence for the double helix model.
51
True or False: Watson and Crick were the first to discover DNA's double helix without any prior contributions from other scientists.
False ## Footnote Their discovery was based on the prior work of Rosalind Franklin and others.
52
Fill in the blank: The DNA structure resembles a _______.
twisted ladder
53
What did Watson and Crick's model of DNA match?
Observations from Franklin's X-ray crystallography ## Footnote Their model was validated by the images provided by Franklin.
54
What has been a common issue regarding the contributions of Rosalind Franklin and others?
Lack of credit ## Footnote Franklin and other scientists have not always been acknowledged for their roles in the discovery.
55
What is the shape of DNA?
Double helix
56
What rules contributed to the understanding of DNA?
Chargaff's rules
57
What type of macromolecule is DNA?
Nucleic acid
58
What are the monomers that make up DNA?
Nucleotide monomers
59
How many polynucleotide chains does the DNA double helix consist of?
Two
60
What three components make up a nucleotide?
* Sugar (deoxyribose) * Phosphate group * Nitrogen-containing base (A, C, G, or T)
61
Fill in the blank: Each nucleotide consists of a sugar, a phosphate group, and a _______.
Nitrogen-containing base
62
True or False: DNA consists of only one polynucleotide chain.
False
63
What type of bonds hold together the two polynucleotide chains of DNA?
Hydrogen bonds ## Footnote These bonds occur between complementary bases.
64
Which base does adenine always bond with?
Thymine
65
Which base does cytosine always bond with?
Guanine
66
What structural difference exists between adenine/guanine and cytosine/thymine?
Adenine and guanine have a two-ring structure, while cytosine and thymine have a one-ring structure.
67
Why is it important for adenine to bond with thymine and cytosine to bond with guanine?
To maintain a constant distance between the two DNA chains.
68
What shape does the uniform distance between DNA chains help maintain?
The shape of the DNA double helix.
69
What do the base pairs (A-T and G-C) form in the DNA structure?
The steps of the twisted ladder.
70
Fill in the blank: Adenine always bonds with its complementary base, _______.
thymine
71
Fill in the blank: Cytosine always bonds with its complementary base, _______.
guanine
72
True or False: The distance between DNA chains is variable if adenine binds with guanine.
True
73
What initiates DNA replication?
An enzyme, DNA helicase ## Footnote DNA helicase breaks the bonds between complementary bases in DNA.
74
What is the role of DNA helicase in DNA replication?
It breaks the bonds between complementary bases in DNA ## Footnote This action exposes the bases inside the molecule.
75
Which enzyme is responsible for reading the exposed bases during DNA replication?
DNA polymerase ## Footnote DNA polymerase reads the bases and builds new DNA strands.
76
How many new DNA strands are formed during DNA replication?
Two new DNA strands ## Footnote These strands are built with complementary bases by DNA polymerase.
77
What do the two daughter molecules contain after DNA replication?
Each contains one strand from the parent molecule and one new complementary strand ## Footnote This results in two identical daughter molecules.
78
What is meant by 'semi-conservative' in the context of DNA replication?
Half of the parent DNA molecule is conserved in each daughter molecule ## Footnote This means that each daughter DNA molecule has one original and one new strand.
79
True or False: The two daughter DNA molecules are identical to the parent molecule.
True ## Footnote The process ensures that the genetic information is preserved.
80
What is the role of RNA in protein synthesis?
RNA helps in conveying genetic information from DNA to the ribosomes for protein synthesis. ## Footnote RNA is essential as DNA is located in the nucleus while proteins are made in the cytoplasm.
81
How does RNA differ from DNA?
RNA differs from DNA in several ways: * Smaller than DNA * Consists of one nucleotide chain instead of two * Contains uracil (U) instead of thymine * Contains ribose sugar instead of deoxyribose. ## Footnote These differences are crucial for the functions of RNA in protein synthesis.
82
What is the function of messenger RNA (mRNA)?
mRNA copies genetic instructions from DNA in the nucleus and carries them to the cytoplasm. ## Footnote mRNA serves as the template for protein synthesis.
83
What is the role of ribosomal RNA (rRNA)?
rRNA helps form ribosomes, the organelle where proteins are assembled. ## Footnote Ribosomes are essential for translating mRNA into proteins.
84
What is the function of transfer RNA (tRNA)?
tRNA brings amino acids to ribosomes, where they are joined together to form proteins. ## Footnote tRNA acts as a bridge between mRNA and the amino acids.
85
Fill in the blank: RNA is a __________ acid.
nucleic
86
True or False: RNA consists of two nucleotide chains.
False
87
Fill in the blank: The sugar present in RNA is __________.
ribose
88
What are the three main types of RNA involved in protein synthesis?
The three main types of RNA are: * Messenger RNA (mRNA) * Ribosomal RNA (rRNA) * Transfer RNA (tRNA) ## Footnote Each type of RNA has a distinct role in the process of protein synthesis.
89
What is the process in which cells make proteins called?
Protein synthesis ## Footnote Protein synthesis consists of two main processes: transcription and translation.
90
What are the two processes that make up protein synthesis?
* Transcription * Translation ## Footnote These processes are essential for the synthesis of proteins in cells.
91
Where does transcription take place in eukaryotic cells?
In the nucleus ## Footnote Transcription involves using DNA as a template to create RNA.
92
What molecule is used as a template during transcription?
DNA ## Footnote DNA provides the genetic instructions for making RNA.
93
What type of RNA is produced during transcription?
Messenger RNA (mRNA) ## Footnote mRNA carries the genetic information from DNA to the ribosomes.
94
What happens to RNA after it is synthesized during transcription?
It leaves the nucleus and goes to a ribosome in the cytoplasm ## Footnote This movement is necessary for the next step, translation.
95
What is the role of translation in protein synthesis?
It reads the genetic code in mRNA and makes a protein ## Footnote Translation is the second part of the protein synthesis process.
96
What is the central dogma of molecular biology?
DNA + RNA ## Footnote This concept describes the flow of genetic information in biological systems.
97
During transcription, what is made that is complementary to a strand of DNA?
A strand of mRNA ## Footnote This complementary relationship is crucial for accurate protein synthesis.
98
What are the three steps of transcription?
Initiation, elongation, termination ## Footnote These steps describe the process of synthesizing mRNA from a DNA template.
99
What occurs during the initiation step of transcription?
RNA polymerase binds to the promoter region of a gene ## Footnote This signals the DNA to unwind for transcription to begin.
100
What is the role of RNA polymerase during elongation?
It reads the unwound DNA strand and builds the mRNA molecule ## Footnote RNA polymerase uses complementary base pairs to add nucleotides.
101
What base in DNA pairs with uracil in RNA during transcription?
Adenine (A) ## Footnote This pairing occurs during the elongation process.
102
What marks the end of transcription?
RNA polymerase crosses a stop (termination) sequence ## Footnote This indicates that the mRNA strand is complete.
103
Fill in the blank: The first step of transcription is called _______.
Initiation ## Footnote This step involves the binding of RNA polymerase to the promoter.
104
True or False: Elongation occurs after termination in the transcription process.
False ## Footnote Elongation occurs before termination.
105
What happens to the mRNA strand during termination?
It detaches from DNA ## Footnote This concludes the transcription process.
106
What is the complementary base to adenine (A) in RNA?
Uracil (U) ## Footnote This base pairing is essential for mRNA synthesis.
107
What must new mRNA undergo before leaving the nucleus in eukaryotes?
Additional processing including splicing, editing, and polyadenylation ## Footnote These processes modify the mRNA in various ways, allowing a single gene to be used to make more than one protein.
108
What is splicing?
The removal of introns from mRNA ## Footnote The remaining mRNA consists only of exons, which are regions that code for proteins.
109
What are introns?
Regions in mRNA that do not code for proteins ## Footnote Introns are removed during the splicing process.
110
What are exons?
Regions in mRNA that code for proteins
111
What are ribonucleoproteins?
Nucleoproteins that contain RNA
112
What role do small nuclear ribonucleoproteins play?
They are involved in pre-mRNA splicing
113
What does editing do to mRNA?
Changes some of the nucleotides in mRNA ## Footnote For example, the human protein APOB has two different forms due to editing.
114
What is an example of a protein affected by editing?
APOB ## Footnote APOB helps transport lipids in the blood and has two different forms because of editing.
115
What is polyadenylation?
The addition of a 'tail' consisting of adenine bases to mRNA
116
What is the function of the polyadenylation tail?
Signals the end of mRNA and protects it from enzymes ## Footnote It is also involved in exporting mRNA from the nucleus.
117
Fill in the blank: The process of removing introns from mRNA is called _______.
splicing
118
True or False: Exons are the non-coding regions of mRNA.
False ## Footnote Exons are the coding regions that remain after splicing.
119
What is the genetic code?
The genetic code is the sequence of nitrogen bases-A, C, G, U-in an mRNA chain.
120
What are the 'letters' of the genetic code?
The letters of the genetic code are A, C, G, U.
121
How are the letters of the genetic code combined?
The letters are combined in groups of three to form code 'words,' called codons.
122
What is a codon?
A codon is a group of three nitrogen bases that encodes one amino acid, or a start or stop signal.
123
How many common amino acids are there in proteins?
There are 20 common amino acids in proteins.
124
How many possible codons exist?
There are 64 possible codons.
125
True or False: The genetic code can code for more amino acids than there are codons.
False
126
Fill in the blank: The genetic code consists of the sequence of nitrogen bases ______ in an mRNA chain.
A, C, G, U
127
What do codons stand for?
Codons stand for (encode) one amino acid, unless it codes for a start or stop signal.
128
What amino acid does the codon AUG code for?
Methionine
129
What is the function of the start codon?
Begins translation and establishes the reading frame of mRNA
130
What is the reading frame in mRNA?
The way the letters are divided into codons
131
How is mRNA read during translation?
Codon by codon until a stop codon is reached
132
What are the stop codons?
UAG, UGA, UAA
133
Do stop codons code for any amino acids?
No
134
What are stop codons also known as?
Termination codons
135
Fill in the blank: The codon _______ establishes the reading frame of mRNA.
AUG
136
True or False: The next three letters after the start codon are read as the first codon.
False
137
What happens after the start codon in mRNA?
The next three letters are read as the second codon
138
What is the universal characteristic of the genetic code?
All known living organisms use the same genetic code ## Footnote This indicates that all organisms share a common evolutionary history.
139
What does it mean for the genetic code to be unambiguous?
Each codon codes for just one amino acid (or start or stop) ## Footnote If codons encoded more than one amino acid, it could lead to confusion in protein synthesis.
140
What is a key feature of the genetic code's redundancy?
Most amino acids are encoded by more than one codon ## Footnote For example, multiple codons can code for the amino acid threonine.
141
Fill in the blank: The genetic code is _______.
redundant
142
What is the second part of the central dogma of molecular biology?
Translation ## Footnote The central dogma is summarized as DNA → RNA → Protein.
143
What is the process of translation?
It is the process in which the genetic code in mRNA is read, one codon at a time, to make a protein.
144
Where does mRNA move after leaving the nucleus?
It moves to a ribosome.
145
What is the composition of a ribosome?
It consists of RNA and proteins.
146
What does the ribosome do with the sequence of codons in mRNA?
It reads the sequence.
147
What brings amino acids to the ribosome during translation?
Molecules of tRNA.
148
Fill in the blank: The genetic code in mRNA is read one _______ at a time.
codon
149
True or False: The ribosome is responsible for translating DNA directly into proteins.
False
150
What is the role of tRNA in translation?
It brings amino acids to the ribosome in the correct sequence.
151
What is the role of tRNA?
To carry amino acids to the ribosome during protein synthesis ## Footnote tRNA serves as the adaptor molecule that translates the genetic code into proteins.
152
What is an anticodon?
A sequence of 3 bases that is complementary to the codon for an amino acid ## Footnote The anticodon is crucial for ensuring the correct amino acid is added during translation.
153
What is the relationship between a codon and its corresponding anticodon?
The anticodon is complementary to the codon ## Footnote For instance, if the codon is AAG, the anticodon would be UUC.
154
What amino acid does the codon AAG correspond to?
Lysine ## Footnote The codon AAG specifically codes for lysine in the genetic code.
155
What happens when a tRNA binds to a codon in mRNA?
The tRNA gives up its amino acid ## Footnote This process is essential for the elongation of the polypeptide chain.
156
What forms between adjacent amino acids during protein synthesis?
Bonds ## Footnote These bonds form as amino acids are sequentially added to the growing polypeptide chain.
157
What continues to happen until a stop codon is reached?
The chain of amino acids keeps growing ## Footnote The presence of a stop codon signals the termination of protein synthesis.
158
Fill in the blank: The anticodon for the amino acid lysine is _______.
UUC
159
What is the anticodon?
It is the sequence of three nucleotides in tRNA that pairs with the complementary codon in mRNA.
160
What happens to a polypeptide chain after it is synthesized?
It may undergo additional processes such as folding and binding with other molecules.
161
What causes a polypeptide to assume a folded shape?
Interactions among its amino acids.
162
With which types of molecules can a polypeptide bind?
It can bind with other polypeptides, lipids, or carbohydrates.
163
Where do many proteins travel to be modified for their specific function?
To the Golgi apparatus.

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