Molecular Genetics Flashcards
1
Q
What 3 things do genes have to be capable of doing?
A
carry information from one generation to the next, put information that they carry to work to produce traits of the organism and copy the gene to replicate every time a cell divides
2
Q
What is a chromosome made of?
A
Half nucleic acid and half protein
3
Q
What did James Watson and Francis Crick discover?
A
The model for the structure of a DNA molecule
4
Q
What are the small units of DNA?
A
nucleotides
5
Q
What do nucleotides consist of?
A
a phosphate group, a 5-carbon sugar and a nitrogen base
6
Q
What is the 5-carbon sugar called?
A
deoxyribose
7
Q
What are the 4 bases found in DNA?
A
Adenine, Guanine, Thymine and Cytosine
8
Q
What is a purine and which bases are purines?
A
a double ringed structure, guanine and adenine
9
Q
What is a pyrimidine and which bases are pyrimidines?
A
a single ringed structure, cytosine and thymine
10
Q
What is the backbone of DNA made of?
A
Alternating sugar and phosphate groups
11
Q
What did Erwin Chargaff discover (Chargaffs rule)?
A
the amount of the base pairs are equal in any sample of DNA
12
Q
What process did Rosalind Franklin use?
A
x-ray diffraction
13
Q
What did Rosalind Franklin discover?
A
DNA is twisted around each other in a shape known as a helix, 2 strands, nitrogen bases were at the center of the molecule
14
Q
What bond is used to bind the 2 sides of the DNA strand?
A
weak hydrogen bonds
15
Q
Which base pairs have 2 hydrogen bonds?
A
Adenine and Thymine
16
Q
Which base pairs have 3 hydrogen bonds?
A
Guanine and Cytosine
17
Q
What is a chromosome composed of?
A
DNA and proteins
18
Q
What is DNA wrapped around?
A
Histones
19
Q
What is a nucleosome?
A
The beadlike structure formed from DNA and histones
20
Q
What are the differences between DNA and RNA?
A
- RNA is single stranded and DNA is double stranded
- The sugar in RNA is called ribose and the sugar in DNA is called deoxyribose
- In RNA, uracil binds with adenine, in DNA thymine binds with adenine
21
Q
What does semiconservative replication mean?
A
separating the 2 parent strands and building a new, complimentary replacement strand for each
22
Q
What does antiparallel mean?
A
The 2 DNA strands run in opposite directions of each other due to bonding arrangements which allow the molecule to be stable
23
Q
What should be attached to the sugar on one end of a DNA strand?
A
a hydroxyl of the 3’ carbon
24
Q
What should be attached to the last sugar on the other end of the DNA strand?
A
a phosphate attached to the 5’ carbon
25
What does DNA polymerase 1 do?
Removes RNA primers
26
What does DNA polymerase 2 do?
Catalyzes the repair of mistake nucleotide pairs
27
What does DNA polymerase 3 do?
Builds new strands of DNA during replication
28
What is the template strand?
The DNA strand that directs the synthesis of the complementary strand
29
What is the lagging strand?
The new DNA strand synthesized in fragments
30
What is the leading strand?
The new DNA strand that is synthesized continuously
31
What does ligase do?
pairs the complementary strands of DNA due to the phosphodiester bonds
32
What does primase do?
Builds the RNA primers
33
What does topoisomerase do?
Relieves tension in DNA while the 2 parent strands are separating
34
What does helicase do?
Unwinds the DNA strands and separates them
35
What is a replication fork?
It keeps the separated strands of DNA apart
36
What are okazaki fragments?
Shot lengths of DNA produced during the synthesis of the lagging strand
37
What is a single stranded binding protein?
The area where DNA polymerase is bound to unwound DNA, prevents parent DNA strands from rejoining to each other once they have separated
38
What is anneling?
links the sugars and phosphates together
39
What is a replication origin?
a starting point on the DNA where helicase attaches on and starts separating the parent strands
40
In what direction is a DNA strand synthesized?
5' to 3' direction
41
In what direction is DNA read from?
3' to 5' direction
42
Why is DNA repair necessary?
Diseases like cancer can result from non-functioning DNA
43
What is eukaryotic DNA organization?
DNA wrapped around histones
44
What is prokaryotic DNA organization?
one chromosome that is commonly circular
45
What is DNA polymerases starting point?
a primer
46
What happens at the end of the lagging strand?
the primer is removed and the new DNA polymerase has no where to go, the section is lost on both strands as it cannot synthesize the end piece of DNA
47
What can happen after many losses of DNA and the shortening of the chromosomes?
loss or damage of important genes
48
What is a telomere?
zones of repetitive, non-coding nucleotide sequences found at the end of eukaryotic chromosomes
49
How do telomeres work?
every time DNA replicates, part of the telomeres are lost and get shorter preventing the loss of the DNA
50
What happens to the telomeres after replication?
They are fully lost and no longer provide protection for the chromosome
51
What happens once enough replications have occurred?
Portions of DNA may be lost resulting in new cells losing their ability to function which can lead to hearing loss, slower cognitive function, slower reaction times
52
What is hayflicks limit?
the number of times a cell can divide (60)
53
What is a gene?
the coded DNA instructions that controls the production of specific proteins which includes enzymes, structural proteins and oxygen-carrying proteins
54
What are proteins?
the links between genotypes and phenotypes
55
What do proteins determine?
traits in offspring
56
What is gene expression?
the process where DNA directs the synthesis of proteins in 2 stages: transcription and translation
57
What are proteins made of?
Amino acids
58
What specifies an amino acid?
3 nucleotides in a sequence
59
What is a triplet nucleotide called?
a codon
60
What does each codon call for?
A specific amino acid
61
What is a start codon?
a specific sequence of nucleotides that indicates where the proteins building instructions begins
62
What is a stop codon?
they act a signal for the end of the protein chain
63
Where are proteins made?
by the ribosomes in the cytoplasm
64
How is a protein made?
the gene of the DNA is copied into RNA, the copy instructions are send to the ribosomes in the cytoplasm, RNA then carries the message from the DNA to the ribosomes, the RNA then tells the ribosomes which protein to make and how
65
What does the mRNA do?
travels from the nucleus to the cytoplasm with instructions to make proteins
66
What is the mRNA?
the messenger between the DNA in the nucleus and the ribose in the cytoplasm
67
What is the structure of tRNA?
a anticodon at one end and an amino acid binding site at the other, bases of the anticodon are complementary to the mRNA codon
68
What does the tRNA do?
reads the messages carried by the mRNA and gathers the amino acids for making proteins
69
How does the tRNA work?
transfers amino acids from the cytoplasm pool of the amino acids to a ribosome, one end attaches to one amino acid and carries it to the ribosome
70
What does rRNA do?
binds mRNA and tRNA to the ribosome and allows all components required for the synthesis of the proteins to be held together
71
What does transcription do?
forms a strand of RNA from a strand of DNA
72
Where does transcription occur?
in the nucleus
73
What enzyme catalyzes transcription?
RNA polymerase
74
What is the promotor region?
the DNA sequence where RNA polymerase attaches and initiates transcription
75
What is the terminator region?
the DNA sequence that signals the end of transcription
76
What are the steps of transcription?
- RNA polymerase binds to the promotor site on the DNA molecule
- RNA polymerase separates the DNA strands
- New nucleotides are inserted base on pairing rules on the template DNA strand
- As the RNA polymerase moves across the DNA molecule, hydrogen bonds between the 2 strands of DNA are reformed
- A single stranded RNA molecule has been transcribed
77
What are introns?
sequences of nitrogenous bases that are not involved in the making of proteins
78
What needs to be cut out of RNA before RNA goes to the ribosomes?
introns
79
What are exons?
sequences of nitrogenous bases that are involved in the making proteins
80
When are introns and exons copied from DNA?
when mRNA is formed
81
When do the introns get cut out of the RNA?
While the RNA is still in the nucleus
82
What happens to the remaining exons in the RNA?
they get spliced together
83
What is added to the final RNA molecule?
a cap and tail
84
What does a cap and tail do?
helps identify the front and back end of the RNA and helps the ribosomes identify the front and back end of the instructions
85
What do introns allow?
a single gene to code for more than one type of protein depending on which segments are exons and introns
86
What is translation?
the synthesis of proteins
87
What happens when each codon of the mRNA molecule moves through the ribosome?
the proper amino acid is brought into the ribosome by the tRNA
88
What does the ribosome do in translation?
hitches the amino acid together with peptide bonds and polypeptides are made
89
What are polypeptides?
a long chain or amino acids but not a functioning protein
90
Where are polypeptides sent?
to the ER and the golgi apparatus where they modify and shape themselves into functioning proteins
91
What happens if a codon is read incorrectly?
a polypeptide will be made by putting the wrong amino acids in order which makes it unlikely for the resulting protein to function
92
What are subunits made of?
proteins in a RNA molecule called rRNA
93
Where are subunits made?
in the nucleus
94
What are the 3 tRNA binding sites?
E site, P site and A site
95
What does the P site hold?
the rRNA carrying the growing polypeptide chain
96
What does the A site hold?
the tRNA carrying the next amino acid for the polypeptide chain
97
What happens at the E site?
where discharged tRNAs leave the ribosome from
98
What are mutations?
mistakes in copying DNA, incorrect nitrogen bases, change in the genetic material of the cell
99
What is a point mutation?
changes in one pair of a gene at a single point in the DNA sequence
100
What is a base pair substitution?
one nitrogen base is changed to another
101
What is a base pair insertion or deletion?
a nitrogen base is added or removed from the DNA sequence
102
What is a frameshift mutation?
a insertion or deletion of a base that causes the bases to be shifted left or right for every codon that follows
103
What does gene on mean?
cell is actively transcribing the DNA into mRNA, the mRNA is being translated to synthesize proteins, gene is being expressed
104
what does gene off mean?
cell is not transcribing or translating DNA, gene is not expressed
105
What is the taxonomy of prokaryotic gene regulation?
kingdom archaebacteria and eubacteria
106
What is the genome size in prokaryotic gene regulation?
very small
107
What is the DNA organization in prokaryotic gene regulation?
circular DNA
108
What is the cellular hierarchy in prokaryotic gene regulation?
unicellular
109
What is a Lac Operon?
insight into how a gene will work in the presence or absence of lactose sugar
110
What is a operator?
location on a prokaryotic DNA where the operon is turned off or on
111
what is a operon?
a group of prokaryotic genes which are transcribed together
112
What happens when there is no lactose in prokaryotic gene regulation?
lac repressor binds tightly to the operator, it gets in RNA polymerases way which prevents transcription and turns the gene off
113
What happens where there is lactose in prokaryotic gene regulation?
allolactose binds to the lac repressor and makes it let go of the operator, RNA polymerase can now transcribe the operon, transcription, translation and protein synthesis can occur
114
What is the taxonomy in eukaryotic gene regulation?
Protista, plantae, animalia, fungi
115
What is the genome size in eukaryotic gene regulation?
very large
116
what is the DNA organization in eukaryotic gene regulation?
chromosomes
117
What is the cellular hierarchy in eukaryotic gene regulation?
unicellular or multicellular
118
What is the promotor/operator/binding site in eukaryotic gene regulation?
location on eukaryotic DNA where the transcription factor proteins bind
119
What are transcription factor proteins?
proteins used during gene expression to turn genes on
120
How do transcription factor proteins work?
they bind to the promotor of the DNA sequence which attacks the RNA polymerase to begin transcription
121
What are activator proteins?
turns the gene on by signaling the mediator proteins to begin binding to assemble the transcription complex
122
What are mediator proteins?
a bridge between the activator proteins and the TATA binding proteins
123
What do TATA binding proteins do?
binds to the TATA box DNA sequence before the exon on the DNA strand and the RNA polymerase so they can begin transcription
124
What is the transcription complex?
the assembly of all the proteins needed for transcription
125
What is a TATA box?
a DNA sequence found in the promoter region of genes in the archaea and eukaryotes
126
What do repressor proteins do?
turns the gene off by binding to the repressor site and to the RNA polymerase, keeping the other transcription factor proteins from binding
127
What does CRISPR stand for?
clustered regularly interspaced short palindromic repeats
128
What is CRISPR?
gene editing systems that can be programmed to target specific sequences of genetic code and to edit DNA at precise locations
129
What do CAS proteins do?
they cut out a portion of the infecting agents DNA and inserts it into the CRISPR region of its own DNA
130
What is the polymerase chain reactions (PCR)?
a lab technique for making millions of copies of a specific DNA region, done without the use of a cell or organism
131
What are the 3 steps to the PCR?
Denaturing, annealing and extension
132
What is denaturing?
heating the reaction to 95 degrees Celsius so the DNA strands separate to provide single-stranded templates
133
What is annealing?
cooling the reaction to 50-55 degrees Celsius so that primers can bind to their complimentary sequences on the single-stranded template DNA
134
What is Extension?
raising the temperature to 72 degrees Celsius 3 so DNA polymerase extends the primers, synthesizing new strands of DNA
