Molecular Basis of Inheritance NCERT Flashcards
Over the next hundred years, the nature of the putative genetic material was investigated, culminating in the realization that ___________ – is the genetic material, at least for the majority of organisms.
DNA – deoxyribonucleic acid
Two types of nucleic acids found in living systems are-
Deoxyribonucleic acid (DNA) and ribonucleic acid(RNA)
_________ acts as the genetic material in most organisms.
DNA
RNA acts as a genetic material in some _______
viruses
RNA though it also acts as a genetic material in some viruses, mostly functions as a __________.
messenger
RNA has additional roles as well. It functions as _________, ________, and in some cases, as a catalytic molecule.
adapter, structural
The determination of complete nucleotide sequence of human genome during last decade has set in a new era of ________.
Genomics
DNA is a long polymer of ________
deoxyribonucleotides
The length of DNA is usually defined as the number of _____________ present in it
nucleotides
A pair of nucleotides is referred as ________
base pairs
A bacteriophage known as phi ×174 has ____ nucleotides
5386
Bacteriophage lambda has _____ base pairs (bp)
48502 base pairs
Escherichia coli has ____ bp
4.6 × 10^6 bp
Haploid content of human DNA is ____ bp
3.3 × 10^9 bp
A nucleotide has three components -
a nitrogenous base, a pentose sugar and a phosphate group
Pentose sugar in the case of RNA is
ribose
Pentose sugar in case of DNA is
deoxyribose
There are two types of nitrogenous bases –
Purines and Pyrimidines
Name two Purines
Adenine and Guanine
Name three Pyrimidines
Cytosine, Uracil and Thymine
Which pyrimidines is common for both DNA and RNA?
Cytosine
Which pyrimidine is present only in RNA?
Uracil
Which pyrimidine is present only in DNA?
Thymine
In a nucleoside, a nitrogenous base is linked to the OH of _________ by N-glycosidic linkage.
1’ C pentose sugar
A nitrogenous base is linked to the OH of 1’ C pentose sugar through a _______________ linkage to form a nucleoside
N-glycosidic
A nitrogenous base is linked to the OH of 1’ C pentose sugar through an N-glycosidic linkage to form a
nucleoside
Name the nucleoside present in the RNA
adenosine, guanosine, cytidine, uridine
Name the nucleoside present in the DNA
deoxyadenosine, deoxyguanosine, deoxycytidine & deoxythymidine
A phosphate group is linked to OH of
5’ C of a nucleoside
A phosphate group is linked to OH of 5’ C of a nucleoside through
phosphoester linkage
When a phosphate group is linked to OH of 5’ C of a nucleoside through phosphoester linkage, a corresponding ____is formed.
nucleotide
When a phosphate group is linked to OH of 5’ C of a nucleoside through phosphoester linkage in DNA, a corresponding _____ is formed
deoxynucleotide
Two nucleotides are linked through ______ linkage.
3’-5’ phosphodiester
Two nucleotides are linked through 3’-5’ phosphodiester linkage to form a
dinucleotide
A polynucleotide chain formed has at one end a free phosphate moiety at 5’ -end of sugar, which is referred to as
5’-end of polynucleotide chain
At the other end of the polymer the sugar has a free OH of 3’C group which is referred to as
3’ -end of the polynucleotide chain
The backbone of a polynucleotide chain is formed due to ____________ and __________
sugar and phosphates
In RNA, every nucleotide residue has an additional –OH group present at _______________ in the ribose
2’ -position
In RNA the ____________ is found at the place of thymine.
uracil
Another chemical name for thymine is
5-methyl uracil
DNA, as an acidic substance present in nucleus was first identified by
Friedrich Meischer
In which year, DNA as an acidic substance present in nucleus was first identified?
1869
Friedrich Meischer named DNA as an acidic substance present in nucleus as
Nuclein
Name two scientists who proposed a very simple but famous Double Helix model for the structure of DNA.
James Watson and Francis Crick
Name two scientists who produced data based on X-ray diffraction.
Maurice Wilkins and Rosalind Franklin
Who gave the observation that for a double-stranded DNA, the ratios between Adenine and Thymine and Guanine and Cytosine are constant and equal one?
Erwin Chargaff
For a double-stranded DNA, the ratios between Adenine and Thymine and Guanine and Cytosine are constant and equals ______.
One
What confers a unique complementary property to the polynucleotide chains?
base pairing
DNA strands are said to be __________ to each other, and therefore if the sequence of bases in one strand is known, then the sequence in other strand can be predicted
complementary
If each strand from a DNA acts as a template for the synthesis of a new strand, the two double-stranded DNA thus, produced would be identical to the___________ molecule.
parental DNA
Double-helix structure of DNA is made of two polynucleotide chains, where the backbone is constituted by
sugar-phosphate
The two DNA chains have _____ polarity
anti-parallel polarity
If one chain has the polarity 5’ —–>3’, the other has __________.
3’ —–>5’
The bases in two strands are paired through ________________ forming base pairs (bp).
hydrogen bond (H-bonds)
Adenine forms ____ bonds with Thymine from opposite strand
two hydrogen bonds
Guanine is bonded with Cytosine with
three H-bonds
A _______ comes opposite to a pyrimidine in base pairing.
purine
A purine comes opposite to a pyrimidine. This generates approximately _________ between the two strands of the helix
uniform distance
The two chains are coiled in a ______________ fashion.
right-handed
The pitch of the helix is _____
3.4 nm
A nanometre is ___ of a metre
one billionth
There are roughly ____ bp in each turn.
10
The distance between a bp in a helix is approximate ________
0.34 nm
The plane of one ____ stacks over the other in double-helix
base pair
Which two things confer stability of the helical structure?
H-bonds & Stacking of plane of one base pair over the other
The proposition of a _________ structure for DNA and its simplicity in explaining the genetic implication became revolutionary.
double helix
Francis Crick proposed the _____________ in molecular biology
Central dogma
Who proposed the Central dogma in molecular biology?
Francis Crick
The Central dogma in molecular biology states that the genetic information flows from ____
DNA →RNA →Protein
In some viruses, the flow of information is from ____ to ____
RNA to DNA
The length of DNA double helix in a typical mammalian cell is calculated by multiplying the __________ of bp with __________ bp.
total number, distance between two consecutive
The length of DNA double helix in a typical mammalian cell is approximate _____
2.2 meters
The dimension of a typical nucleus is approximate ___
10^(–6) m
In prokaryotes, such as E. coli, though they do not have a defined ________, the DNA is not scattered throughout the cell.
nucleus
In prokaryotes, DNA is held with some proteins in a region termed as
‘nucleoid’
The DNA in nucleoid is organized in large loops held by ________.
proteins
In eukaryotes, there is a set of positively charged, basic proteins called
histones
A protein acquires charge depending upon the abundance of ________ residues with charged side chains.
amino acids
Histones are rich in the basic amino acid residues ________ & __________
lysine & arginine
Lysine and arginine carry _______ charges in their side chains.
positive
Histones are organised to form a unit of eight molecules called
histone octamer
The negatively charged DNA is wrapped around the positively charged histone octamer to form a structure called
nucleosome
A typical nucleosome contains ____ of DNA helix
200 bp
Nucleosomes constitute the repeating unit of a structure in nucleus called
chromatin
Chromatin is a thread-like ____ seen in nucleus.
stained (coloured) bodies
The nucleosomes in chromatin are seen as ___ structure when viewed under an electron microscope (EM).
beads-on-string
The beads-on-string structure in chromatin is packaged to form ________
chromatin fibers
Chromatin fibers are further coiled and condensed at which stage to form chromosomes?
metaphase stage
Chromatin fibers are further coiled and condensed at the metaphase stage of cell division to form ______
chromosomes
The packaging of chromatin at a higher level requires an additional set of proteins that collectively are referred to as
Non-histone Chromosomal (NHC) proteins
In a typical nucleus, some regions of chromatin are loosely packed, and stains light are referred to as
euchromatin
The chromatin that is more densely packed and stains dark is called as
Heterochromatin
Euchromatin is said to be ____ chromatin
transcriptionally active
Heterochromatin is said to be ____ chromatin
transcriptionally inactive
Who discovered nuclein?
Friedrich Meischer
By the year _____, the quest to determine the mechanism for genetic inheritance had reached the molecular level.
1926
Previous discoveries by _______, _____ , ___________and numerous other scientists had narrowed the search to the chromosomes located in the nucleus of most cells.
Gregor Mendel, Walter Sutton, Thomas Hunt Morgan
In which year Frederick Griffith witnessed a miraculous transformation in the bacteria.
1928
Who witnessed a miraculous transformation in the bacteria in a series of experiments with Streptococcus pneumoniae?
Frederick Griffith
Frederick Griffith, in a series of experiments with __________, witnessed a miraculous transformation in the bacteria.
Streptococcus pneumoniae
Which bacterium is responsible for pneumonia?
Streptococcus pneumoniae
Streptococcus pneumoniae bacteria is also known as
pneumococcus
When Streptococcus pneumoniae bacteria are grown on a culture plate, some produce ____ while others produce _______
smooth shiny colonies (S) & rough colonies (R).
The S strain bacteria have a ______ coat
mucous
Mice infected with the _________ die from pneumonia infection but mice infected with the _________ do not develop pneumonia.
S strain (virulent), R strain
Griffith was able to kill bacteria by _______ them.
heating
Griffith observed that __________ bacteria injected into mice did not kill them.
heat-killed S strain
When Griffith injected a mixture of heat-killed S and ________ bacteria, the mice died.
live R
Griffith recovered living _____ from the dead mice.
S bacteria
Griffith concluded that the R strain bacteria had somehow been transformed by the _______ strain bacteria.
heat-killed S
Some ‘transforming principle,’ transferred from the heat-killed S strain, had enabled the R strain to synthesize a _____________ and become virulent.
smooth polysaccharide coat
The ________ nature of genetic material was not defined from Griffith’s experiments.
biochemical
Prior to 1933-44, the genetic material was thought to be a __________.
protein
____________, ____________, and ____________ worked together to determine the biochemical nature of the ‘transforming principle’ in Griffith’s experiment.
Oswald Avery, Colin MacLeod and Maclyn McCarty
Oswald Avery, Colin MacLeod, and Maclyn McCarty purified biochemicals (proteins, DNA, RNA, etc.) from the ___________ to see which ones could transform live R cells into S cells.
heat-killed S cells
Oswald Avery, Colin MacLeod, and Maclyn McCarty discovered that _____ alone from S bacteria caused R bacteria to become transformed.
DNA
Which two enzymes did not affect transformation?
proteases & RNases
Protein-digesting enzymes are called
proteases
RNA-digesting enzymes are called
RNases
The transforming substance was not a _______
protein or RNA
Digestion with ________ did inhibit transformation, suggesting that the DNA caused the transformation.
DNase
The unequivocal proof that DNA is the genetic material came from the experiments of
Alfred Hershey & Martha Chase
Viruses that infect bacteria are called
bacteriophages
The bacteriophage attaches to the bacteria, and its ___________ then enters the bacterial cell.
genetic material
___________ and _______________ worked to discover whether it was protein or DNA from the viruses that entered the bacteria.
Hershey and Chase
Hershey and Chase grew some viruses on a medium that contained __________ and some others on a medium that contained _________
radioactive phosphorus & sulphur
Viruses grown in the presence of radioactive phosphorus contained radioactive ____ but not radioactive ______.
DNA ; protein
Protein contains ____ while DNA doesn’t
sulphur
DNA contains ____ while protein doesn’t
phosphorus
Radioactive phages were allowed to attach to ________ bacteria.
E. coli
As the infection proceeded, the viral coats were removed from the bacteria by agitating them in a ___________.
blender
The virus particles were separated from the bacteria by spinning them in a ___
centrifuge
Bacteria that were infected with viruses that had radioactive ________ were not radioactive.
proteins
________ did not enter the bacteria from the viruses.
Proteins
______ is therefore the genetic material that is passed from virus to bacteria
DNA
_____ acts as genetic material.
DNA
Examples of virus having RNA as the genetic material:-
Tobacco Mosaic & QB bacteriophage
A molecule that can act as a genetic material should be able to generate its ________.
replica
A molecule that can act as a genetic material should be stable _______ and ___________.
chemically, structurally
A molecule that can act as a genetic material should provide the scope for slow changes (mutation) that are required for _________.
evolution
A molecule that can act as a genetic material should be able to express itself in the form of ______________.
‘Mendelian Characters’
Because of rule of ___________ and __________, both the nucleic acids (DNA and RNA) have the ability to direct their duplications.
base pairing, complementarity
The genetic material should be stable enough not to change with different stages of _______, ____, or with change in ________ of the organism.
life cycle, age, physiology
_________ as one of the properties of genetic material was very evident in Griffith’s ‘transforming principle’ itself.
Stability
In Griffith’s ‘transforming principle’ heat, which killed the _______, at least did not destroy some of the properties of genetic material.
bacteria
The two DNA strands being _____________ if separated by heating, come together, when appropriate conditions are provided.
complementary
_____ group present at every nucleotide in RNA is a reactive group
2’-OH group
2’-OH group present at every nucleotide in RNA makes it __________ and _________
labile and easily degradable
RNA is also known to be ___________, hence reactive.
catalytic
DNA chemically is less _______ and structurally more ________ when compared to RNA.
reactive, stable
Among the two nucleic acids, the ______ is a better genetic material.
DNA
In fact, the presence of _________ at the place of ______ also confers additional stability to DNA.
thymine, uracil
Both ___ and _____ are able to mutate.
DNA, RNA
In fact, RNA being unstable, ________ at a faster rate.
mutate
Viruses having _____ genome and having shorter ______ mutate and evolve faster.
RNA, life span
RNA can directly code for the synthesis of proteins, hence can easily express the _____.
characters
DNA, however, is dependent on RNA for synthesis of __________.
proteins
The protein synthesizing machinery has evolved around ______.
RNA
DNA being more stable is preferred for storage of __________.
genetic information
For the transmission of genetic information, which nucleic acid is better?
RNA
For the storage of genetic information, which nucleic acid is better?
DNA
_________ was the first genetic material.
RNA
There is now enough evidence to suggest that essential life processes (such as ___________, etc.), evolved around RNA.
metabolism, translation, splicing
There are some important biochemical reactions in living systems that are catalysed by ______ and not by protein enzymes.
RNA catalysts
RNA being a catalyst was reactive and hence __________.
unstable
_______ has evolved from ______ with chemical modifications that make it more stable.
DNA, RNA
DNA being double stranded and having complementary strand further resists changes by evolving a process of ________.
repair
Who and in which year quoted this statement: ‘‘It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material”?
Watson and Crick, 1953
After the completion of replication, each DNA molecule would have one parental and one newly synthesized strand. This scheme was termed as
semiconservative DNA replication
DNA replicates semi conservatively and it was first shown in-
Escherichia coli
_________________ and _____________ performed the experiment in _______ to prove that DNA replicates semi conservatively?
Matthew Meselson and Franklin Stahl, 1958
The heavy isotope of nitrogen is
15N
Heavy DNA molecule could be distinguished from the normal DNA by centrifugation in a _________
cesium chloride (CsCl) density gradient
E. coli divides in _______ minutes
20 minutes
Experiments involving use of radioactive thymidine to detect distribution of newly synthesized DNA in the chromosomes were performed on-
Vicia faba
________ and colleagues in the year ______ proved that the DNA in chromosomes also replicates semi conservatively.
Taylor and colleagues in 1958
In living cells, such as E. coli, the process of replication requires a set of ________.
catalysts (enzymes)
The main enzyme in DNA replication is referred to as ___________
DNA-dependent DNA polymerase
DNA-dependent DNA polymerase uses a DNA template to catalyze the polymerisation of _______
deoxynucleotides
The enzymes are highly _______ enzymes as they have to catalyze the polymerization of a large number of nucleotides in a very short time.
efficient
The DNA content of E. coli ___________ bp.
4.6 ×10^6
E. coli completes the process of replication within _____ minutes.
18 minutes
The average rate of polymerization in E.coli has to be approximate ________ bp per second.
2000
Not only do these polymerases have to be fast, but they also have to catalyze the reaction with a high degree of _________.
accuracy
Any mistake during replication would result into ______
mutations
DNA replication is ______ a very expensive process.
energetically
_______________ serve dual purposes during replication.
Deoxyribonucleoside triphosphates
__________ act as substrates and provide energy for polymerization reaction?
Deoxyribonucleoside triphosphates
The ________________ phosphates in deoxynucleoside triphosphates are high-energy phosphates.
two-terminal
In addition to DNA-dependent DNA polymerases, many additional enzymes are required to complete the process of _______ with a high degree of accuracy.
replication
The two strands of DNA cannot be separated in its entire length due to very high _______ requirement.
energy
The replication occurs within a small opening of the DNA helix, referred to as
replication fork
The DNA-dependent DNA polymerases catalyze polymerization only in one direction, that is _________.
5’→3’
For the template with polarity 3’→5’ , the replication is _____
continuous
For the template with polarity 5’–>3’, the replication is ___
discontinuous
The discontinuously synthesised fragments are joined by the enzyme ________
DNA ligase
The DNA polymerases on their own cannot _______ the process of replication.
initiate
The replication does not initiate __________ at any place in DNA.
randomly
There is a definite region in E. coli DNA where the replication originates. Such regions are termed as
Origin of replication
It is because of the requirement of the __________ that a piece of DNA, if needed to be propagated during recombinant DNA procedures, requires a vector.
origin of replication
The ________ provide the origin of replication.
vectors
In eukaryotes, the replication of DNA takes place at ________ of the cell-cycle
S-phase
The replication of DNA and _________ should be highly coordinated.
cell division cycle
A failure in cell division after DNA replication results into ________
polyploidy
Polyploidy is a __________ anomaly.
chromosomal
The process of copying genetic information from one strand of the DNA into RNA is termed as ____
Transcription
The principle of complementarity governs the process of transcription, except the ________ complements, now forms base pair with _________ instead of thymine
adenosine; uracil
In _________, only a segment of DNA and only one of the strands is copied into RNA.
transcription
If both strands act as a template, they would code for RNA molecule with different __________.
sequences
Both the strands are not copied during transcription because if they code for proteins, the sequence of _________ in the proteins would be different.
amino acids
Both the strands are not copied during transcription because then one segment of the DNA would be coding for two different proteins, and this would complicate the ____________ machinery.
genetic information transfer
If both strands were copied during transcription, the two RNA molecules if produced simultaneously would be complementary to each other, hence would form a _______
double-stranded RNA
A transcription unit in DNA is defined primarily by the three regions in the DNA:
(i) A Promoter
(ii) The Structural gene
(iii) A Terminator
There is a convention in defining the two strands of the DNA in the ___________ of a transcription unit.
structural gene
The strand that has the polarity 3’->5’ acts as a template and is also referred to as
Template strand
The other strand which has the polarity (5’→3’) and the sequence same as RNA (except thymine at the place of uracil), is _________ during transcription.
displaced
The strand which has the polarity 5’–>3’ and does not code for anything is referred to as
Coding strand
All the reference point while defining a transcription unit is made with __________.
coding strand
The ___________ and __________ flank the structural gene in a transcription unit
promoter and terminator
The promoter is said to be located towards _________ of the structural gene
5’-end (upstream)
Promoter is a DNA sequence that provides a binding site for ___________.
RNA polymerase
It is the presence of a _________ in a transcription unit that also defines the template and coding strands.
promoter
By switching its position with ________, the definition of coding and template strands could be reversed.
terminator
The terminator is located towards ___ of the coding strand.
3’-end (downstream)
The terminator is located towards 3’ -end (___________) of the coding strand.
downstream
The ___ usually defines the end of the process of transcription.
terminator
There are additional regulatory sequences that may be present further __________ or _________ to the promoter.
upstream, downstream
A __________ is defined as the functional unit of inheritance.
gene
There is no ambiguity that the genes are located on the ________.
DNA
The DNA sequence coding for ______ or ________ molecule also defines a gene.
tRNA, rRNA
_______ is a segment of DNA coding for a polypeptide
Cistron
By defining a cistron as a segment of DNA coding for a polypeptide, the structural gene in a transcription unit could be said as ________
monocistronic or polycistronic
Monocistronic is mostly present in
eukaryotes
Polycistronic is mostly present in
bacteria or prokaryotes
In __________, the monocistronic structural genes have interrupted coding sequences – the genes in ________ are split.
eukaryotes, eukaryotes
The coding sequences or expressed sequences are defined as
exons
Exons are said to be those sequences that appears in?
mature or processed RNA
The exons are interrupted by _____
introns
_____ do not appear in mature or processed RNA
Introns or intervening sequences
Which arrangement further complicates the definition of a gene in terms of a DNA segment?
split-gene
Inheritance of a ________ is also affected by a promoter and regulatory sequences of a structural gene.
character
Sometimes the ____________ are loosely defined as regulatory genes, even though these sequences do not code for any RNA or protein.
regulatory sequences
In bacteria, there are three major types of RNAs:
mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA).
All three RNAs are needed to synthesize a __________ in a cell
protein
The mRNA provides the _______
template
tRNA brings _____________ and reads the _______
aminoacids; genetic code
rRNAs play ________ and ________ role during translation
structural and catalytic
__________ binds to promoter and initiates transcription
RNA polymerase
RNA polymerase uses ____ as substrate and polymerises in a template depended fashion
nucleoside triphosphates
RNA polymerase somehow also facilitates opening of the helix and continues __________.
elongation
Only a _________ of RNA remains bound to the RNA polymerase enzyme.
short stretch
Once the polymerases reaches the terminator region, the nascent RNA & RNA polymerase falls off. This results in-
termination of transcription
The RNA polymerase is only capable of catalyzing the process of ____________.
elongation
The RNA polymerase associates transiently with __________ to initiate the transcription.
initiation-factor
The RNA polymerase associates transiently with ____to terminate the transcription
termination-factor
Association with the factors alters the specificity of the RNA polymerase to either ______ or _________.
initiate, terminate
In bacteria, the mRNA does not require any processing to become active, and __________ and _________ take place in the same compartment.
transcription, translation
There is no separation of __________ and ______ in bacteria.
cytosol, nucleus
In bacteria __________ can begin much before the mRNA is fully transcribed.
translation
Consequently, the transcription and translation can be _______ in bacteria.
coupled
In eukaryotes, there are at least __________ in the nucleus (in addition to the RNA polymerase found in the organelles).
three RNA polymerases
The ________ transcribes rRNAs in eukaryotes.
RNA polymerase I
The RNA polymerase I transcribe __________
rRNA(28S, 18S, and 5.8S)
The RNA polymerase III is responsible for transcription of __________, ___________ and ________
tRNA, 5srRNA, and snRNAs (small nuclear RNAs)
The RNA polymerase II transcribes ____________
precursor of mRNA
Precursor of mRNA is called the
heterogeneous nuclear RNA (hnRNA)
The primary transcripts contain both the ______ and the _____ and are non-functional.
exons, introns
The primary transcripts are subjected to a process called.
splicing
In splicing, the _______ are removed, and ________ are joined in a defined order.
introns, exons
hnRNA undergoes additional processing called as
capping and tailing
In capping an unusual nucleotide, _____________ is added to the 5’-end of hnRNA.
methyl guanosine triphosphate
In tailing, ___________are added at 3’-end in a template independent manner
adenylate residues (200-300)
It is the fully processed hnRNA, now called _________, that is transported out of the nucleus for translation.
mRNA
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The process of splicing represents the dominance of _________
RNA-world
Who argued that since there are only 4 bases and if they have to code for 20 amino acids, the code should constitute a combination of bases?
George Gamow, a physicist
George Gamow suggested that in order to code for all the 20 amino acids, the code should be made up of _________
three nucleotides
The chemical method developed by ___________ was instrumental in synthesizing RNA molecules with defined combinations of bases (homopolymers and copolymers).
Har Gobind Khorana
Whose cell-free system for protein synthesis finally helped the code to be deciphered?
Marshall Nirenberg
_______ was also helpful in polymerizing RNA with defined sequences in a template-independent manner.
Severo Ochoa enzyme
Severo Ochoa enzyme is a
polynucleotide phosphorylase
The codon is a _______ of bases.
triplet
How many codons code for amino acids?
61 codons
How many codons do not code for any amino acids?
3 codons
Codons which do not code for any amino acids, function as
stop codons
Some amino acids are coded by more than one codon. Hence the code is _______
degenerate
The codon is read in mRNA in a _____
contiguous fashion
The _______ is nearly universal
code
From bacteria to human, UUU would code for _____
Phenylalanine
The code is nearly universal. Some exceptions to this rule have been found in-
mitochondrial codons, and in some protozoans
Which codon has dual functions?
AUG
AUG codes for ____, and it also act as _____
Methionine (met); initiator codon.
Which codons are stop-terminator codons?
UAA, UAG, UGA
A change of single base pair in the gene for beta-globin chain is a classical example of __________
point mutations
A change of single base pair in the gene for beta-globin chain results in the change of amino acid residue _____ to _____
glutamate to valine
A change of amino acid residue glutamate to valine results into a diseased condition called as
sickle cell anemia
Insertion or deletion of one or two bases changes the reading frame from the point of insertion or deletion. Such mutations are referred to as
frameshift insertion or deletion mutations
_____ acts as an adapter molecule that reads the code and also bind to specific amino acids.
tRNA
tRNA has an __________ that has bases complementary to the code
anticodon loop
tRNA has an amino acid ____ to which it binds to amino acids
acceptor end
For initiation, there is another specific tRNA that is referred to as ____
initiator tRNA
In actual structure, the tRNA is a compact molecule which looks like _____
inverted L
The process of polymerization of amino acids to form a polypeptide is called.
Translation
The amino acids are joined by a bond which is known as a
peptide bond
Amino acids are activated in the presence of ATP and linked to their cognate tRNA–a process commonly called as
charging of tRNA or aminoacylation of tRNA
The cellular factory responsible for synthesizing proteins is the _________
ribosome
The ribosome consists of
structural RNAs and about 80 different proteins
In its inactive state, ribosome exists as two subunits:
a large subunit and a small subunit
23S rRNA in bacteria is the enzyme-
ribozyme
_____ in bacteria is the enzyme called ribozyme
23S rRNA
mRNA has some additional sequences that are not translated and are referred as
untranslated regions
An enzyme called ________is synthesized by E. coli and is used to catalyze the hydrolysis of a disaccharide
beta-galactosidase
Regulatory proteins can act both positively, called _______ and negatively called ______
activators; repressors
Elucidation of the lac operon was a result of a close association between a geneticist, __________, and a biochemist, __________
Francois Jacob and Jacque Monod.
In lac operon, lac refers to
lactose
The lac operon consists of one regulatory gene called _____ and three structural genes called _____
i gene; z, y, and a
The i gene codes for the _____
repressor of the lac operon
The z gene codes for ______
beta-galactosidase
The y gene codes for___
permease
Permease increases permeability of the cell to ____
beta-galactosides
The a gene encodes ______
transacetylase
The substrate for the enzyme beta-galactosidase:
Lactose
Lactose regulates ______ of the operon
switching on and off
Lactose regulates switching on and off of the operon. Hence, it is termed as
inducer
In the presence of an inducer, such as ___________, the repressor is inactivated by interaction with the inducer
lactose or allolactose
Regulation of lac operon by a repressor is referred to as
negative regulation
________ was called a mega project
Human Genome Project
The total estimated cost of the Human Genome project would be approximately ____________ dollars
9 billion US dollars
HGP was closely associated with the rapid development of a new area in biology called
Bioinformatics
The Human Genome Project was a ____-year project
13-year
The Human Genome Project was coordinated by ________
The U.S. Department of Energy and the National Institute of Health.
During the early years of the HGP, the _________ became a major partner
Wellcome Trust (U.K.)
The Human Genome project was completed in ______
2003
Few examples of non-human model organisms that have been sequenced are
bacteria, yeast, Caenorhabditis elegans (a free-living non-pathogenic nematode), Drosophila (the fruit fly), plants (rice and Arabidopsis)
All the genes that are expressed as RNA referred to as ______
Expressed Sequence Tags
A term used for assigning different regions in the sequence with functions is
Sequence Annotation
The commonly used hosts were _______ and _________
bacteria and yeast
The commonly used vectors were called as
BAC (bacterial artificial chromosomes), and YAC (yeast artificial chromosomes)
Automated DNA sequencers worked on the principle of a method developed by
Frederick Sanger
Frederick Sanger is credited for developing a method for determination of-
amino acid sequences in proteins
The sequence of chromosome 1 was completed in
May 2006
Repetitive DNA sequences are known as
Microsatellites
The human genome contains ________ bp
3164.7 million
The largest known human gene is __________ at ____________
dystrophin at 2.4 million bases
The total number of genes is estimated at
30,000
The functions are unknown for over ____ percent of the discovered genes.
50 per cent
Less than ______ of the genome codes for proteins.
2 per cent
Chromosome 1 has ____ genes
2968
Chromosome Y has ___ genes
231
Scientists have identified about 1.4 million locations where single-base DNA differences, called ______, occur in humans.
SNPs – single nucleotide polymorphism
How much percent of base sequence among humans is the same?
99.9 per cent
_____________ is a very quick way to compare the DNA sequences of any two individuals.
DNA fingerprinting
DNA fingerprinting involves identifying differences in some specific regions in DNA sequence called as
repetitive DNA
Repetitive DNA are separated from bulk genomic DNA as different peaks during ________
density gradient centrifugation
The ___________ forms a major peak, and the other small peaks are referred to as _____________
bulk DNA; satellite DNA
satellite DNA sequence shows a high degree of _____
polymorphism
satellite DNA sequence forms the basis of _______
DNA fingerprinting
DNA from an individual show the same degree of polymorphism. They become very useful identification tools in-
forensic applications
As the polymorphisms are inheritable from parents to children, DNA fingerprinting is the basis of ____
paternity testing
Polymorphism (variation at genetic level) arises due to _____
mutations
_______________ is described as a DNA polymorphism if more than one variant (allele) at a locus occurs in human population with a frequency greater than 0.01
Allelic sequence variation
_______________ is described as a DNA polymorphism if more than one variant (allele) at a locus occurs in human population with a frequency greater than 0.01
Allelic sequence variation
if an inheritable mutation is observed in a population at high frequency, it is referred to as ____
DNA polymorphism.
The technique of DNA Fingerprinting was initially developed by
Alec Jeffreys
Alec Jeffreys used a __________ as a probe that shows very high degree of polymorphism
satellite DNA
A satellite DNA that shows a very high degree of polymorphism is called as
Variable Number of Tandem Repeats(VNTR)
Examples of synthetic membranes-
nitrocellulose or nylon
The VNTR belongs to a class of satellite DNA referred to as
mini-satellite
The size of VNTR varies in size from ____ to _____
0.1 to 20 kb
Many different probes are used to generate-
DNA fingerprints
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
The ___________ arrangements represent probably an ancient feature of the genome.
split-gene
