principle of inheritance Flashcards
(94 cards)
1
Q
Mutation is —– (def)
A
phenomenon which results in alternation of DNA seqs and consequently results changes in the genotype and phenotype of an organism
2
Q
In addition to —-, mutation is another
phenomenon that leads to —- in DNA.
A
recombination
variation
3
Q
One —- runs continuously from one end to the other in each chromatid, in a —- form.
A
DNA helix
highly supercoiled
4
Q
Therefore loss (—-) or gain (—–) of a —-, result in alteration in —–.
A
deletions
insertion /duplication
segment of dna
chromosomes
5
Q
Since genes are known to be located on chromosomes, alteration in chromosomes results in —- or —-
A
abnormalities or aberrations.
6
Q
Chromosomal aberrations are commonly observed in —-
A
cancer cells
7
Q
In addition to the above, mutation also arise due to change in a single — of DNA. This is known as —-.
A
base pair
point mutation
8
Q
A classical example of — is sickle cell anemia.
A
point mutation
9
Q
Deletions and insertions of base pairs of DNA, causes —- mutations
A
frame-shift mutations
10
Q
There are many — and —– factors that
induce mutations. These are referred to as —.
A
chemical and physical
mutagens
11
Q
—-radiations can
cause mutations in organisms – it is a –.
A
UV
mutagen.
12
Q
The idea that disorders are — has been prevailing in the human society since —. This was based on the heritability of certain—- in families.
A
inherited
long
characteristic features
13
Q
After the rediscovery of Mendel’s work the practice of analysing —- in human beings began.
A
inheritance pattern of traits
14
Q
Since it is evident that —- that can be performed in
pea plant or some other organisms, are not possible in case of human
beings, study of the —- about inheritance of a —
provides an alternative.
A
control crosses
family history
particular trait
15
Q
Such an analysis of traits in a several of generations of a family is called the —-
A
pedigree analysis
16
Q
In the pedigree analysis the inheritance of a particular trait is represented in the — over generations.
A
family
tree
17
Q
In human genetics, — provides a strong tool, which is utilised to trace the inheritance of a —-, — or —–
A
pedigree study
specific trait, abnormality or disease.
18
Q
Each and every feature in any organism is controlled by —- located on the DNA present in the chromosome.
A
one or the other gene
19
Q
DNA is the carrier of —.
A
genetic information
20
Q
DNA is hence transmitted from one generation to the other without any —. However, changes or alteration do take place occasionally. Such an alteration or change in the —- is referred to as
—.
A
change or alteration
genetic material
mutation
21
Q
A number of disorders in human beings have been found to be associated with the inheritance of —-
A
changed or altered genes or chromosomes.
22
Q
Broadly, genetic disorders may be grouped into two
categories – —- and —-
A
Mendelian disorders and Chromosomal disorders.
23
Q
Mendelian disorders are mainly determined by alteration or mutation in the —-.
A
SINGLE GENE
24
Q
—- disorders are transmitted to the
offspring on the same lines as we have studied in the principle of inheritance.
A
Mendellian
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The --- of such Mendelian disorders can be traced in a family by the pedigree analysis.
pattern of inheritance
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Most common and prevalent Mendelian disorders are ---- (6) etc.
Haemophilia, Cystic fibrosis, Sickle-cell anaemia,
Colour blindness, Phenylketonuria, Thalassemia,
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It is important to mention here that such Mendelian
disorders may be --- or ---.
dominant or recessive
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By pedigree analysis one can --- whether the trait in question is dominant or recessive. Similarly,
the trait may also be ----
as in case of haemophilia.
easily understand
linked to the sex chromosome
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It is evident that this ---
shows transmission from carrier female to male progeny.
X-linked recessive trait
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Haemophilia : This sex linked --- disease, which shows its transmission from --- female to -- of the male progeny has been widely studied. In this disease, a single protein that is a part
of the cascade of proteins involved in the clotting of blood is affected.
Due to this, in an affected individual a simple cut will result in non-stop
bleeding. The heterozygous female (carrier) for haemophilia may transmit
the disease to sons. The possibility of a female becoming a haemophilic
is extremely rare because mother of such a female has to be at least
carrier and the father should be haemophilic (unviable in the later stage
of life). The family pedigree of Queen Victoria shows a number of
haemophilic descendents as she was a carrier of the disease
recessive
unaffected carrier
some
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In heamophilia, a --- that is a part of the --- of proteins involved in the clotting of blood is affected.
single protein
cascade
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Due to this, in an affected individual a --- will result in non-stop bleeding.
simple cut
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The heterozygous female (----) for haemophilia may transmit the disease to ---.
carrier
sons
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The possibility of a female becoming a haemophilic
is ---- because mother of such a female has to be --- and the father should be --- (--- in the later stage
of life).
extremely rare
at least carrier
haemophilic-unviable
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The family pedigree of --- shows a number of
--- descendents as she was a carrier of the disease
Queen Victoria
haemophilic
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Sickle-cell anaemia : This is an ---- trait that can
be transmitted from parents to the offspring when both the partners are --- for the gene (or --).
autosome linked recessive
carrier- heterozygous
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Sickle cell anemia is controlled by a --- allele, HbA and HbS
single pair of
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Out of the three possible genotypes in SCA only
---- show the diseased phenotype.
homozygous individuals for HbS (HbSHbS)
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Heterozygous (HbAHbS) individuals appear --- but they are carrier of the disease as there is 50 per cent probability of transmission of the ---gene to the progeny, thus exhibiting sickle-cell trait
apparently unaffected
mutant
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SCA is caused by the substitution of --- by --- ) at the --- position of the --- chain of the --- molecule.
Glutamic acid (Glu) by valine (Val)
sixth
beta globin
haemoglobin
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The substitution of amino acid in the globin protein results due to the --- substitution at the sixth --- of the beta globin gene from ---- to ----
single base
codon
GAG to GUG.
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The mutant haemoglobin molecule undergoes
polymerisation under ---- causing the change in the shape of the RBC from ---- to ---- structure
low oxygen tension
biconcave disc to elongated sickle like
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Phenylketonuria :
This ---- is also inherited as the autosomal --- trait.
inborn error of metabolism
recessive
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The PKU affected individual lacks --- that converts the amino acid ---- to ----
an enzyme
phenylalanine into tyrosine
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As a result of this, in PKU phenylalanine is accumulated and converted into --- and ----
phenylpyruvic acid
and other derivatives.
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Accumulation of phenyl pyruvic acids and derivatives in brain results in ----.
These are also excreted through --- because of its ----
mental retardation
urine
poor absorption by kidney.
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The chromosomal disorders on the other hand are caused due to ----, --- or ---- of one or more chromosomes.
absence or excess or abnormal arrangement
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Failure of ---- during cell division cycle results
in the gain or loss of a chromosome(s), called ---.
segregation of chromatids
aneuploidy
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--- results in the gain of extra copy of chromosome 21.
Down’s syndrome
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Similarly, --- results due to loss of an X chromosome in human ---.
Turner’s syndrome
females
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Failure of --- after --- stage of cell division results in an increase in a whole set of chromosomes in an organism and, this phenomenon is known as polyploidy.
cytokinesis
telophase
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polyploidy is often seen in ---.
plants
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The total number of chromosomes in a
normal human cell is 46 (23 pairs). Out of these
--- are autosomes and one pair of chromosomes are --- chromosome.
22 pairs
sex
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Sometimes, ---, either an additional copy of a chromosome may be included in an individual or an individual may lack --- of chromosomes. These situations are
known as --- or -- of a
chromosome, respectively.
though rarely
one of any one pair
trisomy or monosomy
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Such a situation of mono/trisomy
leads to --- consequences in the individual. Down’s syndrome, Turner’s
syndrome, --- syndrome are common examples of chromosomal disorders.
very serious
Klinefelter’s
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Down’s Syndrome :
The cause of this genetic
disorder is the presence of an additional copy
of the chromosome number 21 (---).
trisomy of 21
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Downs syndrome was first described by ---
Langdon Down (1866).
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The down syndrome affected individual is --- with ---, and ----
Palm is --- with ---.
short statured
small round head
furrowed tongue
partially open mouth
broad
characteristic palm crease
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In down syndrome- ---, --- and ---- development is retarded
Physical, psychomotor and mental
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Klinefelter’s Syndrome : This genetic disorder is also caused due to the presence of an additional copy of --- resulting into
a karyotype of ---
X-chromosome
47, XXY.
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Inds with Klinefilter has
overall --- development , however, the ---development (development of ---) is also expressed
Such individuals are ---.
masculine
feminine
breast,
i.e., Gynaecomastia
sterile
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Turner’s Syndrome :
Such a disorder is
caused due to the --- of one of the X chromosomes, i.e., ---,
absence
45 with X0
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Females with turners
are sterile as --- besides
other features including ---
ovaries are rudimentary
lack of other secondary
sexual characters
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The mechanism of --- has
always been a puzzle before the geneticists.
The initial clue about the genetic/
chromosomal mechanism of sex
determination can be traced back to some
of the experiments carried out in insects. In
fact, the cytological observations made in a
number of insects led to the development of
the concept of genetic/chromosomal basis
of sex-determination
sex determination
66
The initial clue about the --- mechanism of sex
determination can be traced back to some
of the experiments carried out in --- . In
fact, the cytological observations made in a
number of insects led to the development of
the concept of genetic/chromosomal basis
of sex-determination
genetic/ chromosomal
insects
67
In fact, the --- made in a
number of insects led to the development of
the concept of
genetic/chromosomal basis of sex-determination
cytological observations
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---- could trace a specific ---structure all through
spermatogenesis in a few insects, and it was also observed by him that ---- of the sperm received this structure after
spermatogenesis, whereas the other --- sperm did not receive it
Henking (1891)
nuclear
50 per cent, 50 per
cent
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Henking gave a name to this structure as the --- but he could not explain its ---.
X body
significance
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Further investigations by other scientists led to the
conclusion that the ‘X body’ of --- was in fact a --- and that is why it was given the name X-chromosome.
Henking
chromosome
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It was also observed that in a ---- the mechanism of sex determination is of the XO type, i.e., all --- bear an additional
X-chromosome besides the other chromosomes (---)
large number of insects
eggs
autosomes
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On the other hand, some of the --- bear the
X-chromosome whereas some do not in insects.
Eggs fertilised by sperm having an X-chromosome become --- and, those fertilised by sperms that do not have an X-chromosome become ---.
sperms
females
males
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Due to the involvement of the X-chromosome in the
---, it was designated to
be the sex chromosome, and the rest of the chromosomes were named as autosomes
determination of sex
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Grasshopper is an example of XO type of sex
determination in which the males have --- whereas females have a ----
only one X-chromosome besides the autosomes,
pair of X-chromosomes.
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These observations led to the --- of a number of species to understand the mechanism of sex determination.
investigation
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In a number of other
--- and ---- XY type of sex determination is seen where both male and female have --- of chromosomes.
insects and mammals including man,
same number
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In mammals and other insects, Among the males an X-chromosome is present but its counter part is-- and called the Y-chromosome.
Females, however, have
a pair of X-chromosomes. Both males and females bear same number of
--- . Hence, the males have autosomes plus XY, while female have autosomes plus XX.
distinctly smaller
autosomes
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In --- and --- the males have one X and one Y chromosome, whereas females have a pair of Xchromosomes besides autosomes
human beings and in Drosophila
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In both XO type and XY type, --- produce two different types of gametes, (a) either with or without X-chromosome or (b) some gametes with X-chromosome and some with Y-chromosome.
Such types of sex determination mechanism is designated to be the example of ----.
males
male heterogamety
80
In some other organisms, e.g., --- , a different mechanism of sex determination is seen where total number of chromosome is same in both males and females. But two ---- in terms of the sex chromosomes, are produced by females, i.e., ---.
birds
different types of gametes
female heterogamety
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In order to have a distinction with the mechanism of sex determination described earlier, the two different sex chromosomes
of a female bird has been designated to be the --- chromosomes.
Z and W
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In birds, the females have one Z and one W chromosome,
whereas males have a ---besides the autosomes.
pair of Z-chromosomes
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sex determining mechanism in case of humans is --- type.
XY type
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The presence of an X and Y chromosome are --- of the male characteristic in humans.
determinant
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In humans, There is an --- of fertilisation of the ovum with the sperm carrying either X or Y chromosome. Thus, it is evident that it is the --- of --- that determines the sex of the child.
It is also evident that in --- there is always 50 per cent probability of either a male or a female child.
equal probability
genetic makeup of the
sperm
each pregnancy
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It is unfortunate that in our society women are blamed for giving birth to female children and have been ---- and ---- because of this false notion.
ostracised and ill-treated
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Thalassemia:
is also an autosomal linked ---- --- disease transmitted when both the partners are --- of the gene (heterozygous)
unaffected carriers
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Thalassemia could be due to ---- or ---- which ultimately results into reduced rate of ------ that make up the ---
This causes ----- resulting into --- which is a characteristic of this disease
mutation/ deletion
synthesis of any on of globin chains (alpha, beta)
haemoglobin
abnormal hb mol
anaemia
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Thalassemia can be classified acc to ----
which chain of hb is affected
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alpha Thalassemia is controlled by ---- gene ----- on chromosome --- of --- parent and it is observed dut to ---- of one or more of the --- genes
The more the genes get affected- the ---- ---- molecules produced
2 closely linked genes
HBA1, HBA2
16, each
deletion/mutation
4
less alpha globin
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Beta thalassemia is controlled by a ---- gene ---- on chromosome --- of --- parent and occurs due to --- of ---- of the genes
single
HBB
11- each
mutation of one or more
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Thalassemia differs from SCA in the former being ----- of synthesising --- hb mols while the latter is a ---- problem of synthesising ----- globin
quantitative
too few
qualitative
incorrectly synthesising
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