principle of inheritance Flashcards
Mutation is —– (def)
phenomenon which results in alternation of DNA seqs and consequently results changes in the genotype and phenotype of an organism
In addition to —-, mutation is another
phenomenon that leads to —- in DNA.
recombination
variation
One —- runs continuously from one end to the other in each chromatid, in a —- form.
DNA helix
highly supercoiled
Therefore loss (—-) or gain (—–) of a —-, result in alteration in —–.
deletions
insertion /duplication
segment of dna
chromosomes
Since genes are known to be located on chromosomes, alteration in chromosomes results in —- or —-
abnormalities or aberrations.
Chromosomal aberrations are commonly observed in —-
cancer cells
In addition to the above, mutation also arise due to change in a single — of DNA. This is known as —-.
base pair
point mutation
A classical example of — is sickle cell anemia.
point mutation
Deletions and insertions of base pairs of DNA, causes —- mutations
frame-shift mutations
There are many — and —– factors that
induce mutations. These are referred to as —.
chemical and physical
mutagens
—-radiations can
cause mutations in organisms – it is a –.
UV
mutagen.
The idea that disorders are — has been prevailing in the human society since —. This was based on the heritability of certain—- in families.
inherited
long
characteristic features
After the rediscovery of Mendel’s work the practice of analysing —- in human beings began.
inheritance pattern of traits
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.
control crosses
family history
particular trait
Such an analysis of traits in a several of generations of a family is called the —-
pedigree analysis
In the pedigree analysis the inheritance of a particular trait is represented in the — over generations.
family
tree
In human genetics, — provides a strong tool, which is utilised to trace the inheritance of a —-, — or —–
pedigree study
specific trait, abnormality or disease.
Each and every feature in any organism is controlled by —- located on the DNA present in the chromosome.
one or the other gene
DNA is the carrier of —.
genetic information
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
—.
change or alteration
genetic material
mutation
A number of disorders in human beings have been found to be associated with the inheritance of —-
changed or altered genes or chromosomes.
Broadly, genetic disorders may be grouped into two
categories – —- and —-
Mendelian disorders and Chromosomal disorders.
Mendelian disorders are mainly determined by alteration or mutation in the —-.
SINGLE GENE
—- disorders are transmitted to the
offspring on the same lines as we have studied in the principle of inheritance.
Mendellian
The — of such Mendelian disorders can be traced in a family by the pedigree analysis.
pattern of inheritance
Most common and prevalent Mendelian disorders are —- (6) etc.
Haemophilia, Cystic fibrosis, Sickle-cell anaemia,
Colour blindness, Phenylketonuria, Thalassemia,
It is important to mention here that such Mendelian
disorders may be — or —.
dominant or recessive
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
It is evident that this —
shows transmission from carrier female to male progeny.
X-linked recessive trait
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
In heamophilia, a — that is a part of the — of proteins involved in the clotting of blood is affected.
single protein
cascade
Due to this, in an affected individual a — will result in non-stop bleeding.
simple cut
The heterozygous female (—-) for haemophilia may transmit the disease to —.
carrier
sons
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
The family pedigree of — shows a number of
— descendents as she was a carrier of the disease
Queen Victoria
haemophilic
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
Sickle cell anemia is controlled by a — allele, HbA and HbS
single pair of
Out of the three possible genotypes in SCA only
—- show the diseased phenotype.
homozygous individuals for HbS (HbSHbS)
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
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
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.
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
Phenylketonuria :
This —- is also inherited as the autosomal — trait.
inborn error of metabolism
recessive
The PKU affected individual lacks — that converts the amino acid —- to —-
an enzyme
phenylalanine into tyrosine
As a result of this, in PKU phenylalanine is accumulated and converted into — and —-
phenylpyruvic acid
and other derivatives.
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.
The chromosomal disorders on the other hand are caused due to —-, — or —- of one or more chromosomes.
absence or excess or abnormal arrangement
Failure of —- during cell division cycle results
in the gain or loss of a chromosome(s), called —.
segregation of chromatids
aneuploidy
— results in the gain of extra copy of chromosome 21.
Down’s syndrome
Similarly, — results due to loss of an X chromosome in human —.
Turner’s syndrome
females
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
polyploidy is often seen in —.
plants
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
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
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
Down’s Syndrome :
The cause of this genetic
disorder is the presence of an additional copy
of the chromosome number 21 (—).
trisomy of 21
Downs syndrome was first described by —
Langdon Down (1866).
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
In down syndrome- —, — and —- development is retarded
Physical, psychomotor and mental
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.
Inds with Klinefilter has
overall — development , however, the —development (development of —) is also expressed
Such individuals are —.
masculine
feminine
breast,
i.e., Gynaecomastia
sterile
Turner’s Syndrome :
Such a disorder is
caused due to the — of one of the X chromosomes, i.e., —,
absence
45 with X0
Females with turners
are sterile as — besides
other features including —
ovaries are rudimentary
lack of other secondary
sexual characters
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
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
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
—- 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
Henking gave a name to this structure as the — but he could not explain its —.
X body
significance
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
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
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
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
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.
These observations led to the — of a number of species to understand the mechanism of sex determination.
investigation
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
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
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
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
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
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
In birds, the females have one Z and one W chromosome,
whereas males have a —besides the autosomes.
pair of Z-chromosomes
sex determining mechanism in case of humans is — type.
XY type
The presence of an X and Y chromosome are — of the male characteristic in humans.
determinant
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
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
Thalassemia:
is also an autosomal linked —- — disease transmitted when both the partners are — of the gene (heterozygous)
unaffected carriers
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
Thalassemia can be classified acc to —-
which chain of hb is affected
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
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
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
