Topic 3+10
GENETICS
By A rathi Anand
,⑧ LB W BI Aiofngwemi estatda specitt-futhataraa.ee?hMnsin
length of occupying particular position
a DNA a
sing
on chromosomes .
°
Humans have between 22 , 000 -
23,000 protein coding genes
o The number of genes in an organism 's genome does not indicate how
complicated an organism is, for example dogs have a
larger genome than
human .
°
Each gene occupies
Base substitution
wet earwax vs Dry earwax
in d
CTC aaa CCA CTC A GG CC A
Glycine Arginine
Gene mutation : is
permanent change in the base sequence of DNA
a .
→ when one of the bases is changed , this will cause a change in the
mRNA sequence when the DNA is copied during transcription of
the gene .
° SILENT MUTATION : a mutation in DNA sequence will not change in
protein structure .
( multiple codons for one amino acid)
o MISSENSE MUTATION : a mutation in DNA sequence leads to a
change in
protein structure .
e -
g . Sickle cell
( change in amino acid sequence )
-
°
NONSENSE MUTATION : a mutation in DNA shortens the
polypeptide
chains .
( codons mutate to become a stop signal ) e.g cystitis
SUBSTITUTION : switch of base
INSERTION : Add a base
dangerous 3 :
reading frame shifted
DELETION : Remove base
Mutated Genes that codes for proteins could cause problems :
→ effect when where ,
, , and how much of proteins
are made .
, 8800088800 Ars OG 80
Disease caused by gene mutation
°
This disease allele arose from a base substitution mutation -
where a single
in the
base was
changed gene sequence .
causes :
results from change a to the 6th codon for the beta chain of
of haemoglobin .
Mutated gene codes for abnormal protein due to non -
polarity
bonds not formed
q
o Disease that causes red blood cell to form a sickle shape ( half
moon ) These sickle d blood cells cannot carry as much oxygen
.
as normal red blood cells They can cause clots in blood vessels
.
( capillaries ) because of their abnormal shape and inflexibility
caused by crystallization of the abnormal hemoglobin .
°
Sickle cell anaemia occurs on chromosome II , happens Ob
gene H BB ( beta globin )
-
.
o sickle cell is caused by a base substitution when the a-ate nine
-
base in aAa is replaced by a thymine base ,
changing the
triplet to Uta .
° Glutamic acid then changed to valine , a negatirecharged
amino acid changed
to neutral one .
Amino acid sequence will then lead to in
pwtei
°
change a change
structure .
6¥
°
Glutamic acid valine
/
causes :
→ blood clots
→ Joint pains
→ lack Of oxygen
the change in amino acid sequence causes hemoglobin molecules to
when oxygen levels in the blood are low As a result , red
crystallize .
blood cells sickle and get stuck in small blood vessels .
GENETICS
By A rathi Anand
,⑧ LB W BI Aiofngwemi estatda specitt-futhataraa.ee?hMnsin
length of occupying particular position
a DNA a
sing
on chromosomes .
°
Humans have between 22 , 000 -
23,000 protein coding genes
o The number of genes in an organism 's genome does not indicate how
complicated an organism is, for example dogs have a
larger genome than
human .
°
Each gene occupies
Base substitution
wet earwax vs Dry earwax
in d
CTC aaa CCA CTC A GG CC A
Glycine Arginine
Gene mutation : is
permanent change in the base sequence of DNA
a .
→ when one of the bases is changed , this will cause a change in the
mRNA sequence when the DNA is copied during transcription of
the gene .
° SILENT MUTATION : a mutation in DNA sequence will not change in
protein structure .
( multiple codons for one amino acid)
o MISSENSE MUTATION : a mutation in DNA sequence leads to a
change in
protein structure .
e -
g . Sickle cell
( change in amino acid sequence )
-
°
NONSENSE MUTATION : a mutation in DNA shortens the
polypeptide
chains .
( codons mutate to become a stop signal ) e.g cystitis
SUBSTITUTION : switch of base
INSERTION : Add a base
dangerous 3 :
reading frame shifted
DELETION : Remove base
Mutated Genes that codes for proteins could cause problems :
→ effect when where ,
, , and how much of proteins
are made .
, 8800088800 Ars OG 80
Disease caused by gene mutation
°
This disease allele arose from a base substitution mutation -
where a single
in the
base was
changed gene sequence .
causes :
results from change a to the 6th codon for the beta chain of
of haemoglobin .
Mutated gene codes for abnormal protein due to non -
polarity
bonds not formed
q
o Disease that causes red blood cell to form a sickle shape ( half
moon ) These sickle d blood cells cannot carry as much oxygen
.
as normal red blood cells They can cause clots in blood vessels
.
( capillaries ) because of their abnormal shape and inflexibility
caused by crystallization of the abnormal hemoglobin .
°
Sickle cell anaemia occurs on chromosome II , happens Ob
gene H BB ( beta globin )
-
.
o sickle cell is caused by a base substitution when the a-ate nine
-
base in aAa is replaced by a thymine base ,
changing the
triplet to Uta .
° Glutamic acid then changed to valine , a negatirecharged
amino acid changed
to neutral one .
Amino acid sequence will then lead to in
pwtei
°
change a change
structure .
6¥
°
Glutamic acid valine
/
causes :
→ blood clots
→ Joint pains
→ lack Of oxygen
the change in amino acid sequence causes hemoglobin molecules to
when oxygen levels in the blood are low As a result , red
crystallize .
blood cells sickle and get stuck in small blood vessels .
