B2 Biology

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B2 Biology Topic
Inside Living Cells
There
are 23 Chromosomes i n a
huma n cell
the
chromosome s
con si
s t
o f
l
ong,
coi
led
molecul
es call
ed DNA (deoxyribonucleic acid). A
gene i
s a
secti
on
of a D NA whi
ch
codes
for
inheri
ted
character
ist
ics
(i
.e.
at
tac hed o r
unat
tached
ear
lobe). T he
DNA
consi
sted
o f
two
str
and s
(of
chr
o mosome s) coi
led
to
for
m a double helix. The
str
ands
ar
e l
inked to
a ser
ies
of
pa i
red
bases:
Adenine (A) l
i
n ked
wit
h Thymine (T) +
Cytosine (C) l
i
n ked
wit
h onl
y Guanine (G).
The
DNA c ontai
ns i
nst
ruct
ions
on how t
o make pr
o t
eins. To
e nabl
e genes to
code
for
pr
otei
ns ,
t
h e bases
A,
T,
G
and C go
in
tr
ipl
ets,
one
triplet of bases codes f
or
one
amino acid, t
he amino
aci
ds j
oin
in
long
mo l
ecules
to ma ke
a
parti
cul
ar pr
o t
ein.
Ther
e about
20 amino acids i
n t
otal
(
arr
anged
in
dif
fer
ent
or
der
s and
combi
nat
ions)
.
Organelles ar
e c
e l
l
s wi
th
a speci
fi
c f
unct
ion
in
the
cytoplasm
i.
e.
ribosome's i
nvol
ved
i
n pr
otei
n synt
hesi
s.
1.
The coding strands o f D NA
unravel
. 2 .
The
D NA
is
copied
to
ma ke a (
un li
ke t
he
DN A,
it
's
a s i
ng l
e strand)
mo l
ecule
of
messenger RNA (mRNA). Th i
s i
s cal
le d
Transcription. 3. The mRNA mo ves
from t
h e nucleus
to t
he cyt
oplasm. 4. I
n
mRNA t he
c ode Thymine (T) is
tur
ned
to
Uracil (U) (
neede d
to
ma ke pr
otein)
. 5.
The RN A con t
a i
ns the code
for
li
nking
the
a mino acid
the
ribosome (rRNA) interpret
s
thi
s c
o de t
o
li
nk
the amino
a ci
d s
(carr
ied
by the
tRNA) a nd for
m a polypeptide
(pr
otein).
This i
s translation.
Genetic Engineering i
s
w hen
secti
ons of DN A t
hat
code
for
a
specif
i
c pr
otei
n can
be
t
ransf
e rr
e d
int
o microorganisms. Insulin can
be made
int
o l
arge
quant
it
ies
by
g enet
ic
engi
ne eri
ng.
(Look at diagram on page 37).
Fermentation i
s t
he pr
ocess where
microor
gani
sm take
food
fr
om t
heir
envi
ronment
(an
ener
g y sour
ce),
and excr
ete
wa st
e pr
oduct
s i
.e.
car
bon di
oxi
de t
o change
subst
ances
over
ti
me .
A
fermenter (
lar
ge
v e ssel
u sed to
cult
i
vate
micr
o or
gani
sms)
i
s a
contr
oll
ed
envi
ronment whi
ch
h a s i
dea l
con d i
ti
ons f
or
micr
oorgani
sms
to
li
ve,
f
eed and
produce
pr
otei
ns t
hey
need.
It requires...
Aseptic (sterile) conditions micr
oorgani
sms
mu st
not
become cont
ami
nat
ed.
Nutrients in o rder f
or
mi croor
gani
sms t
o grow.
An optimum temperature s uit
abl
e f
or
the
microorgani
sms t
o
grow.
The correct PH level.
Oxygenation mi cr
oorga ni
sms
need
oxygen t
o r
espir
e.
1
Chido Mawoneke

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Page 2

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Agitation (stirring) t
o maint
ain
an even
tempe ratu r
e .
(Look at page 38 for the diagram)
The following structures are put in an industrial fermenter...
Stirrer
kee ps mi cr
o or
ganisms i
n susp ension
an d ma i
ntai
ns an e ven
temper
atur
e.
Watercooled jacked r emoves hea t
produced b y
r espir
ing
mic r oorgani
sms.
Outlet tap to coll
ec t
pr
otei
ns.…read more

Page 3

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Page 4

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Divide & Develop
Remember: How my tall sis grows. How my own sis was made from a gamete.
Mitosis
is
a t
ype
of
divi
si
on
in
a cel
l'
s nucl
eus
whi
ch
produces
diploid,
cel
ls
for
gr
owt
h,
or
replace
damaged or
worn
out
cel
ls.
Meiosis i
s a
type
of
div
isi
on
in
cel
ls
w hi
ch
produces
sex
cel
ls
(gametes)
.…read more

Page 5

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Light for
p hot
o synthesi
s (absorbe d t
hrough l
ea ves)
Carbon Dioxide f or
photosynthes i
s (absorbed
from air
thr
o ugh
lea ves )
Oxygen f o r
respir
a t
ion
(abso r
bed fr
om ai
r
through l
ea v es)
Nutrients (nit
rates & phospha t
es)
for
he al
thy
grow t
h a nd de ve l
o pme n t
a bsorbed f
rom
th e
soil
Temperature ( wa r
mth)…read more

Page 6

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Mo st
ce l
ls
a r
e sp eciali
sed t
o
all
ow
them to p erform a parti
cu l
ar j
ob .
Th e pr
o cess
by
w hich
they
beco me spe cial
ised i
s cal
led differentiation.
Stem cells a r
e u nd i
ff
e r
en ti
ated (i
.e.
unspe ciali
se d)
.…read more

Page 7

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Abortion i s th e prema ture termination o f pregnancy. I
n huma ns,
pregnancy
lasts
for
a n
ave ra g e 4 0 w eeks.
T he lega l
ti
me
li
mi t
for an abort
ion
is
24 wee ks
(det
ermined by
s u r
viv
a l o f fo e tu s ).…read more

Page 8

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Osmosis ( op posi
te to
dif
fusi
on )
i
s t
he
mo veme nt of water
from a
less concentrat
ed
d i
lut
e solut
ion t
o a mo r
e concentrat
ed thr
oug h a partially permeable membrane.…read more

Page 9

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Fish farms c onsi
s t
of
l
arge ca ge s
susp end ed i
n l
akes/l
oc hs.
Th e fi
sh are
e ncour
a ged
to
grow
by .
..…read more

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Fe w
li
chen s
ind i
c a t
e hig h
sulphur
dioxi
de i
n ai
r:
many l
ichens
indicat
e l
ow
c oncentr
a ti
on of
su l
p hu r i
n air
.
Water pollution ma y co n si
st
o f.
..…read more

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