This Grade 12 IEB Life Sciences summary provides an in-depth exploration of cellular and tissue-level biology, including the structure and functions of DNA and RNA, protein synthesis, cell division (mitosis and meiosis), and the genetic principles governing inheritance. Perfect for students aiming ...
Liffe at a molecular and , cellular
Elsessme levell
T H E S T R U C T U R E o f DN A a n d R N A
The nucleic acds DNA and RNA are polymers of
estides
molecular structure made of three units
-complicated
.
phosphate
phosphate group baseermamide
&
=
&
e
Sugar
=
phosphate 7 baseme
=
nitrogenous base
ribonucleic and
I sugar I sugar
#
The four RNA bases
-
:
covalenton is
called :
phosphodiester bond
Adenine :
Kal :
O
N Il
-
One nucleotide bonds to
-
purine -
prymidine
I
·
#
Only RNA
-
in
another between the First
nucleotides the
·
and
sugar
phosphate of the next
Canine :g Cayosine :
nucleotide via a covalent
Il -
purina NHz
bond and this will take
H An-pyrimid
a
J
·
until we have a large
i
place
i polymer
nucleotides
- - - - - - -
with
many RNA
-
# deoxyribonucleic
add
Guanine is alway double bonded to cytosine All bases the except that
*
stay same
3' strand and thymine is
always triple bonded Instead of uracil that is
only found in
5'strand
& to Adenine :
RNA there is
&
swamust
G => C , A =
T mine HzC 9
I·
ant
--- this
a
is
complementary
purine always joins
base
to a
pairing as
pyramidine Y
be summer a
---
Antiparallel :
-je
double helix made of two 51
* DNA is a
a
antiparallel strands of nucleotides
Phosphodiester bond linkedby hydrogen bonding between
- -
bonds
hydrogen complementary base pairs
- :
9
, -
differences between RNA and DNA
-structural
-
TYPES OF RNA AND DNA
provisionI
=
1) MRNA-messenger RNA
found
· made in the nucleus
using DNA as a template · in the nucleus and
packaged in structures
transports code for protein synthesis to ribosome called chromosomes in association with histone proteins
I
2) tRNA-transfer RNA 2) mtDNA- Mitochondrial DNA
found
· made in nucleus and its function is to
bring · in Mitochondria and are ring shaped
amino acids to ribosome for protein inherited from mother only (found in egg cell)
synthesis ·
J 16 500 base pairs
rRNA-ribosomal RNA
minsets or
endosympathetic theory
, The function of DNA
carries the code for protein production . This code is passed on from parent to
offspring
and is therefore known as hereditary material . The code is carried on the
genes
DNA (STR) important concepts :
non-coding >
-
different species have different numbers of
&
chromosomes
-
I cell in the
body has the exact copy
- -
every
of DNA
gene
In the
>
-
body cells the chromosomes come in
pairs
DNA REPLICAT ION
↳ known as semi-conservative replication
> interphase
In
as
-
cytokinesis
the newly formed DNA , she strand is new - >
-
goth
and the other is conserved from original DNA mitosis/
·
Meiosis
PROCESS :
-
I
G DNA unwinds and unzips . -NA
E
↑
② I bonds between complementary bases break. replication
-
· ③ organelle
+
.
catalyzed by the enzyme hellcase rowth
-
replication
& free DNA nucleotides in nucleus will le next to their
j complementary base. [A=T and G =
C)
⑤ H bonds form between complementary bases and sugar phosphate backbone reforms
&
⑳ DNA can only replicate in the 5' to 3 direction (the 5'strand is called the leading Strand
·
.
and nucleotides are laid down in a continuous manner
& The 3'strand nucleotides down discontinous
is called
lagging strand
the + are laid in a
manner . (i .
e in
fragments
A T
I &
- template
jAT-
·
E
In
GC
GC
replication
= & GC
original
&
GC
new
G
new
C
-
2 new Identical DNA strands
PCR Technology
:
↳ polymerase chain reaction
blotechnology process used to amplify a sample of DNA .
-
/
y?
1. forensics to make more DNA Found at a crime scene .
amplify genes to be used
I . in recombant
technology -
.
3 Inexpensive and fast .
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