Page 6 - Chromosome_genes_DNA_FULL

L

DNA

DNA Shape and Composition

Double-stranded DNA (deoxyribonucleic acid) has a twisted ladder-like shape called a
double helix. Each DNA strand is composed of a series of nucleotides.

A nucleotide contains phosphate
a sugar, phosphate, DNA
and nitrogen base— sugar
adenine (A), guanine(G),
cytosine(C), or thymine(T). nitrogen A C
base

The nitrogen bases pair G
with each other, adenine nucleotide T
with thymine and cytosine
with guanine. These are
called complementary base pairs.
Replication
T DNA
Template DNA

G T T C A G
Role of DNA in Replication

The sequence of these DNA
N
new nitrogen bases provides a code.
DNA The code serves as a template
DNA
when DNA is copied in a
process called replication.
Transcription

Template DNA
C A A G T C T DNA
G T T C A G
Role of DNA in Transcription

In a similar process called transcription,
the DNA code is used to make RNA
(ribonucleic acid).
RNA
RNA

C A A G T C

4 © Copyright NewPath Learning www.newpathlearning.com