Life Sciences: Grade 12 Notes
Introduction to DNA Structure
These notes are introductory notes on DNA: The code of life. These notes look at basic
principles relating to the structure and function of DNA .
What is DNA?
DNA stands for Deoxyribonucleic acid. Therefore, DNA is technically a nucleic acid.
DNA is a molecule that stores all the information that is needed to control cellular activity.
Cellular activity includes things like the specialization of cells and the arrangement of our tissues
into organs.
DNA is also responsible for controlling the synthesis of proteins.
The name Deoxyribonucleic Acid (DNA) comes from the structure of the molecule. We can
break the name up into “Deoxy”,“ribo” and “nucleic acid”. This is the structure of the molecule in
terms of its shape and backbone.
DEOXY/RIBO/ NUCLEIC ACID
Where do we find DNA?
DNA is found in almost every cell. The DNA is found in the nucleus of the cell
DNA is found here in the nucleus of
the cell
, When we find DNA in a cell we have the nucleus and inside that nucleus is the DNA. The DNA is
shown as chromosomes in the picture above but it’s important to understand that the DNA
doesn’t come in the condensed format as a chromosome. Instead, DNA is found in a long
spaghetti like structure called the chromatin network as shown below.
Most of the time the DNA strand in the nucleus of the cell exists in the form of the chromatin
network except for when:
1. It wants to replicate a cell
2. To reproduce a new cell (in order for reproduction to take place)
3. To repair something.
The chromatin network will condense, and it will form the chromosomes that we see inside the
nucleus (shown below):
So a chromosome is essentially a condensed piece of DNA. Humans have 46 chromosomes. 23
chromosomes come from the mother while the other 23 chromosomes come from the father.
Chromosomes are long, thin intertwined thread-like structures that are made up of a strand of
DNA that is wound around some proteins. If we were to stretch it out, you would see a DNA
structure that looks like a double helix ladder as shown below.
Introduction to DNA Structure
These notes are introductory notes on DNA: The code of life. These notes look at basic
principles relating to the structure and function of DNA .
What is DNA?
DNA stands for Deoxyribonucleic acid. Therefore, DNA is technically a nucleic acid.
DNA is a molecule that stores all the information that is needed to control cellular activity.
Cellular activity includes things like the specialization of cells and the arrangement of our tissues
into organs.
DNA is also responsible for controlling the synthesis of proteins.
The name Deoxyribonucleic Acid (DNA) comes from the structure of the molecule. We can
break the name up into “Deoxy”,“ribo” and “nucleic acid”. This is the structure of the molecule in
terms of its shape and backbone.
DEOXY/RIBO/ NUCLEIC ACID
Where do we find DNA?
DNA is found in almost every cell. The DNA is found in the nucleus of the cell
DNA is found here in the nucleus of
the cell
, When we find DNA in a cell we have the nucleus and inside that nucleus is the DNA. The DNA is
shown as chromosomes in the picture above but it’s important to understand that the DNA
doesn’t come in the condensed format as a chromosome. Instead, DNA is found in a long
spaghetti like structure called the chromatin network as shown below.
Most of the time the DNA strand in the nucleus of the cell exists in the form of the chromatin
network except for when:
1. It wants to replicate a cell
2. To reproduce a new cell (in order for reproduction to take place)
3. To repair something.
The chromatin network will condense, and it will form the chromosomes that we see inside the
nucleus (shown below):
So a chromosome is essentially a condensed piece of DNA. Humans have 46 chromosomes. 23
chromosomes come from the mother while the other 23 chromosomes come from the father.
Chromosomes are long, thin intertwined thread-like structures that are made up of a strand of
DNA that is wound around some proteins. If we were to stretch it out, you would see a DNA
structure that looks like a double helix ladder as shown below.
