CHAPTER 2: GENETICS AND BIOTECHNOLOGY
NALEDI NOXOLO BHENGU
BIOLOGY: GRADE 11
1. NUCLEIC ACIDS
What are Nucleic Acids?
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They are VERY large molecules that contain the genetic code(information) of an organism.
They are found in all living organisms (plants and animals)
Nucleic acids are made up of NUCLEOTIDES -also called the building blocks of nucleic acids
A GENOME is the total DNA found inside the nucleus of each cell.
Nucleotides
Building blocks of Nucleic acids
Why are Nucleic acids important?
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We need Nucleic Acids to transmit (send) the genetic information from parent to offspring
Nucleic Acids are also responsible for making very important proteins in our bodies like
Melanin
There are TWO types of Nucleic acids
NUCLEIC
ACIDS
DNA
DNA-DEOXYRIBOSE NUCLEIC ACID
RNA
RNA- RIBOSE NUCLEIC ACID
CHAPTER 2: GENETICS AND BIOTECHNOLOGY
NALEDI NOXOLO BHENGU
2. GENETIC ENGINEERING
 Its technology used by scientists.
 It involves manipulating the DNA of an organism in order to insert (put in) the DNA of
another organism
 DNA of another organism is called EXOGENOUS DNA
 The genes of an organism are changed during genetic engineering and we can now say that
the DNA has been recombined since it has been mixed with another organism’s DNA
 This process is called DNA Recombinant
Why is Recombinant DNA important?
It is used to study individual genes inside the Genome
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When doing recombinant DNA, we are manipulating the DNA of an organism, meaning that
we are changing the proteins being made.
3. DNA TOOLS
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When scientists want to study genes, they use DNA tools
DNA tools are able to manipulate, isolate (separate) specific genes from the rest of the
Genome.
Scientists are able to increase or decrease the expression of a gene in selected (it can not be
done in all organisms) organisms.
DNA TOOL #1: RESTRICTION ENZYMES- also called ENDONUCLEASE
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Before looking at restriction Enzymes, do you know what a bacteria is?
Bacteria are biological cells that come in many shapes and sizes.
CHAPTER 2: GENETICS AND BIOTECHNOLOGY
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NALEDI NOXOLO BHENGU
Bacteria are called micro-organisms because they can only be seen by using a
microscope, meaning they are very small
Bacteria can be good or they can be bad.
Some bacteria contain very powerful defences again viruses.
FOR YOU TO DO: What is a virus?
Answer: ______________________________________________________________
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These bacterial cells have proteins which are called RESTRICTION ENZYMES
What do Restriction Enzymes do?
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When the DNA enters the bacterial cell, the restriction enzyme is able to cut a
specific sequence of the DNA into many different pieces (segments) which are
unique to every individual.
Restriction enzymes are very important, Why? Because they can isolate a specific
gene or region (certain area) of a genome.
Below is a diagram showing how a restriction enzyme cut DNA. The name of this
Restriction enzyme is called EcoRI
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What we need to know about EcoRI
EcoRI cuts ONLY DNA that has the sequence GAATTC.
When EcoRi cuts this specific DNA, the end become STICKY
DIAGRAM 1: DNA enters the bacterial cell that contains the enzyme EcoRI
DIAGRAM 2: EcoRI cuts the specific sequence GAATTC, when EcoRI cuts the DNA at
GAATTC it makes the ends sticky.
Now the question is, what happens to the cut DNA? –
DIAGRAM 3: The cut DNA will then meet a complementary sequence that also has
sticky ends and they will stick together.
DIAGRAM 4: Look at Diagram 3, notice the small gap between G and A and A and G?
Another enzyme will act as a glue stick to stick the parts that are not stuck together
properly. The name of this enzyme is DNA LIGASE
CHAPTER 2: GENETICS AND BIOTECHNOLOGY
NALEDI NOXOLO BHENGU
DNA TOOL #2: GEL ELECTROPHORESIS
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An electric current is used
This electric current separates the DNA fragments
This is called GEL ELECTROPHORESIS
What happens during GEL ELECTROPHORESIS?
DNA fragments of different sizes (big and small) are put on each of the 4 holes on top, this is the
negative side
The holes have a gel inside them
Power is turned on, an electric current is applied
The DNA fragments moves down towards the positive side.
The small fragments move faster and further while the big fragments move slower.
The movement creates a pattern.
This pattern can be taken and compared to another
RECOMBINANT DNA TECHNOLOGY