,Life Sciences Gr 12 Cape Winelands Survival Kit - PAPER 2 2022
DNA, RNA, Protein Synthesis (Paper 2- 27 marks)
DNA is the basic unit of genetics.
DNA provides the code for production of proteins, a process called protein synthesis.
There are two types of nucleic acids: DNA and RNA
• DNA is found (or located) in the nucleus of cells
is also found in the mitochondria of cells
• RNA is found in the nucleus
also found at the ribosomes in the cytoplasm of a cell.
• RNA plays a role in protein synthesis by joining amino acids in the correct sequence,
according to the instructions which DNA provides
STRUCTURE OF DNA: Double helix
Consists of two strands of nucleotides that form a twisted ladder (double helix)
Double Helix
A DNA molecule is made up of building-blocks or monomeres, called nucleotides
NB : Each DNA nucleotide is made up of three components:
1. Nitrogenous bases linked by weak hydrogen
bonds
The four nitrogen bases: adenine (A)
thymine (T)
cytosine (C)
guanine (G)
2. Sugar portion (deoxyribose in DNA)
3. Phosphate portion
Specific base pairing arrangement are known as complimentary
bases.
A always pairs with T (A-T)
C always pairs with G (C-G)
NB!!: Nitrogen bases attach to the sugar portion of the
nucleotide
Know the stick diagram of DNA to
illustrate its structure:
When you learn this topic, practice to draw
a nucleotide AND
be able to label the different parts of the
DNA stick diagram
2
,Life Sciences Gr 12 Cape Winelands Survival Kit - PAPER 2 2022
FUNCTIONS OF DNA:
1. Sections of DNA-forming genes carry hereditary information
2. DNA contains coded information for protein synthesis
PROCESS OF DNA REPLICATION
(Meaning of replicate = to make an exact copy of)
When does DNA replication take place?
During INTERPHASE
Where does DNA replication take place?
In the nucleus
Significance (or importance) of DNA replication:
• Doubles the genetic material so it can be shared between the resulting daughter cells
during cell division.
• Results in the formation of identical daughter cells during mitosis
How DNA replication takes place:
(you must be able to describe this process)
Definition of a DNA profile:
It can be described as an arrangement of black bars representing DNA fragments of the person.
Uses of DNA profiles:
• Identify criminals
• Identify dead bodies
• Identify relatives
• Identify paternity
3
, Life Sciences Gr 12 Cape Winelands Survival Kit - PAPER 2 2022
Interpretation of DNA profiles:
Compare the DNA profile found at the crime scene to the DNA profile of the suspects.
Suspect 2 is most probably guilty as all the bars on his DNA profile are the same as the bars
of the DNA profile found at the crime scene.
Exemplar Questions on DNA
Question 1:
1. The diagram below represents a portion of a DNA molecule.
1.1 Identify parts B, C and D. (3)
1.2 Name:
(a) Monomer A (1)
(b) ONE organelle in a cell where DNA is
located (1)
1.3 How many nucleotides are shown in the
diagram? (1)
Answer:
1.1 B – nitrogen base
C – phosphate group
D - hydrogen bonds (weak)
1.2 (a) nucleotide (monomere = building block)
(b) nucleus or mitochondria
1.3 8
Question 2
The diagram below represents part of a DNA molecule.
2.1 Identify the:
(a) Molecule X
(b) Sugar at Y
(c) Bond W (3)
2.2 Give the collective name of the parts X, Y
and Z. (1)
2.3 State the natural shape of the DNA
molecule. (1)
2.4 Name the process wherebyDNA makes a
copy of itself. (1)
2.5 Name TWO places in an animal cell where
DNA is located. (2)
4
DNA, RNA, Protein Synthesis (Paper 2- 27 marks)
DNA is the basic unit of genetics.
DNA provides the code for production of proteins, a process called protein synthesis.
There are two types of nucleic acids: DNA and RNA
• DNA is found (or located) in the nucleus of cells
is also found in the mitochondria of cells
• RNA is found in the nucleus
also found at the ribosomes in the cytoplasm of a cell.
• RNA plays a role in protein synthesis by joining amino acids in the correct sequence,
according to the instructions which DNA provides
STRUCTURE OF DNA: Double helix
Consists of two strands of nucleotides that form a twisted ladder (double helix)
Double Helix
A DNA molecule is made up of building-blocks or monomeres, called nucleotides
NB : Each DNA nucleotide is made up of three components:
1. Nitrogenous bases linked by weak hydrogen
bonds
The four nitrogen bases: adenine (A)
thymine (T)
cytosine (C)
guanine (G)
2. Sugar portion (deoxyribose in DNA)
3. Phosphate portion
Specific base pairing arrangement are known as complimentary
bases.
A always pairs with T (A-T)
C always pairs with G (C-G)
NB!!: Nitrogen bases attach to the sugar portion of the
nucleotide
Know the stick diagram of DNA to
illustrate its structure:
When you learn this topic, practice to draw
a nucleotide AND
be able to label the different parts of the
DNA stick diagram
2
,Life Sciences Gr 12 Cape Winelands Survival Kit - PAPER 2 2022
FUNCTIONS OF DNA:
1. Sections of DNA-forming genes carry hereditary information
2. DNA contains coded information for protein synthesis
PROCESS OF DNA REPLICATION
(Meaning of replicate = to make an exact copy of)
When does DNA replication take place?
During INTERPHASE
Where does DNA replication take place?
In the nucleus
Significance (or importance) of DNA replication:
• Doubles the genetic material so it can be shared between the resulting daughter cells
during cell division.
• Results in the formation of identical daughter cells during mitosis
How DNA replication takes place:
(you must be able to describe this process)
Definition of a DNA profile:
It can be described as an arrangement of black bars representing DNA fragments of the person.
Uses of DNA profiles:
• Identify criminals
• Identify dead bodies
• Identify relatives
• Identify paternity
3
, Life Sciences Gr 12 Cape Winelands Survival Kit - PAPER 2 2022
Interpretation of DNA profiles:
Compare the DNA profile found at the crime scene to the DNA profile of the suspects.
Suspect 2 is most probably guilty as all the bars on his DNA profile are the same as the bars
of the DNA profile found at the crime scene.
Exemplar Questions on DNA
Question 1:
1. The diagram below represents a portion of a DNA molecule.
1.1 Identify parts B, C and D. (3)
1.2 Name:
(a) Monomer A (1)
(b) ONE organelle in a cell where DNA is
located (1)
1.3 How many nucleotides are shown in the
diagram? (1)
Answer:
1.1 B – nitrogen base
C – phosphate group
D - hydrogen bonds (weak)
1.2 (a) nucleotide (monomere = building block)
(b) nucleus or mitochondria
1.3 8
Question 2
The diagram below represents part of a DNA molecule.
2.1 Identify the:
(a) Molecule X
(b) Sugar at Y
(c) Bond W (3)
2.2 Give the collective name of the parts X, Y
and Z. (1)
2.3 State the natural shape of the DNA
molecule. (1)
2.4 Name the process wherebyDNA makes a
copy of itself. (1)
2.5 Name TWO places in an animal cell where
DNA is located. (2)
4
