DNA
What do you know about it?
The Secret of Life…
Watch the following video and answer the
questions about the discovery of DNA!
DNA Extraction
• Having looked at
the card sort try to
put the steps in
order.
• Why is each step
important?
DNA Extraction
1 – Collect berries as allocated and a pestle and
mortar.
2 - Mash the berries using the pestle and
mortar.
This is to break open some of the cells.
3 – To make an extraction buffer, add 10ml water,
1ml detergent and 1 spatula of salt to a small
beaker and stir slowly until the salt dissolves.
4 - Add the extraction buffer to the mashed up
berries and mix well using the pestle and
mortar.
DNA Extraction
5 – Transfer the mixture to a test tube and incubate at 60oC
for 15 minutes.
This starts to break down the cell’s membranes.
6 - Filter the berry mixture through a funnel & filter
paper into a clean test tube until it is about 1/3
full.
This separates the parts of the cell leaving a liquid
containing the berry DNA.
7 – Using a dropper pour the ice cold ethanol slowly down
the side of the test tube. The ethanol makes the DNA
visible as it is insoluble in ethanol.
8- Use a paperclip to hook the white jelly-like substance
forming. This is the DNA!
DNA
Genetic information is stored in the
nucleus of a cell.
• Genetic information is especially found on
thread-like structures called, chromosomes.
• Genes are located on chromosomes in the
nucleus.
• Genes and chromosomes are made of
DNA.
• DNA stands for Deoxyribonucleic Acid.
• DNA has a double helix shape and is
made of 4 bases.
• The 4 bases are shown as; A, C, T and G
Organisms to Bases...
• Cut out the names and definitions in the
cardsort.
• Arrange the names in order of size –
The largest at the top down to the
smallest.
• Then match the definitions to the
names.
Genes
• Genes are sections
of DNA containing
the instructions
needed to make
proteins which are
made of amino
acids.
Decoding…
• Collect a DNA sequence – this will
have a string of letters A, T, G and C
to represent the 4 DNA bases.
• Re-write the DNA sequence leaving a
space after every third letter e.g.
TACACGACCGTCTAG becomes TAC
ACG ACC GTC TAG
Decoding…
• Collect a decoder key
• Use the decoder to find out which amino
acid (represented by a different shape for
each amino acid) comes first in the
sequence e.g. in the sequence above TAC is
the first code which in the key means
‘START’
• Find the next amino acid in your sequence
using the key e.g. ACG is
• Continue adding the correct amino acids to
the chain until the chain is complete.
Decoding Posters
• Make a poster showing your;
•
•
•
•
Starting code - TACACGACCGTCTAG
Triplets - TAC ACG ACC GTC TAG
Amino acids Protein –
• Are any 2 proteins the same? Why?
Why do we need proteins?
• Enzymes are proteins that help us
digest food.
• Hair is protein.
• Skin contains protein.
• Antibodies which fight disease are
proteins.
• Our blood contains proteins.
Questions
• Where are genes located?
• Where are chromosomes found?
• What do genes contain the instructions
for making?
• Give 3 examples of proteins found in
your body.
Inheritance
• Each person’s DNA is unique.
• This is because they inherit their genes
from their parents.
Inheritance
• Sometimes a change if the order of the
code occurs in the genes which are
passed on from parents to offspring.
• This leads to faulty proteins and
inherited diseases.
• Examples include; Cystic Fibrosis and
Huntingdon’s Disease.
Questions
• Why can DNA be used to identify the
father or a child?
• Why can DNA be used to identify
criminals?
• Explain how inherited diseases arise?
Inherited Diseases Task
Collect an inherited disorder Case Study card.
You have been given a scenario related to a specific disease
caused by a problem with the genetic code for a particular
gene.
Starter sites for research:
http://learn.genetics.utah.edu/content/disorders/whataregd
/ (Huntington’s and cystic fibrosis)
http://genome.wellcome.ac.uk/doc_wtd020857.html or
http://www.genome.gov/10001214 (haemochromotosis)
http://www.genome.gov/10001220 (Tay Sachs)
DNA Structure
DNA is double stranded.
DNA is a double helix
shape.
The “rungs” of the
ladder of DNA are made
of 4 bases, A, C, T, G.
DNA Structure
DNA carries the
instructions to make
proteins.
The order of bases
determines the order of
amino acids.
The amino acid sequence
determines the type of
protein which is made.
DNA Bracelet
• From the sequence you have been given
make a bracelet to show the order of
bases which codes for……
DNA Bracelet
• Use your instructions sheet to make
your bracelet.
• Be careful to use the right colour for
each base!
• Remember A matches T, C matches G!
Edible DNA!!
• Follow the recipe to make your edible
DNA!
Edible DNA!!
• Using your bracelet and edible DNA
explain to your partner the structure of
DNA.
• Tell your partner why the order of the
bases is important?
• What does your sequence code for?
Quick Check
• What instructions does DNA carry?
• Where is DNA found in the cell?
• Where are proteins made in the cell?
DNA to Protein
• Watch the following video as an
introduction to DNA being used to make
protein.
DNA to Protein
• So that the instructions for making
protein can pass from the nucleus to the
ribosome a new molecule must be
made……..
• Messenger RNA (mRNA)
DNA to Protein
• Messenger RNA (mRNA) takes a copy of
the code from DNA in the nucleus to
the ribosome.
• At the ribosome amino acids are
assembled into a protein as directed by
the code.