Unit 1: DNA and the Genome Key area 4: Cellular differentiation Stem cells and meristems.
Unit 1: DNA and the Genome DNA and the Genome Unit 1: CFE Higher Biology June – October Unit...
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Transcript of Unit 1: DNA and the Genome DNA and the Genome Unit 1: CFE Higher Biology June – October Unit...
Unit 1: DNA and the Genome
DNA and the Genome
Unit 1: CFE Higher BiologyJune – October
Unit Assessment – before October break
CFE Higher BiologyDNA and
the Genome
Take a moment…think…
What have you learned about DNA so far?In groups, collect an sheet of poster paper.
Nominate a scribe. Write down as many things you can remember about DNA from your school/life so far.
DNA
CFE Higher BiologyDNA and
the Genome
Carousel
Pass the sheets around.
Read the facts/comments. Put a tick next to any you had on your sheet.
Add any you had that are missing.
CFE Higher BiologyDNA and
the Genome
Share with class
Share what is on your sheet with the class.
The aim is to fill a sheet of your jotter with “DNA background information”.
CFE Higher BiologyDNA and
the Genome
Key concepts• DNA is inherited.• DNA is the genetic material of living things.• DNA is located within the nucleus of all cells apart from red
blood cells.• DNA is a long chemical sequence and this sequence contains
the information needed for that living thing to develop, survive and pass its genetic information on to the next generation.
• The DNA chemical sequence differs between individuals. The pattern of this sequence is called the genotype.
CFE Higher BiologyDNA and
the Genome
Deoxyribonucleic acid
The DNA molecule is comprised of two chains of nucleotides.
The nucleotides are comprised of a sugar, a phosphate and a base.
CFE Higher BiologyDNA and
the Genome
Nucleotides
Phosphate
Sugar
Base5’ end
3’ end5’
pronounced “5 prime”
CFE Higher BiologyDNA and
the Genome
Why 5’ and 3’?This is what a nucleotide looks like at the molecular level…
…lets zoom in to look at the sugar in more detail…
CFE Higher BiologyDNA and
the Genome
Nucleotides in a chain are joined together by sugar-phosphate bond to make long chains of nucleotides – called polynucleotides.
(poly = many)
CFE Higher BiologyDNA and
the Genome
The bases
In DNA there are four different bases:AdenineThymineCytosineGuanine
or A, T, C and G
CFE Higher BiologyDNA and
the Genome
Base pairing
These bases are described as being complementary to each other. This means their shapes match up.
CFE Higher BiologyDNA and
the Genome
DNA base pair rules
Adenine always joins to Thymine
Cytosine always joins with Guanine
The bases are joined by hydrogen bonds.
CFE Higher BiologyDNA and
the Genome
The double helix
The chains of polynucleotides are joined together by the bases, by hydrogen bonds, for form a double helix structure.
CFE Higher BiologyDNA and
the Genome
Imagine the sugars and phosphates joined together making the side of a ladder, with the pairs of bases forming the rungs.
Then the ladder gets twisted…
CFE Higher BiologyDNA and
the Genome
The double helix is described as having two anti-parallel chains of nucleotides because one side goes from 5’ to 3’ and the opposite side goes from 3’ to 5’.
CFE Higher BiologyDNA and
the Genome
How was all this discovered?Who would have thought that science could produce such a story of intrigue and characters? Like all major scientific discoveries, the discovery of the structure of DNA by James Watson and Francis Crick in 1953 was the result of years of work from a great number of scientists. Not only is the story one of great scientific interest, it is also one of great human interest and controversy.
CFE Higher BiologyDNA and
the Genome
Your taskThis task will see you research one of the individuals or groups of scientists whose work contributed to the discovery. There are six people to choose from and your teacher will help you decide which one to focus on:•Griffiths•Avery et al.•Hershey and Chase•Chargaff•Franklin and Wilkins•Watson and Crick
CFE Higher BiologyDNA and
the Genome
The results of your research will then be produced as a scientific poster, which you will present to the class.• who the scientist(s) is, where they worked
and when• the aims of the experiments• what the experiments were, including a
diagram• what the conclusions were• other interesting information that you have
gathered that lends interest to the story.
CFE Higher BiologyDNA and
the Genome
Key concepts• DNA is composed of two polynucleotide chains.• Nucleotides consist of a sugar, phosphate and base.• Nucleotides bond to form a sugar–phosphate
backbone.• The two polynucleotide chains run antiparallel, with a
deoxyribose sugar at the 3′ end and a phosphate group at the 5′ end.
• The nucleic acid bases are paired by hydrogen bonding in the centre to form a double helix.
• Base pairing is specific, with adenine pairing with thymine and cytosine pairing with guanine.