1. 3.1 Genes
Genes and hence genetic information is inherited from parents, but the combination of genes inherited from parents by each offspring will be different. In sexual reproduction each parent can only pass on 50% of there genes as the other 50% comes from the second parent.

2. 3.1 Genes
Essential idea: Every living organism inherits a blueprint for life from its parents.

3. Genetics is the study of .
The traits we inherit are controlled by our chromosomes.
Chromosomes are made of chromatin ( )
What do we call the process where chromatin shortens and thickens to form chromosomes?

4. 3.1.U1 A gene is a heritable factor that consists of a length of DNA and influences a specific characteristic. AND 3.1.U2 A gene occupies a specific position on a chromosome. AND 3.1.U3 The various specific forms of a gene are alleles. AND 3.1.U4 Alleles differ from each other by one or only a few bases.
A gene is a

5. 3.1.U1 A gene is a heritable factor that consists of a length of DNA and influences a specific characteristic. AND 3.1.U2 A gene occupies a specific position on a chromosome. AND 3.1.U3 The various specific forms of a gene are alleles. AND 3.1.U4 Alleles differ from each other by one or only a few bases.
Alleles of a gene are found at the same locus, but have a different DNA base sequence. The sequence tends to be very similar, differing only by a few bases. As shown later on [3.1.A1] a mutation causing a change to a single base can have a large impact on the structure and function of the protein synthesized.

6. 3. 1. U3 The various specific forms of a gene are alleles. 3. 1
3.1.U3 The various specific forms of a gene are alleles U4 Alleles differ from each other by one or only a few bases.
Alternative versions of genes account for variations in inherited characteristics
These alternate versions are called .
An allele is one specific version of a gene,
Allele for purple flower
Locus for flower-color gene
Homologous pair of chromosomes
Allele for white flower

7. 3.1.A2 Comparison of the number of genes in humans with other species.
Humans see themselves as being more complex and evolved than other species. Therefore you might well expect to see a larger number of genes in humans than in other organisms.
Plant
Mammal
Bird
Insect
It is not just plants such as the grapevine that have large numbers of genes; water fleas are an animal example of an organism with more genes than humans.
Bacterium
Virus
Microscopic water flea
31,000 genes!

8. DNA Supercoiling: https://youtu.be/AF2wwMReTf8

9. 3.1.U6 The genome is the whole of the genetic information of an organism. AND 3.1.U7 The entire base sequence of human genes was sequenced in the Human Genome Project.
The Human Genome* Project (HGP) was an international 13-year effort, 1990 to Primary goals were to discover the complete set of human genes and make them accessible for further biological study, and determine the complete sequence of DNA bases in the human genome.
*The genome is It consists of DNA (or RNA in RNA viruses) and includes both the genes and the non-coding sequences.

10. Nature of Science: Developments in scientific research follow improvements in technology - gene sequencers are used for the sequencing of genes. (1.8)
“The first methods for sequencing DNA were developed in the mid-1970s. At that time, scientists could sequence only a few base pairs per year, not nearly enough to sequence a single gene, much less the entire human genome. By the time the HGP began in 1990, only a few laboratories had managed to sequence a mere 100,000 bases, and the cost of sequencing remained very high. Since then, technological improvements and automation have increased speed and lowered cost to the point where individual genes can be sequenced routinely, and some labs can sequence well over 100 million bases per year.” (

11. Key advances in technology:
Nature of Science: Developments in scientific research follow improvements in technology - gene sequencers are used for the sequencing of genes. (1.8)
Key advances in technology:
Biotechnology techniques such as PCR are used to prepare samples: the DNA needs to be copied to prepare a sufficiently large pure samples to sequence
Computers automate the sequencing process
Fluorescent labeling techniques enable all four nucleotides to be analyzed together
Lasers are used to fluoresce the dye markers
Digital camera technology reads the dye markers
Computers are used to assemble the base sequence

12. 3.1.A1 The causes of sickle cell anemia, including a base substitution mutation, a change to the base sequence of mRNA transcribed from it and a change to the sequence of a polypeptide in hemoglobin.
mRNA
Amino acids

13. 3.1.A1 The causes of sickle cell anemia, including a base substitution mutation, a change to the base sequence of mRNA transcribed from it and a change to the sequence of a polypeptide in hemoglobin.

14. 3.1.A1 The causes of sickle cell anemia, including a base substitution mutation, a change to the base sequence of mRNA transcribed from it and a change to the sequence of a polypeptide in hemoglobin.

15. 3.1.A1 The causes of sickle cell anemia, including a base substitution mutation, a change to the base sequence of mRNA transcribed from it and a change to the sequence of a polypeptide in hemoglobin.

16. 3.1.A1 The causes of sickle cell anemia, including a base substitution mutation, a change to the base sequence of mRNA transcribed from it and a change to the sequence of a polypeptide in hemoglobin.

17. 3.1.A1 The causes of sickle cell anemia, including a base substitution mutation, a change to the base sequence of mRNA transcribed from it and a change to the sequence of a polypeptide in hemoglobin.

18. 3.1.A1 The causes of sickle cell anemia, including a base substitution mutation, a change to the base sequence of mRNA transcribed from it and a change to the sequence of a polypeptide in hemoglobin.

19. Learn.Genetics: What Is Mutation?
3.1.U5 New alleles are formed by mutation.
Learn.Genetics: What Is Mutation?

20. 3.1.U5 New alleles are formed by mutation.

21. 3.1.U5 New alleles are formed by mutation.

22. 3.1.U5 New alleles are formed by mutation.

23. 6th amino acid in the sequence
3.1.A1 The causes of sickle cell anemia, including a base substitution mutation, a change to the base sequence of mRNA transcribed from it and a change to the sequence of a polypeptide in hemoglobin.
6th amino acid in the sequence

24. 3.1.A1 The causes of sickle cell anemia, including a base substitution mutation, a change to the base sequence of mRNA transcribed from it and a change to the sequence of a polypeptide in hemoglobin.

25. https://youtu.be/1fN7rOwDyMQ
3.1.A1 The causes of sickle cell anemia, including a base substitution mutation, a change to the base sequence of mRNA transcribed from it and a change to the sequence of a polypeptide in hemoglobin.