1. Chromosomes, genes, alleles, and mutations.
4.1
Chromosomes, genes, alleles, and mutations.

2. A chromosome is made of TWO main parts:
-DNA
-histones
The chromosome is super coiled by a factor around x16,000. The DNA molecule is about 1.8m long but is located in the nucleus which is only 10um in diameter!
This image was taken shortly after DNA a replication but before the prophase. It is composed of two daughter chromatids joined at the centromere.

3. Let’s take it back….

4. Let’s take it back….

5. Let’s take it back….

6. Let’s take it back….

7. Let’s take it back….

9. Gene: heritable factor that controls a specific characteristic

10. Gene: heritable factor that controls a specific characteristic
Allele: one specific form of a gene, differing form other alleles by one or a few bases only and occupying the same gene locus as other alleles of that gene.

11. Gene: heritable factor that controls a specific characteristic
Allele: one specific form of a gene, differing form other alleles by one or a few bases only and occupying the same gene locus as other alleles of that gene.
Genome: the whole genetic information of the organism.

12. MUTATION
Gene mutation is a change in base sequence of an allele

13. MUTATION What is a base sequence?
Gene mutation is a change in base sequence of an allele
What is a base sequence?

14. MUTATION What is a base sequence?
Gene mutation is a change in base sequence of an allele
What is a base sequence?
Example: AGCCAGCTTACG

15. MUTATION What is a base sequence?
Gene mutation is a change in base sequence of an allele
What is a base sequence?
Example: AGCCAGCTTACG
Changes in base sequence may…..

16. MUTATION What is a base sequence?
Gene mutation is a change in base sequence of an allele
What is a base sequence?
Example: AGCCAGCTTACG
Changes in base sequence may…..
produce a different amino acid sequence in the protein translated

17. MUTATION What is a base sequence?
Gene mutation is a change in base sequence of an allele
What is a base sequence?
Example: AGCCAGCTTACG
Changes in base sequence may…..
-produce a different amino acid sequence in the protein translated
-not change the protein due to degenerate nature of the genetic code

18. MUTATION What is a base sequence?
Gene mutation is a change in base sequence of an allele
What is a base sequence?
Example: AGCCAGCTTACG
Changes in base sequence may…..
-produce a different amino acid sequence in the protein translated
-not change the protein due to degenerate nature of the genetic code

19. CHANGE IN BASE SEQUENCE CAN OCCUR BY….
The expression of the mutated gene may or may not be beneficial to the organism.

20. MUTATION FAQs
Coined by Hugo de Vries (Dutch)
Testing Mendel’s work
Thought of mutations as evolutionary “jumping” mechanism
They are NOT rare
As you’re reading this...thousands of mutations have occurred…
Creates raw material for the process of evolution
Process of a mutation is in itself random mistakes
Mutagens: what cause mutations (usually radiation, but also chemical)

21. Mutation Example: SICKLE CELL ANEMIA Genetic disease
Frequency is about 1 in 655 African Americans
Is INHERITED not contracted by infectious routes….

22. At the tissue level…

23. At the tissue level…
(a) Normal haemoglobin has two of four proteins changed in the mutation.

24. At the tissue level…
(a) Normal haemoglobin has two of four proteins changed in the mutation.
(b) The normal biconcave disc shape of the red blood cell is changed to a 'sickle' shape.

25. At the tissue level…
(a) Normal haemoglobin has two of four proteins changed in the mutation.
(b) The normal biconcave disc shape of the red blood cell is changed to a 'sickle' shape.
(c) In addition to not carrying oxygen correctly (anaemia) the cells also causes local clots (infarctions) such as is shown in the kidney tubules. This leads to necrosis of the tubules, kidney damage, kidney failure and possible to death.

26. Chromosome 11
The gene loci for the normal beta chain of haemoglobin is on chromosome 11.
The normal allele carried the triplet GAG at the sixth amino acid position for the beta chain (146 amino acids).
This transcribed and translates into the negatively charged Glutamic acid.

27. Base sequencing ?

28. Base sequencing ?

29. Base sequencing ? ?

30. Base sequencing ? ?

31. Base sequencing
The mutation changes a single base ( T replaces A) and this transcribes and translates into the amino acid Valine.
Valine has a neutral charge and the result is a change in the shape of the beta chain with long needle like structures forming. ?

32. Change in RBC due to mutation

33. HW: A mutation story…
Write a paragraph on what you learned from reading the article and watching the video.