1. Human Cells Genes and proteins in health and disease
Higher Human Biology
Human Cells
Genes and proteins in health and disease

2. a. Protein structure and function
What do you remember?
Write down 10 words you associate with protein structure and function

3. What you need to know The elements that are found in proteins
The bonds that build protein shape
The variety and function of proteins

4. Protein structure
The elements making proteins are C, H, O, N and often S
Amino acids are joined with peptide bonds (polypeptides)
Hydrogen bonds form between amino acids giving initial folding or coiling (sheets/helices)
Sulfur bridges and other interactions between negative and positive charges
More than 1 chain of amino acids can join together
Non protein molecules can be associated with proteins
3 dimensional shape

6. Fibrous
Globular

7. What type of protein? What type of protein are these? What do they do?
Collagen
Somatotrophin
Ligament
Mucus
Tubulin
Testosterone
Trypsin
Endorphins
Immunoglobulin
What type of protein are these?
What do they do?
How is their structure related to their function?

8. Types of protein Protein structure allows protein function
Enzymes – globular . Folded proteins exposing active sites to binds specific substrate. Speed up biochemical reactions.
Structural proteins – fibrous often globular but too. Cell membranes, muscle fibres
Hormones – globular . Folded into specific shape to bind to receptors at specific sites. Regulate growth and metabolism
Antibodies –globular Y shape . Bind to specific antigens
Haemoglobin – conjugated. Protein with non protein molecule attached to transport oxygen

9. What do you know? Name the elements in proteins
State the number of amino acids in human proteins
Name the 3 types of bonds involved in protein structure
Name the 3 broad groups of protein
For each group of protein name an example
For each protein example describe how its structure relates to its function
Complete the questions from page 50 in the textbook

10. b. Mutations and their effect on protein function
What do you remember?
Write down 10 words you associate with mutations, proteins and their function

11. What you need to know
Some types of gene mutations, what causes them and how they affect protein function
Some types of chromosome mutations, what causes them and how they affect protein function or organism function

12. Mutations A change in an organisms genome
Could be small with a single gene
Could be larger change to chromosome structure or number
Occur spontaneously, naturally, randomly, rarely
Rate can be artificially increased by mutagenic agents e.g. UV light, X-rays, gamma rays, mustard gas etc.
These mutations would be described as induced

13. Mutations and protein function
Proteins are essential for life
Proteins are structural and control the metabolism
If a gene coding for a protein mutates, the amino acid sequence could be altered
Faulty protein gives faulty structure or faulty metabolic pathway
If a gene coding for a protein mutates, the protein may not be made at all
Missing protein could mean non-functioning metabolic pathway

14. Gene mutations
Mutations on a single gene would alter the nucleotide sequence
Point mutations are the change in one nucleotide
Could be deletion of one nucleotide changing all the following codons and hence amino acid sequence.
Could be insertion of one nucleotide changing all the following codons and hence amino acid sequence.
These two are both frameshift mutations
Could be the substitution of one nucleotide for another altering only 1 codon and amino acid in the sequence

15. Gene mutations - Normal

16. Gene mutations - Deletion

17. Gene mutations - Insertion

18. Gene mutations - Substitution

19. Gene mutations Splice site mutations
during processing of primary transcript mRNA the introns are removed. Exons join together by splicing to give coding for aa’s.
Splicing is controlled by nucleotide sequences at splice sites on introns next to exons.
If a mutation occurs at splice sites some introns may be left in and coded for in the mature mRNA

20. Gene mutations
Splice site mutations

21. Gene mutations Nucleotide sequence repeat expansion
A mutation that produces a repeat of a triplet of nucleotides (trinucleotide).
This inserted repeat of the same triplet codon (often many times) stops the protein from functioning, due too many aa’s.

22. Gene mutations
Nucleotide sequence repeat expansion

23. How do gene mutations change protein structure
Substitutions alter only 1 codon so only 1 aa is affected
When the code still makes sense but is different from original it is called a missense mutation.
When the code causes the sequence to stop being read as the mutation produces a stop codon it is called a nonsense mutation. The polypeptide chain is shortened and the protein is not properly formed.

25. How do gene mutations change protein structure
Splice site mutation (retaining introns)
Modifying mRNA can give altered protein structure.
Frameshift (seen in nucleotide insertions or deletions)
These change all the codons after the change so all the amino acids change after it.
The protein produced is likely to be non-functional

26. How do gene mutations change protein structure
Nucleotide sequence repeat expansion
This is producing multiple copies of the same codon.
Can give extra amino acids of the same type.
Can expand the sequence so much that protein fails to be produced.
Most of the gene mutations produce genetic disorders that have adverse effects on the individuals who suffer from it.

27. Effects on Health
Many gene mutations have an effect on the structure and function of proteins.
These changes have an effect on health for e.g.
Sickle cell disease (anaemia) missense
PKU missense
Duchenne muscular dystrophy nonsense
Tay-Sachs syndrome frameshift insertion
Cystic fibrosis frameshift deletion
Beta thalessemia splice site mutation
Fragile X syndrome nucleotide sequence repeat expansion
Huntingdon’s disease nucleotide sequence repeat expansion

28. Chromosome mutations These affect the structure of a whole chromosome.
These include:
Deletion where part of a chromosome is lost
Duplication where part of the chromosome is repeated
Translocation where 2 or more chromosomes rearrange materials between them
Because these are such large changes they are often lethal in their effect.

29. Chromosome deletion

30. Chromosome duplication

31. Chromosome translocation

32. What do you know now?
What 2 effects can a mutation have on protein production?
What are the 3 types of single gene mutation?
What is a missense mutation?
What is a nonsense mutation?
What is a splice site mutation
What 2 types of nucleotide changes are frameshift mutations?
What is a nucleotide sequence repeat mutation?
What are the 3 chromosome mutations?
What happens in each of these mutations?

33. Consolidation Reading PPT, textbook or scholar and making own notes.
Completing textbook questions page 50 and p62
Answer multiple choice questions chapter 4