Genetics Lesson Objectives To define the key terms in genetics To describe a genetic mutation To evaluate the causes, effects and benefits of Sickle Cell Anaemia

What are the key components of chromosomes? A.DNA -heterochromatin -euchromatin B.Proteins C.Found in nucleus D.You should understand the relationship between DNA and proteins (chromatin packing and histones)

Key terms A.Eukaryotic chromosomes-made of DNA and proteins (histones) B.Gene-heritable factor that controls specific characteristics -made up of a length of DNA, found on a specific chromosome location (a locus) C. Allele-one specific form of a gene (all found at the same locus) -Example: Everyone has the gene for eye color. The possible alleles are blue, brown, green, etc.

More Key Terms D. Genome-total genetic material of an organism or species (Example: The Human Genome) E. Gene pool-total of all genes carried by individuals in a population

Mutations A.Chromosome mutations-involve large sections of chromosomes (or the whole thing) -Ex: Down’s syndrome, Turner’s syndrome

B. Gene mutation-involves changes in single base pairs -Some mutations may not have any effect on the cell and may involve: 1. part of the sense strand of DNA which is not transcribed 2. part of the DNA that a cell does not use 3. changes in second or third bases of a codon (since the genetic code is degenerate the same base may still be coded for) Mutations

B. Gene mutation-involves changes in single base pairs Example: Insertion or deletion of single organic bases -changes the DNA sequence that will be transcribed and translated original DNA sequence: ATG-TCG-AAG-CCC transcribed: UAC-AGC-UUC-GGG translated: tyr-ser-phe-gly addition of base A: ATA-GTC-GAA-GCC-C transcribed: UAU-CAG-CUU-CGG translated: thy-glu-leu-arg

A.Hemoglobin-protein that helps RBC carry oxygen B.Hb is a gene that codes for hemoglobin -made of 146 amino acids C. In some cases one base is substituted for another normal: (Hb A )base substitution: (Hb S ) CTCCAC GAGGUG -after transcription and translation Hb A produces glutamic acid and Hb S produces valine Mutations: Base substitutions and sickle-cell anemia

D. The altered hemoglobin Hb S is crystalline at low oxygen levels causing the RBC to become sickled and less efficient at oxygen transport E. Symptoms of sickle cell anemia -physical weakness -heart or/and kidney damage -death Mutations: base substitutions and sickle-cell anemia

F. In heterozygous people (one normal allele and one sickle cell allele) -the alleles are codominant, but the normal allele is expressed more strongly -in codominance both alleles are expressed (one is not dominant to the other) -some sickled cells present, but most are normal -some people show mild anemia (deficiency of the hemoglobin, often accompanied by a reduced number of red blood cells and causing paleness, weakness, and breathlessness) Mutations: base substitutions and sickle-cell anemia

G. Advantages of being heterozygous -In areas where malaria is infested: -Plasmodium cannot live in erythrocytes with Hb S -Heterozygous individuals have a reduced chance of contracting the protist that is carried by mosquitoes Mutations: base substitutions and sickle-cell anemia

Extended Writing: Sickle Cell Anaemia Curse or Blessing? Introduction Main points Discussion Conclusion Bibliography