Unit 6 Human Genetics
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Transcript of Unit 6 Human Genetics
UNIT 6: HUMAN GENETICS
INDEX1. Inheritance and Human Variation2. Diagnosis of Genetic Diseases3. Human Genetic Disorders
1. Inheritance and HumanVariation
The characteristics
of the individuals
depend on two factors:
Genetic traits
Genotype
Inherited
Environmental factors (food,
lifestyle habits…)
Phenotype
Usually not transmissible
Types of traits
Quantitative
Skin colour
Eyes colour (they have a range of
possible expressions)
Qualitative Examples of quantitative traits: skin and eyes colour
Qualitative traits in humanbeings
Dominantallele
Recessiveallele
Curly hair Straight hair
Ability to roll the tongue
Inability to roll the tongue
Thick lips Thin lips
Long eyelash Short eyelash
Detached earlobes
Attached earlobes
Blood group A and B
Blood group 0
Blood groupRh+
Blood groupRh-
Straight and curly hair
The ABO system establishes four blood groups (A, B, AB and O) according to the presence or absence of certain proteins, called A and B, in the membrane of the red blood cells.
Antibodies react against specific antigens destroying them.
Phenotypes Group A Group B Group AB Group 0
Genotypes AA BB AB 00
A0 B0
Alleles A and B are codominant.Alleles A and B are dominant over allele 0, which is recessive
Rh System
Rhesus factor is another antigen which can be present (Rh+) or not (Rh-) inthe red blood cells.
Rh+ is dominantRh- is recessiv
Blood typing virtual lab:http://www.nobelprize.org/educational/medicine/bloodtypinggame/gamev2/index.html
Page 109 activity 3, 4, 5, 9
Phenotypes Rh+ Rh-
Genotypes Rh+Rh+ Rh-Rh-
Rh+Rh-
Erytroblastosis fetalis: http://education-portal.com/academy/lesson/rh-blood-group-rh-factor-erythoblasotis-fetalis.html
AB- group
Test tubes containing the corresponding antibody
A double homozigous 0+ woman decides to have a baby with a A- man, whose father was 0-.What is the probability to obtain an A- baby?
00Rh+Rh+ x A0Rh-Rh-
From the father
ARh- 0Rh-
0Rh+ A0Rh+Rh- 00Rh+Rh-
Sol.: 0% (none of the babies will be Rh negative)
2. Diagnosis of Genetic Diseases
Amniocentesis
Foetus cells from the amniotic fluid are extracted with a needle. The DNA isanalysed and possible chromosom or metabolic disorders are detected
Recommendation foramniocentesis
Couples already witha child with a chromosome
anomaly
Parents’ family withgenetic disease
Pregnant womenover 35 years old
3. Human Genetic Disorders
Autosomal dominant (A)
Autosomal recessiv (a)Linked to the X chromosomeDaltonism, haemophilia
4. Some examples of Pedigree Charts
• At least 3 generations• Phenotype coloured• Indicate genotypes• Indicate type of allele• Include cousins
Autosomal dominant