Download Chromosome - Russell-Moro

CLIL MODULE – DNA and GENETIC DISEASES
2° Liceo Scientifico
Istituto Sant’Anna
Prof.ssa Elena Tibaldi
AS 2013-2014
1
To know:
• concept of chromosome, gene and allele
• concept of homozygous and heterozygous
Content
objectives
To be able to:
• predict the genotype and phenotype of the offspring using Punnett
square
To be aware of:
• the effect of genetic mutations in the onset of genetic disorders
• the effect of non-disjunction during meiosis
• recent discoveries on gene therapy
Language
objectives
Expand knowledge of content-specific vocabulary
Working on scientific words: use of prefixes and suffixes to convey
precise meaning
Describe a process/an experiment and motivate results
Passive forms of the verbs
Link words and sequencers
Prerequisites
The structure of DNA Æ see review slide
Cell cycle and division; mitosis and meiosis Æ see review slides
Task-based
activity
Groupwork: powerpoint presentation
Timing
Second term; II year
Classes: IIA and IIB Liceo
2
GLOSSARY Æ CONTENT-SPECIFIC VOCABULARY
TERM
(translation)
DEFINITION
Heredity / Inheritance
(
)
Genetic information is passed on from parents to their offspring
Chromosome
(
Thread-like structure made up of DNA and proteins
)
Gene
(
Sequence of DNA coding for a protein
)
Gamete
(
)
Male cell (sperm) or female cell (egg) are produced in the gonads
and join together (fertilization) to form a new organism (zygote)
)
Alternative forms of a gene which are found on a chromosome.
It can be dominant (A) or recessive (a)
Allele
(
Genotype
(
)
Phenotype
(
)
The genotype is the actual genetic make up of an individual and
derives from the combination of alleles of the genes from both
parents.
The phenotype is what that individual looks like. The phenotype
is the visible expression of genes.
3
BRAINSTORMING Æ
COMPARE INHERITED HUMAN TRAITS
Other
human
genetic
traits
Dark/blond hair
Curly/straight hair
Dark/light-coloured skin
4
HUMAN TRAITS DEPEND ON THE INFORMATION
CONTAINED IN THE DNA
DNA is a double helical structure consisting of two
filaments (strands) made of nucleotides.
The
two
strands
are
complementary in nucleotidic
sequence (Adenine - Thymine)
and (Cytosine - Guanine) and
are held together by hydrogen
bonds
between
the
complementary bases of the
two strands.
5
LAB ACTIVITY: DNA EXTRACTION FROM FRUIT
Materials:
• 100g of fruit pulp (½ banana /3 kiwis / ½ pear /some strawberries)
• salt
• liquid detergent (not from concentrate)
1-2
• Pineapple juice
• Plastic pipettes
• 5ml syringes
• plastic dishes, forks, knives and spoons
• Beakers and cylinders
•Test tubes
• 95% ice-cold alcohol
Experimental procedure:
1. Peel the fruit and place it in a plastic
dish
2. Using knife and fork, mash the fruit
pulp for several minutes
3. In a 250 ml beaker prepare the
extraction solution by adding:
3g (½ tablespoon) of salt
90 ml distilled water
10 ml liquid detergent
3
6
http://www.funsci.com/fun3_en/dna/dnaen.htm
4. Add the mashed pulp into the extraction solution and
stir for 10 minutes without making bubbles.
4
5. Filter the solution through a paper filter into a 100ml
beaker. Make sure the top part of the filter is folded
over the top of the beaker and that the bottom of the
filter does not touch the bottom of the cup
6. Put 5ml of the filtrate into a test tube.
5
7. Add 1ml of pineapple juice. Mix 2-3 minutes.
8. Slowly add 6ml of ice-cold alcohol.
9. Wait a few minutes until you see the DNA coming
out of solution as a cotton thread in the tube.
6-7
10. Collect the DNA with a toothpick
8
9-10
7
http://www.funsci.com/fun3_en/dna/dnaen.htm
AT THE END OF THE LAB ACTIVITY,
ANSWER THE FOLLOWING QUESTIONS
1. What is the purpose of mashing up the fruit pulp?................................................
2. What does the extraction solution do?...................................................................
3. What is the purpose of the detergent in the extraction solution?
‰ To destroy cell membrane
‰ To digest fruit fibers
‰ To make DNA precipitation
4. Why do we filter the solution?...............................................................................
5. What is the purpose of adding the pineapple juice?..............................................
6. What happens when you add the alcohol to the filtrate?.....................................
7. What does the DNA look like?...............................................................................
8. Why are bubbles formed during ethanol precipitation?
‰ Bromeline contained in the pineapple juice
‰ Low temperature of ethanol
‰ Presence of detergent
9. Place the following steps of the experimental procedure in the correct
order
‰ digestion of proteins
‰ ethanol precipitation
‰ break down of cell membranes
8
DNA IS ORGANIZED IN CHROMOSOMES
9
WORD STUDY: THE CHROMOSOME
The prefix CHROM- is referred to colour
Exercise Æ find out the meaning of the following
terms:
• Chromatin: ........................................................................
• Sister chromatids: ..........................................................
The prefix or suffix SOME is referred to body.
Exercise Æ find out the
meaning of the following
terms:
• Nucleosome: ..........................................................................................................................................
• Lysosome: ..............................................................................................................................................
• Centrosome: ............................................................................................................................................
• Somatic cell: ........................................................................................................................................
CHROMOSOME =
stained (=coloured) body
Walther Flemming (1843-1905), a German biologist
and founder of cytogenetics, was the first scientist
that stained the chromatin in the nucleus using aniline
dye. He correlated the chromatin with the threadlike structures that were lately named chromosomes.
Other dyes for nuclear staining are commonly used in
10
the lab: Giemsa, methylene blue and acridine orange.
GUESS WHO ...?
..........................................................
discovered the chromosomes and
the process of mitosis.
Walter Flemming
..........................................................
discovered the structure of DNA.
Gregor Mendel
..........................................................
identified laws of inheritance
working with pea plants.
James Watson and Francis Crick
11
DEFECTS IN THE NUMBER OF CHROMOSOMES
Non-disjunction during meiosis causes the altered number of chromosomes in the gamete.
Here a few examples of chromosomal defects.
1) Defects in the number of sexual chromosomes: individuals can live normally, but are
generally sterile.
• Turner syndrome (XO) Æ female with only one X chromosome
• Klinefelter syndrome (XXY) Æ male, with two X chromosomes
2) Defects in the number of autosomes: in the majority of cases, defects in the number of
autosome causes abortion; the only possibility of survival is:
• Edwards syndrome (trisomy of chr. 18) Æ 90% of affected children die within the first
six months because of heart damage and failure.
• Patau syndrome (trisomy of chr. 13) Æ affected children die within the first three
months because of damage to the nervous system and heart failure.
• Down syndrome (trisomy of chr.21) Æ affected children show mental retardation and
delay in physical growth. Many children with Down syndrome are educated in regular school
classes while others require specialised educational facilities. Education and proper care
has been shown to improve quality of life significantly. Many adults with Down Syndrome
are able to work at paid employment in the community, while others require a more
sheltered work environment. Life expectancy depends on the severity of the disease. 12
TRISOMY 21: THE STORY OF DOWN SYNDROME
Dr. John Langdon Down was a British medical doctor
who first observed children with a special kind of
mental disability and common physical characteristics
and published his findings in 1866.
In July 1958, Dr. Jerome Lejeune, while studying
chromosomes linked to Down syndrome, discovered
the existence of an additional chromosome on the 21st
pair. He therefore renamed the condition trisomy 21
to accurately describe the genetic abnormality.
For the first time Dr. Lejeune had established a link
between an intellectual disability and its genetic
cause.
GENETIC DISORDERS:
MUTATIONS ON A SINGLE GENE
AUTOSOMAL DOMINANT =
Mutation occurs in the dominant allele
(A*)Æ Both homozygous dominant
(A*A*) and heterozygous (AA*)
individuals are sick
Ex. Huntington’s disease
X-LINKED DOMINANT = Mutation
occurs in an allele on the X chromosome
(X*):
X*X* Æ homozygous female, sick
X*X Æ heterozygous female, sick
X*Y Æ male, sick
Ex. Rett syndrome
AUTOSOMAL RECESSIVE =
Mutation occurs in the recessive allele (a*)
Æ Homozygous recessive (a*a*) individual
is sick; heterozygous (Aa*) is carrier.
Ex. Albinism; sickle-cell anemia; cystic
fibrosis; Tay-Sachs syndrome.
X-LINKED RECESSIVE =
Mutation occurs in an allele on the X
chromosome (X*):
X*X* Æ homozygous female, sick
X*X Æ heterozygous female, carrier
X*Y Æ male, sick
Ex. Duchenne muscolar dystrophy; haemophilia;
color blindness (daltonism)
Y-LINKED = Mutation occurs in an allele on the Y chromosome
(Y*):
XY Æ healthy male
XY* Æ sick male
14
THE SICKLE-CELL ANEMIA
HbAHbS
HbAHbA
HbAHbS
HbAHbS
HbSHbS
The heterozygous HbAHbS shows an
advantage in case of malaria: Plasmodium
falciparum does not live in sickle cell,
therefore heterozygous individuals are not
affected by malaria.
15
ALBINISM Æ NOT ONLY A HUMAN CONDITION
Albinism (from Latin “Albus” = white) is caused by a genetic mutation of a gene coding for
an enzyme involved in the production of melanin in skin, eyes and hair.
16
COLOUR BLINDNESS (DALTONISM)
Colour blindness or colour vision deficiency is the inability or decreased ability to see
colours, or perceive colour differences, under normal lighting conditions.
The English chemist John Dalton published the first scientific paper on this subject in
1798, "Extraordinary facts relating to the vision of colours", after having become aware
of his own colour blindness.
Because of Dalton's work, the general condition has been called daltonism.
Vision is allowed by photoreceptors called cone cells
(active in normal daylight) and rod cells (active in low
light). Colour blindness is caused by mutations of genes
involved in colour vision which are present on the Xchromosome.
COLOUR BLINDNESS TEST
17
HAEMOPHILIA AND THE
ENGLISH ROYAL FAMILY
Haemophilia is caused by a mutation in the gene coding for the
clotting factor VIII. Such mutation causes problems during blood
clotting after injures.
Since this recessive gene is encoded on the X chromosome, males
can be healthy or sick; females can be carriers.
18
stemcells.nih.gov/info/Regenerative_Medicine/Pages/2006Chapter4.aspx
GENE THERAPY:
A SOLUTION FOR GENETIC DISEASES?
TASK-BASED ACTIVITY
Aim of the
activity
Each group elaborates a powerpoint presentation in which the
outstanding results on topics related to genetics are described and
presented it to the whole class.
Procedure
Students, in small groups, should choose one of the following topic and
elaborate a powerpoint presentation on:
9 Information about scientists such as Lejeune, Watson and Crick,
Flemming or others related to genetics or medicine
9 Description of a chromosomal or a genetic disorder
9 Recent discoveries on gene therapy
Students can find the above information by consulting science
textbooks, other books, internet.
Bibliography and sitography must be included in the presentation.
Language skills
Oral activity Æ speaking in small groups / with whole class
Written activity Æ powerpoint presentation
Use of content-specific language
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BIBLIOGRAPHY and SITOGRAPHY
Books and textbooks:
• Gateway to Science – Thompson Heinle
• Biology. Course companion – Allott and Mindorff- Oxford
• Science. Oxford content and language support – Kauser and O’Donoghue - Oxford
• Science – Keith Kelly – Macmillan Vocabulary Practice Series – Macmillan
• Biology for IB diploma – Standard and high level – Andrew Allott – Oxford
• Edexcel IGCSE Biology – Bradfield and Potter- Pearson
Websites
http://www.bbc.co.uk/schools/gcsebitesize/science/
http://www.cellsalive.com/cells/3dcell.htm
http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/cells
http://www.bbc.co.uk/scotland/learning/bitesize/standard/biology/investigating_cells/
cells_and_diffusion_rev2.shtml
http://www.cellsalive.com/cell_cycle.htm
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokine
sis.html
http://www.cellsalive.com/mitosis.htm
http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/celldivision/
http://www.cellsalive.com/puzzles/mitosis/index.html
http://science.education.nih.gov/supplements/nih1/cancer/activities/activity2_animatio
ns.htm
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https://wikispaces.psu.edu/display/bio110/Home