Instructional presentation on basic concepts in genetics, (definitions, examples and explanations)

1. Bio101: An Introduction
to Human Genetics
Instructional Presentation
Adam Wasilko
Amnah Albuloushi
Michaela Noakes

2. Genetics: The Basics
• The science of biological inheritance
• The study of heredity, how traits are
passed on from one generation to
another, and what makes each species
unique

3. What traits do you share with your:
• parents?
• Grandparents?
• Siblings?

4. The discovery of genetics
– Gregor Mendel
– Austrian monk
– The ‘father of genetics’
– Famous experiments with pea
plants

5. Hereditary Genetics

6. Pea Plants?
– What might make this a good plant to study?

7. Main reasons:
• Presence of observable traits with contrasting
forms
• Produces many offspring in one cross
• Short life cycle
• Ease in manipulating pollination (can easily cross
pollinate)

8. • Mendel used true-breeding plants which
means if they were left to breed with
themselves they would produce offspring
identical to themselves.
• Mendel studied 7 different traits in pea
plants.
• A trait is a specific characteristic that
varies from one individual to another.

9. The language of genetics
Gene:
A segment of a chromosome that
produces a particular trait.

10. • Each trait is produced by a pair of hereditary
factors collectively know as GENES.
• Within a chromosome, there are many genes,
each of which controls the inheritance of a
particular trait.
• A gene is a segment of a chromosome that
produces a particular trait.
• As we discussed, in pea plants, there’s a gene on
the chromosome that holds the code for seed
coat color

11. Alleles
A pair of hereditary factors that
make up a gene
or
(different forms of a gene)

12. • A gene usually consists of a pair of
hereditary factors called alleles.
• Each organism carries two alleles for a
particular trait, one from the mother and
one from the father.
• Another way to say this is that two
alleles make up a gene, which in turn
produces a particular trait.

13. • Dominant Allele
• A hereditary factor that “takes over” the gene
determining the trait
• Recessive Allele
• A hereditary factor that is hidden by a dominant allele
• A genetics ‘boxing match’
• The ‘winner’ gets to express
their trait

14. • some alleles are dominant and others are
recessive.
• Dominant alleles are always expressed.
• Recessive alleles are only expressed if both
alleles are recessive.

15. • an allele can be DOMINANT or RECESSIVE.
• A Dominant allele – ‘wins’.
• Written with an UPPERCASE letter. T, B, N
• A Recessive allele – hidden by the dominant.
Written with a lowercase letter. t,b,n

16. • Homozygous
Two identical alleles for a particular trait.
BB or b
(blue eye, blue eye)
(brown eye, brown eye)
• Heterozygous
Two different alleles for a particular trait.
Bb
(brown eye, blue eye)

17. • Genotype
•The genetic makeup of an organism
due to the genes present
•The biological coding that expressed
your eye color, hair color, etc.

18. • Phenotype
The actual trait that is expressed by your genes
such as hair color or eye color

19. Parent vs. filial generation
• The first generation is always called the
parent or P1 GENERATION.
• The offspring of the P1 generation are called
the first filial or F1 generation.
• The offspring of the F1 generation are called
the F2 generation.

20. How can we predict outcomes?
• Punnett Squares used to predict genetic
crosses.
• Make a two by two box, fill in known
information and “cross” them

21. • Here we will cross two heterozygous traits, tT
and tT
• Which trait will be expressed in each of the
four scenarios?
• What is most likely to happen?

22. • These can be very complicated, or simple,
depending on what you are trying to predict
• Back to Mendel and the peas:

23. Mendel’s Laws
• Over many generations Mendel was able to observe
some things that always happened!
Here is what he said:
• The inheritance of biological characteristics are
determined by genes.
• For two or more forms of a gene, dominance and
recessive forms may exist.
• Most sexually reproductive organisms have two sets of
genes that separate during gamete formation.
• Alleles segregate independently.

24. It’s not always that easy!
• Codominance – Both alleles contribute to the
phenotype. Red cow X White Cow = Roan
Cow.

25. • Incomplete Dominance – One allele is not
completely dominant over the other. White
flower crosses with a red = pink flower.

26. • Multiple Alleles – More than two alleles
control the phenotype. Coat color of rabbits.

27. • Polygenic traits – Several genes control the
trait. Skin color in humans.

28. Research Assignment
• Now that we know some basics of genetics,
we can apply them to real world situations.
• Many common diseases are classified as
genetic diseases, meaning they are passed on
through family lines

29. • 22q11.2 deletion syndrome
• Angelman syndrome
• Canavan disease
• Celiac disease
• Charcot-Marie-Tooth disease
• Color blindness
• Cri du chat
• Cystic fibrosis
• Down syndrome
• Duchenne muscular dystrophy
• Haemochromatosis
• Haemophilia
• Klinefelter's syndrome
• Neurofibromatosis
• Phenylketonuria
• Polycystic kidney disease
• Prader-Willi syndrome
• Sickle-cell disease
• Tay-Sachs disease
• Turner syndrome

30. Wiki Assignment
• Form groups of 3
• Using the blackboard wiki tool write a wiki
based on the genetic disease of your group’s
choice
• Include
– background information,
– what type is it (dominant, sex linked, recessive)
– Treatment and detection of the disease
– Current research on the disease

31. Supplemental Material
• Go through the flashcards a few times
• Become familiar with the vocabulary of
genetics
• This will be our “language” for the whole
semester!
http://www.flashcardexchange.com/flashcar
ds/view/1555508)