An Introduction to Genetics

Developmental Learning Style!I “sensimotors” are

going to begin.

Lesson #1: Basic Genetics

• Keep track of your answers.

• Good luck.• Ready?• NOTE: light blue

underlined text leads to a Hyperlink. Click for more information or the option you desire.

Let’s ring the bell to start.

Genetics: study of how inheritable characteristics are passed from one generation to

another.

Genetic information (genes) are located in our chromosomes. Chromosomes are made up of

deoxyribonucleic acid (DNA).

DNA contains codes for organisms to make PROTEINS, which are essential for the body to

function properly.

General Background Information:

• Let’s start learning!• Question: How many chromosomes do humans

have?• A) 23• B) 36• C) 46• D) 50• Answer: C. Humans have 46 chromosomes. If

you were right, good job! If you were wrong, don’t forget this number.

• Remember genes are located in ?• Chromosomes!• The genetic information is DNA.• How many chromosomes do we have?• 46!• How many?• 46• Genetics passes characteristics from

generation to generation.

• Characteristics describes an observable feature that can appear in more than one form.

• Trait is a variation of a characteristic. • Soda Analogy: • A soda drink is like a characteristic (type of

drink). • A trait would be a variation of that characteristic

like Sprite, Coke, or Pepsi.

• Humans have different traits for the same characteristic.

• For example, eye colour is a characteristic. • A trait for eye colour could be:• Brown or blue etc. • You may have even heard of a case of two

parents with brown eyes having a blue eye child.

• Some other people, like actress Kate Bosworth, have two different eye colours!

• Purebred: all the parents and offspring have the same single TRAIT.

• Hybrid: when you mate two purebreeds with different traits.

• Soda Analogy:• Mix Coke with Coke = still a purebred Coke• Mix Coke with Sprite = Swamp soda! A hybrid

• If parents with purebred brown eyes mate, all their offspring would have?

• Brown eyes!

• How did Kate Bosworth get two different eye colours?

• Maybe she got one trait from mom and the other trait from dad.

• (Note: Unfortunately, eye colour does not work that simply, but this example still shows the difference between purebreeds and hybrids.)

We wonder what would happen if Kate Bosworth and David Bowie had children?

• 1) What if you mated a purebreed purple flower with a purebreed purple flower? What colour would all of the offspring look like?

• A) Purple?• B) White?• C) Light Purple?• The correct answer is PURPLE. Good for you if you’re right! If

not, you better start paying closer attention. • What would the characteristic be?• Flower colour.• What would the traits be?• Purple OR White

• 2) What if you mated a purebreed white flower with a purebreed white flower? What colour would all of the offspring look like?

• A) Purple?• B) White?• C) Light Purple?• The correct answer is WHITE. That should have

been obvious.• Characteristics are still flower colour.• Traits are still purple OR white.

• 3) What if you mated a purebreed purple flower with a purebreed white flower? What colour would all of the offspring look like?

• A) Purple?• B) White?• C) Light Purple?• The correct answer is PURPLE. Huh?

Note the offspring is a HYBRID.

Make a selection before continuing:

• A If you think you have a good grasp on the differences between characteristics/traits/purebreed/hybrid, good work and skip ahead.

• B If you have no idea what we are talking about still, continue on with the tutorial.

• 1) What if you mated a purebreed tall plant with a purebreed short plant? What the offspring look like?

• A) Tall?• B) Short?• C) In between height?• The correct answer is TALL. • Characteristics?• Height of the plant.• Traits?• Tall or short.

• 2) What if you mated a purebreed short plant with a purebreed short plant? What would the offspring look like?

• A) Tall?• B) Short?• C) In between height?• The correct answer is SHORT. Great

work if you are getting all this so far!

• 3) What if you mated a purebreed tall plant with a purebreed short plant? What would the offspring look like?

• A) Tall?• B) Short?• C) In between?• The answer is TALL. This offspring is a

HYBRID. Not getting it yet?

• Summary:• The slides 4-16 use patterns of behaviorist theories and

developmental learning theories.• Behaviourism: The exercise uses repetition as a way for the

learner to be exposed to the material. Notice the straight-forward acquisition of language. The terms were presented in a list and in a repetitive manner.

• Piaget: Testing to see what would happen in certain mating scenarios.

• Vygotsky & Bruner: Building on pre-existing knowledge in the use of the soda analogy.

• The exercises were fairly simple and not entirely interactive.

• We need some more definitions:• A Trait can be DOMINANT or RECESSIVE• Dominant: this is trait that appears even in a hybrid.• Recessive: the trait that is not expressed in a hybrid.

The trait is not visible if paired with a dominant trait.• Soda analogy:• When mixing Coke with Sprite, Coke dominates over

Sprite in terms of colour.

• Brown eye colour is dominant over blue.

• We have already seen:• Purebred purple x purebred white = hybrid• All the hybrids are PURPLE. • Purple is dominant and it is the trait expressed in a

hybrid. • WHITE trait is hidden, therefore it is recessive.

• Soda Analogy:• Mixing Coke with Sprite gives a lighter coloured drink.

This does not happen in genetics. The Coke/Sprite hybrid would look completely like Coke.

Make a selection before continuing:

• A If you think you have a good grasp on the differences between dominant and recessive, good work and skip ahead.

• B If you have no idea what we are talking about still, continue on with the tutorial.

• Last set of questions: If brown eyes are a dominant trait and blue eyes are a recessive trait:

• The characteristics?• Eye colour• The traits?• Brown or blue colour.• The purebred dominant has: • Brown eyes• The purebred recessive has: • Blue eyes• The hybrid has:• Brown eyes

Start of next lesson:

• Keep in mind what you have learned thus far.

• Were you able to follow the terms?

• Do you have a mastery of basic genetic concepts?

• What were the deficiencies of the previous lesson?

Time to get in the “zone”.

Make a selection before continuing:

• A If you know your genetics, feel free to skip ahead to try out some simple Punnett square problems.

• B If you have no idea what we are talking about, continue on with the tutorial.

• Genetics passes characteristics from generation to generation. All organisms have DNA information, which is needed for life.

• Question: Who gave us our genetic material?• Answer: Your mother and father.• If we have 46 chromosomes, how many chromosomes did

each of your parents give you? • 23 chromosomes from each parent for a total of 46. • That is the basis of sexual reproduction (genetics style).• Your genes come in pairs (one from mom and one from

dad).

• Each possible version of a gene is called an ALLELE (fancy way of saying trait).

• For example: • A purebred brown eyed mother has TWO alleles

for eye colour:• One brown allele + one brown allele• A dominant allele is written with a capital letter

like “B”.

• What if a father is purebred blue eyes?

• His two alleles are?• A blue allele and a blue allele.• We represent a recessive allele with a lower case

letter “b”.

• What happens when these parents mate?

• MATING OF TWO PUREBREEDS

• The mother has BB. The father has bb.• Each parent can pass ONE allele (trait) and every

human needs TWO alleles to express a specific trait.

• Mother can pass “B” or “B”.• Father can pass “b” or “b”.• That means a hybrid is formed:

Bb = brown eyes

A Punnett square is used in genetics to figure out the probability of what the offspring will look like.

• Use the following link to verify that two purebreeds produce a hybrid

• Also note: The hybrid shows the DOMINANT trait not the recessive one.

• Don’t worry about all the terminology on the page. • Just look at the squares

Punnet square with pea plants.

• Before we start predicting offspring and using Punnett squares, we need to look at our last terminology.

• If you notice you can have two types of purebreeds: BB or bb

• The scientific words for purebreeds are:• Homozygous DOMINANT = BB• Homozygous RECESSIVE = bb• For our hybrid (a mix of two alleles) = Bb• Heterozygous = Bb = hybrid

• BB, Bb, bb = These letter combinations are called GENOTYPES

• The genotypes tell us the PHysical expressions which we call PHenotypes

• Soda Analogy:• Coke is made up of chemicals (genotype)

that produce its taste and look (phenotype).

Trait Genotype Phenotype

Purebreed

Homozygous dominant

BB brown eyes

Hybrid:

Heterozygous

Bb brown eyesNote: two possible alleles from this parent: B or b

Purebreed:

Homozygous recessive

bb blue eyes

• Let’s try some practice questions:• First read this website page, then click “

Practice Quiz” at the bottom of the page.

Let’s go a bit further:

• Try some of these problems on your own.

• Review gametes (alleles)• Try the Test Cross and Monohyb

rid review (if you are feel like you have mastery try the DIHYBRID cross)

• This last link is OPTIONAL. It is a difficult site with some terms you haven’t seen, but it includes a nice tutorial.

Socially I feel good about

myself.

• Summary: Slides 18-33• We purposely slowly phased out the repetition

(behaviorism).• Piaget: There are small examples of the four stages of

development• Sensorimotor skills: following the links and points• Preoperational: anticipating the results of the mating• Concrete: performing Punnett squares to see probability• Formal operations: The harder quizzes at the end is

asking you to develop new knowledge

• Vygotsky Summary:• There was a need to develop the genetic language in order to

“play”.• Play was developed using Punnett squares.• Scaffolding was presented through the use of the soda analogy.• The more difficult genetics terminology raised the learner into a

zone of proximal development.• We purposely increased the level of difficulty in the last portion of

slides.• The website links allowed for computer interaction, but social

collaboration is key part missing through the exercise.

• Bruner Summary:• By laying out the material in small categories and building

upon pre-existing knowledge (the genetic terms presented earlier), hopefully the learner was able to access the more difficult genetic material.

• The use of analogy allowed to organize information and compare existing schema.

• Seeing a real-life example (Kate Bosworth) allowed integretion with previous knowledge (scaffolding again).

• Quizzes were able to lead the viewer and allow for correction.

• Questions:• Did you have difficulty doing some of the problems

without knowing all of the language that geneticists use, such as gametes, Punnett square and F1 generation?

• What about the lack of connection of the genetics concept with sexual reproduction and meiosis? Did you find it difficult not knowing why/how parents give one allele up?

• How would face to face interaction impact your learning of genetic concepts?

References

Science Foundations 10, 2004 Edvantage Press Lt., Victoria, British Columbia, Canada