Chapter 2Getting into the Genes

Learning Intensions • You will describe DNA and its role as the

blueprint for controlling the characteristics of organisms

• You will iIdentify the different types of Chromosomes and understand their role in genetics

• You will use inquiry skills to perform an experiments on working with DNA

2.1 Patterns,order and organisation:

nuclear matters pg. 50

Class Discussion and Title Page

Your Group Quest

Complete Think, Share and Discuss pg. 49Q 1 to 4 and 5

How can this be?

Black and white twins again.

Saturday, January 24th, 2009. The two-tone miracle repeated after

7 years for the mixed-race couple Dean Durrant and Alison.

When the first set of twins arrived in 2001, the couple were astonished to see that Lauren took after her white mum, with blue eyes and red hair, while Hayleigh had black skin and hair like dad Dean.

Then this year Alison, 27, found she was expecting again — and lightning struck twice.

She had twin girls again. And little Miya was born with dark skin like her dad and Leah is white like former recruitment consultant Alison.

Nigerian Family Gave Birth To White Girl With Blue Eyes

Monday, July 26, 2010, 10:28

British black family gave birth to a baby girl with white skin, blue eyes and fair hair. Doctors say that the newly born is not an albino. The family had three children who, like their parents, have black skin.

Gene experts can’t explain how Nigerian couple could give birth to a European looking child.

Brain Sacks from the Oxford University says that the birth is extraordinary. Giving birth to such child should mean any white ancestors of the parents. But Ben and Angela Ihegboro claim they don’t remember any relatives who even remotely looked like whites.

Think, Share and Discuss1. Record any patterns.2. If second generation had

another child, suggest what eye colour they may be and give a reason.

3.Suggest a reason why second generation had brown and blue eyed children.

4. Suggest a reasons why Third generation had only blue eyed children.

5. if the female in Fourth generation married a man also with blue eyes, what colour eyes could their children have?

Genes are located in all our cells. How complex are our cells?

Have you ever wondered what we are all made of?

Game – DNA Challenge Use Worksheet to complete A to Z.

Deoxyribonucleic acid

• How many words can you make out of this word.

• 4 mins INDIVIUALLY GO..................

• Prize for top 3 students with most words – Lollies

Cell Nucleus Chromosome Gene DNA

DNA – deoxyribonucleic acid

Molecule Found in nucleusGenetic code passed

on through generations

Makes your features / traits eg. Ear lobes / widows peak

DNA

Genes

Each set (group of DNA) that code for a trait / feature eg. Eye colour, longer second toe = GENE

Many genes make a larger structure ………

…..the chromosome

Chromosomes are a long, continuous pieces of DNA (groups of genes), found in the nucleus of our cells.

Chromatid is one of the two identical parts of the chromosome.

Centromere is the point where the two chromatids touch

Short arm and the long arm

Pairs - Copy the following diagram and label

• Each pair of chromosomes contain one chromosome from your father and one from your mother.

• This is how you get a mixture of genes, therefore characteristics from both parents.

Chromosome pair number

1

Chromosome

ChromatidChromatid

A pair

Gene Gene

Read only - Your eyes are green

But his are grey and mine are brown.

This is all caused by how the DNA is structured to make the gene.

Green eyes??? Hazel eyes??? The eye color is given by the amount of melanin (same pigment as for hair and skin). The higher the melanin, the darker the eye color, and vice-versa. Green and Hazel linked with Brown eyes – Brown eyes can have many shades of colour.Blue eyes only have blue.

Video

Write these questions leaving a couple of lines and answer them using the following

slides• 1.How many chromosomes do humans contain?• 2.How many pairs do we contain?• 3.What is pair number 23 called? Why?• 4. What do we call all the other normal chromosomes pair no. 1 to 22?• 5. What sex chromosomes would i) maleii) Females have?• 6. Define Karyotype• 7. Define Homologous chromosome• 8. Define Non-homologous chromosome• 9. Define mitosis?• 10. Define gamete cells?• 11. Define somatic cells?• 12. How many chromosomes are in an egg?• 13. How many chromosomes are in the sperm?• 14. Why do gametes or sex cells (egg an sperm) only contain 23 single

chromosomes not 46 like all the other normal cells in the body?

Chromosome Number

Humans have 23 pairs of chromosomes or 46 individual chromosomes in every normal cell.

Chromosomes can be placed in pairs from largest to smallest.

Autosomes – all the normal chromosomes pair no. 1 to 22.

Sex Chromosomes – pair no. 23 – determines your gender

Female = XXMale = XYKaryotype -the no. and appearance of chromosomes in the cells nucleus.

Autosomes

• Homologous = matching /

same pairs of chromosomes

• eg. chromosome 1 and 1• Each pair same size, same

banding pattern and contain same genes for traits, 1 from mum and 1 from dad

• Non-homologous = non matching chromosomes eg.chromosome 21 and 3

Mum Dad

Table 1: Examples of chromosome numbers

(diploid).•Species

# of chromosomes

Species # of

chromosomes

Fruit fly 8 Human 46

Rye 14 Ape 48

Guinea Pig 16 Sheep 54

Dove 16 Horse 66

edible snail 24 Chicken 78

Earthworm 32 Carp 104

Pig 40 Butterflies ~380

Wheat 42 Fern ~1200

STOP • Circle each chromosome pair (its matching chromosome with the same size and pattern), number each biggest being number 1,down to smallest being number 22 and with sex chromosomes at the end being number 23. If time you could cut and paste in order as shown. See picture here for example.

• Determine the gender.

Activity – See Karyotype Normal worksheet.

Investigation 2.1

• Alternative Practical to pg. 53

• Extracting DNA from Strawberries.

• Refer instructions sheet.

Working with DNA

Textbook Exercises pg. 54

Remember questions:1.(a to k), 2, 3, 4, 5 (a, b, c, d, g)* 6 all