b1-l1, how do we vary? lo: what makes us all different? what are genes and what do they do? look at...

B1-L1, How do we vary?LO: What makes us all different?

What are genes and what do they do?

Look at the person next to you.

Name 5 things that are different about you

Now sort them into two boxes

Things we got or inherited

from our parents

Things that happened as we grew up or are changed

by the environment

Inherited or environmental variation?

OK: so how do you Inherit features?

See if you can explain the following facts:

1. 50% of what makes ‘you’ comes from your dad2. There is 50% chance of a child being male or female3. A child with one brown haired parent is more likely to

have brown hair than blond4. We may be able to choose what our children look like in

the future.

People are all very similar but still unique.

How does this happen?

All the information to make this baby came from

his parents.

Information from each parent is carried in their

sex cells.

All the information to develop a human being has to fit

inside the nucleus of a fertilized egg cell.

• There are about

30 000 pieces of

information in the

nucleus.

• Each piece of

information is called a

gene. And it tells the

body how to make

proteins

• Genes are joined up in

chains called

chromosomes.

Each chromosome in the nucleus contains thousands of genes.

Copy me:

• Inside a cell

• These are all the

chromosomes from

one human cell.

• 99.9% of the

information in any

fertilized egg is the

same.

• Only 0.1% of the

information they carry

makes this person

unique.

Most features are controlled by several genes and

are also affected by the environment, e.g. height.

Hair colour.

True of False

• Chromosomes are found in the nucleus.

• Sperm and egg cells have the same amount of information as other body cells.

• When we are adults our cells stop dividing.

• Everyone in this room in unique.

• Genes are joined up into chains called chromosomes.

• The environment we grow up in causes variation.

• Our genetic information causes variation.

• Only the environment and genetics causes variation.

1 in 25 people carry the faulty gene that causes

cystic fibrosis.

1. Name one inherited variation you have?

2. Name one environmental variation you have?

3. What p_____ is made by the instructions on our genes?

4. Why are we different from each other?

5. Match up the following letters and words: Chromosome GeneNucleus

Each chromosome in the nucleus contains thousands of genes.

A

B

C

B1-L2, How do we vary?LO: To know how sex cells are made and the numbers

of chromosomes involved.

• Sometimes genes are faulty.

• How many people in this photograph do you think

have no faulty genes?

• None?

• We all have some faulty genes.

A small number of faulty

genes cause diseases.

This person has cystic

fibrosis.

• Cystic fibrosis is the most common inherited

disease in the UK.

• It affects 1 in every 2500 people.

Growth vs. Gametes

Mitosis – Growth (asexual reproduction)

Meiosis – Gametes (sex cells)

50% of what makes ‘you’ comes from each parent

23 pairs = 46 chromosomes

In a woman each pair splits giving an egg cell

In an man each pair splits giving a sperm cell

Male body cell46 Chromosomes

Female body cell46 Chromosomes

Egg cell23 Chromosomes

Sperm cell23 Chromosomes

Baby cell46 Chromosomes50% Mum and 50% Dad

It’s true, Boys do have a little ‘y’ chromosome.

Practice Exam Questions

• For your progress folders

• EXAM CONDITIONS

1. chromosomes in a human body cell2. pair of chromosomes which controls what sex a person is 3. pair of sex chromosomes a woman has4. pair of sex chromosomes a man has5. chromosomes in a egg or sperm cell

B1-L3, Dominant and recessiveLO: To know how pairs of genes control features

23 46 XY 23rd XX

ALLELESDominant and Recessive

Dragons

Help! Only two dragons in the world are left. What might their children be like??

These things all depend on the combination of genes - alleles

Breaths fire?How many toes?Tail spikes?Colour?

q

Q

q

Q

e

E

e

E

D

d

D

d

L

l

L

l

A

a

A

a

M

m

M

m

t

T

t

T

Blue are daddy dragon genes and Yellow are mummy dragon genes.

Plenary – write a definition for these words

• Chromosome• Gene• Alleles• Dominant• Reccesive• Genotype• Phenotype

B1-L4, Punnett squares and Variation

LO: To know how pairs of genes control features

BB = Brown eyes and B is dominantbb = Blue eyesComplete these squares to show all the combinations of alleles

MUM = Brown eyes

B B

Dad

= B

lue

eyes b

b

MUM = Brown eyes

B b

Dad

= B

row

n e

yes

B

b

Eye colourIn eye colour the brown eye allele is dominant, so we call it B, and the blue eye is recessive, so we call it b:

bbBB Bb

Homozygous brown-eyed

parent

Heterozygous brown-eyed

parent

Blue-eyed parent

What would the offspring have?

B B

b

b

Another methodExample 1: A Homozygous brown-eyed father and a blue-eyed mother:

B B

b Bb Bb

b Bb Bb

Father

Mother

All offspring have brown eyes

B b

B

b

Another methodExample 2: Two heterozygous brown-eyed parents:

B b

BB Bb

b Bb bb

Father

Mother

25% chance of blue eyes

B b

b

b

Another methodExample 3: A heterozygous brown-eyed father and a blue-eyed mother:

B b

b Bb bb

b Bb bb

Father

Mother

GENETIC CROSSES

The inheritance of dimples

• A person with the genes DD will have dimples.

• A person with the genes dd will not have dimples.

• A person with the genes Dd will have dimples.

The inheritance of dimples• In a person with the

genes Dd only the effect of gene D shows.

• The effect of gene D dominates the effect of gene d.

• Gene D is dominant to gene d.

• Gene d is recessive to gene D.

D is the gene for dimples d is the gene for no dimples


Parents

DD ddBody cell in father with a pair of genes for dimples

Body cell in mother with a pair of genes for no dimples


Parents



Gametes


Parents



Gametes

D Deach sperm has a gene for dimples


Parents



Gametes


d deach ovum has a gene for no dimples


Parents



Gametes



At fertilization

There are 4 possible ways of joining a sperm to an ovum


Parents



Gametes



At fertilization

There are 4 possible ways of joining a sperm to an ovum D

D


Parents



Gametes



At fertilization

There are 4 possible ways of joining a sperm to an ovum D

D

d d


Parents



Gametes



At fertilization

There are 4 possible ways of joining a sperm to an ovum Dd Dd

Dd Dd

D

D

d d


Parents



Gametes



At fertilization

There are 4 possible ways of joining a sperm to an ovum Dd Dd

Dd Dd

D

D

d d

All the children of this generation have genotype Dd and phenotype - dimples

Parents

Dd Ddfather with dimples

mother with dimples

Gametes

At fertilization

What would happen in this example?

Parents

Dd Ddfather with dimples

mother with dimples

Gametes

D d D d

At fertilization

DD Dd

Dd dd

D

d

D d

A child who inherits the genes DD will have dimples

A child who inherits the genes Dd will have dimples

A child who inherits the genes dd will not have dimples

In this generation the ratio of dimpled children to non-dimpled will be 3 to 1

Answer:

DANGLY

ATTACHED

Continuous and Discrete variation?

• Helpful videos –

• Huntingtons 1

• 2

• 3

• 4

Produce a poster about

• Huntingtons pg 12

• Cystic fibrosis pg 16 and 17

• Jan – pg 19

• Rhys and SCID – pg 29

B1-L5, genetic diseasesLO: To know how disease can be inherited

True or false??

1. Xx is female2. BB is brown eyes3. Bb is blue eyes4. There are 23 chromosomes in a body cell5. Chromosomes are part of a gene6. Alleles are types of gene7. Dd + Dd means a 50% chance of DD8. Testosterone is a hormone that decides if you will be a

boy

write a definition for these words

• Genotype

• Phenotype

what are proteins used for???

Genetic diseases• Can anyone name a genetic disease?

Trait

Chromosome for Gene

Location

GenotypeRecessive or

dominant

skin cancer 1 Cc or CC D

cystic fibrosis 7 qq R

albinism 11 aa R

Breast cancer 17 Nn or NN D

Muscular Dystrophy

X sex chromos

ome

Mm or MM (girls only)

D

Huntingtons 4 Hh or HH D

Down’s Syndrome

Extra copy of 21

HUNTINGTON’S DISORDER

1. Huntingtons disease is a dominant one.

2. Do 4 genetic crosses to determine the chance of these couples having children with Huntington’s disorder:

a. Hh x hh b. HH x hh

c. HH x Hh d. Hh x Hh

CYSTIC FIBROSIS

1. Cystic fibrosis is a recessive one.

2. Do 3 genetic crosses to determine the chance of these couples having children with Cystic fibrosis:

a. Ff x ff b. Ff x Ff

c. FF x Ff

• Cystic fibrosis 1

• 2

• 3

WS Huntington’s and Cystic fibrosis

Now what??

• You know you both carry the recessive gene?

• What would you do??

Genetic testingIt is now possible to test individuals before they are born for any faulty alleles. There are two main methods:

1) Amniocentesis testing:

- Done at 14-16 weeks

- 0.5% chance of miscarriage

(5 in 1000)

- Small chance of infection

Genetic testingIt is now possible to test individuals before they are born for any faulty alleles. There are two main methods:

2) Maternal serum screening:

- Blood test of mother

- 0% chance of miscarriage

- Does not give precise results

-High or Low risk of having a poorly baby . . .

DIFFERENT IDEAS ABOUT GENETIC SCREENING FOR CYSTIC FIBROSIS

Read pages 22-23 to find out what genetic screening is.

Which opinion do you agree with?

It is very dangerous.

People should not have to worry

about this information.

There’s nothing wrong in having

an ill child.

What if my husband and I both had the

faulty allele? Would we have children?

I want to choose my medical

treatment – not have any forced

on me!

We should give people all the

information we can about their health.

Then they can make an informed

decision.

For some causes ofinfertility, IVF provides awonderful opportunity

The financial and emotional conflicts that arise out of IVF can put huge strains on a relationship

Any society where people can afford IVF will be one where overpopulation will not…

• Exam question!

You can have IVF treatment to make sure your next baby doesn’t have

cystic fibrosis

What should we

do, Doctor?

Decision 1

How do you make an ethical

decision?

Imagine you are one of the Simpletons.You have been asked about IVF.

How will you respond?

My approach to ethical dilemmas:

Weigh up the benefits and costs and choose the

option that makes most people happy.

This is the ‘utilitarian approach’

My approach to ethical decisions: Before I do anything, I make sure it does

not violate other people’s rights.

This is rights-based thinking

My approach to ethical decisions:

Be caring and compassionate about people and

relationships.

This is care-based thinking

My approach to ethical decisions:

I simply choose the option that turns out best

for me.

This is self-centred thinking

What are the

problems (cons) of

doing this?

What are the benefits

(pros) of doing this?

Who is affected?

Utilitarian

What must I decide about?

Conclusion

My approach to ethical decisions: Weigh up the benefits and costs and choose the

option that makes most people happy.

Will the decision violate

(go against) any rights?

How?

What rights do we want to protect?

(e.g. choice, freedom, life)

Who is affected?

Rights-based

Conclusion


My approach to ethical decisions: Before I do anything, I make sure it does not

violate other people’s rights.

How will doing this make their life worse?

How will doing this make their life better?

Who is affected?

Care-based

Conclusion


My approach to ethical decisions: Be caring and compassionate about

people and relationships.

How important is this to me?

Is this a good thing for me or a bad thing for me?

Who is affected?

Self-centred

Conclusion


My approach to ethical decisions: Simply choose the option that turns

out best for me.

Exam question starter

CAN YOU CHOOSE YOUR CHILD?

Define the following words:

1. embryo2. implantation3. in vitro fertilisation4. pre-implantation genetic diagnosis

GENE THERAPY

Read page 28-29 :

Questions 1-5

And write the definitions for the following words

Gene therapyGenetic modification

GENE THERAPY

Gene therapy – a treatment where a normal gene is put into cells of someone with a genetic disorder.Genetic modification – the changing of an organism’s genes. In gene therapy this is by the addition of normal genes.

How many things could you use a

clone for?

Asexual reproduction in cells

Each daughter cell has the same number of chromosomes and

genetic information as the parent.

Natural clones

How to clone

A plant

An animal

Cloning Animals

Host mother

Clone

• Should we try to develop cloning technology?

• Should we change faulty genes? (gene therapy, pre-

implantation genetic diagnosis, genetic modification)

• How can we go about making this type

of decision?

Stem cell researchStem cells are cells that have not yet specialised:

Egg and

sperm

Embryo

Cloned embryo

s

These stem cells have the potential to develop into any kind of cell. The rest of the embryo is destroyed. Most of these embryos come from unused IVF treatments.

The ethical issue:

Should these embryos be treated as humans?

Making decisionsSome questions cannot be answered by science and need to be considered on ethical grounds.

Factors that might influence a decision:

• Beliefs/religion

• What does “the right thing” mean?

• “Playing God”

• Risks – acceptable or unacceptable?

• Social and economic contexts

Draw a cartoon to show the cloning process.

include science diagrams too!

Fill in the G A P SClones of ________ can occur when an embryo splits up

naturally.

Embryonic ________ cells are _____________ cells that can

grow into any type of cell.

These cells can be grown from ________ left over from ________

treatments.

Embryonic stem cells may be useful in the future for treating

_________.

animals embryos illnesses IVF stem unspecialised

should we be able to clone embryos?

Cloning with cuttingsTo doFill a small pot with compost.Cut the stem about 10 cm from the tip. Cut just below a leaf at an angle. Don’t cut straight across.

Take off the leaves at the bottom of your cutting.Dip the cut end in rooting powder if you have some.Put the cutting in your compost. Push it in gently until the compost is just below the bottom leaf.Label your pot with your name and the date.

Put a plastic bag loosely over your plant.In a few weeks your plants will have grown roots.