b1-l1, how do we vary? lo: what makes us all different? what are genes and what do they do? look at...
TRANSCRIPT
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?
Inherited or environmental variation?
Inherited or environmental variation?
Inherited or environmental variation?
Inherited or environmental variation?
Inherited or environmental variation?
Inherited or environmental variation?
Inherited or environmental variation?
Inherited or environmental variation?
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
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
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
Gametes
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
Gametes
D Deach sperm has a gene for dimples
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
Gametes
D Deach sperm has a gene for dimples
d deach ovum has a gene for no dimples
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
Gametes
D Deach sperm has a gene for dimples
d deach ovum has a gene for no dimples
At fertilization
There are 4 possible ways of joining a sperm to an ovum
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
Gametes
D Deach sperm has a gene for dimples
d deach ovum has a gene for no dimples
At fertilization
There are 4 possible ways of joining a sperm to an ovum D
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
Gametes
D Deach sperm has a gene for dimples
d deach ovum has a gene for no dimples
At fertilization
There are 4 possible ways of joining a sperm to an ovum D
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
Gametes
D Deach sperm has a gene for dimples
d deach ovum has a gene for no dimples
At fertilization
There are 4 possible ways of joining a sperm to an ovum D
D
d 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
Gametes
D Deach sperm has a gene for dimples
d deach ovum has a gene for no dimples
At fertilization
There are 4 possible ways of joining a sperm to an ovum Dd Dd
Dd Dd
D
D
d 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
Gametes
D Deach sperm has a gene for dimples
d deach ovum has a gene for no dimples
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
What must I decide about?
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
What must I decide about?
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
What must I decide about?
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.