Download File

Lesson Sequence
Lesson
Title
1
What do your genes do / variation
2
3
4
Alleles
Genetic Crosses
Inherited Disorders
5
Preparing for Assessment / APP
6
7
8
Genetic testing / ethics
Cloning
Stem Cells
9
Controlled Assessment Practice
10
Exam paper
Resources needed:
• Comic strip sheet photocopied onto
A3 X class set
Julien
Tamara
Jamal
Vivian
Said
Jija
Remick
Muna
Chad
Moesha
Dylan
Jorge
Emma
Salmon
Mohamed
James
Katia
Bukhari
Siratillah
Mina
Denzil
Kade
Saacid
Makayla
Shannon
Abdul
Roberta
Rui Dong
Board
mardi 23 mai 2017
Tuesday, 23 May 2017
martes, 23 de mayo de 2017
Genes and Chromosomes
Level
Objective
Outcome
E/D
Match offspring to parents
using features
Describe what a gene is
Match up the Simpsons characters with their family, describing
how you have done it.
Draw a picture to show what a gene is.
C/B
Explain what a gene is and
where in the body they are
Label the diagram of a gene and explain its relationship to
DNA and chromosomes.
A/A*
Justify whether genes or
upbringing is more important
in determining characteristics
Define genotype and phenotype.
Answered questions on variation in twins.
Starter: Complete the genetic
jargon worksheet by matching
up the keyword to its
definition.
Keywords
Genes,
chromosomes, DNA,
varaition, inheritance
Genetic jargon
What has caused these features?
To do now:
Make a list of features
controlled by genes. Make a
list of features controlled by
the environment. Circle any
that appear on both of your
lists.
Inherited variation is of 2 types:
Continuous and discontinuous variation
Discontinuous variation
has distinct groups.
Some examples of
discontinuous variation
are :
tongue rolling
Continuous variation
doesn't have 2 distinct
groups
Some examples of
continuous variation are :
height
blood
groups
heart rate
weight
finger prints
Continuous variation
• Sometimes, several genes work together
to determine a feature.
An example is human
eye colour. There is a
wide range of
possible outcomes
and this is called
continuous variation.
Continuous variation
• Continuously varying genetic outcomes
may also be affected by environmental
factors e.g. milk yield in cows.
To do now:
Explain, using ideas about
continuous variation, why
the average human male
height in the UK has
increased in the last
century from 166cm to
175cm.
Nature versus nuture
The genetic makeup of an individual organism is called the genotype.
The physical characteristics that an individual displays are called the
phenotype.
To do now:
Explain why identical twins (who share the same genotype) might have
different phenotypes.
The disease phenylketonuria (PKU), which is a genetic disorder that
causes the amino acid phenylalanine to build up in the blood. Infants are
tested for PKU very early because the mental retardation it causes if
untreated can be avoided with a special diet.
Explain whether the cause and effects of this disease are genetic or
environmental. Try to use ideas about genotype and phenotype in your
answer.
Twin studies
Twin studies help us learn how much variation is
______________ and how much is due to the
______________ .
Identical twins are genetically ______________ , so any
differences between them must be due to the environment.
Non-identical twins are genetically ______________ but they
grew up in the same surroundings. Similarities between nonidentical twins are probably due to the ______________ .
Explain why identical twins share all their genetic information
but fraternal twins do not.
Where does the information come
from?
Making a sperm CELL
Father Cell
How many
Chromosomes?
23/05/2017
Father Sperm
How many
Chromosomes?
Making an egg CELL
Mother Cell
How many
Chromosomes?
23/05/2017
Egg Cell
How many
Chromosomes?
Different versions of genes
Chromosomes in a pair contain the same type of genes that code for
the same characteristics, such as eye colour.
Each chromosome in the
pair, however, may have a
different version of the
gene e.g. one for blue
eyes and one for brown
eyes.
allele for
brown
eyes
Each different version of a gene is called an allele.
allele for
blue
eyes
• There are two types of alleles (different
versions of a gene for the same characteristic).
• One is homozygous alleles
• The other is heterozygous alleles
• Zygous means from the zygote – when the egg
and sperm cells meet and join.
Homozygous alleles
If the alleles for a characteristic in a pair are the same, the organism is
said to be homozygous for that characteristic.
What colour eyes will these homozygous pairs of alleles produce?
allele for
brown eyes
allele for
brown eyes
allele for
blue eyes
allele for
blue eyes
Heterozygous alleles
If the alleles for a characteristic in a pair are different, the organism is
said to be heterozygous for that characteristic.
What colour eyes will this heterozygous pair of alleles produce?
?
allele for
brown eyes
allele for
blue eyes
The characteristic expressed by
heterozygous alleles will depend
on which allele is dominant and
which allele is recessive.
Task:
• What is an allele?
• What is a homozygous allele? Can you give an example?
• What is a heterozygous allele? Can you give an example?
Dominant or recessive?
The phenotype for a particular characteristic depends on
which allele is dominant and which allele is recessive.
 Dominant alleles are always expressed in a cell’s
phenotype. Only one copy of the dominant allele needs
to be inherited in order for it to be expressed. Dominant
alleles (e.g. brown eyes) are represented by an upper
case letter (e.g. ‘B’).
 Recessive alleles are only expressed in a cell’s
phenotype if two copies of it are present. If only one
copy is present, its effect is ‘masked’ by the dominant
allele. Recessive alleles (e.g. blue eyes) are
represented by a lower case letter (e.g. ‘b’).
Task:
• What is the difference between a dominant and recessive
allele?
• Which is the dominant allele in the following pairs: Bb, BB, Hh,
rR, rr?
How have we done today?
Level
Objective
Outcome
E/D
Match offspring to parents
using features
Describe what a gene is
Match up the Simpsons characters with their family, describing
how you have done it.
Draw a picture to show what a gene is.
C/B
Explain what a gene is and
where in the body they are
Label the diagram of a gene and explain its relationship to
DNA and chromosomes.
A/A*
Justify whether genes or
upbringing is more important
in determining characteristics
Define genotype and phenotype.
Answered questions on variation in twins.
Pack away and get ready for the hot seat quiz…
• phenotype
• Allele
• Dominant
• Identical twins
• Heterozygous allele
Which features are inherited?