This lesson is being recorded

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This lesson is
being recorded

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STARTER
What is the difference between dihybrid inheritance and monohybrid inheritance?

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For today’s biology lesson, you need to be:
Ready to think
Ready to discuss
thoughts and ideas
Ready to complete
activities
This Photo by Unknown Author is licensed under CC BY
This Photo by Uknown Author is licensed under CC BY-SANC
ALWAYS have the tools you may need:
writing equipment i.e. pens, pencils, ruler etc; lined, plain and
graph paper and a calculator

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Previous knowledge
to build on
• Genetics
• DNA and RNA structure
• Protein synthesis
• Alleles and genes

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Useful words
for this week
• Locus
• Gene
• Allele
• Inheritance
• Polygenic
• Phenotype and genotype

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Week 17 BIO UK Explore – Cell Differentiation, Gene
Interactions & Controlling Gene Expression
Textbook Ref: page 126 – 139

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Learning Objectives
3.8 i) Know that a locus (plural = loci) is the location of genes on a
chromosome. ii) Understand the linkage of genes on a chromosome and
sex linkage. (Highlighted part covered in week 10; rest this week)
3.12 understand how cells become specialised through differential gene
expression, producing active mRNA, leading to the synthesis of proteins
which, in turn, control cell processes or determine cell structure in animals
and plants, including the Lac operon
3.15 understand how some phenotypes are affected by multiple alleles for
the same gene at many loci (polygenic inheritance), as well as the
environment, and how this can give rise to phenotypes that show
continuous variation
RECOMMENDED ADDITIONAL PRACTICAL AP6 Investigate factors
affecting the growth of pollen tubes

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Locus, Dominant, Recessive,
Heterozygous Recap

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Questions to think about…..
1. What are linked genes?
2. How are they inherited?
3. Can anything change how they are inherited?

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Consider this cross….
Purple flowers with long pollen grains were crossed with red flowers
with round pollen grains.
Other information you need to know:
Purple is dominant over red
Long is dominant over round
Both flowers were purebreds
What ratio of offspring would you expect in the F2 generation?

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Parental Phenotype:
Purple Flowers, Long Pollen Grains x Red Flowers, Round Pollen Grains
Parental Genotype:
PPLL
x
ppll
Gametes:
PL
x
pl
F1 Offspring:
All PpLl
All purple flowers, long pollen grains
Parental Phenotype:
Parental Genotype:
Gametes:
F2 Offspring:
Purple Flowers, Long Pollen Grains x Purple Flowers, Long Pollen Grains
PpLl
x
PpLl
PL Pl pL pl
x
PL Pl pL pl
9 Purple Long: 3 Purple Round: 3 Red Long; 1 Red Round
This is the EXPECTED ratios of the phenotypes
in the F2 generation

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The observed numbers…..
296 Purple Long
19 Purple Round
27 Red Long
85 Red Round
What is the ratio for this?

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Questions to think about….
1. What did that ratio tell us?
2. How can we explain the other two phenotypes that appeared in
lower numbers?

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Exam Question

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Mark Scheme

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How many marks?
This one scored full marks and actually had
all the mark points in there.

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Can you differentiate between
cell differentiation and cell
specialisation?

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Exam Question

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Mark Scheme

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The Lac Operon

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Question
What is the benefit to the cell of having such a mechanism to regulate gene expression?

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Checkpoint

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Answers

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Checkpoint

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Answers

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Hydrangea Question
Take a look on the Learning Platform:
Week 17 BIO UK Resource – Hydrangea Question

29.

Apply
Week 17 BIO UK Apply – Cell Differentiation, Gene Interactions & Controlling Gene
Expression

30.

Poll Time!
Add two things you have learned in today’s
learn lesson

31.

What were the
useful words
for this week?
• Locus
• Gene
• Allele
• Inheritance
• Polygenic
• Phenotype and genotype

32.

How confident do you feel about
today’s objectives?
3.8 i) Know that a locus (plural = loci) is the location of genes on a chromosome. ii)
Understand the linkage of genes on a chromosome and sex linkage. (Highlighted part
covered in week 10; rest this week)
3.12 understand how cells become specialised through differential gene expression,
producing active mRNA, leading to the synthesis of proteins which, in turn, control
cell processes or determine cell structure in animals and plants, including the Lac
operon
3.15 understand how some phenotypes are affected by multiple alleles for the same
gene at many loci (polygenic inheritance), as well as the environment, and how this
can give rise to phenotypes that show continuous variation
RECOMMENDED ADDITIONAL PRACTICAL AP6 Investigate factors
affecting the growth of pollen tubes

33.

In week 18 you will study
Stem cell
Differentiation
• Text book page: 126, 134138
• Inspired AI
Epigenetic examples and
mechanisms
Stem cells and dif f erentiation
• Weblink: here
• Video: here

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Lesson complete!
See you next lesson