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OCR 21st Century GCSE: (B5) Growth and development

Growing & Changing - Growing Plants - Phototropism - Mitosis - Meiosis - Inheritance - Inside the Nucleus - Making Proteins - Stem Cells - Cloning
by

J Amuah-Fuster

on 11 September 2016

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Transcript of OCR 21st Century GCSE: (B5) Growth and development

OCR 21st Century gcse:
B5 - Growth and development

what you should know
Genes affect the way organisms develop
Clones (such as plants) grown from cuttings are more similar to each other then organisms with a combination of their parents' genes.
Organisms are made up of cells, and these divide and develop into the whole organism.

growing and changing
FIND OUT ABOUT:
Different cells, tissues and organs.

Growing up from single cell to adult.
growing plants
FIND OUT ABOUT:

Why plants are so good at repairing damage
phototropism
FIND OUT ABOUT:

Why plants grow towards light.
inside the nucleus
FIND OUT ABOUT:

Where genes are kept inside yor cells.
mitosis - making new cells
FIND OUT ABOUT:

How your cells divide for growth and to repair your body.
Meiosis - sexual reproduction
FIND OUT ABOUT:

Cell division to make gametes.
inheritance
FIND OUT ABOUT:

The structure of DNA.

How DNA is copied for cell division
making proteins
FIND OUT ABOUT:

How DNA controls which protein a cell makes
specialised cells and proteins
stem cells + cloning
FIND OUT ABOUT:

Some different proteins in your body.

Why cells become specialised.
FIND OUT ABOUT:

Scientific research to use syem cells for treating some diseases.
Describe the process of fertilisation to form a zygote.

Describe the steps of development of the zygote.

Understand the process of specialisation from stem cells.
Design a story board to show each of the following stages:
Fertilization
Zygote
8 cell embryo – last stage where embryonic stem cells are present, after which specialization of cells to form tissues and organs occurs
100 cell embryo (blastocyte) – first formation of tissues
2nd trimester formation of organs
3rd trimester growth. Some cells remain partially specialised (adult stem cells) e.g. in bone marrow.
Keywords & Questions
zygote
clone
embryonic stem cells
meristem cells
fetus
What is a zygote?

When does a human embryos become a fetus?
Define the term specialist cell.

Recall that tissues are made of groups of specialist cells.

Recall that organs are made of groups of tissues.
Learning Objectives
Cells > tissues > organs
Multicellular organisms share the same organisational structure.

Groups of cells form tissue and tissue groups form organs.
Levels of organisation
Specialist cells
Eg. A muscle cell is a specialist cell, it works with other muscle cells as muscle tissue. This tissue allows movement in the multicellular organism.
Specialist cells
Scientific diagrams using microscopes
Use microscopes to view pre-prepared slides e.g. cheek lining cells, cartilage, bone, smooth muscle, blood, cross section of a leaf, cross section of a stem etc.

Pick one plant example and one animal example to sketch and try and identify different components e.g. cells, nuclei, vacuole etc.
Describe and make notes on how specialised cells form tissues and how tissues form organs.
The next few slides contain images that illustrate:
Examples of specialist cell types
Image gallery
Red blood cells

Large surface area, for oxygen to pass
Contains haemoglobin, joins with oxygen
Long
Connections at each end
Can carry electrical signals
Nerve cells

Root hair cells

Large surface area to absorb water and minerals
Define the term unspecialised cell.

Explain how the form of a specialised cell is directly related to its function.

Describe the relationship between cells, tissue and organs, using an example from the circulatory system.
Plenary
Red Blood Cell
Animal Cell
Sperm Cell
Plant Cell
Nerve Cell
Root Hair Cell
Ciliated Epithelial Cell
Identify each of the specialised cells
blood one specialised muscles organs brain multicellular roots flowers tissues 300
Humans, animals and plants are ________. This means they are made up of more than ________ cell. Our bodies have over ________ different kinds of cells which are all ________ to do a different job.
Newly made human cells look the same but then develop into groups of specialised cells called ________. Tissues in our body include ________, fatty tissues and the ________.
Groups of tissues arrange themselves into ________. Examples of organs include the heart and ________ in humans, and ________, leaves and ________ in plants.
Cells, Tissues and Organs - Activity (10 mins)
V


Z


1. What is V?

A Nucleus
B Glycogen granules
C Starch grains
D Chloroplast
Look at the diagram above.
Y


X


2. What is X?

A Nucleus
B Cytoplasm
C Cell Membrane
D Cell wall
3. What is Y?

A Nucleus
B Cytoplasm
C Cell wall
D Chloroplast
4. What is Z?

A Cell membrane
B Vacuole
C Cytoplasm
D Nucleus
A It is a jelly-like substance in
which most of the chemical reactions take place.

B It controls the movement of substances
into and out of the cell.

C It is the site of photosynthesis.

D It controls the activities of the cell.
5. Which of the following descriptions represents the function of the membrane?
6. Which of the following descriptions represents the function of the nucleus?
A It is a jelly-like substance in which
most of the chemical reactions take place.

B It controls the movement of substances into
and out of the cell.

C It is the site of photosynthesis.

D It controls the activities of the cell.
7. Which of the following represents the function of the cytoplasm?
A It is a jelly-like substance in which
most of the chemical reactions take place.

B It controls the movement of substances
into and out of the cell.

C It is the site of photosynthesis.

D It controls the activities of the cell.
Look at the diagram below.
R


N


P


O


Q


M


8. What is M?

A Cell membrane
B Cytoplasm
C Cell coat
D Cell wall
10. What is O?

A Nucleus
B Starch grain
C Glycogen granule
D Chloroplast
9. What is N?

A Cytoplasm
B Vacuole
C Cell membrane
D Starch grain
11. What is P?

A Nucleus
B Starch grain
C Glycogen granule
D Chloroplast
12. What is Q?

A Cytoplasm
B Vacuole
C Nucleus
D Chloroplast
13. What is R?

A Cell wall
B Vacuole lining
C Cell membrane
D Cell coat
14. Which of the following descriptions represents the function of the chloroplast?
A storage site

B site of photosynthesis

C site of reproduction

D site of excretion
15. Which of the following types of tissue is capable of contracting and causing movement?
A glandular tissue

B liver tissue

C muscle tissue

D brain tissue
16. Which of the following types of tissue is capable of making useful substances (e.g. enzymes)?
A glandular tissue

B liver tissue

C muscle tissue

D brain tissue
18. Which of the following describes a group of tissues working together to do the same job?
A cell

B organ

C organ system

D tissue
17. Which of the following describes a group of cells of the same type all doing the same job?
A cell

B organ

C organ system

D tissue
plenary
Learning Objectives
Locate where meristem cells are found in plants.
 
Understand that meristem cells are mitotically active.

Understand that meristem cells can form plant tissues and organs.
REMINDER: Levels of organisation
All multicellular organisms share the same organisational structure.

Groups of cells form tissue and tissue groups form organs.
Stem
Xylem cells
>
Same in plants
Cells > Tissues > Organs
Vascular tissue
Roots
Absorb nutrients and H2O. Regions of growth (meristem cells), stability.
Stem
Support, growth regions (meristem cells), some photosynthetic tissue.
Leaves
Capture light energy, CO2 and H2O. Exit point for O2 and H2O (photosynthesis).
Flowers
Attract “vectors” for pollination, contain sex cells/structures for reproduction.
Plant organs
Meristem tissue
For a plant to grow, tissue must develop.

Meristem cells (unspecialised), are concentrated in the root and shoot tips of plants.

They divide by mitosis when conditions are right, and together form more tissue.
>
The next few slides contain images that illustrate:

Examples of plant cell types
Regions of growth in plants
Mitosis in meristem cells
Image gallery
Celery stem - tissue types
Cross section of a leaf
Onion root cells - meristem tissue
Vascular tissue -– xylem/phloem
Practical
Observe and draw the following:

transection of a leaf (identify variety of cells)
exposure of vascular tissue in a leaf
meristem cells in an onion root (mitosis visible)

Make your own cross section of a stem – demo station with teacher.
Mitosis - cell division
SUMMARY
Describe, in detail, your process of taking cuttings.
Predict which of the cuttings will develop quickest, into an independent plant.
Justify your prediction, by explaining how the cutting process works (using your knowledge of cloning and meristem cells and auxins).
Learning Objectives
Describe the process of taking cuttings.

Understand that cuttings are clones of the original plant.

Understand how auxins can promote rooting.
HOMEWORK
Expand on your acquired knowledge:
Finish “SUMMARY” from today’s lesson.
Research into auxins. Use reliable resources, such as GCSE Bitesize, to lead you (open ended).
Take two cuttings.
Dip both cuttings in water.
Dip one cutting in rooting compound (hormone).
Carefully place each cutting in separate plant pots containing the same amount of soil.
Spray cuttings/soil with a little water.
Investigate the effect of auxins
Plant hormones are added
Cells grow rapidly into small masses of tissue
The tiny plantlets are transferred into potting trays where they develop into plants
How do we clone plants?
Tissue culture
Small amounts of parent tissue are taken
The plant material is transferred to plates containing sterile nutrient agar jelly
How do we clone plants?
Cuttings

A branch from the parent plant is cut off.
Plant hormones are added, to encourage new roots to develop.
Cover in a clear plastic bag to keep it moist and warm.
What is a clone?
What is a clone?
(write as much as you can – Key words: genes, parent, DNA, generation)

Lesson 4

Cloning Plants
Auxins are made in the
tips of a growing root or
shoot (near meristem cells).

These plant hormones
speed up division in the meristem cells of a plant.
The role of hormones
How does a plant clone itself?
Meristem cells are unspecialised, they can differentiate.
Answer these Questions:

Where are meristem cells located?

What is their role in cloning?
Food
Decoration
We can increase production by artificially producing clones of plants with favourable traits.
Plants can be produced commercially and cheaply, on a massive scale, in a short space of time.

For example:

Why do we clone plants?
Potatoes contain meristem cells
Which means that plants (as well as other asexually producing organisms) can generate a new individual by the division of meristem cells that specialise into root, stem and leaf cells.
Genetically identical offspring
What other environmental stimuli would affect plant growth?
Plenary
Define the term phototropism.

Describe how phototropism increases the plant’s chance of survival.

Explain the roles of auxins in the process of phototropism.
Learning Objectives
Define the term phototropism.

Understand how phototropism increases the plant’s chance of survival.

Explain the roles of auxins in the process of phototropism.
Why?
The direction from which the light comes, affects the direction of plant growth.

This increases the plant’s chances of survival because more light means more photosynthesis.
© solyogatrips.com

Socratea durissima grows new roots in the direction of sunny patches in the forest.
Old roots, that are shaded, rot.
The plant, over time, moves across the forest floor.
Your Experiment
Set up an experiment that demonstrates the role of auxins in plant growth.
Your materials:

Seeds
Petri dishes x 3
Black card
Cotton wool
Cling film
Remember from last lesson?...
Auxins are made in the
tips of a growing root or
shoot.

These plant hormones
speed up division in the meristem cells of a plant
The walking palm tree
Copy the flow chart and complete the third box to show what you think happened.

Justify your prediction by explaining your diagram.
?

Darwin’s Experiment
When a shoot gets light from one side, the auxins are not evenly spread out in the shoot.

More auxin on the shaded side of the plant, makes meristem cells divide faster. This forces the plant towards the light.
Auxins and phototropism
When a growing shoot gets light from above, the auxins spread out evenly and the shoot grows straight up.
light
Auxins and phototropism
light
Auxins and phototropism
Phototropism experiments
Asexual reproduction produces offspring - clones - that are genetically identical to their parents.

In plants, clones can develop naturally through bulbs and runners.
Medicine
What could cause this?

How could we treat/prevent it?

Why don’t we get cancer more often?
What would happen if mitosis wasn’t carefully controlled?
Divide mitosis into 5 stages
Draw a diagram for each on a separate page
Write 4 questions on the last page.
Staple together in correct order


Swop and peer mark – have they missed anything?
Can you answer their questions?
Mitosis Flick-book
What are the stages in mitosis?
http://www.johnkyrk.com/mitosis.html

Answer questions 1-4 page 147
Define key terms pg 146
What happens to our cells when we grow?
MITOSIS:
Cell division that makes 2 cells genetically identical to each other and to the parent cell

Needed for:

growth
repair (replace damaged cells)
asexual reproduction (where ONLY 1 parent is needed to produce offspring genetically identical to the parent)
Define mitosis.

Describe the steps of mitosis.

Give examples of processes that use mitosis
Lesson objectives
SALTWATER CROCODILE
SNAKE
MOUSE
MEERKAT
ELEPHANT
What animal would this embryo become?
T,T,F,F,T
D, B, C, A
B, E, D, A, C
Define the term meiosis. 

Describe the steps of meiosis

Compare mitosis and meiosis
How were these offspring produced?
How do we produce gametes?
MEIOSIS:
Cell division that
halves
the number of chromosomes to produce gametes (egg and sperm cells) that are
genetically different to each other and the parent cell
.
Used in
sexual reproduction
.
learning objectives
Recall the double helix structure of DNA.
 
Describe the process of base pairing in DNA replication
Specification points:
 
B5.3.1.
Recall that DNA has a double helix structure.

B5.3.2.
Recall that both strands of the DNA molecule are made up of four different bases which always pair up in the same way: A with T, and C with G.
The two strands are twisted around each other – a helix
Each DNA molecule is made up of TWO strands
DNA: the double helix
G binds to C

A binds to T
Base pairing
The molecule of DNA is held together by bonds between the bases on each strand…
Is science sexist?
Rosalind Franklin
(1953, Kings College)
Gee whizz Frank that was neat
“By choice she did not emphasize her feminine qualities. . . . There was never lipstick to contrast with her straight black hair, while at the age of thirty-one her dresses showed all the imagination of English blue-stocking adolescents. So it was quite easy to imagine her the product of an unsatisfied mother who unduly stressed the desirability of professional careers that could save bright girls from marriages to dull men. . . . Clearly Rosy had to go or be put in her place. The former was obviously preferable because, given her belligerent moods, it would be very difficult for Maurice [Wilkins] to maintain a dominant position that would allow him to think unhindered about DNA. . . . The thought could not be avoided that the best home for a feminist was in another person's lab.”

James Watson
Managed to get a sneaky peek at that bird’s photo… and EUREKA!
This looks interesting….
Take the heads of each jelly baby
Complete the table below:












Join the correct bases together using the cocktail sticks
Link to the laces
Twist to make a helix!


Are sweets a good model to demonstrate the structure of DNA?

What are the advantages of the model?

What are the disadvantages of the model?

Build your own DNA model
the mystery of inheritance
Gregor Mendel
(1865)
I know that characteristics are passed down from parents to offspring, but I don't know how!
You see James.. it's a bit curly wurly-like
Oh yes Francis... curly wurly...!!
Lots of hard work...
James Watson & Francis Crick (1953, Cambridge)
and creative thinking
How does the ribosome read the genetic code ?
T
h
e
T
r
i
p
l
e
t
C
o
d
e
Turning mRNA into Protein - Translation
Making messenger RNA - transcription
Turning DNA into Proteins
learning objectives
Explain how the DNA code leads to the production of proteins.

Describe where the steps in protein synthesis take place.

Explain how messenger RNA is involved in protein synthesis. (H tier only)

Describe the nature of the triplet code. (H tier only)
The genetic code is a
triplet code


3 bases on mRNA code for 1 amino acid
in the protein chain
The mRNA leaves the nucleus and attaches to a ribosome in the cytoplasm.
A ribosome ‘reads’ the code and puts amino acids into a sequence in a protein.
In the nucleus, a gene (short section of DNA) is copied to make a messenger RNA (mRNA) molecule.
Genes code for proteins
While you are waiting…

Colour in the DNA strand and free bases
Cut out the free bases and stick them to their complementary base on the DNA strand

Extracting DNA
Keywords?
Describe the structure of DNA and explain how the bases are arranged.
Extended answer question
B5: Growth and development
Lesson 9 Extracting DNA
Learning objectives:
 
Recall the double helix structure of DNA.

 
Describe the process of base pairing.
Specification points:
 
B5.3.1.
Recall that DNA has a double helix structure.

B5.3.2.
Recall that both strands of the DNA molecule are made up of four different bases which always pair up in the same way: A with T, and C with G.
This purple stuff is DNA… the instructions for life!

Why do we want to extract DNA from cells?
A DNA sample can be used to find out which alleles you have for each gene and can predict your risk of developing some diseases e.g. heart disease
A DNA sample can be used to make a genetic fingerprint that will identify individuals e.g. paternity and forensic testing
Step 3: place the plastic bag into a water bath for 10 minutes
Step 2: add 50cm3 extracting fluid to the bag and pulp and mix gently
Step 1: place the fruit into a plastic bag and gently squeeze to make a pulp (no big bits!)
Extracting DNA
Step 4: pour the fruit pulp through filter paper (in a funnel) and collect 4cm of fluid in a boiling tube
Step 6: use the yellow loop to carefully collect the DNA from in between the pulp extract and ethanol
Step 5: gently pour ice cold ethanol down the inside of the boiling tube taking care not to disturb the fruit pulp extract
The ethical use of Stem cells
Is it right to use human embryos?
How does it do that?
Benefits, drawbacks and risks answers

Stem cells are capable of turning into any type of cell. (B)
Some of the most useful and versatile stem cells are extracted from embryos. (D)
A human egg has the same moral status as a human, so using embryonic
cells is the equivalent to murder. (D)
Stem cell therapy may increase the chance of developing cancer. (R)
Stem cells could be used to test the effects of new drugs. (B)
Stem cells are rare and hard to find in the adult body. (D)
Stem cells from adults can be used which do not harm the donor. (B)
Transplants using stem cell therapy may pass on viruses and other diseases to the recipient. (R)
Stem cells have the potential to cure a wide range of diseases. (B)
Uses of stem cells: Video Links
Where can we take stem cells from?
ASC – adult stem cells
ESC – embryonic stem cells

Adult stem cells have started to specialise.
Stem cells may reverse paralysis, brain damage and organ failure
What is a ‘stem cell’ and what conditions could stem cells be used to treat?
An unspecialised cell with all genes switched on that can divide and develop into a specialised cell.

What is the difference between therapeutic and reproductive cloning??

dnalc cloning 101
Explain how stem cells are used to repair damaged tissues.

Describe how gene switching occurs in mammalian cloning to form specific tissue types (HT)
‘Star Trek ‘skin gun’ used to cure 2nd degree burns and scarring’ –

but how does it work?
Regulation of stem cell research varies widely between different European countries:
some
prohibit

human
embryonic stem (HES) cell research;
7 permit the production of human stem cells from
spare
in vitro fertilisation (IVF) embryos;
3 (the UK, Belgium and Sweden)
allow the creation of embryos
purely for research, albeit under strict regulation;
6 have
no legislative policies
at all.
6 mark exam question:

Describe how stem cells can be obtained and discuss why the use of embryonic stem cells for medical research is legal in some countries and not in others.

A difference of opinion?
Put yourself in the role of a chosen board representative (
Healthcare secretary, Bioengineering executive, Cultural & Ethical consultant, Mothers Group representative)
and try to answer these questions:

Should human embryos be used for stem cell research?

Should women be allowed to “sell” unfertilized eggs to be used to produce embryonic stem cells (currently they can only be donated)?

Should stem cell research be allowed to produce tissues to treat diseases (therapeutic cloning).
http://www.hfea.gov.uk/authority-members.html

HFEA

The ESC (embryonic stem cell) debate:
Video Clips
Michael J Fox and use of ESCs



The ESC debate is dead



Against ESC research


Previously in Biology….

What is a ‘stem’ cell?

Name 3 diseases that could be treated with stem cells.

Stem cells can be taken from adults or embryos (ESCs). Which type of stem cell is most useful for therapeutic treatments?

Are stem cells the most important medical discovery of the past 100 years? Justify your answer:
Stem cells can be obtained:
By cloning adult cells (t---------c cloning)
From human embryos
Where can we obtain stem cells for research?
Explain that ethical decisions need to be taken when using embryonic stem cells. 
Explain that this work is subject to government regulation.
http://www.tes.co.uk/teaching-resource/KS3-4-Science-Stem-Cell-Research-The-Issue-6047949/
The Great Stem Cell Debate!
What are the arguments FOR and AGAINST the use of Embryonic Stem cells for medical research?
Stem cell research - the issue
Lesson Outcomes
?
2
46
Identical
Growth / repair
Identical
sexual
Asexual
sex cells
Non-identical
Non-identical
23
4
Learning objectives
lesson outcomes
Equipment:

4 jelly babies (2 different colours)
2 laces
4 cocktail sticks

‘making a model of DNA’…
1. DNA unzips
3. mRNA bases are joined together to form a strand of mRNA
2. mRNA bases (G,C,A,U
[U replaces T]
) in the nucleus pair with one DNA strand
Protein synthesis overview
In order
to make proteins
, first, our cells have to
make amino acids
.
Each of the 20
amino acids are made in ribosomes
, found in the cell cytoplasm. The ribosomes
require a certain code
(
triplet

code
or
codon
) to produce a certain amino acid. This codon comes
from a

strand of mRNA
, which is
created from a strand of DNA
in the nucleus.
1.The strand of mRNA leaves the nucleus.
2. Ribosomes in the cytoplasm attach to the mRNA and begin reading the genetic code.
3. Every group of 3 bases (codon) codes for an amino acid made by the ribosomes.
4. A chain of amino acids made by ribosomes produce a protein.
Learning outcomes
What are the benefits, drawbacks and risks of using stem cells?
Using stem cells to create the first synthetic burger
New ways to heal bones
First spinal cord surgery with stem cells
http://www.bbc.co.uk/news/science-environment-17104501
Why don’t these mistakes happen more often?

Learning objectives
Define the term gene switching.
 
Explain how gene switching leads to the formation of specialised cells from stem cells.
Can we turn a chicken into a dinosaur?
How do cells become specialised?
An unspecialised cell is called a ‘----’ cell.
It has all the genes switched on so can make any -------coded for by your DNA.
As your cells specialise, ----- can be switched off or left on depending on what type of cell is being produced.
E.g. Red blood cell
Haemoglobin gene ON
Amylase gene OFF

What proteins are needed in our organs?
Exam question answers:

http://www.bbc.co.uk/apps/ifl/schools/gcsebitesize/science/quizengine?quiz=add_21c_controlling_growth_htest&templateStyle=science
Quiz
Which type of stem cell is more useful for therapeutic treatments? Why?
Learning outcomes
Copy & Complete
Social
Economical
Ethical
Stem cells can be obtained:
By cloning adult cells (
therapeutic
cloning)
From human embryos
A report from the European Science Foundation (ESF) examined key issues in human stem cell research and regenerative medicine, which it hails as having the promise to be ‘one of the most fascinating and controversial scientific developments of the 21st century’.
Legislation
Full transcript