Learning Intentions

• describe what a species is
• understand the words fertile and infertile
• give an example of a hybrid

Cells Recap

• All living organisms are made of cells.
• An important part of the cell is the nucleus. Its job is to control all of the cell's activities
• It also contains the cell's DNA!

DNA

In this unit we are going to learn more about this DNA, what its job is and why it is so important.

Watch the video below to find out more.

Species

• A species is a group of organisms which can interbreed to produce fertile offspring
• Fertile offspring are young that are able to produce more of their kind when they reach sexual maturity

Infertile Offspring

• If members of different species interbreed then their offspring will be infertile
• This means they are NOT able to produce their own offspring when they reach maturity

Activity - Hybrids

Animals that are born from parents that are different species (like a mule) are called hybrids. They are infertile.

Can you figure out which animals were involved in creating the following hybrids?

______ + Shetland Pony = Zebrony

Grizzly Bear + __________ = Grolar Bear

Cow + _________ = Beefalo

Camel + _____ = Cama

Serval + ______ = Savannah Cat

________ + Goat = Geep

My favourite example of a hybrid is ___________ it is created from a _________ and a __________

Learning Intentions

• Give the definition of variation.
• Describe the 2 causes of variation.
• Draw graphs to show variation.

Variation

Although members of the same species are very similar to one another they are not identical. This is because variation exists within a species.

Variation is the differences between members of the same species

Watch the clip below on variation.

Spot the Difference

Activity - What differences exist between humans?

Copy the table below into your notes.

Use your table to record the different eye colours of people in your class.

Copy the table below into your notes.

Use your table to record the number of tongue rollers in your class.

Copy the table below into your notes.

Use it to record the hand span of people in your class.

Draw a bar graph of at least one of your tables.

Draw a line graph of at least one of your tables.

Learning Intentions

• state that DNA is found in structures called chromosomes.
• state how many chromosomes are in most human cells.
• describe the shape of a DNA molecule.
• use base pairing to work out the sequence of bases.

Notes - Inside the Nucleus

• the nucleus contains all our genetic material (aka DNA)
• this DNA is found in structures called chromosomes
• Most human cells contain 46 chromosomes

Notes - DNA

• DNA stands for DeoxyriboNucleic Acid
• It is made up of two strands containing bases
• These are twisted around each other to create a double helix shape

Note - Base Pairs

DNA has 4 different bases along the strands

• cytosine (C)
• thymine (T)
• adenine (A)
• guanine (G)

Note - Important

Adenine and Thymine always join together

Cytosine and Guanine always join together

Activity - Let's Practise

What would be the matching strand for this piece of DNA?

Learning Intention

• Build a model to show the 3D structure of DNA

DNA models

We are going to create origami models of DNA.

To get them to work we have to be careful how we colour it in and how we fold them.

You will need to download and print a template to do this activity.

Download a template (PDF or Word):

Download PDF template Download Word template

Instructions

Note: all folds should have a thin line on the inside and a thick line on the outside.

Learning Intention

• Describe how to extract DNA from fruit.

Activity - Extracting DNA from Strawberries

Watch the video below on extracting DNA from strawberries.

Instructions

1. Place one strawberry in a poly bag.
2. Keeping the top closed, pulp the strawberry for 2 minutes.
3. Using 10 ml measuring cylinder, add 10 ml extraction buffer to the bag.
4. Mush again for 1 minute.
5. Filter through tea strainer into beaker.
6. Pour 1 - 2 cm of filtrate into a test tube.
7. Tilt the test tube and slowly pipette ice cold alcohol into the neck of the test tube, so that it 'floats' on the strawberry filtrate, until the test tube is half full.
8. After several minutes, tiny crystals of DNA should precipitate out of solution at the interface. The DNA can be spooled out on the tip of a glass rod or wooden splint.

Questions on Extracting DNA from Strawberries

1. Why do we crush the strawberries?
Answer
2. What does the extraction buffer do?
Answer
3. Why do we filter the mushed up strawberry and buffer?
Answer
4. Why do we add alcohol?
Answer

DNA Recap

Watch the video below to recap what you have learned so far about DNA.

Learning Intentions

• Explain the role DNA plays in creating protein.
• Select information from a table.
• Use a DNA code to produce a protein sequence.

DNA is a code!

The order of the bases creates a code. This code is used as the instructions to make protein. Although there are only 4 bases, they can make lots of different proteins e.g.

Think about a cake....

The recipe is the instructions that tell you what ingredients to use to make the cake.

In a cell DNA is the instructions for how to make a protein.

DNA to Proteins

Proteins are made from amino acids. The sequence of bases is read by the cell in groups of 3. This tells the cell what amino acids to use to make the protein

• DNA = Instructions
• Amino acids = ingredients
• protein = cake

Activity - Cracking the Code

You are going to act like the cell and try to read DNA sequences

Each group of 3 bases will represent a particular amino acid

The amino acids match to letters which can then be put together to provide a secret spy note

Can you crack the code and save the world???

How to read the code......

We read the code in groups of 3 bases read from the inner circle out.

So if we had TTG the amino acid would be leucine.

Now that we know the amino acid we can match it to a letter

Leucine would be an L

Practice

What would be the amino acid and letter for the following?

Now try cracking the code:

Greetings, Agent

Intelligence sources have revealed to us that the terrorist organisation CLONE (Conspiracy to Liberate Obnoxious and Nasty Enemies) is preparing to threaten the free World with a terrible and secret plot. Our agents have intercepted several messages from CLONE which we believe may contain information about this dreaded plot. Unfortunately, all of the messages are written in the insidious GENETIC CODE.

Your mission is to translate the codes, using the code key provided. Fill in the correct single-Letter abbreviation for the amino acid that is coded by each triplet. Good Luck!

Learning Intention

• State that DNA profiling can be used in a variety of applications such as forensics, paternity testing, disease testing and food fraud

DNA Fingerprinting

Watch the video below on how DNA fingerprinting is used.

DNA Profiling

DNA profiling/DNA fingerprinting has many uses

Forensics

DNA can be used to help with investigations to identify and eliminate suspects:

Paternity testing

DNA can be used to find out who the biological father of a child is:

Genetic testing

DNA can be used to work out if someone has inherited a genetic disease:

Food Fraud

DNA can be used to identify the source of meat in supermarket ready meals:

Learning Intentions

• State the importance of reproduction
• Name the male and female sex cells
• Name and describe the parts of the male and female reproductive systems

Reproduction

Notes - Reproduction

Reproduction is the production of new members of a species.

For a species to survive, it must produce enough young to replace those that die.

Sexual Reproduction

Sexual reproduction needs two parents. Each parent has to produce special sex cells, which are made in the sex organs (reproductive system).

Sex Cells

Watch the video below on the male and female sex cells.

Notes - Sex Cells

Animals have specialist cells for reproduction.

• male sex cells are called s____ c____
• female sex cells are called e__ c____

The Male Reproductive Organs

Copy the diagram into your notes.

Diagram Solution

Female Reproductive Organs

Copy the diagram below into your notes.

Complete the following table and stick it into your notes.

Diagram Solution

Learning Intentions

• Name and describe the parts of the female reproductive system.
• Describe the sequence of events involved in fertilisation.
• State where fertilisation occurs.
• Describe where our 46 chromosomes come from.

Fertilisation

After intercourse sperm are released into the vagina and their epic journey begins. Click on the picture to see this journey.

The Journey to the Egg

Fertilisation occurs when the nucleus from the sperm joins with the nucleus of the egg.

Notes - Fertilisation

When the head of one sperm gets into the egg, the male nucleus fuses with the female nucleus. This is fertilisation.

The fertilised egg now has a complete set of DNA. 23 chromosomes from the male and 23 chromosomes from the female.

What happens next?

The newly fertilised egg is now known as an embryo.

Watch the video below to see this process.

Learning Intentions

• Describe the basic development of a human embryo.
• Use the words foetus, amniotic sac, placenta and umbilical cord to label a diagram.
• State the role of the placenta.

Pregnancy

In humans pregnancy lasts approximately 40 weeks. In this time the embryo that started out as a single cell will develop all the characteristics that make us human. The average weight at birth is 7.7lbs (3.5kg). Pregnancy is split into 3 stages called trimesters each lasting approximately 3 months.

First Trimester

Watch the video below on the first trimester.

Second Trimester

Watch the video below on the second trimester.

Third Trimester

Watch the video below on the third trimester.

Development of the Foetus

Label the diagram using the words below.

Notes - Pregnancy

Pregnancy in humans lasts 40 weeks. While in the uterus the p_______ provides the foetus with food and oxygen from the mother and takes away waste materials.

Questions - Pregnancy

1. How long is a human pregnancy?
2. How many trimesters are there?
3. What is the purpose of the placenta?
4. What is the purpose of the amniotic sac?
5. At what point in pregnancy is an embryo known as a foetus?

Learning Intentions

• State some of the risks to a developing embryo.

Risks to the Embryo

Copy the spider diagram below into your notes

Download the file below on risks to the embryo.

Download PDF Download Word document

Use the information in the document to help you complete your spider diagram.