LEARNING INTENTION
• Understand what are basics genetics and identify some common misconceptions.
• Explain how DNA relates to structures and function in an organism
ACTIVITY
Read the article and highlight key ideas within the piece
When you're tuning a guitar, the smallest of tweaks can make a big difference to the way the
instrument sounds. And in books, small changes in the way the words are put together can change
how the story unfolds – little changes can have big effects. The same applies to DNA – the molecule that
carries the genetic information you inherited from your parents. Your DNA directly affects how your body
is built and functions, and small changes in the information it contains – mutations – can have a big
impact.
• Often these mutations occur because the processes used to copy DNA are imperfect. Very
occasionally the misspellings originate in your own body, but most often they are inherited from
parents, who in turn likely inherited them from their parents. The mutations can alter the construction
of proteins vital to our bodies, with significant harmful results. On the other hand, many mutations have
no noticeable effects at all.
• BRCA2 is a very well studied gene because it has a mutation that increases a woman's chance
of breast cancer five to ten times. In fact, the gene's name stands for Breast Cancer 2. But recently
scientists found a new mutation on the same gene. It also increases the risk of breast cancer but is
dangerous in a different way as well – it significantly increases the risk of lung cancer in smokers. This
goes to show how two small tweaks in the same gene can carry two very different – and dangerous –
tunes.
QUESTIONS
1) If you look more like one parent then you have inherited more of that parent’s genes.
A) True
B) False
C) I’m not sure
2) Boys get all their traits from their fathers and girls get their traits from their mothers.
A) True
B) False
C) I’m not sure
3) The genetic information passed on to you from your parents came from their sex cells –
that is, from your father's sperm and your mother's egg cells.
A) True
B) False
C) I’m not sure
4) Your genes determine all your characteristics.
A) True
B) False
C) I’m not sure
ANSWERS
If you look more like one parent then you have inherited more of that parent’s genes. False - Each
parent contributes an equal amount of genetic information.
Boys get all their traits from their fathers and girls get their traits from their mothers. False - Apart
from the genes that determine your sex, you inherit genes from both parents for every characteristic.
The genetic information passed on to you from your parents came from their sex cells – that is, from
your father's sperm and your mother's egg cells. – True, You begin from a single sperm cell from your
father fusing with a single egg cell from your mother.
Your genes determine all your characteristics. – False -genes and environment play roughly equal
roles in determining people's characteristics.
WHY ARE WE SIMILAR BUT DIFFERENT?
• Why do different species look and behave differently yet have similar genetic information?
• All organisms have different “blueprints”
• The blueprint for a living thing is the genetic information contained in the cells that make
it up. Nearly every cell in your body contains the exact same genetic information.Your
genetic information is found in the Nucleus of a cell
WHAT IS YOUR GENETIC INFORMATION?
• The genetic information is contained in a complex molecule called DNA –
Deoxyribonucleic Acid. “Di – Oxy – rye – bo – new – clay – ic
Acid
• The information determines what organs and parts should be developed, the order in
which these parts should be assembled and how they should work together –
VIDEO
• https://www.youtube.com/watch?v=zwibgNGe4aY
QUESTIONS
1) What is DNA?
2) What is meant by DNA being the blueprint for living things?
THE STRUCTURE OF DNA
• DNA is a molecule made up of thousands of atoms. It consists of;
• Phosphate
• Deoxyribo/Deoxyribose sugar (Hence the name DNA )
• Nitrogenous/ nitrogen base pairs
DNA
• There are 2 phosphate backbones which twist around each other known as a double helix
• If you were to straighten out DNA it would look like a ladder
• Each “rung” of the ladder is made up of two Nitrogen bases
• There are 4 different bases
• Adenine = A
• Thymine = T
• Guanine = G
• Cytosine = C
Each base can only pair with its specific counterpart. Adenine and Thymine will pair together and Guanine and Cytosine
will pair together i.e. A-T/ T-A and G-C/ C-G
This is known as the “Base Pairing Rule”
NUCLEOTIDES
• One phosphate, one deoxyribose sugar and one nitrogenous base are together called a
Nucleotide
• DNA is made up of repeating nucleotides
• This makes nucleotides the basic building blocks of
DNA
How many nucleotides are there in the picture?
ACTIVITY
• Look at the section of DNA – Complete the other section of DNA by adding in the correct
bases
DNA Strand = C A A T G T A C G G C T
Complimentary=G T T A C A T G C C G A
QUESTION
• If 30% of the bases in a particular DNA molecule are guanine (G), what percentage of the
bases would be thymine (T)? Explain your reasoning.
ACTIVITY
• Make a DNA molecule
• https://learn.genetics.utah.edu/content/basics/builddna/
LEARNING INTENTION
• Explain the role that nucleotide sequences play in making proteins
• Explain the connection between proteins and genes
• Identify nucleotide sequences and correctly match base pairs
GENES
• A string of DNA can be wound up or condensed into a structures called chromosomes
• One chromosome is made from a single, long string of DNA
• Chromosomes are found in the nucleus of cells
• “if DNA is yarn, then chromosomes are like the balls of yarn, used to organise DNA”
• The human body has 46 chromosomes, a fruit fly has 8 chromosomes
GENES
• Your genes are inherited from your parents
• Genes are packets of genetic information – sections of a DNA molecule that provides
instructions for building specific proteins
• Different genes contain information for different characteristics/ traits (Code for specific
proteins)
• Humans have about 20,000 genes
VIDEO
• https://www.youtube.com/watch?v=5MQdXjRPHmQ
ACTIVITY
• Complete “Label DNA and Chromosomes” worksheet
WHAT ARE PROTEINS
• Proteins are molecules that perform different functions
• Some proteins will deposit pigment in your eyes, hair and skin – these proteins control
your hair colour, eye colour and skin colour
• Genes are the recipes for proteins
• Proteins are molecules that control traits/ characteristics
• Genes code for traits
FILL IN THE GAPS
Each _______ serves as a recipe for a ________. Another way to say this is that a gene
_______ for a _______. This means the gene contains the _________ necessary to make
that protein
Word Bank: Gene, Protein, Protein, Codes, Information
HOW DO NUCLEOTIDES FIT IN?
• Genes, being lengths of DNA are made up of a series of nucleotides.
• The order and number of these nucleotides makes up the nucleotide sequence e.g.
{ATCGTGACGTACTGTACGGAATCA} Gene
When a gene codes for a protein, it is the order of the nucleotides that determine which protein is
made.
• Nucleotides are read in threes which is called a codon
• How many codons are present in the above gene?
{ATC GTG ACG TAC TGT ACG GAA TCA}
CODONS FORMING AMINO ACIDS
Codons are read by other molecules to build things called Amino Acids.
Amino acid chains once complete are your proteins
e.g.
{ATC GTG ACG TAC TGT ACG GAA TCA}
What does each codon represent?
QUESTIONS
• Explain why we need to have four types of nitrogenous bases? Why don’t we just have
one?
• Imagine that a single gene is 5 base pairs long. Calculate the number of different
combinations of base pairs that you could have.
• 4x4x4x4x4 = 1024 different combinations
• Using the codon wheel – identify 2 different codons that code for the same amino acid
molecule. If I have ATCGTGACGTACTGTACGGAATCA as my gene and there is a
mutation within the code ATCGTGACGTACTGTACAGAATCA. Would anything happen
to the protein?
LEARNING INTENTIONS
• Define the term homologous chromosomes
• Explain the difference between diploid and haploid
CHROMOSOMES
• Each one of your cells has 46 chromosomes. It doesn’t matter if it is a nerve cell or
muscle cell.
• Your 46 chromosomes are organised into 23 pairs of chromosomes. Each pair contains
two chromosomes that are very similar in length and gene location e.g. eye colour is
located in the same position.
• You get 23 chromosomes from your mum and 23 chromosomes from you dad = 46
chromosomes
HOMOLOGOUS CHROMOSOMES
• Chromosomes that carry the same genes and are the same size are paired together =
Homologous Chromosomes
• You have 22 Homologous pairs of chromosomes
QUESTION
• Is the picture below showing an homologous pair of chromosomes? Why/ why not
DIPLOID VS HAPLOID
• In your body you have Diploid and Haploid cells – cells that have two copies of each
chromosome e.g. skin cell and cells that have single copies of each chromosome e.g.
sperm and egg cells (gametes.
• Diploid cells have 46 chromosomes whilst Haploid cells have 23 chromosomes
QUESTION
• Is the cell below Diploid or Haploid? Why/ Why not?
• Is the cell below Diploid or Haploid? Why/ Why not?
ACTIVITY
• Making a Karyotype
• https://learn.genetics.utah.edu/content/basics/karyotype/
ACTIVITY
• Look at the Karyotype below and identify which chromosome has the 3rd copy. Research
what this condition is called
SEX CHROMOSOMES
• Your sex chromosomes are obtained from your Mum and Dad
• Females have XX for their sex chromosomes while Males have XY
• Since your gametes are Haploid cells (only have 1 copy of the chromosome) Females will
always have an X chromosome in their gametes whilst Male gametes will be made of X
and Y chromosomes.
• We technically never say that humans have 23 Homologous Pairs instead we have 22
Homologous pairs and a pair of sex chromosomes
LEARNING INTENTION
• Explain what mitosis Is
• Be able to outline the steps involved in Mitosis
FERTILISATION
• You and I began as one tiny cell. This cell was created when a Sperm and Egg fused
together (Fertilisation) and formed a Zygote (the tiny cell).
• https://www.youtube.com/watch?v=pOLBP3eMjQE
CELL DIVISION
• How does that tiny little cell turn into trillions of cells within the human body allowing us to
grow to adulthood? Mitosis
• Our cells replicate themselves and divide – this process is called cell division
• There are two types of cell division;
• Division of your Somatic cells (body cells) = Mitosis
• Cell division for the production of Gamete cells e.g. Sperm and Egg = Meiosis
• The human body produces ~ 60 billion new cells per day
MITOSIS
• Mitosis is important as it allows you to grow but it also allows your body to repair itself as it needs to
replace cells that die or are injured.
• Without mitosis your bones and hair would not grow – mitosis is always occurring in your cells
• In mitosis one cell splits (parent cell) into two new identical daughter cells – You basically clone
yourself 
• There are a series of steps involved in Cell Division; (IPMAT)
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase
STAGES OF MITOSIS
• Moving from Interphase and completing telophase is called a Cell Cycle
• There are 5 stages of Mitosis
• Interphase = Cell copies it’s DNA (Longest phase of the cell cycle)
• Prophase = The cell prepares for division; the chromosomes condense and the nucleus starts
to breakdown
• Metaphase = The chromosomes line up along the middle of the cell
• Anaphase = The chromosomes separate and are dragged to opposite ends of the cell
• Telophase = Two nuclei form, each with its own set of identical DNA
INTERPHASE
PROPHASE
METAPHASE
ANAPHASE
TELOPHASE
ACTIVITY
Complete the Mitosis worksheet in your book
MEIOSIS
• Sex cells are called Gametes. In animals, female sex cells are called eggs and male sex cells
are sperm
• A sperm and egg need to come together and fuse together (fertilisation). The genetic
information from the egg and sperm form a cell with 46 chromosomes
• Meiosis is a special type of cell division that produces sex cells e.g. eggs and sperm. It
involves two cycles of cell division resulting in four daughter cells which aren’t identical,
compared to Mitosis which has two identical daughter cells.
THE STAGES
• Meiosis is very similar to Mitosis in that they have the same stages, however, Gamete cells
go through the process twice
QUESTIONS
1.
Identify the parts of the body in which Mitosis occurs?
2.
Identify the parts of the body in which meiosis occurs?
3.
Outline the purpose of Mitosis and Meiosis?
4.
What are the names given to the daughter cells produced during meiosis?
5.
Complete the table
After DNA is copied during
interphase
After Meiosis I
After Meiosis II
Number of Chromosomes
Double or Single Stranded
46
Double-Stranded
Mitosis
Number of Daughter cells
produced
Number of chromosomes in
parent cells of humans
Number of chromosomes in
daughter cells in humans
Meiosis
LEARNING INTENTIONS
• Define the terms inheritance, dominant and recessive
• Understand different modes of inheritance
INHERITANCE
• Friends and family might have come up and said “Hey, you have your dads nose, your mums
eyes” etc.
• This is also true for many other animals e.g. dogs having similar coat colours etc.
• Each gene carries 2 alleles
• This is due to inheritance - the passing of traits from parents to offspring.
• You inherit your genes from your parents and different genes code for different characteristics
e.g. hair colour, eye colour
• These different characteristics can have different variations e.g. brown hair, blonde hair, black
hair etc. These variations are called alleles
MENDEL THE GODFATHER
• Gregor Mendel studied patterns of inheritance
• He bred pea plants to study the inheritance of traits. He looked at pea colour, pea shape
and height
• He discovered the Dominant & recessive mode of inheritance
DOMINANT & RECESSIVE
• Mendel discovered that there were alleles which were dominant and alleles that were
recessive.
• If a flower has a Red Colour allele and a White colour allele the red colour would be
seen in the plant making the red colour “dominant” over the white “recessive”
QUESTION
• Is hair colour a gene or allele?
• Is having blonde hair a gene or allele?
• Is eye colour a gene or allele?
• Is having blue eyes a gene or allele?
GENOTYPES VS PHENOTYPE
• A genotype describes the alleles which make up that persons gene
• A phenotype is the observable characteristic we can see
• An example, Susan has two alleles for a gene controlling eye colour. One codes for
Brown eyes (B) and one codes for Blue eyes (b). Her genotype is therefore Bb. Her
phenotype would be Brown eyes
HOMOZYGOUS VS HETEROZYGOUS
• Genetics has some very interesting terminology that is used to describe different alleles or the same
alleles
• There are 2 main categories;
• Homozygous (don’t get confused with homologous)
• Heterozygous
If an individual has the same alleles e.g. AA, BB, CC, DD etc they are Homozygous Dominant (Capital refers
to dominant allele)
If an individual has different alleles e.g. Ab, Ba, Cd, they are considered Heterozygous
QUESTION
• If there was a gene which had aa,bb,cc,dd,ee for its alleles what would the name be?
• A Labrador puppy has two copies of the allele for yellow fur (bb). Is the Labrador
heterozygous or homozygous for fur colour?
ACTIVITY
• Complete worksheet “L06 - Dominant and recessive genes worksheet”
LEARNING INTENTIONS
• Be able to construct a punnet square to work out the probability of offspring having
certain traits
PUNNET SQUARES
• Punnet squares are used to show all of the possible genotypes that the offspring could
have and determine how likely each genotype is to occur
HOW TO COMPLETE A PUNNET SQUARE
• A green pea plant (GG) is being crossed with a green pea plant (Gg). Work out the
possible offspring.
• ****Teacher to complete)
ACTIVITY
• Complete worksheet “Punnett Square Worksheet”
LEARNING INTENTIONS
• Understand other types of inheritance
• Be able to complete punnet squares for each mode of inheritance
INCOMPLETE DOMINANCE
• In incomplete dominance, neither allele is dominant or recessive.
• Instead both alleles contribute to the phenotype.
• Mixing of colours (think of making new colours e.g. red and yellow making orange)
• An example is Andalusian Chicken
INCOMPLETE DOMINANCE
Let’s complete a Punnett Square to see how all of this works:
Teacher Demonstration
CO-DOMINANCE
• When neither dominant or recessive, however, are a mixture of the two alleles
CODOMINANCE
Let’s complete a Punnett Square to see how all of this works:
• Teacher Demonstration
BLOOD TYPING
• There are many different blood types. Blood types are considered CO-dominant as they “coexist’ together
If someone is IA IA they will have blood type A
If someone is IB IB they will have blood type B
If someone is IA IB they will have blood type AB
If someone is ii they will have blood type O
BLOOD TYPE PUNNET SQUARE
• Teacher Demonstration
LEARNING INTENTION
• Explain what pedigrees show
• Be able to read a pedigree and determine alleles for different generations and individuals
PEDIGREES
• Pedigrees are diagrams used to show how individuals are related to one another
• They allow you to track how alleles have been passed from parents to offspring across
many generations
SYMBOLS
• Unaffected Female
Unaffected Male
• Affected Female
Affected Male
• Carrier Female
Carrier Male
• Mating
• Offspring
ACTIVITY
• Complete worksheet “L11 - Pedigree Analysis”
• L11 - Constructing a Pedigree - Gonzales family