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SNC2D Genes
Did you know?
The source of smelly feet, like smelly armpits,
is sweat. And people sweat buckets from their
feet. A pair of feet have 500,000 sweat glands
and can produce more than a pint of sweat a
day.
PKU?
• PKU = phenylketonuria
– A genetic condition
– If not caught early by genetic
screening, could lead to
severe brain damage
– Can be corrected by
increasing intake of a specific
protein
– knowledge and
understanding of the cell has
led to discovering what
causes this disease
Activity Time!
• Get into groups of 4
• Letter off your group members from A-D
• Each person will be responsible for taking notes on a
topic and then your topic to the rest of the group – make
it simple and easy to understand (use examples,
analogies, etc.) **ALL GROUP MEMBERS SHOULD
HAVE NOTES ON ALL TOPICS
• Let’s practice – look to p10, how can we summarize?
– A – DNA Screening p19
– B – Drug Research p22
– C – Transgenic Organisms p23
– D – Cloning p24-25
Where is the Genetic Information?
• Nucleus
– Genetic information (DNA)
carried in structures called
chromosomes
– Genetic information =
Instructions for…
• What each cell will
become
• How the cell will function
• How long the cell will
live before it divides
Well, duh!
DNA = Instructions
Let’s learn about DNA!
• Short video
Multicellular Organisms
• Humans have 46 chromosomes in each somatic
(body) cell (except the gametes = ovum/sperm, which
have 23)
• Different species may have different numbers of
chromosomes
•
•
•
•
•
•
Horse  64
Cat  38
Dog  78
Pea  14
Rice  24
Apple  34
DNA: the Code
• Each chromosome is made up of a single molecule of
DNA
• DNA is divided into segments called genes
• Genes provide instructions for making proteins, which
control the cell’s activities
• How can such a long molecule be stored in a small
space? Check this out!
Draw this!
DNA Structure
• DNA appears as a twisted
ladder that is called a double
helix (two strands of DNA
twisted around an axis)
• Each “rung” of the ladder is a
building block of the molecule
• When the building blocks are
strung together, a molecule of
DNA forms – like this!
DNA Structure
• Made up of 4 types of
building blocks (like
Lego!) that are
represented by letters:
– A (for adenine)
– T (for thymine)
– C (for cytosine)
– G (for guanine)
Food for thought.. (don’t write)
• How do we communicate to each other?
• What does each of the following mean?
– kobo
– meti
– etwar
• But what happens when I rearrange the
letters?
– book
– time
– water
DNA Structure
• The order in which A, T,
C, and G are put together
is called the genetic
code
• Genetic code is different
for every person!
• The code is a message
that tells the cell how to
make specific proteins
(like a factory!) that helps
an organism function
Proteins everywhere!
DNA Structure (continued)
Base pairs are joined by hydrogen bonds according to
the following rules:
1. A pairs up with T
2. G pairs up with C
You better
know your
base pairing
rules!
Why is DNA important?
• DNA contains thousands of genes that controls many
of your features
• How many letters? 6 billion!
• Can you think of any features determined by DNA?
–
–
–
–
Hair colour
Eye colour
Height
Whether you can digest milk!
Try this!
• If you have the sequence of one DNA strand, you
can determine the sequence of the other DNA
strand. For example:
Sequence of First
Strand of DNA
Sequence of Second
Strand of DNA
ACGTAGCGGG
CCTAGGCTATCCGA
Mutations
• Changes in the DNA of an
organism
• Caused by mutagens like
UV rays, radiation, and
harsh chemicals like
mercury
Are they all bad?
DNA Screening
DNA Screening is the process
of testing individuals to
determine whether they have
the gene or genes associated
with certain genetic disorders
(i.e. cancer, cystic fibrosis, and
spina bifida)
Two ways:
1. amniocentesis – fluid is
taken from the amniotic sac
that surrounds the growing
fetus  e.g. test for PKU
DNA Screening
2. We can test for diseases like Down Syndrome with
karyotypes
Altering Genes
• Genetic engineering combine genes from different
species
• GMO’s – genetically modified
organisms or transgenic
organisms
• Benefits? Read p 23 and make
a list!
Cloning
• Cloning – the process of
creating identical genetic
copies of an organism
• Why?
– Address organ
shortage
– Agriculture – feed the
growing population!
Homework
•
•
•
•
Do “Learning Check” #1-4 p18, #5,6 p22
Make a list of the benefits of GMOs  p 23
Do #6,8 on p28
Tomorrow? Read p22  answer #4 p28
DO YOUR
HOMEWORK!
Or else…