Download Unit 4: Genetics

In the beginning…
Think
of a book, TV show or
movie you like that involves a
mystery.
 What
is the main detective looking for?
 How do they find what they’re looking
for?
Geneticists
are detectives looking for
clues in the mystery of inheritance.
By
the early 1900’s, scientists knew
that genetic information was carried
on the chromosomes
 They
also knew the 2 main components
of a chromosome were…
 DNA
 Proteins
Which
macromolecule is the
source of genetic information?
 Carbohydrates
 Lipids
 Proteins
 Nucleic
Acids
Studied
the bacteria that causes
pneumonia
Experiments
showed that
genetic material can pass from
one bacterial cell to another
 Called
it Transformation
*Pathogen – something that can cause a disease (like bacteria)
•
Question: What is the transforming
substance?
 Continued
Griffith’s experiments and
showed that DNA was the transforming
factor by…
1.) He used an enzyme that destroys DNA
and the genetic material did not pass
from one cell to another
2.) He used an enzyme that destroys
proteins and it did not stop genetic
materials from passing from one cell to
another.
…but of course, many people still thought
proteins carried genetic information because they
thought the genetic material in bacteria might be
different from other organisms…

Used a bacteriophage or “phage”
 A virus that infects bacteria (and is composed
of DNA & protein)
Showed
that when bacteriophages
infect bacteria, their DNA enters
the host bacterial cell, but most
of their protein does not.
 Provided
material
evidence that DNA is the genetic
This will be collected!
 Today,
you will extract DNA from a
strawberry!
 Strawberries
have 8 copies of each type
of chromosome. This large number of
chromosomes will filter out of your
solution and you will get to actually see
DNA.
Place
one strawberry in a ziploc
bag (remove stem first!)
Smash/grind
the strawberry using
your fist and fingers for 2
minutes. Careful not to break the
bag!!
Add
10mL of the extraction
buffer (water/salt/soap solution)
Kneed/mush
the strawberry in
the bag for 1 more minute.
Assemble
your filtration
apparatus
Pour
the strawberry slurry into
the filtration apparatus and let
it drip directly into your test
tube.
Slowly
pour 20mL of cold ethanol
into the test tube
Dip
the popsicle stick into the tube
where the strawberry extract and
ethanol layers come into contact
with each other
 Complete
sheet!
the questions on the back of the data
A
macromolecule (nucleic acid) that
stores genetic information in all
organisms
Primary function of nucleic acids
 Provide instruction to build proteins
Monomer:
 Nucleotides
*A DNA molecule is a chain of repeating units
These
repeating units are
composed of:
A
ring-shaped sugar (deoxyribose)
A
phosphate group

1 phosphorus with 4 oxygens
A
nitrogenous base
Adenine
(A)
Thymine (T)
Cytosine (C)
Guanine (G)
Built
the first DNA model using data
from other scientists
Double Helix (Two strands of DNA wind around
each other like a twisted ladder)
 Rails
– alternating deoxyribose and
phosphate (aka sugar/phosphate backbone)
 Rungs/Steps
– base pairs
Adenine pairs with Thymine
A=T
Cytosine pairs with Guanine
C=G
*Sugar-phosphate
Backbone
To
use the materials given to create a
model of a DNA molecule
Model
the sequence including
complimentary base pairs:
Sequence 1: T A C G T A
Sequence 2: C G G T A C
Sequence 3: A C G C T T
Sequence 4: G A C C T A
In a sample of yeast DNA, 31.5%
of the bases are Adenine (A).
Predict the amounts of T, C and
G.

Test your knowledge
by answering the
following questions…
What
is the shape of DNA?
Who created the first DNA
model?
Adenine always pairs with _____.
The sides of the DNA ladder are
deoxyribose and _________.
Guanine always pairs with _____.
What
is the complimentary
sequence to “A A T G C A”
Base pairs are held together by
___ bonds.
DNA is an example of what
macromolecule?
What is the monomer of the
above macromolecule?
The process by which
DNA is copied during
the S-phase of the
cell cycle (occurs in
nucleus!)
Semi-conservative replication:
Half of the old strand is saved
The
DNA double helix unwinds
(unzips) and complimentary base
pairs are separated by enzymes
called helicases (break H bonds).
Replication
begins on both strands
of the molecule at the same time.
Each
existing strand of the DNA
molecule is a template for a new
strand.
Free-floating
nucleotides in the
nucleus pair up with the exposed bases
on each template strand.
DNA
polymerases (a group of enzymes)
bond these nucleotides together to
form the 2 new strands.
The
2 completed DNA double
helixes (identical) now wind up
again.
The
replicated DNA can now
become part of a new cell.
If
the wrong nucleotide is added
to the new strand of DNA, DNA
polymerase can detect the error
and fix it.
A
change in the nucleotide
sequence
Example:
A
Sickle Cell Anemia
disorder in which the body make sickle
shaped red blood cells
 They are stiff and sticky and tend to block
blood flow in the blood vessels causing pain
and organ damage.
Ribonucleic Acid
RNA
= the secretary. It takes
the message from the boss
(DNA) and delivers the message
to the factory (ribosomes)
where proteins are produced.
A
nucleic acid made up of
repeating subunits called
nucleotides
Single-stranded
A
5 carbon sugar (ribose)
A
phosphate group
4
nitrogen bases
 Guanine
(G)
 Cytosine (C)
 Adenine (A)
 Uracil (U) – instead of Thymine
Formation of proteins
using the information
(blueprints) from DNA
 DNA
 It
is the boss of the nucleus!
copies itself in a process called
replication (DNA untwists & unzips
with the aid of enzymes called
helicases)
 The
information on DNA is copied
(transcribed) onto a mRNA strand
The
process of copying a
sequence of DNA (a gene) to
produce a complementary
strand of RNA.
 #3
– Thymine is replaced by
Uracil
Language
of DNA = A, T, C, G
Language
of RNA = A, U, C, G
Language
of Proteins = 20 Amino Acids
 Sequence:
TACGTATGAAAC
 Complimentary
base pairs (DNA)?
A T G C A T A C T T T G
 Transcribe
DNA to mRNA?
U A C G U A U G A A A C
 The
mRNA carries the genetic code
“blueprint” (to make proteins) out
of the nucleus and into the
cytoplasm
 The
mRNA “foreman” tells the tRNA
which amino acids to put together to
make a protein at the ribosome.
 The
process in which mRNA is decoded
and a protein is produced.
 tRNA
reads the mRNA 3 bases at a
time (called a codon)
*Codon – a 3 nucleotide sequence that codes for
an amino acid (amino acids make up proteins)
Codons
are read, without spaces, as
a series of 3 nucleotides
DNA to RNA = Transcription
RNA to Protein = Translation
Alligator Book
Page 338
 Each
codon “codes” for/determines an
amino acid
 Amino
Acids are joined together to
make a protein
 Amino
acids are added until a “stop
codon” is reached
 UAG,
UAA, UGA
“Stop” = end of a polypeptide chain
 The
basic components of DNA are the
same in all living things.
 Example:
the codon (amino acid) UUU will
code for the amino acid Phenylalanine in an
armadillo, a cactus, yeast, a human, etc.
 This
also means a scientist can insert a
gene from 1 organism into another to
make a functional protein.
DNA
Function
# of
Strands
Type of
Sugar
Bases
Processes
Involved in:
RNA
DNA
RNA
Creates genes
(which code for
proteins)
(mRNA) Takes the
DNA code to the
ribosome
2
1
Type of
Sugar
Deoxyribose
Ribose
Bases
A, T, G, C
A, U, G, C
Processes
Involved in:
Replication &
Transcription
Transcription &
Translation
Function
# of
Strands
Using
the Key, record the DNA sequence
that was used along with the
complimentary base pairs
Transcribe
the complimentary base pairs
into RNA
Circle
Use
the 2 codons
the chart to determine which amino
acids your codons code for