•Humans share 50% of their DNA with bananas.
•Cells can contain 6-9 feet of DNA. If all the DNA in your body
was put end to end, it would reach to the sun and back over 600
times.
•DNA in all humans is 99.9 percent identical. It is about one tenth
of one percent that makes us all unique, or about 3 million
nucleotides difference.
•DNA can store 25 gigabytes of information per inch and is the
most efficient storage system known to human. So, humans are
better than computers!!
•In an average meal, you eat approximately 55,000,000 cells or
between 63,000 to 93,000 miles of DNA.
•It would take a person typing 60 words per minute, eight hours a
day, around 50 years to type the human genome.
1. Name the four bases in DNA and describe the structure of DNA
using the following terms: Nucleotide (sugar, phosphate,
base), Complementary base pairing, Double Helix, and
Hydrogen bonding
2. Describe DNA replication with reference to three basic steps:
“Unzipping”, Complementary base pairing, and Joining of
adjacent nucleotides.
3. Define recombinant DNA
4. Describe three uses for recombinant DNA
5. Compare and contrast the general structural composition of
DNA and RNA
DNA is composed of units called NUCLEOTIDES, which are
composed of three sub-molecules:
1. Pentose Sugar (deoxyribose)
2. Phosphate
3. Nitrogen Base (purine or pyrimidine)
DNA is composed of two
complimentary strands of nucleotides
joined by hydrogen bonds:
Adenine with Thymine (A-T or T-A)
They join with 2 hydrogen bonds
Cytosine with Guanine (C-G or G-C)
They join with 3 hydrogen bonds
DNA twists into a double helix
http://highered.mcgrawhill.com/sites/0073383198/student_view0/chapte
r2/animation_quiz_-_dna_structure.html
http://www.biostudio.com/demo_freeman_dna_coiling.htm
1. DNA directs the machinery of a cell to make specific
proteins, and, therefore, DNA indirectly controls all of the
functioning of all living things.
2. DNA stores the hereditary information of an individual
3. DNA has the ability to mutate (change). This allows for
new characteristics and abilities to appear which may help
an individual to survive and reproduce (EVOLUTION).
4. Self replication: DNA has the ability to
make copies of itself
1. DNA replication is called ‘semi-conservative’.
2. Semi-conservative replication is the process in which the
original strands of DNA remain intact and act as
templates for the synthesis of duplicate strands of DNA.
3. One copy of a DNA molecule will split apart to make two
complete copies of itself. Each new DNA molecule is
made up of half of the old molecule and half of a new
molecule.
SHORT CLIP: http://www.youtube.com/watch?v=Tjl_BBQtXNE
1. UNZIPPING: The DNA molecule ‘Unzips’
as the hydrogen bonds between the base
pairs are broken. The enzyme
HELICASE causes this unzipping to occur.
2. COMPLEMENTARY
BASE PAIRING:
Complementary
nucleotides move into
position to bond with the
complementary bases on
the DNA chain.
3. FORM NEW SUGAR PHOSPHATE BACKBONE: The
nucleotides join as the sugars and phosphates bond to
form a new backbone. This process occurs due to the
enzyme DNA POLYMERASE which also checks for
mistakes as it goes.
4. This process continues along the primary chain until we
have 2 IDENTICAL STRANDS of DNA molecules
(assuming there have been no errors made).
SHORT VIDEO CLIP
‘DNA Replication Process’ (3-D
animation):
https://www.youtube.com/watch?v=27TxKoF
U2Nw
Goes into a little more detail than we’ll cover,
but it’s the ‘whole story’!
1) Mutations can occur
naturally or through
environmental factors.
Environmental mutagens
include some chemicals
(food additives, pesticides,
plastics) and radiation
(X-rays to UV light).
2) A gene mutation is a change of one or more
nucleotides in a single gene. There are 3 types.
a) Addition
b) Deletion
c) Substitution
GENE MUTATIONS
Deletion: one nucleotide base is left out. All of the amino acids after
a deletion will be wrong, so SHAPE and FUNCTION of protein are altered.
Serious.
Addition: one extra nucleotide base is added. This will also change
the entire amino acid sequence of the protein, so SHAPE and FUNCTION
of protein are altered. Serious.
Substitution: when single bases or short pieces are replaced with
one another.
Example: Sickle-Cell Anemia, only one nucleotide base is switched.
This causes only 1 amino acid to change, but it is an important one.
This type of mutation is usually not as serious as the 1st two. It just
depends on which amino acid is affected (does it have an ‘R’ group with
a +,-, or S group?)
3. Chromosomal mutations: a mutation of all or part
of a chromosome. These affect many genes.
Example #1: crossing
over where one part of a
chromosome changes
places with another.
This can cause extra
pieces, missing pieces, or
the exchange of pieces of
chromosomes.
Cri du Chat Syndrome
("Cry of the cat" in French) is a genetic
disorder caused by the loss or
misplacement of genetic material from
the 5th chromosome.
It was first identified in 1963 by Professor
Lejeune. He described the syndrome after the
sound that many of the babies and young
children make when crying.
Charlotte has Cri du Chat
syndrome.
Cri du Chat causes a varied level of
mental handicap. The majority of the
children need more specialized education.
Example #2:
non-disjunction = extra
chromosomes or missing
chromosomes due to
mistakes made during
meiosis.
Down Syndrome occurs in approx. 1 in 700 births in Canada. A person with
Down Syndrome has 47 chromosomes in each cell instead of 46. The chance
of having a baby with Down Syndrome increases significantly with age; for
example, between 20 and 24 years of age, the chance of conceiving a child
with Down syndrome is 1 in 1,450, while at age 45 this probability increases
to 1 in 32.
WHAT IS KLINEFELTER SYNDROME? Discovered in
1942 by Dr. Harry Klinefelter. He studied 9 men who
had enlarged breasts, sparse facial and body hair, small
testes, and an inability to produce sperm.
By the late 1950s, it was discovered that men with
Klinefelter syndrome, had an extra sex chromosome,
XXY instead of the usual male arrangement, XY.
WHAT IS TURNER’S SYNDROME? A disorder that
results from a non-disjunction of the X chromosomes
during meiosis = X0 instead of XX. Individuals are
short and stocky; also sterile.
Definition: combining the DNA of two species.
1. Gene displacing: add an extra copy of a gene (cows
with huge teats to make double the milk) or deleting
genes (removing the rotting hormone from tomatoes).
2.
3.
Gene modification: repairing a gene (as in gene
therapy).
Gene transformation: inserting genes from a different
species to give a new function (as in making goats with
spider proteins in their milk or making bacteria that create
human insulin).
Recombinant DNA
refers to DNA which
has been altered
by joining genetic
material from two
different sources!
http://www.sumanasinc.com/webcontent/anisamples/m
olecularbiology/plasmidcloning_fla.html