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Chapter 11 466
Character Traits
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(p.350)
Humans are different in many
ways.
Character traits are the
physical, psychological, and
physiological attributes that
vary from individual to
individual.
Chromosomes
Most eukaryotic cells
contain a nucleus.
 The nucleus contains the
genetic information.
 The main component of the
nucleus is chromatin.
 Chromatin is a mass of DNA
and proteins.
 Humans have 46
chromosomes.

Chromosomes are visible
under a microscope.
 They are formed when
chromatin contracts.
 Chromosomes are the carriers
of the gene or unit of heredity.

DNA p.353
(Deoxyribonucleic Acid)

GENES – a DNA
segment that
contains info for
making proteins
which CODE FOR A
SPECIFIC TRAIT

DNA is made up of
repeating molecules
called
NUCLEOTIDES
DNA Nucleotide
Phosphate
Group
O
5
O=P-O CH2
O
O
N
C1
C4
Sugar
(deoxyribose)
C3
C2
Nitrogenous bas
(A, G, C, or T)
Watson & Crick proposed…
•DNA had specific pairing between
the nitrogen bases:
ADENINE – THYMINE
CYTOSINE - GUANINE
•DNA is made of 2 long strands of
nucleotides arranged in a specific
way called the “Complementary
Rule”
DNA Double Helix
“Rungs of ladder”
Nitrogenous
Base (A,T,G or C)
“Legs of ladder”
Phosphate &
Sugar Backbone
PROTEINS (p.355)
Proteins are responsible for
our physical appearance,
they also make sure that our
body can function.
 The human body has more
than 100 000 proteins each
with a specific role.
 Genes provide the
information to make
proteins.

Example of Protein Tasks
Support: Elastin is a protein
that make our skin firm yet
elastic.
 Transport of substances:
Hemoglobin is a protein that
carries O2 in the blood.
 Immunity: Antibodies are
proteins that protect us
from disease.

 Control
and Message
Relay: Hormones
areproteins that help
make the body develop
properly.
 Catalysis: Enzymes are
proteins that speed up
biochemical reactions in
the body.
Protein Structure p.356
Proteins are made up of one
or more chains of small
units called amino acids.
 There are 20 different amino
acids.
 Some chains are very long,
containing 600 amino acids.
 Usually proteins have an
average of 100-200 amino
acids.

Protein Synthesis

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Our cells have the ability to
make the proteins they need.
The genes that have the
instructions to make the
proteins are in the cell nucleus.
The actual process is carried
out by ribosomes, which are
outside the nucleus.
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Since DNA cannot leave the
nucleus, a messenger is needed
to bring the information from
the DNA to the ribosome.
This messanger is RNAribonucleic acid.
RNA is a single strand.
In RNA, Thymine(T) is replaced
with Uracil (U).
The sugar in DNA is deoxyribose
but in RNA it is ribose.
Two types of RNA
Messanger RNA (mRNA) is
the messenger for carrying
the instructions from the
gene to the ribosome.
 Transfer RNA (tRNA)
transfers the amino acid in
the cell’s cytoplasm to the
ribosomes in order to make
proteins.

DNA RNA  protein: and overview of
information flow in a cell

Making a protein
from the
instructions in the
DNA is a two step
process:
Transcription and
Translation
Read p.358-359
Principals of Heredity p.358
 There
are similarities
between members of the
same family.
 Heredity is the
transmission of parent’s
character traits to their
offspring.
Gregor Mendel “father of
genetics”
Please copy
 Mendel
studied the inheritance
of one trait. (for example plant's
height, color of flowers or
shape of seeds).

Crossbreeding: Is the exchange of
gametes between 2 different
individuals during sexual reproduction.
Steps of
Mendel's
Experimentcrossbreeding
p.360-361
Alleles
p.362
When Mendel was doing his
research he did know about
chromosomes or genes.
 He did know that there must
be several possible
alternatives for each “gene”.
These different forms are
called alleles.
 An allele is a possible form
of a gene.

Homozygotes and
Heterozygotes p.362

When both alleles for a
certain character trait are
identical, this is a
homozygote. (e.g. RR or rr)

When both alleles are
different for a given trait,
this is a heteozygote. (e.g.
Rr)
Dominant and Recessive
Alleles p.363
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Mendel discovered that some
alleles are dominant and others
recessive.
The allele that is expressed is
the dominant allele.
Genotype and Phenotype p.364
A genotype is the person’s
genetic inheritance.
 A phenotype is the way a
genotype expresses itself.
 Each allele is represented
by a letter.
 A dominant allele uses a
capital letter and a
recessive allele a lower
case letter.

Cloning
p.369
There are 2 natural
methods of reproduction:
sexual and asexual.
 Until now, we have the
transmission of heredity
through sexual
reproduction.
 Asexual reproduction
involves only one parent.

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Cloning is the reproduction of an
individual, part of that individual or
one of its genes in order to obtain an
exact copy.
 There are 2 types of cloning: natural
and artificial.
When cloning happens in nature
without any human intervention it
is called natural cloning. (p.369)

Natural cloning
produces
genetically
identical
individuals
through asexual
reproduction.
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There are 3 forms of
natural cloning:
Budding
Layering
Propagation by cutting
Artificial Plant Cloning
p.370
Have you or your parents or
grandparents ever taken a
cutting from a plant, put it in
water until roots grow and
then transfer it to a pot.
This is an example of
artificial plant cloning.
 Farmers often use the in
vitro method to clone crops.
 Read p.371 carefully.

Animal Cloning

p.372
To clone animals artificially
the steps are:
1) remove a cell containing the DNA of
the animal to be cloned.
2) take an ovum from another animal
and remove its nucleus
3) combine the DNA cell and the DNAless ovum
4) implant the new cell in the uterus of
a surrogate mother
5) A clone of the target animal will
develop in the surrogate mother.
Who did they clone?

In 1997, they
successfully cloned
the first animal- a
lamb named Dolly.
Why do they want to
clone animals?
 They do this to study
genetic disorders and
disease susceptibility.
 It is done strictly for
medical research.
Human Cloning p.373
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There are 2 forms of human cloning:
REPRODUCTIVE cloning: Using cloning
techniques to obtain a new individual
genetically identical to the one being
cloned.
Therapeutic Cloning: Using cloning
techniques to obtain tissues or organs
genetically identical to those of the person
in need of a transplant.