Download Chp 11.2: Nucleic Acid structure and sequence

DNA was discovered(?) by James
Watson
and Francis Crick in 1953.
Theorized by Gregor Mendel in
the mid 1800s.
DNA stands for Deoxyribonucleic Acid.
It is a molecule made from a long pattern of 4 different
pieces called ‘nucleotides.’
DNA contains a patterned ‘code’ that is unique to each
person. This is called the ‘Genetic Code.’
The Genetic Code is read as directions by cell
ribosomes to produce EVERYTHING about your
body—its features, coloring, blood type, even
personality and intelligence.
4 Nucleotides together in DNA
DNA’s basic shape
is a twisted
ladder.
A. The outside
supports of DNA’s
‘ladder’ is an
alternating pattern
of sugar and
phosphate
molecules.
B. The inside ‘rungs’ of the ladder are 1 of the 4
Nitrogen-based molecules –these molecules make the
actual Genetic Code’s pattern.
The 4 N-bases are…
1. Adenine (A)
2. Thymine (T)
3. Cytosine (C)
4. Guanine (G)
Each and every thing made by,
done, or built by the body is
done when cells read the genetic
code in DNA as directions to
make or do something.
The nitrogen-based molecules
of DNA’s code are always
paired together with another.
This is called Complimentary
Base Pairing.
Because of their molecular shape, each nitrogen base
pair will ONLY pair up with another pair.
The pairing-up (compliment) rule is…
1. Guanine ALWAYS compliments with Cytosine
2. Adenine ALWAYS compliments with Thymine
The DNA itself is divided into sections, “chapters”,
and pieces for organization reasons.
A.
1 DNA is divided into 46 ‘chapters’ called
Chromosomes.
Human DNA has 46 chromosomes
Monkey DNA is 42 chromosomes
Dog DNA has 76 chromosomes
Fruit Fly DNA has 8 chromosomes
Potato DNA has 48 chromosomes
Each chromosome is
divided into thousands of
small sections called Genes.
Each Gene is divided into
section of 3 base pairs called
a Codon.
Everything in the body are made from carbon-based
molecules called proteins.
Proteins are made by combinations of 20 ‘ingredients’
called amino acids.
proteins are made
when the cell reads
the Genetic Code as
directions to
assemble amino
acids into proteins.
The proteins
themselves are used to
do things like repair the
body, create new
hormones and fluids,
and perform certain
processes, like
digestion.
The first Codon (3
base pair set) tells
the ribosome what
the gene is, like a
title page of a book.
The next codons are
the step-by-step
directions how to
combine amino
acids to make the
protein.
The very last codon tells the ribosome that the job is
finished, and it can stop working (conveniently called
the ‘Stop-Codon’)
DNA Replication is the process used to make daughter
chromosomes during Mitosis.
1.
When a cell copies DNA,
the Twisted DNA strand
straightens, like a ladder.
2. An enzyme called DNA
Polymerases separates the
2 backbones of the DNA
molecule between the
Nitrogen Bases, forming 2
half-strands of DNA—like
a zipper.
3. After splitting the molecule,
a new half on DNA is
made.
4. The new half is made to
match the original DNA
half using Nitrogen Base
Pairing
(C + G, T + A)
5. Each original DNA
molecule half is given a new
matching half, creating 2 new
strands of DNA
DNA = Deoxyribose Nucleic Acid
RNA = Ribonucleic Acid
RNA is a copied
piece of a DNA
molecule that
contains a
certain gene and
is used to create
characteristics.
--A Copy of a gene is used to make
proteins instead of the original
DNA code in order to protect the
original DNA from corruption.
1.
DNA = entire genetic code—
RNA = only 1 gene/part from
your DNA.
2. DNA = twisted double strand—
RNA 1 single strand.
3. DNA Nitrogen Bases= A, C, G T
RNA Nitrogen bases = A C G and
Uracil (replaces Thymine)
Step 1 –Transcription
--RNA Polymerase enzyme separates a piece of DNA
containing a certain gene, like (hair color)
Step 1 –Transcription
--The enzymes then create
RNA (copied DNA Gene
segment) using Nitrogen
Base Pairing from the
Genetic Code.
Step 3; After the RNA is
made, the DNA is closed
together again.
Step 4: Translation—The
“code” of the newly made
RNA is sent out of the cell
nucleus and sent to
ribosomes.
The ribosomes translate RNA codes into the
directions to make proteins for traits. (like color
pigments)
Remember: DNA is basically a set of directions that tell
cells how to construct your traits or how a cell should
be made.
A mutation is the result of
DNA that has been copied
wrongly or made incorrectly
whenever normal body cells
replicate or when an egg cell
becomes fertilized .
These errors in DNA can be caused by long-term
chemical or radiation exposure.
These errors in Gene copies can either replace the
correct, normal Genetic Codes with a different Code,
or leave out a piece of a trait’s code completely.
Mutation in a regular body cell’s DNA as it replicates
itself will create a new, irregular, harmful cell known
as Cancer Cells.
DNA mutations during the conception of an
organism lead to birth defects, Genetically linked
diseases, or Albino creatures
–an example of a harmful
mutation of the genes
used to make the human
skeleton.
Although many mutations are harmful to cells and
organisms, some are actually helpful, and can create
improved versions of an organism.