Biology
1
Chapter
11
DNA and Genes
Chapter 11 Terms
CHROMOSOMAL
MUTATION NONDISJUNCTION
CODON POINT MUTATION
DOUBLE HELIX REPLICATION
FRAMESHIFT
MUTATION RIBOSOMAL
RNA
MESSENGER RNA TRANSCRIPTION
MONOSOMY TRANSFER
RNA
MUTATION TRANSLATION
NITROGEN BASE TRISOMY
Every cell must _____________and
____________information needed to make proteins.
DNA (deoxyribonucleic acid) - stores information
RNA (ribonucleic acid) – transmits information
I. DISCOVERY OF DNA
A.
Rosalind Franklin (1952)-
took photograph of DNA
molecule’s double helix structure using x-ray crystallography
B.
James Watson and Francis Crick- came up with current 3D model
of DNA structure
C.
Erwin Chargaff- showed
how nucleotides specifically pair and why
II. DNA
(deoxyribonucleic acid) - complex, organic
molecule found in the _______ which is responsible for the diversity of cells
and life.
A.
Primary functions
1.
________ and ______
information to ___________ all cell activities
2.
copies itself __________so
new cells can be created
B.
Structure of DNA
1.
Double helix
2.
Sides of ladder made
up of alternating sugar and phosphate molecules
3.
Steps of ladder made
up of pairs of nitrogenous bases
III. BASES
A.
Purines- larger in size; double ring structure
1.
Adenine
2.
Guanine
B.
Pyrimidines- smaller size; single ring structure
1.
Thymine
2.
Cytosine
3.
Uracil
C.
Purines bond _______
with pyrimidines and are attached by
___________ bonds
Adenine (A) only bonds to Thymine (T)
Guanine
(G) only bonds to Cytosine (C)
D.
Why purines only bond with pyrimidines:
1.
________- a small with a
large allows the width of the ladder to
be more consistent; it is more stable and has more
strength
2.
________- each base has
their own unique shape; they fit together
like puzzle pieces
IV. REPLICATION OF DNA
A.
replication – the
process of producing an _________ copy of DNA
1.
takes about ____ hours
to complete
2.
takes place in the _________
3.
extremely accurate
because of built in proof reader system
(only one mistake
per 1 billion copies)
B.
Steps of Replication
1.
An ___________, DNA
Helicase, attaches to DNA and “unzips” the two strands; therefore ____________
the Hydrogen bonds.
Draw this
step
2.
The original strand of
DNA serves as a template (____________).
Draw this
step
3.
The newly unpaired
bases, pair with free-floating bases that are ________________ to the original
side.
Draw this
step
4.
Another enzyme, RNA Polymerase,
____________ (puts together) the bonds between the “new” bases to the “old”
bases, and the sugars to the phosphates.
Draw this
step
5.
_____ “new” DNA molecules
are formed, each containing an old and
a new strand.
Draw this
step
v
Replication occurs ________________ at many points along the DNA
molecule.
§
______ provides the
energy for this process
§
Factors that can
damage DNA are known as ___________
(heat,
radiation, chemicals)
V. RNA (ribonucleic acid)- a _________ strand of bases, sugar,
phosphates;
they are found _____________ the cell and are
responsible for ________________
A.
Ways RNA differs from
DNA
RNA
DNA
1.
single stranded double stranded
2.
sugar = ribose deoxyribose
3.
base Uracil Thymine
B.
Types of RNA
1.
mRNA (_____________ RNA)-
made in nucleus, carries a single message from DNA to ribosomes.
2.
tRNA (____________ RNA)- floats around in cytoplasm picking
up _____________; it carries the amino acids to the ribosomes.
3.
rRNA (____________ RNA)- the _______ of protein synthesis
C.
Codon- a 3 base long
unit of ________; each codon codes for or recognizes a specific amino acid.(64
possible codons)
1.
Initiator codon- the
spot on the mRNA strand where making the protein
_________ (AUG- start
codon)
2.
Stop codon- the spot
on the mRNA where the protein ______ being made
(UAA, UAG, UGA- stop codons)
VI. TRANSCRIPTION- the process that _________ RNA from DNA
* DNA must be unwound for this to take place
Step 1: An enzyme, RNA polymerase, binds to DNA, causing
DNA to “unzip” and
separate into 2 separate strands.
Draw this step
Step 2: RNA polymerase directs the formation of H- bonds between
DNA and the free-floating nucleotides
Draw this step
Step 3:
Once the complementary base pairs are formed, RNA
polymerase moves along the “new” RNA strand forming the
sugar/phosphate
bonds.
Draw this step
Step 4: When all of the bonds are completed, and when RNA
polymerase reaches
the “stop” codon, the new single strand of
RNA is released.
Draw this step
VII. Protein-
a long chain of amino acids (50-3000 amino acids long)
A.
May use any ______________
of the 20 amino acids found in nature
B.
The sequence of amino acids will vary
depending on the protein being made
C.
Protein synthesis- the
__________ of making a protein
§
happens inside the ribosomes
VIII. Translation-
the process of making a protein using mRNA
Step 1: mRNA leaves the nucleus
Step 2: mRNA goes to the ribosomes (the site where proteins are put
together)
Step 3: Free-floating amino acids are
transported by tRNA to the
ribosome
(anticodon- 3 base
unit of tRNA complementary to a
codon)
Step 4: Polypeptide assembly begins
when ribosome attaches at the AUG
codon on the mRNA strand
Step 5: The tRNA anticodon UAG brings the proper amino acid to
the
complimentary codon on
mRNA
(several ribosomes are
translating the mRNA at the same
time)
As the ribosome moves down the mRNA, amino acids are
added to the chain.
Step 6: When ribosomes reach “stop”
signal, the mRNA is released
and the polypeptide
is complete.
Gene- the area of DNA
that directs the formation of a polypeptide; several genes’
information may be needed to make a particular protein
IX. Mutation-
a change in DNA (______ mistake or change in the DNA sequence).
Types of
mutations:
1. Point mutation- a __________ amino acid placed in the wrong spot; a
change in a single base pair
THE DOG BIT THE CAT
THE DOG BIT THE CAR
2. Frameshift mutation- a single base pair ________or ____________
from the DNA strand
(every codon after the mutation would be incorrect)
THE FAT CAT ATE
THE HAT
Deletion THE ATC ATA TET HEH AT
Insertion THE FAT CCA TAT ETH EHA T
3. Chromosomal mutation- chromosomes may have _________ broken
off or lost during mitosis or
meiosis; the
broken off parts may reattach____________.
Types of chromosome mutations:
1.
Deletion- when part
of a chromosome is broken off and
__________ reattach
2.
Insertion- part of a
chromatid breaks off and reattaches to the
_____________________ (gene duplication on the
same chromosome)
3.
Inversion- part of a
chromosome breaks off and reattached
_____________
4.
Translocation- part
of one chromosome breaks off and is added to
a
____________ chromosome
5.
Disjunction- failure
of a chromosome to _____________ properly
during meiosis (i.e. Trisomy 21- Down Syndrome)
Causes of
Mutations
1.
Mutagen- ______ substance that causes a mutation
2.
Carcinogen- a mutagen that specifically causes ___________
3.
Terratagen- a mutagen that
causes defects in __________ children
Environmental factors- pesticides, UV rays,
x-rays, radioactive
substances, other chemicals