Chapter 12: DNA: The Molecule of
Heredity Notes
DNA determines the structure of _________
 ____ living things contain proteins
 Provides complete ___________ for making
proteins
 Made up of ___________
**Look at Chart handout for History of DNA
DNA in cells
 Located in the _______ of cells as
_____________
 Packed __________
 Consists of more than ___________ base
pairs
 _______________ DNA strands
o Can use 1 strand to make a copy of the
other strand using ________________
Nucleotides
 Make up _______
 3 parts to a ___________:
o
o
o
 Diagram (draw and label):
Nitrogen Bases
 4 possible nitrogen bases:
o ___________
o ___________
o ___________
o ___________
 Adenine (A) and Guanine (G)
o
o
o Diagram: Adenine (A) & Guanine (G)
 Thymine (T) and Cytosine (C)
o
o
o Diagram: Thymine (T) & Cytosine (C)
Chargaff:
o
o
 Nucleotides join together to form _____ chains
of ___________ base pairs
o _________ always pairs with ________
(_____ or _____)
o _________ always pairs with ________
(_____ or _____)
Structure of DNA:
o Each strand acts as a _______ or model
to make new DNA strands
 Makes new complimentary strands
through ____-______
 Example:

______ of ladder: alternating _______ groups
and ______ molecules
______ of ladder: pairs of ________ bases
(joined by weak _______ bonds)
DNA Replication:
 _____________: making a copy of ______
 DNA is copied _______ cell division
o Takes ___ hours in ______
o During the ____ phase of ________
 DNA will separate into ________
o Carried out by _________
 ______ DNA by _________
hydrogen bonds to _______ the
_______ ______
After DNA is replicated:
The Genetic Code:
 DNA controls _______ synthesis
 Proteins have chains of _____ _____
 A _____ is needed to convert _________
_____ (mRNA) into a protein
 ______________
o ______: a group of ___ Nitrogen bases
that code for an _____ ____
 ___ possible combinations of _____
 Some code for _____ ____
 Some code for making _______
 More than 1 codon can code for the
same amino acid
 There is 1 ____ codon (amino acid
___________)
o DNA  TAC RNA  AUG
 There are 3 _____ codons
o Code for no amino acids
o *** Refer to amino acid charts given in class
o The sequence of nucleotides (N-bases) is
the code for what controls the production of
all proteins
Transcription:




Occurs in the ________
Making an _____ copy of a part of ____
Makes __________ ____ (mRNA)
Requires: ______________________
o
o
o
 4 Steps:
1. ________________________________
2. __________________________________
______________________________
3. __________________________________
______________________________
4. __________________________________
______________________________
 Result of ________: formation of 1 ______stranded ____ molecule
 Example:
DNA  mRNA  Amino acid
2 Types of Nucleic Acids:
DNA
RNA
Sugar
Bases
Structure
Location in a
cell
Base pairing
3 Types of RNA
 Messenger RNA:
 Ribosomal RNA:
 Transfer RNA:
RNA Editing
• DNA has ______ (sequences of _______)
o Not involved in ________________
• _______: code for __________
o Remaining pieces of DNA  put
together with cap and tail = final RNA
molecule
DNA Controls Protein Synthesis
 What are _______?
o Long chains of ______ ______
o Key structures and regulators of _____
______
 Help with ________ parts
 Enzymes  _________ ________
 Help in ________ through cell
membrane
 Making Proteins
o Protein production is similar to building
a _____
 DNA provides _________ with
instructions for making proteins
 Workers build ________ (____)
 Other workers bring parts
(________) to the assembly line
Translation
 Process of building ___________
 Takes place in the __________
 _______ ___ (tRNA) brings amino acids to
the ribosomes
o Attaches to only 1 type of _______
____
o Amino acid will become bonded to 1
side of the _____
o The other side of the tRNA has 3
nitrogen bases called an ________
 Pairs up with mRNA ______
 Amino acids are joined by ______ ______
 Anticodon bind to the codon of mRNA
through ____ ______
o Example:
 A chain of amino acids form until a _____
codon is reached
o _______ will end
o Amino acid strand is released from the
ribosome to become ______
Mutations
 Any change in the ________ of DNA
 Can be caused by errors in:
o ______________
o ______________
o ______________
o ______________
 Mutations in reproductive cells: called
_______ _______
o Within the ____ or ______ cells (_____)
o Can produce new ________
o Can result in _______ that do not work
(can _____ organism)
o Could have ________ effects
 _______
 _______
 __________________________
 Mutations in Somatic (Body) cells:
o Not ________ on to offspring
o May _______ cell function
o Can affect ______ that control _____
division (______)
 3 types of mutations
o Point mutation (substitution)
 Change in _________ in DNA
Example: CGATTACGC (normal DNA)
CGATTTCGC (mutated DNA)
 Albinism
o
o
o Frameshift mutation
 1 N-base is ______ or ________
 Changes all ________ from that point
on
Example: CGATTACGC
CGAATTACGC (N-base added)
Example: CGATTACGC
CGTTACGC (N-base deleted)
 May cause no problems or can be
severe
 More ___________ than point
mutations
o Chromosomal mutations
 Involve many _________
 Usually very _______
 Can change location of genes or
number of copies
 Involve changes in number or structure
of chromosomes
 4 types:
 ________  taking away
 ________  adding
 ________  switching parts ex: abba
 ____________  breaking off
 Many occur from improper ________
during meiosis (_________)
 Causes of mutations:
o ___________ or random mutations
o _________ (things that cause ________)


o Source of _______________________
Gene Regulation
• Certain DNA sequences serve as _______
(binding sites for _____ polymerase)
• Prokaryotes (Ex: E. coli)
o Group of 3 genes that are turned on and
off together (called an ________)
o E. coli uses _______ as food
• Genes must be expressed  called
__________
o Lac genes turned off by ________ (binds
to ________)
• Prevents __________ of its genes
o Lac genes turned ____ by presence of
_______
• Binds to ________, allowing RNA
polymerase to transcribe genes
o Operons generally not found in
__________ cells
• Eukaryotic cells (more complex)
o Has short region of DNA (_____ box)
• ___ base pairs long
• Helps RNA __________ position
itself
o _____ genes
• Series of genes that controls ______
and _______ that develop in
_______
• Determine basic body _____
• Mutations can change organs
• Ex: fruit fly
• Expressed genes are transcribed into RNA
o Genes are expressed with help from
DNA-binding proteins