Download DNA - My CCSD

Biology I – NOTES - DNA Structure & Function
Name: ________________________________
The Structure of DNA
•DNA is often called the ______________________________________________________.
•In simple terms, DNA contains the instructions for making __________________ within the cell.
•Proteins are important. All chemical reactions needed for life depends on
________________________________ which are proteins.
•Watson & Crick first discovered the _________________________ structure of DNA in
______________________________.
Why do we study DNA?
•Its central importance to all life on Earth
•Medical benefits such as ___________________________________________________________
•Better food crops: __________________________________________________________________
•CSI: __________________________________________________________________________________
Chromosomes and DNA
•Our genes are on our ___________________________________.
•Chromosomes are made up of a chemical called DNA.
The Shape of the Molecule
•DNA is a very long ______________________________.
•The basic shape is like a twisted ladder or zipper.
•This is called a __________________________________________________.
The Double Helix Molecule
•The DNA double helix has ___________________ strands twisted together.
One Strand of DNA
•The backbone of the molecule is alternating _______________________________
•and ______________________________________ sugar
•The teeth are ____________________________________ bases.
One Strand of DNA
•One strand of DNA is a __________________________________ of nucleotides.
•One strand of DNA has many millions of nucleotides.
Biology I – NOTES - DNA Structure & Function
Nucleotides
•One deoxyribose together with its phosphate and base make a
__________________________________________________.
Four Nitrogenous Bases
• ______________________
• ______________________
• ______________________
• ______________________
C
T
A
G
Two Kinds of Bases in DNA
•___________________________________________________________ are single ring bases.
•__________________________________________________________ are double ring bases.
•__________________________ and ___________________________ are pyrimidines.
•___________________________________________________________________________ (pyrimidines)
•__________________________ and ___________________________ are purines.
•________________________________________________________________________________ (purines)
Two Stranded DNA
•Remember, DNA has two strands that fit together something like a zipper.
•The teeth are the nitrogenous bases but why do they stick together?
•The bases attract each other because of ___________________________________________.
Hydrogen Bonds
•Hydrogen bonds are weak but there are millions and millions of them in a single molecule of DNA.
•The bonds between cytosine and guanine are shown in (a) with dotted lines
(a)
C
N
C
NC C
NN
NC
C
C CO
N
C N
N
(b)
O
C
OCN CC
C
C
NC NN
CN C
NC
N
Biology I – NOTES - DNA Structure & Function
•The bonds between adenine and thymine are shown in (b) with dotted lines
•When making hydrogen bonds, _________________ always pairs up with _____________
•_____________________ always pairs up with ___________________
Chargraff’s Rule
• Adenine and Thymine always join together: A
• Cytosine and Guanine always join together: C
T
G
DNA by the Numbers
•Each cell has about _______________________________ of DNA.
•The average human has 75 ________________________________ cells.
•The average human has enough DNA to go from the earth to the sun more than
___________________________ times.
•DNA has a diameter of only 0.000000002 m.
DNA Replication
•DNA replication produces ____________________ molecules from one.
•DNA replication begins with an ___________________ that breaks the hydrogen bonds between the
nitrogen bases and ____________________________________________________________________________________.
• Nucleotides that are floating free in the nucleus bond to the single stands by __________________________.
•Each new strand is a complement of the one of the original.
•
Let’s Practice:
Write the complimentary strand for DNA…
TGACCGAT
______________________________________________
TGGCCAATATA
______________________________________________
Biology I – NOTES - DNA Structure & Function
Protein Synthesis
•The basic shape is like a twisted ladder or zipper.
•The protein’s “code” is supplied by the DNA in the __________________________________________________.
•But proteins are “manufactured” in the ribosomes in the __________________________________________.
•STEP 1: _________________________________________________________________________
•STEP 2: __________________________________________________________________________
Protein Synthesis
•RNA is a ___________________________________ strand.
•The simple sugar in RNA is ___________________________________________.
Nitrogen Bases in RNA:
•______________________
• ______________________
• ______________________
• ______________________
A
G
C
U (replaces thymine – bonds with adenine)
Types of RNA
•_________________________________________ brings information from the DNA in the nucleus to the cell’s
cytoplasm.
•_________________________________________ part of the ribosome that clamps onto the mRNA and helps to
assemble the amino acids in the correct order.
•_________________________________________ transports amino acids to the ribosomes to be assembled into a
protein.
Protein Synthesis - Transcription
•Process: Enzyme __________________________ the DNA molecule
•Free _____________________________________ pair with complementary DNA nucleotides.
•When pairing is complete, mRNA breaks away. The DNA rejoins the original strand. The mRNA
leaves the ___________________ and enters the ________________________ to join with the ribosome.
Let’s Practice:
Write the complimentary strand for mRNA…
TGACCGAT
______________________________________________
TGGCCAATATA
______________________________________________
Protein Synthesis - Translation
1. Once the newly made mRNA leaves the nucleus, it attached to the ___________________________________.
Biology I – NOTES - DNA Structure & Function
2. Ribosomes will “read” 3 nucleotides called _____________________________ in the mRNA code at a time.
•Each codon codes for:
•____________________________________________________________________
•____________________________________________________________________
•____________________________________________________________________
3. When the ribosome reads the start sequence ( AUG ), a tRNA molecule comes along with the
_________________________________________________ ( UAC ) and the amino acid ( MET ). The anticodon is the
complementary sequence.
4. The ribosome then reads the next codons on the mRNA and tRNA transfers the amino acids to
build the protein until a “stop” codon is read.
Let’s Break the Genetic Code
1. Start with DNA:
_________________________________________________________________________________________________________
2. Write the complimentary strand for mRNA:
_________________________________________________________________________________________________________
3. Identify the codons on the mRNA:
_________________________________________________________________________________________________________
4. Identify the anticodons on the tRNA:
_________________________________________________________________________________________________________
5. Identify the amino acid sequence from the mRNA:
_________________________________________________________________________________________________________
Biology I – NOTES - DNA Structure & Function
Genetic Mutations
•Any change in the DNA sequence is called a _____________________________________________________.
•Mutations can effect _______________________________________________, which will be passed on the
offspring.
•Mutations can effect _______________________________________________, an example of which is
cancer.
•Everyone acquires some changes to their DNA during the course of their lives.
•These changes occur in a number of ways:
o
o
Sometimes there are simple _______________________________ errors that are introduced
when DNA replicates itself.
Other changes are introduced as a result of DNA damage through
____________________________________ including sunlight, cigarette smoke & radiation.
•Our cells have built in mechanisms that _________________ and ___________________ most of the
changes that occur during DNA replication or from environmental damage.
•Some of these changes occur in cells of the body – such as in skin cells as a result of sun
exposure – but are not passed on to children.
•Other errors in DNA of cells that produce the egg and sperm.
These are called
__________________________________________ and can be passed on from parent to child.
•There are three types of genetic Mutations:
1. ___________________________________________________________________________________
2. ___________________________________________________________________________________
3. ___________________________________________________________________________________
Not All Mutations are Bad
•Some result in characteristics that give the organism a great chance of _______________.
•Example: ___________________________________________________________________________________.
Point Mutation
•A change in a single __________________________________ in DNA.
•Example: __________________________________________________________________________________
__________________________________________________________________________________
Biology I – NOTES - DNA Structure & Function
Frameshift Mutation
•A single ___________________________________________ in DNA is deleted or added .
•Example: _____________________________________________________________________________________
____________________________________________________________________________________
Inversion Mutation
•An entire section of DNA is ___________________________________________.
•Example: _____________________________________________________________________________________
_____________________________________________________________________________________
Causes of Mutations
•Spontaneous - Mistake in base pairing during _____________________________________.
•________________________________ agent that causes DNA change. Examples, high energy
radiation (x-rays), chemicals (dioxins, asbestos, benzene, cyanide, formaldehyde) and high
temperatures
4 Types of Chromosomal Mutations
•______________________________________ occur when part of the chromosome is left out.
•______________________________________ occur when a part of a chromatid breaks off and attaches
to its sister chromatid.
•______________________________________ occur when part of the chromosome breaks off and is
reinserted backwards.
•______________________________________ occur when part of one chromosome breaks off and is
added to a different chromosome.
Biology I – NOTES - DNA Structure & Function