PPT# 4 Notes: Mutations and Regulation ... Date______________Per._______

PPT# 4 Notes: Mutations and Regulation
Name_______________________
Date______________Per._______
I. Making Mistakes
ƒMutations = _________________in the genetic material (mistakes)
Several types:
1. Gene mutations = mutation to a single __________________
2. Chromosomal mutations = mutations to the whole _______________________
1. GENE Mutations
ƒPoint mutations – involve changes to one or a few nucleotides;
affect a _____________________ in the DNA sequence
Examples of Point Mutations
a) Substitutions - one nucleotide base is _____________________ for another
Ex: AGGUC changed to ACGUC
The dog bit the cat
changed to… The dog bit the __________.
ƒAffects ___________ amino acid – ______________ damage!
(but can still be bad! (sickle cell anemia for example))
b) Insertion: one nucleotide ________________
…AAU CGC GGG… becomes …ACA UCG CGG…
c) Deletion: one nucleotide _________________
…AAU CGC GGG… becomes …AAU GCC GGG
ƒTHESE can be very ____________!!!
Because they are Frameshift Mutations
ƒFrameshift mutations – adding or deleting a nucleotide
causing a ________________ of codons.
ƒAUG GCC UAC CGA…
AUU GGC CUA CCG A…
Or
ƒAUG GCC UAC CGA
AGG CCU ACC GA…
It’s like this…frameshifting.
ƒThe cat ate the fat rat.
Tec ata tet hef atr at…
Or
ƒThe dog ran and bit the cow.
The edo gra nan dbi tth eco w.
ƒThese can totally ____________a whole gene!!! (depending on where it occurs)
2. Chromosomal Mutations
ƒInvolves changes in the number or structure of the entire ______________________.
There are:
a) Deletions – _____________ of part of the chromosome
b) Duplications – ________________ copies of part of the chromosome is made
c) Inversions – ___________________ the direction of some of the chromosome
d) Translocations – part breaks off and ___________________ to another
chromosome
3) Polyploidy: an organism has an _____________ set of chromosomes.
ƒLethal or harmful to ________________
Ex: Most die as embryos or fetuses; defects in nearly all organs.
ƒ Plants that are polyploid are often ________________ and _________________!!
Ex: (bananas, strawberries, pumpkins, other fruits/veggies)
Luckily…
ƒMost mutations are ________________ – have little or no affect on the organism
ƒOthers are ________________ (disorders, cancer, etc.)
ƒBut, they are the source of genetic ________________ though!! Help things adapt.
II. Gene Regulation
1. DNA and RNA polymerase and other enzymes also “_________________” the
DNA and RNA to fix mutations if possible.
2. Repressors are proteins that bind to specific genes on chromosomes
________________ transcription of a gene until conditions are such that the gene
is needed.
3.Other types of proteins can _____________________ transcription if necessary.
III. Differentiation
ƒA life starts with ___________ cell.
ƒThey have to “know” to ______________ (differentiate)
ƒ___________ genes control differentiation – they are the master control gene!
ƒIf __________________, problems arise – you can grow legs instead of antennae on
fruit flies!!
ƒThe control genes are ____________________ in all animals – they took an eye
gene and put it in the leg gene of a fruit fly and grew an eye on the fruit fly’s leg!
ƒThis is where _________________ cell research comes in!!!
CRITICAL THINKING: DNA AND SUN EXPOSURE
Analyzing processes can help you understand how a complex system works. When you analyze, you
break something down into its parts. You examine how each part contributes to the functioning of the
whole. Once you understand how the parts are related you should be able to explain the process to
someone else.
It is now common knowledge that exposure to the ultraviolet rays (UVR) of the
sun can lead to several types of skin cancer and to premature aging of the skin. The
intensity of the ultraviolet rays actually alters and breaks certain sections of the DNA
strand; thus mutations occur.
To repair the structural damage done by the sun, a group of proteins, ultraviolet
radiation A, B, and C (better known as Uvr A,B, C) work together with adenosine
triphosphate (ATP). In this process, the UVr ABC proteins attach to the ends of DNA
molecules and move along the strand like a zipper. As the proteins advance, they
unwind the coiled DNA one section at a time. Once a section of DNA is unwound, it is
accessible for repair by another protein, Uvr D. The Uvr D protein cuts out the sundamaged area, and DNA polymerases create a new section of DNA and insert it into
the strand. The energy for this process is derived from, the energu-storing molecule
ATP.
The more often people are exposed to the ultraviolet rays of the sun, the harder it
is for their Uvr proteins to repair their DNA. The results of one study suggest that
reduced repair of DNA can lead directly to the development of basal cell carcinoma
(BCC), a fatal skin cancer. The ability of DNA to repair itself declines normally with age.
This means that, in terms of DNA repair, a teenager who spends a lot of time in the
sun is as likely to develop BCC as a person in their 60s!
APPLICATION: Write a complete sentence to each question.
1. How does ultraviolet light damage the DNA of skin cells?
2. What chemical compounds help to repair the damage done to the DNA
strands?
3. Describe the process by which these compounds repair the DNA.
4. What two factors contribute to the development of Basal Cell Carcinoma?
5. Why is this information important ?
6. Summarize this information in 3 sentences.
Electromagnetic radiation exists in a range of wavelengths, which are cut
into major divisions for our convenience. Ultraviolet B radiation, harmful to
living organisms, represents a small portion of the spectrum, from 290 to
320 nanometer wavelengths. (Illustration by Robert Simmon)
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