August 27, 2015
Bell Work:
• True or False: All genes are exhibited 100% of the time.
Objective:
The student will be able to…
1.
List the steps of translation by taking notes, participating in
activities, and watching a video.
2.
Describe how cells control transcription by taking notes and
participating in activities.
3.
Explain what happens when DNA replication, transcription,
or translation does not happen accurately by taking notes
and participating in activities.
Today in History
• 1859
Edwin L. Drake drilled the first
successful U.S. oil well near
Titusville, PA
• 1962
The United States launched the
Mariner 2 space probe, which flew
past Venus the following December.
Announcements
• Spirit
Week
Tomorrow is Cougar Crazy Day Friday!
• Quiz
Retakes
You must first make corrections to your
previous quiz.
You must schedule a time to retake with
me.
Controlling
Transcription
• Most
gene regulation in eukaryotes
controls the onset of transcription
This means gene regulation controls when
RNA polymerase binds to a gene
• Cells
this
use regulatory proteins to do
Called transcription factors
Controlling
Transcription
• Enhancer:
a sequence of DNA that can be
bound by a transcription factor
 Located thousands of nucleotide bases away
from the promoter
•A
loop in the DNA may bring the
enhancer and its attached transcription
factor (called an activator) into contact
with the transcription factors and RNA
polymerase at the promoter
Intervening DNA
• Genes
are interrupted by introns
 Introns: long segments of nucleotides that
have no coding information
• Exon:
the portion of a gene that is
translated into proteins
• After
a gene is transcribe introns are cut
out of the mRNA by spliceosomes and the
exons are stitched back together
Mutations
•A
change in the DNA of a gene is
called a mutation
While rare, mutations can happen
• Mutations
in gametes can be passed
on to offspring of the affected
individual, but mutations in body cells
only affect the individual
Mutations
• Mutations
that move an entire gene
location are called gene
rearrangements
Often disrupts the gene’s function
because the gene is exposed to new
regulatory controls
An example of gene rearrangements is
gene transposition
Mutations
• Gene
alterations: mutations that change a gene
 Usually result in the placement of the wrong amino acid in
a protein
• Point
mutations are single nucleotide changes
• In insertion, a sizeable length of DNA is inserted in a
gene
 Often result when transposons (mobile segments of DNA)
move randomly from one position to another
 Transposons make up 45% of the human genome
Mutations
• In
deletion segments of DNA are lost
Deletion can upset triplet groupings
• Frameshift
mutations causes a gene
to be read in the wrong threenucleotide sequence
Crash Course Biology
DNA, Hot Pockets, and the Longest Word Ever
Ticket Out
• Explain
mutations.