Thursday, December 10, 2015
Wednesday, December 9, 2015
18.1 Bacteria often respond to environmental change by regulating transcription Notes
18.1 Bacteria
often respond to environmental change by regulating transcription
o
Bacterial cells that can conserve resources and
energy have a selective advantage over cells that are unable to do so.
o
Natural selection has favored bacteria that
express only the genes whose products are needed by the cell.
o
Metabolic control occurs on 2 levels.
§
1st cells can adjust the activity of
enzymes already present. This is a fairly fast response, which relies on the
sensitivity of many enzymes to chemical cues that increase or decrease their
catalytic activity. The activity of the first enzyme in the tryptophan
synthesis pathway is inhibited by the pathway’s end product.
§
2nd cells can adjust the production
level of certain enzymes; that is, they can regulate the expression of the
genes encoding the enzymes. Many genes of the bacterial genome are switched on
or off by changes in the metabolic status of the cell.
Operons: The Basic Concept
o
E. coli synthesizes the amino acid tryptophan
from a precursor molecule
o
Transcription gives rise to one long mRNA
molecule that codes for the five polypeptides making up the enzymes in the
tryptophan pathway
o
When an E. coli cell must make tryptophan for
itself because the nutrition medium lacks his amino acid, all the enzymes for
the metabolic pathway are synthesized at one time.
o
The switch is a segment of DNA called an
operator.
o
Altogether, the operator and the promoter, and
the genes they control constitute and operon
o
The operon can be switched off by a protein call
the trp repressor
o
The trp repressor is the protein product of a
regulatory gene called trpR, which is located some distance from the trp operon
and has its own promoter
o
Tryptophan functions in this system as
corepressor, a small molecule that cooperates with a repressor protein to
switch an operon off.
Repressible and Inducible operons: Two Types
of Negative Gene Regulation
o
The trp operon is said to be a repressible
operon because its transcription is usually on but can be inhibited when a
specific small molecule binds allosterically to a regulatory protein.
o
An inducible operon is usually off but can be
stimulated when a specific small molecule interacts with a regulatory protein
o
Inducer inactivates the repressor
o
FIGURE 18.4
o
For the lac operon, the inducer is allolactose,
an isomer of lactose formed in small amounts from lactose that enters the cell.
o
In gene regulation, the enzymes of the lactose
pathway are referred to as inducible enzymes because their synthesis is induced
by a chemical signal
Positive Gene Regulations
o
When glucose and lactose are both present in its
environment, E coli preferentially uses glucose.
o
Mechanism depends on the interaction of an
allosteric regulatory protein with a small organic molecule, in this case
cyclic AMP
o
The regulatory protein, called catabolite
activator protein (CAP), is an activator, a protein that binds to DNA and
stimulates transcription of a gene
Virus Structure- 19.1
Virus Structure Notes- 19.1
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C:\Users\Madison\AppData\Local\Microsoft\Windows\INetCache\IE\94XOKLUC\IMG_0832.JPG
Wednesday, December 2, 2015
17.2 Transcription Notes
17.2 Transcription
- RNA polymerase: put together RNA nucleotides to DNA strand
- In bacteria:
- Promoter- where RNA starts
- Terminator- ends
- Transcription unit- piece that is transcribed
- 3 stages of Transcription
- Initiation
- Elongation
- Termination
- Promoter called a TATA box is crucial in forming the initiation complex in eukaryotes
ELONGATION OF THE RNA STRAND
- As RNA Polymerase moves along the DNA, it untwists the double helix, 10-20 bases at a time
- Transcription progresses at a rate of 40 nucleotides per second in eukaryotes
- Gene can be transcribed simultaneously by several RNA polymerases
- Nucleotides are added to the 3' end of the frowing RNA molecule
TERMINATION OF TRANSCRIPTION
- In eukaryotes, RNA polymerase II transcribes the polyadenylation signal sequences
- The RNA transcript is poreleased 10-35 nucleotides past this polyadenylation sequence
Tuesday, December 1, 2015
Monday, November 30, 2015
17.3-Modifying RNA notes
17.3-Modifying RNA
- Alteration
- The 5’ end receives a modified nucleotide 5’ cap.
- The 3’ end gets a poly-A tail
- Functions
- They seem to facilitate the expert of mRNA to the cytoplasm
- They protect mRNA from hydrolytic enzymes
- They help ribosomes attach to the 5’ end
- Split genes and RNA splicing
- Introns are noncoding regions
- Exons are eventually expressed
- RNA splicing removes introns and joins exons
- RNS splicing is carried out by spliceosomes
- Spliceosomes proteins several small nuclear ribonucleoproteins (snRNPs)
- Ribozymes
- Catalytic RNA molecules that function as enzymes and can splice RNA
- The discovery of ribosomes rendered obsolete the belief that all biological catalysts were proteins.
- 3D proteins of RNA enable it to function as an enzyme
- Form a 3D structure, base pair with itself
- Functional groups participate in catalysis
- Hydrogen-bond with other nucleic acid molecules
Tuesday, November 24, 2015
Thursday, November 19, 2015
14.4 Notes- Human Traits
Chapter 14.4- Human Traits
·
Pedigree Analysis
o
Family Pedigree- history for a particular trait
and assembling this information into a family tree describing the traits of
parents and children of a certain generation.
 |
o
The figure above shows the pedigree of a family
with a widow-peaked hairline.
o
The importance of a pedigree is to help
calculate that probability of a future child.
o
Pedigrees are more serious when the alleles
could cause a serious disease or disorder
·
Recessively Inherited Disorders
o
Carriers- heterozygotes may transmit the
recessive allele to their offspring
o
Genetic disorders are not distributed among all
group of people
o
When a disease-causing recessive allele is rare,
it is relatively unlikely that two carriers of the same harmful allele will
meet and mate.
o
Cystic Fibrosis- most common lethal genetic
disease in the United States
o
Sickle-Cell Disease- most common inherited
disorder among people of African descent
·
Dominantly Inherited Disorders-
o
Dominant alleles that cause a lethal disease are
much less common than recessive alleles that have lethal effects
o
Huntington’s Disease- a degenerative disease of
the nervous system, is caused by a lethal dominant allele
·
Genetic Testing
o
Avoiding simple Mendelian disorders is possible
when the risk of a particular genetic disorder can be assessed before a child
is conceived
o
Fetal Testing
§
Amniocentesis- tests performed in the 14th-16th
week of pregnancy
§
(CVS)- physician inserts a narrow tube through
the cervix into the uterus and suctions out a tiny sample of tissue
o
Newborn Screening
§
Some genetic disorders can be detected at birth
simply by biochemical tests.
§
(PKU) is the most common newborn screening test.
§
Fetal and newborn screening for serious
inherited diseases, tests for identifying carriers, and genetic counseling.
Tuesday, November 17, 2015
Monday, November 16, 2015
15.2 Sex-Linked Traits
Here is the Mcgraw Hill animation of Sex-Linked Traitshttp://glencoe.mheducation.com/sites/dl/free/0078802849/383935/BL_15.html.
Wednesday, October 28, 2015
Tuesday, October 20, 2015
11.2 Notes
Chapter 11
11.2- Reception
·
Ligand is highly specific
·
There will be a shape change in a receptor
·
Most signal proteins are plasma membrane
proteins
·
3 Receptor in plasm a membrane
o
G-Protein- coupled
o
Receptor tyrosine kinases
o
Ion channel receptors
·
G protein- coupled receptors (GPCR)
o
Largest family
o
Works with help of a G protein
o
G protein acts as an on/off switch- if GDP is
bound to the G protein, the G protein is inactive
·
Receptor tyrosine kinases (RTKs)
o
Attach phosphates to tyrosine
o
Can trigger multiple signal transduction pathways
at once
o
Abnormal functioning is associated with cancers
·
Ligand- gated ion channel
o
Acts as a gate when receptor changes shape
o
When a signal molecules binds as a ligand to the
receptor, the gate allows specific ions, such as NA+ or CA+,
through a channel in the receptor
·
Intracellular Receptor
o
Found in the cytosol or nucleus of target cells
o
Small or hydrophobic chemical messengers
§
Activate receptors
·
EX: Steroid/ Thyroid hormone
o
An activated hormone receptor complex can act as
a transcription factor, turning on specific genes
Wednesday, October 14, 2015
Read Something, Say Something
I have shared two articles with you in class. The first was Tiny Cavers, about the discovery of a new early human species. The second was Overthinking Worriers, about how overthinking worriers may be creative geniuses. Please read one of these articles and write a comment below, tell us what article you read and tell us about what you thought was most interesting in that article.
Tuesday, October 13, 2015
Monday, October 12, 2015
Thursday, October 8, 2015
Drawing Flies - Biology Comics
If you need to study, but need a little comic relief as well, check out the Drawing Flies Blog. Go learn something!
Tuesday, October 6, 2015
Tuesday, September 29, 2015
Legacy of Learning: Cells
I have uploaded your Cell LoL documents. Click here to view the documents.
BioChem folder Available on Google Drive
If you want to check out your LoL Projects I have added the scanned documents to a Google Drive Folder. While you are at it feel free to add the pdfs to the appropriate Live Binder pages (you know, in all your free time). Click here for the link to the folder!! You should be able to click on each document for a better view.
Monday, September 28, 2015
Metabolism & Enzyme Notes
My version of the notes is available on Google Drive. The notes are not divided by section of the book, you will have to go through to book also.
Wednesday, September 23, 2015
7.3 Passive Transport
Passive transport is diffusion of a substance across a membrane with no energy involved. Diffusion is the movement of molecules of any substance so that they spread out evenly into the available space. 
The movement of particles will flow from high concentration to low concentration. Note, to go from low to high you need energy in the from of ATP to move the solute against its concentration gradient.
Osmosis is the diffusion of water through a semi-permeable membrane. This is especially important when the solute particles are too big to flow through the membrane. In this case the water moves to equalize the concentrations.
Tonicity is the ability of the surrounding solution to cause a cell to gain or lose water.
There are many examples of diffusion, some of which include proteins, and this process is vital to cell function and overall health.
Tim Barber
The movement of particles will flow from high concentration to low concentration. Note, to go from low to high you need energy in the from of ATP to move the solute against its concentration gradient.
Osmosis is the diffusion of water through a semi-permeable membrane. This is especially important when the solute particles are too big to flow through the membrane. In this case the water moves to equalize the concentrations.
Tonicity is the ability of the surrounding solution to cause a cell to gain or lose water.
There are many examples of diffusion, some of which include proteins, and this process is vital to cell function and overall health.
Tim Barber
6.5 study guide
6.5- Study Guide
1.) The theory that an early ancestor of eukaryotic cells engulfed an oxygen-using nonphotosynthetic prokaryotic cell is? Endosymbiont Theory
2.) Mitochondria is the site of what? Cellular Respiration
3.) Infoldings in the inner membrane that prevent it from being smooth are called? Cristae
4.) Site of photosynthesis that contains green chlorophylls is called? Chloroplasts
5.) Flattened, interconnected sacs that make up another membranous system inside of chloroplast are called? Thylakoids
6.) What do peroxisomes do? Take toxins and convert them to water
Tuesday, September 22, 2015
Friday, September 4, 2015
5.4 Proteins
Proteins are large macro molecules consisting of one or more long chains of Amino Acids(Polypeptides). Proteins have several functions in the body. They speed up chemical reactions(enzymes), defend the body against foreign agents(antibodies), communicate between cells or coordinate processes(messengers), provide structural support, and they can store and transport 'Nutrients'.
TRB
TRB
Thursday, September 3, 2015
Thursday, August 27, 2015
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