BISC 101 Study Guide - Final Guide: Posterior Pituitary, Eudicots, Sebaceous Gland

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Cell Membrane Function/Structure
Describe what the events look like for a cell when its Hypertonic,Hypotonic, &
isotonic?
-Hypertonic: Cell ‘shrivels up
-Hypotonic: Cell ‘swells up’ or bursts (Lysis): Lesser solute concentration
-Isotonic: Cell stays the same
What is a cell membrane permeable and impermeable to, when given a
description of what happens to a cell in a specific solution
-Hypertonic in cell: (2 cases)
(1) The cell membrane is permeable to the solute which causes it to leave the cell
and water follows, causing it to shrivel up.
(2) The cell membrane is not permeable to the solute and only water leaves the cell.
-Hypotonic in the cell: (2 cases)
(1) The cell membrane is permeable to the solute, causing solute to diffuse into the
cell bringing water via osmosis behind it making the cell swell.
(2) The cell is not permeable to the solute , causing water to diffuse into the cell and
make it swell.
-Isotonic: (2 cases)
(1&2)The cell can be permeable and impermeable to the solute, but the {Con} is the
same outside and in, so it’ already at equilibrium
How does polarity and ‘partition coefficient’ play a role in a membrane's
permeability?
The ‘Partition coefficient’ is a coefficient that describes a solvents solubility in oil
between 0---1 whereas 1 is non polar (high solubility in oil) and 0 is polar. Both of
these properties have different ways of crossing a cell membrane.
Based on whether a molecule is polar or nonpolar how will it cross the cell
membrane?
Polar Molecules: Small polar molecules (such as water) scan just diffuse across the
membrane but larger molecules need some sort of protein transport.
Nonpolar Molecules: Can naturally diffuse that plasma membrane.
What factors contribute to having a faster or slower lysis time?
Nonpolar molecules: tend to cross the membrane faster than a polar molecule
since they don’t need a protein transport.
Temperature: Increasing the temperature causes the cell membrane to be more fluid
making it easier for molecules to cross it. Having it colder will cause it to be less
permeable.
*Note* having a a very high temperature can cause the cell to lyse in it’s own right
and not have anything to do with cell permeability
What are ‘negative/positive controls and why are they useful tools in an
experiment?
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Negative control: An outcome where no response is expected
Positive control: An outcome where a response is expected or known to happen
Both are useful for interpreting data, both act as a negative and positive control group
Molecular Biology (DNA stuff)
Identify the components of the DNA double Helix
With a given DNA sequence what mRNA sequence would be coded from it,
what amino acid sequence would you see from the mRna?
What is ‘Transcription’ and what are the steps to accomplish it?
1) Initiation: Recognizing the promoter/recruiting RNA poly.
Eukaryotic RNA: Proteins called transcription factors bind to
promoters/TATA BOX
After both it recruits RNA poly.
Recognizes -10 box/-35 box
-10 is 10 bases upstream from +1
-35 is 35 bases upstream +1
RNA poly. Starts complementary base pairing on the template
strand.
Coding strand is is similar to mRNA
DNA located in the direction of RNA polymerase goes Downstream
(3’)
DNA located in the opposite directions of RNA polymerase
goes Upstream (5’)
2) Elongation: RNA poly adding new nucleotides
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RNA poly. move along DNA 3’ to 5’/ synthesizing DNA template to 5’
to 3’ through complementary base pairing
■ The enzyme adds ribonucleotides triphosphate (substrate) that
are complementary to the template strand to the 3’ end caused by
RNA poly.
3) Termination
RNA poly. reaches a DNA termination sequence and it falls off the
DNA template
Primary RNA: Contains exon and intron (RNA processing)
1) Splicing: Introns removed from growing RNA strand in
transcription
Exons intact and used
AFTER THIS (RNA processing)
Enzyme add a 2) 5’ cap and 3) a poly(A) tail to spliced
transcripts producing a mature mRNA that is ready to be
translated
5’ cap has 7-methyl-guanylate and three phosphate
groups
Allows for recognition by ribosome
Enzyme cleaves the 3’ end of RNA and another
enzyme is added to adenine nucleotides not eroded on
DNA template called poly(A)tail
Allows for protein binding to mRNA
Protects mRNA from degradation by
ribonucleotides/enhance efficiency of
translation
What is ‘Translation’ and what are the steps to accomplish it?
Direction is N-terminus to C-terminus (adding Amino Acids)
Ribosome reads 5’ to 3’
IN CYTOPLASM
Molecule being synthesized direction of strand being made
1) Initiation: Ribosome recognizes mRNA/ here to find start codon
1) Small ribosome subunit (Shine-Dalgarno sequence) binds to mRNA (4-6
upstream or before AUG)
Mediated by proteins called initiation factors that bind to mRNA and
guide ribosome
○ 2) Initiator tRNA binds to the start codon in the mRNA
3) Large subunit of ribosome attaches to the small subunit to complete the
ribosome P-SITE
2) Elongation (E/A are empty): Adding Amino Acids
1) Appropriate tRNA enters A (acceptor) site and anticodon base pairs
with mRNA codon
E (exit) site on the left has no amino acid and tRNA leaves
through here
○ 2) Peptide Bond forms between amino acid held by tRNA in the A site
and polypeptide held by the tRNA in the P(peptidyl) site.
3) Translocation: Proteins called elongation factors move the
mRNA so that it ratchets the ribosome in 5’ to 3’ direction
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