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UNT / Biology / BIOL 3510 / What is the cell theory?

What is the cell theory?

What is the cell theory?

Description

School: University of North Texas
Department: Biology
Course: Cell Biology
Professor: Chapman
Term: Spring 2016
Tags: Cell Biology
Cost: 50
Name: Review for Exam 1
Description: This study guide provides detailed explanations to each item on the Section 1 Review Sheet posted on Blackboard. I've included explanatory diagrams, a table with what you need to know (and not a letter more) about amino acids, and several links to other helpful materials. Happy studying!
Uploaded: 02/08/2016
11 Pages 12 Views 10 Unlocks
Reviews


Exam 1 Study Guide | BIOL 3510 Notes by Marin Young □ What technological development and subsequent observations led to the birth of cell biology?


What is the cell theory?



1665: Robert Hooke saw dead cork cells (plant cell walls) under his early microscope and coined "cells" to  describe little rooms like monks lived in

• 1838/1839: Schleiden says plants are made of cells, Schwann says animals are made of cells ○ Schwann cells, which wrap around and insulate long neurons, are named after this Schwann □ What is the cell theory?

• idea that all living things come from division of existing cells, and cells are "basic unit of life" □ What are the average sizes of cells and organelles and the resolution limits of different types of microscopes? • Eukaryotic cells: 10-50 µm

• Prokaryotic cells: 1-3 µm

Light  

microscopy  (three types)

0.2 µm

200 nm

Visible-light microscopy: requires staining and fixing (usually with heat) to see  well, or differential interference contrast (like phase-contrast) to see living cells  with optics tricks

Epifluorescent: uses a fluorescent stain to label structures and a UV lamp to  cause the dye to emit visible light; best for living cells

Confocal fluorescent: uses a laser beam instead of a UV lamp to illuminate  sample, which improves image quality by helping focus on a 3-D sample •

Remember, the resolution is still 200 nm, but focus depends on sample  thickness; you've probably run into this problem in labs where you can't  see an entire object in focus at the same time (I'm thinking of diatoms, for  anyone who took micro)

Scanning  

electron  

microscopy

20 nm

Specimen coated with a thin layer of heavy metal like gold and blasted at an  angle with a beam of electrons, which bounce off the metal and onto a detector.  A connected computer uses the electron pattern to determine structure based on angles of "reflection" where electrons bounced.

Transmission electron  

microscopy

2 nm

This is a lot more like light microscopy with electrons instead of light: a condenser  focuses electrons on a thin sample, which can be stained with electron-dense  chemicals like uranium acetate or lead citrate. Some areas absorb more electrons  than others. The electrons go through electromagnetic objective and projector  lenses and hit a detector screen to make a digital image.


What are the four levels of structural organization of protein, and what characterizes each level?



If you want to learn more check out bio 110 purdue

 

□ Compare and contrast different types of light microscopy and electron microscopy.

• See chart above!

What do images produced by the different types of microscopy look like? (Check out the relevant figures in your  book).

Visible-light microscopy using stains

From  

<https://upload.wikimedia.org/wikipedia/commons/1/ 15/Cilia_light_micrograph.jpg>

Differential-interference contrast


How do proteins fold?



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From  

<https://commons.wikimedia.org/wiki/File:S_cerevisia e_under_DIC_microscopy.jpg>  

Epifluorescence

From  

<https://commons.wikimedia.org/wiki/File:Dyeing_the _reactive_astrocytes_by_using_anti-GFAP_antibodies_ 2.jpg>

Confocal fluorescence

From http://www.pha.jhu.edu/ 

~ghzheng/old/webct/note1_1.files/09_ 019.jpg

Scanning electron microscopy

(Public domain, accessed via  

https://en.wikipedia.org/wiki/Scanning_elec tron_microscope#/media/File:Misc_pollen.jp g)

Looks like a photograph of a 3-dimensional  metal replica

Don't forget about the age old question of stoge food

Transmission electron microscopy

We also discuss several other topics like econ2101

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From  

https://upload.wikimedia.org/wikipedia/com 

mons/c/c1/Myelinated_neuron.jpg 

Looks like a light micrograph in incredibly  

high resolution

□ What are the differences and similarities between prokaryotic and eukaryotic cells?

Similarities: reproduction, expression of DNA via transcription and translation, phospholipid bilayer cell  membrane

Differences: presence or absence of membrane-bound organelles and nucleus, presence or absence of  introns, number of origins of replication

What are the subcellular organelles/components and their general functions in cells? What cellular components  are unique to plants?  

• I recommend http://facstaff.cbu.edu/~seisen/EukaryoticCellStructure.htm if you need a refresher on this Don't forget about the age old question of penn state university economics

□ Be familiar with the general structure of amino acids, peptide bonds and polypeptide chains (or proteins).  

Amino acids: Peptide bond:

 Amino acids in a peptide are called amino acid residues

While I don’t expect you to memorize the amino acid side chains, I do expect you to be able to tell if they are  nonpolar, acidic etc if the structure is provide as well as their abbreviations

Basic/Positive

Lysine

Arginine

Histidine

Acidic/Negative

Aspartate

Glutamate

Uncharged and Polar

Asparagine

Glutamine

Tyrosine

Serine

Threonine

Nonpolar

Proline

Glycine

Alanine

Valine

We also discuss several other topics like history 101 final exam

Lys Arg His Asp

Glu Asn Gln Tyr Ser Thr Pro Gly Ala Val

Note that all abbreviations are just the  first three letters except asparagine,  glutamine, and tryptophan!

Leucine Leu

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Leucine Leu

Isoleucine

Phenylalanine

Tryptophan

Cysteine

Methionine

Iso

Phe Trp Cys Met

□ What are the four levels of structural organization of protein and what characterizes each level? Protein structure

Primary structure: order of amino acids (Asp Lys-Gly-Tyr…)

Determined by covalent bonds in  

backbone

Secondary structure: alpha helices and beta  pleated sheets

○ If you want to learn more check out the occupational outlook handbook is updated every _____ years

Determined by hydrogen bonds in  backbone

An alpha helix has R-groups facing out  and 3.6 residues per turn--the carboxyl  group on residue 1 accepts a hydrogen  bond from the amino group on residue  5 (NCC-NCC-NCC-NCC-NCC)

Beta sheets are accordion-folded and  can be parallel (NCC-NCC-NCC backbone  runs the same direction) or antiparallel

• Tertiary structure: folding into actual shapes

Determined by noncovalent interactions  (hydrogen bonds, hydrophobic  

interactions, ionic bonds) plus covalent  disulfide bonds between R groups ○

Domains are sections of a protein that  can fold independently (even without  the other sections of the same protein)

Gene regions for domains can be  spliced together to create new  proteins, in the lab or in cells  (translocation mutations)

Quaternary structure: interaction of multiple  polypeptide subunits

Some proteins are a single polypeptide  chain and don't really have 4ostructure ○

Proteins can be called homo___mers or  hetero___mers

The blank is the number (di, tri,  tetra)

Homo = identical subunits, hetero  = different subunits

Rubisco (a plant protein, most abundant  protein on Earth) has 8 large subunits  (encoded in nuclear genome) and 8  small subunits (encoded in chloroplast  genome)

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genome)

□ What are covalent bonds (both polar and nonpolar)? • Strong bonds involving sharing electrons

• In nonpolar bonds, electrons are shared fairly

• In polar bonds, electrons are shared unfairly/unequally ○ Some molecules with polar bonds are polar molecules

CH3Cl is polar because the side with the Cl has a partial negative charge and the side away  from it has a partial positive charge

CCl4 is nonpolar because the polar bonds all cancel each other out: the outer chlorines have  partial negative charges and the inner carbon has a partial positive charge, but there's no  partially positive or negative "side"

□ What are 4 types of non-covalent bonds/forces relevant to cells? Be able to describe them.

Van der Waals interactions: all atoms are slightly attracted to each other by "induced dipoles" (polarity  wobble)

○ This is most important in nonpolar amino acid residues

Hydrophobic interactions: very nonpolar particles stick together to minimize exposure to water (this is why  oil and water don't mix

Hydrogen bonds: occur between an oxygen or nitrogen with a lone pair, and a hydrogen on an oxygen or  nitrogen--hydrogens on carbon atoms do NOT make hydrogen bonds

Ionic or electrostatic attractions: opposites attract! Positive and negative charges are attracted to each  other

□ How do proteins fold?

Domains are independently folding sections that are small enough for noncovalent interactions to pull the  amino acid residues into place

• Domains then fit into each other

□ What are α helices and β sheets? How are they formed?

• Types of secondary structure formed by hydrogen bonds within the NCC backbone of a polypeptide □ What is a protein domain? What are chaperones?  

• Domain: independently folding section

• Chaperone: protein that helps facilitate correct folding

□ What are binding sites, ligands, substrates, active sites, catalysts, enzymes, and allosteric proteins? • Binding site: a region of a protein with a structure adapted for binding to another molecule • Ligand: a molecule such as a hormone that binds to a receptor or other protein • Substrate: a molecule that undergoes an enzyme-catalyzed reaction

• Active site: a site where a protein's activity takes place (usually also a binding site)

Catalyst: any substance that increases a reaction rate by lowering activation energy without being changed  or altering the free energy change of the reaction

• Enzymes: biological catalysts, usually proteins but sometimes RNA molecules ○ Can catalyze reactions by:

□ holding substrates near each other,  

bending bond angles to help break a bond ("stabilize the transition state"--help form the very  middle of a reaction step where one bond is half broken and another is half formed), or

□ temporarily holding "extra" protons or electrons to stabilize an intermediate

Allosteric protein: a protein whose activity is regulated by molecules binding at a site besides the active  site (like an inhibitor deactivating a protein by binding to a special regulatory binding site)

□ How does feedback regulation work?

A product of a reaction or set of reactions inhibits the same reaction(s), usually by allosterically inhibiting  an enzyme that catalyzes an earlier step

□ What are four ways protein activities are modulated in a cell?  

Feedback inhibition, phosphorylation/dephosphorylation, degrading ubiquitin-tagged proteins, allosteric  regulation, and possibly also controlling the amount of transcription/translation that occurs

□ What do conformational changes have to do with protein activity?  

Changing the shape of a protein can expose a previously buried active site, move an important catalytic  amino acid residue into a useful place, or even get the protein out of its own way--structure determines  

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amino acid residue into a useful place, or even get the protein out of its own way--structure determines  function, so changing structure changes function and can turn a protein from on to off

□ What are kinases, phosphatases, and GTPases (GTP binding proteins)? How does these regulate protein activity? • Kinases are enzymes that phosphorylate (stick a phosphate group onto) other proteins/enzymes ○ This often activates the target enzyme, but some enzymes are deactivated by phosphorylation • Phosphatases are enzymes that dephosphorylate (take a phosphate group off of) a target protein

This is the opposite of what a kinase does--likewise, it deactivates most target proteins but activates  some

○ This also usually releases some energy

• GTPases bind GTP and then hydrolyze it to produce GDP and Pi (phosphate)

GTPases, which include the G proteins that work with G-protein-coupled receptors, often have other  functions, and they're active when bound to GTP

□ This means they deactivate themselves by hydrolyzing GTP

• All of these are means of "switching" proteins between on and off, or between one activity and another □ What are antibodies? How are these produced?

• Antibodies are small proteins that bind to foreign molecules called antigens

They're produced in the body by intron splicing and recombination of domains that have different  shapes

They're produced in the lab by regularly injecting an animal with the antigen so its immune system  produces antibodies against it, and then harvesting the antibodies by drawing blood

□ Be familiar with the general structure of nucleotides, phosphodiester bonds, and nucleic acids.  • Two thymine nucleotides are shown, with a phosphodiester bond circled in red

• Cytosine and guanine form three hydrogen bonds; adenine and thymine form two ○ Mnemonic for base pairing: AT&T and Cingular, the cell phone companies ○ Adenine and guanine are purines, which means their structures are bicyclic ("PUGA-2") ○ Cytosine and thymine are pyrimidines

○ One purine and one pyrimidine always base-pair to keep width consistent

A DNA double helix has two antiparallel strands in a right-handed  spiral with 10 bp per turn

Antiparallel: one goes 5' to 3' (has a phosphate at one end  and a sugar at the other) and one goes 3' to 5' (sugar at one  end, phosphate at other)

Minor and major grooves alternate because of the offset  between the two strands

▪ Proteins to bind to DNA based on this pattern/shape

Compare and contrast: Purines vs pyrimidines, ribose vs deoxyribose, RNA vs DNA, heterochromatin vs  euchromatin.

• A purine has two rings and is wider; a pyrimidine has one ring and is narrower

• Ribose has an -OH group on the 2' carbon; deoxyribose has a hydrogen there instead • Heterochromatin is condensed and hard to express; euchromatin is more open and easier to express □

How are these terms related to each other in the context of double stranded DNA?-- hydrogen bonds,  complementary base pairing, anti-parallel, and polarity. How are complementary sequences “written” with  

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complementary base pairing, anti-parallel, and polarity. How are complementary sequences “written” with  respect to polarity (DNA and RNA)?  

• Hydrogen bonds between bases are responsible for complementary base pairing

The polarity of DNA means there's a 5' end (the end with the phosphate group, which is attached to the 5'  carbon) and a 3' end (the end with the sugar, which has an -OH group on the 3' carbon

• Antiparallel means the strands go in opposite directions (more on this above) □

What are genomes, karyotypes, chromosomes, homologous chromosome, chromatin, and epigenetic  inheritance?

• Genome: the set of all genetic material in an organism

Karyotype: an image of all the mitotic chromosomes in an organism's genome, dyed different colors with  fluorescent molecules

• Chromosome: a complete DNA molecule folded into a condensed structure

Homologous chromosomes: a pair of chromosomes containing the same sequence of genes, with varying  alleles because one chromosome comes from each parent (meaning, they're not exactly identical)

• Chromatin: the combination of DNA and proteins (mostly histones) that resides in the nucleus of the cell

Epigenetic inheritance: passing down epigenetic ("above the genome") modifications like methylation or  acetylation of certain histones

○ This allows inheritance of gene expression patterns, not just the genes themselves

Very important in cell division, since epigenetic modifications are crucial to determining what genes  are expressed in a cell type

□ What three general sequence elements are needed for chromosome replication and segregation? • Telomere, replication origin, and centromere

What are the various levels of chromatin organization and what proteins and interactions lead to their formation?

• DNA wraps around specialized proteins called histones

A histone complex is an octamer with two each of H2A, H2B,  H3, and H4

A 147-bp length of DNA wraps twice around each histone  

complex, with a 50-ish-bp segment of linker DNA between histone complexes

○ Nucleosome = one histone complex plus its wrapped and linker DNA

If this "beads on a string" chromatin (DNA + histones) was exposed to a nuclease, the linker  segments would be destroyed and yield nucleosome core particles (histone complexes with  wrapped DNA)

Histone proteins contain many Arg and Lys residues (+ charges attract DNA) and are highly  conserved among species

▪ H3 subunits' tails are most used for regulation

• Nucleosomes are packed into 30 nm fibers

Histone H1 (NOT part of the octamer) binds between wrapped  and linker DNA to hold nucleosomes close together

○ Histone tails can also interact

• 30 nm fibers form 300 nm loops

• 300 nm loops are squished and folded together to form a mitotic (condensed) chromosome □ How do DNA binding proteins access nucleosome-wrapped DNA?

• The chromatin remodeling complex slides DNA over the histone complex to expose a different segment □ What is the relationship between the amount of DNA condensation and the level of transcription? • More condensation (tighter packing) correlates with less transcription

□ What are the main structural components of the nucleus?

• Nuclear envelope: two concentric lipid bilayers (like two cell membranes, one lining the other)

Nuclear lamina: mesh of intermediate filaments (a type of cytoskeletal filament) that supports shape of  nucleus

Nuclear pores: channels through the nuclear envelope, made of proteins that selectively allow certain  molecules to enter or exit

○ Controls when mRNA can leave (only when capped, tailed, and spliced)

• Nucleolus: an important biochemical neighborhood in the nucleus where ribosomes are manufactured  Cell Biolo Pae 7

• Nucleolus: an important biochemical neighborhood in the nucleus where ribosomes are manufactured ○ Ribosomal genes are transcribed to RNA

Some is considered rRNA and will become part of the ribosome; some is mRNA and will be  transcribed

The mRNA exits the nucleus and gets transcribed in the cytoplasm, and then the proteins  synthesized re-enter the nucleus

○ The ribosomal proteins and rRNAs are assembled in the nucleolus □ What is a biochemical “neighborhood”?

An area within the nucleus with characteristics that facilitate different biochemical activities, like an area  with lots of RNA polymerase that's good for transcription or an area with lots of spliceosomes for mRNA  processing

□ What are characteristics unique to RNA?

• Uracil instead of thymine

• Ribose instead of deoxyribose

• Usually single-stranded and can take on many, many different structures • Sometimes has catalytic activity (ribozymes)

Sometimes capable of unconventional base-pairing, like two hydrogen bonds forming between an  adenine and a cytosine--it's not perfect, but it's better than nothing

○ Stabilizes a structure just enough to still be dynamic

Can also allow different widths of base pairs: an adenine-guanine pair would be wider than a usual  bp, and a cytosine-thymine pair would be narrower

□ What do polymerases do? Remember 5’ to 3’.

• Synthesize a polymer of DNA or RNA in the 5' to 3' direction • This means they read the template strand from 3' to 5'

What are the main steps in prokaryotic transcription? What is the role of the promoter (-10 and -35 sequences),  sigma factor, RNA polymerase, and termination sequence?

• Initiation, elongation, and termination

There are two short promoter regions, one about 10 bp before the origin and one about 35 bp before the  origin

• The sigma factor binds to both these promoter regions and helps RNA polymerase bind to the DNA • The termination sequence causes RNA polymerase to stop transcribing and leave the DNA ○ This can happen with or without proteins, but this wasn't covered in class

What are the main steps in eukaryotic transcription? What are the roles of the promoter (TATA box), general  transcription factors (especially TFIID and TFIIH), RNA pol II, and the C-terminal domain of RNA pol II? • Still initiation, elongation, and termination, but a bit more complex

• The promoter/TATA box binds transcription factors

○ TFIID binds to the TATA box

• TFIIH phosphorylates the C-terminal domain/cytoplasmic tail domain of RNA pol II, which activates it

□ How are eukaryotic transcripts processed prior to exiting the nucleus?  • Introns are spliced out

• A methylated GTP cap is attached to the 5' end, via a triphosphate bridge • The 3' end is polyadenylated (a long tail of 150-250 adenosine nucleotides is added) □ What is the role and composition of the spliceosome?  

• Made of catalytic RNAs and proteins

• Pulls out introns in a lariat (lasso) shape and splices/joins exons together □ What is the advantage of alternative splicing?

Multiple different polypeptides can be synthesized to express a single gene, depending on the  combination and order of exons spliced into the final mRNA

□ How is eukaryotic transcription regulated?

Enhancer regions (located upstream/before the TATA box and gene to transcribe) bind activator proteins,  which help the mediator protein set up the RNA polymerase complex

○ Activator proteins bind specifically to the DNA sequence of their enhancer regions

• Repressor proteins can get in the way of RNA polymerase assembly and transcription Repressor proteins bind to the silencer region

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○ Repressor proteins bind to the silencer region

Note that neither enhancers nor repressors bind to the promoter region; transcription factors and  RNA polymerase do

Transcription is regulated by a complex "team," with various specialized roles that help in different ways  (and some that instead slow progress, just like teams in real life)

Transcription factors, histone modifiers, and the chromatin remodeling complex can all bind to DNA  sequences or to the mediator

Regulation with many variables or inputs is called combinatorial control and allows fine-tuning the  rate of transcription

Some regulatory proteins allow the expression of genes that make other regulatory proteins that allow the  expression of genes that do all kinds of other stuff and make more regulatory proteins that…and so forth ○ These are sometimes called linchpin/keystone transcription factors

In Drosophila (fruit flies), the protein ey is normally expressed in the eye region but can make a  replica eye on the fly's leg if expressed in the leg

MyoD causes a chicken fibroblast to become a muscle cell line, which is useful for growing flavorless  chicken meat in the lab

□ What are codons, the genetic code, redundancy, and reading frames?

• Codon: group of three consecutive nucleotides in mRNA

• Genetic code: each codon corresponds to a specific amino acid

• Redundancy: some amino acids are represented by multiple codons

○ But not the other way around--amino acids are a function of codons, if you like math

Reading frames: where each group of three nucleotides starts (123 456 789 vs 234 567 890; like the  placement of bar lines to divide measures of music, if you like)

□ What are the important structural features of a tRNA? How is it charged? How is the charging checked? • The anticodon loop is complementary to the mRNA codon

• The 3' end carries an amino acid corresponding to the codon complementary to the tRNA's anticodon • There are two other loops to make an overall clover-shaped or t-shaped structure • A tRNA is "charged" with an amino acid by an aminoacyl-tRNA synthetase

Charging is checked two ways: the amino acid should fit in the synthesis site and not fit in the editing site  of the aminoacyl-tRNA synthetase

What are ribosomes made of? What are the roles of the large and small subunit? What are the E, P, and A  sites?

• Many proteins and several catalytic rRNA molecules

• Large subunit catalyzes peptide bond formation

• Small subunit binds mRNA

A (aminoacyl-tRNA-binding) site is where a tRNA enters and brings an amino acid into position to bond  with the one before it (on the tRNA in the P site)

P (peptidyl-tRNA-binding) site is where the amino acid leaves the tRNA so that the next amino acid can  form a peptide bond to its carboxyl group

• E (exit) site is where the tRNA leaves without its amino acid

• I highly recommend watching an animation of this process

What are the steps in translation including initiation, elongation, and termination? What are the roles of the  initiator tRNA, MET-tRNA, release factors, and GTP hydrolysis in translation?

• Initiation: the initiator tRNA is a methionyl-tRNA; it and some initiation factors bind to the small subunit ○ Then mRNA binds

Then the small subunit carries MET-tRNA down the mRNA until they find a start codon  (complementary to the MET-tRNA's anticodon)

○ And THEN the large subunit can bind, with the MET-tRNA ending up in the P site • Elongation: an aminoacyl-tRNA enters the A site

○ Its anticodon is complementary to the codon facing the A site

At about the same time, the newest amino acid forms a peptide bond to the previous amino acid,  and the large subunit translocates (moves a bit towards the 3' end of the mRNA)

Forming a peptide bond to the previous amino acid requires that previous amino acid to break  its bond to its tRNA, which ends up in the E site when the large subunit moves

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its bond to its tRNA, which ends up in the E site when the large subunit moves

▪ The amino acid just added is still attached to its tRNA, which is now in the P site ▪ The A site is briefly empty until another aminoacyl-tRNA comes in

○ The small subunit translocates as the tRNA in the E site leaves

○ GTP hydrolysis provides the energy for these bonds to form and translocations to occur ▪ Elongation factors like EF-Tu help with this

Termination: a release factor, which acts a lot like an aminoacyl-tRNA, enters the A site and binds to the  stop codon

When the large subunit translocates and the last amino acid leaves its tRNA, the release factor ends  up in the P site, which causes the ribosome to disassemble and release the new polypeptide

□ What do proteasomes, ubiquitin, and proteases have to do with protein degradation? • Proteasome: protein complex with two cylindrical caps providing channels to a protease core

Ubiquitin: attaches to target proteins, recognized by proteasome caps, causes target proteins to enter  proteasome

Protease: responsible for protein degradation by hydrolyzing peptide bonds in the proteins that enter the  proteasome's core

□ X-ray crystallography?

• Make a pure, solid crystal of a protein and shoot X-rays through it

• The diffraction pattern can be mathematically analyzed to find atomic structures • This is how Rosalind Franklin (NOT Watson and Crick) figured out that DNA was a double helix □ Nuclear magnetic resonance spectroscopy?

Applying a strong magnetic field to a protein sample causes measurable atomic vibrations in patterns  depending on how close hydrogen atoms are to each other

This only works for fairly small proteins--it's the same NMR used in organic chem, and it gets really  complicated really fast

□ Use of antibodies in immunoprecipitation and as molecular tags?

• Antibodies for a specific protein will selectively bind to that protein

• This can cause it to precipitate (like agglutination in blood typing), which isolates the protein

If the antibodies are covalently bound to radioactive labels or fluorescent dye molecules, they work as  molecular tags to visualize protein locations

□ Restriction nuclease digestion?

I'm not sure we talked about this in class, but it's a method of slicing up DNA in a way that leaves "sticky  ends" that can anneal to each other

• Combining various DNA molecules with the same sticky ends can create a big recombinant DNA molecule □ Electrophoresis?

DNA goes in wells at the negative end of the gel and is electrostatically attracted to the positive end of the  gel

Smaller molecules move faster, so in a period of time, the DNA molecules will be spread out over the gel  according to their size

Combining this with restriction nuclease digestion allows restriction fragment length polymorphism, or  DNA fingerprinting

□ Hybridization and northern and southern blotting?

I'll update this study guide if these topics are covered in class on Tuesday the 9th, but otherwise, I don't  believe they'll be tested

□ Genome editing by nucleases?

• CRISPR: Clustered Regularly Interspaced Short Palindromic Repeats

Basically, this is a thing bacteria have to "train" their nucleases to target virus sequences for  chopping up, and molecular biologists figured out how to use this to target specific sequences for  opening in a way that lets them insert more DNA

The explanation in the lecture notes is…fun. Rather than try to recap that, I highly recommend this article:  http://gizmodo.com/everything-you-need-to-know-about-crispr-the-new-tool-1702114381 •

The video embedded is also nice--here's a direct link to start at the beginning:  

https://www.youtube.com/watch?v=2pp17E4E-O8 

Fair warning: this starts with an overview of basic DNA structure, so you may want to skip forward a  

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Fair warning: this starts with an overview of basic DNA structure, so you may want to skip forward a  bit (or enjoy the confidence boost from knowing what they're talking about)

□ That's all for now!

Congratulations on making it through Dr. Chapman's giant test review! I hope reading this for you is as  helpful as making it was for me. Happy studying, and good luck!

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