Gene expression and regulation concepts

Key finding of the Griffith experiment

DNA can be transferred from one cell to another horizontally, rather than being inherited

Key finding of the Hershey-Chase experiment

DNA, not protein, is the hereditary material

Bases that are purines

Adenine and guanine

Bases that are pyrimidines

Cytosine and Thymine

Bases with two hydrogen bonds between them

Adenine and thymine

Bases with three hydrogen bonds between them

Cytosine and guanine

Who discovered DNA’s double-helix shape

Watson and Crick, based on the work of Rosalind Franklin

Why DNA is coiled

To fit inside the nucleus

Where the phosphate attaches to the deoxyribose

5’ carbon

Where the hydroxyl group attaches to the deoxyribose

3’ carbon

Bond type between nitrogenous bases

Hydrogen bond

Bond type between nucleotides

Covalent bonds

Direction that DNA polymerase adds bases

5’ to 3’

Prokaryotic DNA structure

Singular, circular chromosome

What happens to telomeres over time

They may shrink as cells and DNA continue dividing and they don’t

Presence of telomerase in different cells

Present in gametes, absent in somatic cells

Numbers of origins of replication in different organism types

Only one in prokaryotes, many in eukaryotes

How DNA is different between cell types

Every cell in an organism has the same DNA, but different genes are expressed

Conditions needed to turn on the lac operon

Glucose is absent, lactose is present

Genes contained in the lac operon

lacZ, lacY, and lacA

What the lac operon codes for

Proteins that metabolize lactose by breaking it down into glucose and galactose

Activator in the lac operon

cAMP-CAP

Permanence of epigenetics

Temporary and reversible

Stages of regulation examples

RNA processing, translation, chemical modifications

Relationship between RNA stability and gene expression

As decay rate increases, protein production decreases

Advantage of using DNA over mRNA in biotech

mRNA is often less stable than DNA

What must happen to study or manipulate nucleic acids

DNA or RNA must be extracted from the cell and isolated

Charge of DNA fragments

Negative

Gel electrophoresis overview

DNA fragments are loaded into the casting tray near the negative electrode and the electric current is turned on. DNA moves toward the positive electrode on the other side. Smaller fragments move faster than larger ones, so different fragments appear as bands at different distances from the top

What is loaded into each well

DNA from different organisms

Three steps of PCR

Denaturation, annealing, extension

Connection between PCR and gel electrophoresis

The results of PCR reactions are made visible using gel electrophoresis

Why PCR is important

Many copies of DNA must be present before it can be seen by eye

Uses of DNA cloning examples

Making insulin for diabetic patients, making human growth hormones for people who can’t, inserting normal genes into patients who lack their functional forms

Why government agencies monitor transgenic plants

To make sure that they are fit for human consumption and to not endanger other plant and animal life

Why extensive testing is needed to ensure ecological stability of transgenic organisms

Foreign genes can spread to other species in the environment

Transgenic animal examples

Mice with human-like immune systems to use for animal testing, livestock with extra growth hormone genes, animal hosts for certain medicines

Benefits of GMOs

Increased crop productivity, harsh environment tolerance, improved nutrition, possible future use of good as vaccines

Drawbacks of GMOs

Unintended harm to non-target organisms, pesticides become less effective, loss of biodiversity

Central dogma AKAs

Protein synthesis, gene expression

RNA components

Ribose sugar, phosphate, nitrogenous base

RNA bases

Guanine, cytosine, adenine, and uracil

Three types of RNA

Messenger (mRNA), ribosomal (rRNA), and transfer (tRNA)

Why transcription occurs

So that the information in DNA can leave the nucleus even though the DNA itself cannot and so that the DNA remains intact and protected

Template strand AKAs

Noncoding strand, minus strand, antisense strand

Steps of transcription

Initiation, elongation, and termination

Roles of the different RNA polymerases in eukaryotes

RNA polymerase I transcribes rRNA, III does rRNA and tRNA, and II does mRNA

Direction that RNA polymerase adds nucleotides

5’ to 3’

Primer requirements of DNA vs RNA polymerase

DNA polymerase requires a primer, RNA polymerase does not

When transcription factors or sigma subunit detach

Once RNA polymerase binds to the template DNA strand

Addition to 5’ end during RNA processing

GTP cap that prevents the mRNA from being broken down and helps it attach to the ribosome

Addition to 3’ end during RNA processing

Poly-A tail that protects the mRNA and helps it leave the nucleus

RNA processing in eukaryotic vs prokaryotic cells

Occurs in eukaryotic cells but not prokaryotes

Why translation can begin before transcription finishes in prokaryotes

Everything occurs in the cytoplasm, there is no nucleus to separate the processes

Steps of translation elongation

Codon recognition, peptide bond formation, translocation

Left-to-right order of large ribosomal subunit sites

P site then A site

Site where the initiator tRNA binds

P site

Process that forms peptide bonds

Dehydration synthesis

How mRNA moves along the ribosome

The codon and anticodon remain binded, so the mRNA moves along with the tRNA during translocation

What happens to most proteins made in free ribosomes

They function in the cytosol

What happens to most proteins made in ribosomes attached to the rough ER

They are transported to the golgi body and packaged to exit the cell membrane

Functions of proteins in the body

Enzymes that perform chemical reactions, structural proteins that create body structures

How retroviruses work

Reverse transcriptase copies their RNA into DNA, which integrates into the host’s genome and is transcribed and translated into more viruses

Mutagen examples

Chemicals, pollution, UV radiation, tobacco, smoke

Where mutations are found that are passed onto offspring

Gametes

Primary source of genetic variation in organisms

Mutations

How viral genetic variation occurs

Related viruses can combine genetic information if they infect the same host