Unit 7 Protein Synthesis/GE

What phase of the cell cycle does protein synthesis take place?

G1 and G2.

DNA to RNA. What do we call this process?

Transcription.

Where does it occur?

The nucleus.

What enzyme add nucleotides to the template strand ("leading")

RNA polymerase.

DNA and RNA have two structural differences: What is the difference in the sugar? The nucleotides?

RNA has an extra oxygen and uses uracil (extra methyl group). DNA uses thymine (contains a hydrogen).

What is messenger RNA?

Code for the protein.

What is ribosomal RNA?

Used to make ribosomes.

What are transfer RNAs?

Transfers amino acids to the mRNA.

How is mRNA edited before it leaves the nucleus? (distinguish exon from intron).

Non-coding regions (introns) are removed, and coding regions (exons) are joined together.

What is a ribozyme?

An RNA molecule that can catalyze chemical reactions.

What is RNAi? How do scientists use it?

RNAi is a way cells turn off genes using small RNA pieces.
Scientists use it to block certain genes to study them or treat diseases.

RNA to Proteins What do we call the process?

Translation.

Where are the ribosome subunits put together in the cell?

The nucleolus.

What is associated with the ribosome besides RNA?

Ribosomal proteins.

What are the three binding sites on a ribosome? In order of first, second and third.

The A site, the P site, and the E site.

What type of RNA binds to those binding sites on the ribosome?

tRNA.

What is the role of tRNA?

tRNA carries amino acids to the ribosome for protein synthesis.

What do we call the 3 nucleotides at the bottom of the tRNA that bind with the mRNA?

The anticodon.

Since there are 20 amino acids and there are only 4 nucleotides. It can not be a 1:1 ratio. What is the ratio of nucleotides : 1 amino acids? What do we call that?

The ratio of nucleotides to one amino acid is 3∶1, and this ratio is called a codon.

How many different ways can 4 letters be arranged in triplets?

64 different ways.

What is redundancy a good thing?

It is a way to avoid mutations and mullify.

What is the start codon? How many stop codons are there?

The start codon is AUG, and there are three stop codons.

What are the three stages of translation?

Initiation, elongation, and termination.

What codon shows up on the A site of the ribosome during initiation?

AUG.

What is the longest of the three stages? Why?

Elongation, is the stage where the protein is growing.

How much energy is used per peptide bond to make a protein?

4 ATP.

At what stage does the protein release factor bind to the mRNA codon? (note: there are three different protein released factors)

Termination.

What is the difference between the protein release factor and the other tRNAs?

The protein release factor lacks an amino acid.

Where in the cell does translation take place?

Cytoplasm.

What is a polyribosome?

Multiple ribosomes lined up together.

The endoplasmic reticulum is a membrane continuous with what other membrane?

The nuclear membrane.

What do we call the endoplasmic reticulum that has ribosomes attached to it? (note there are also free(unattached) ribosomes in the cytoplasm)

The rough endoplasmic reticulum (RER).

Where do proteins go to get a small sugar attached to them after they are made?

The Golgi apparatus.

In what structure do proteins travel from the ER to the Golgi body?

Vesicles.

They move along microtubule tracks from the ER to the Golgi: what moves them along the tract?

Motor proteins.

What is the evidence that the "RNA World "came before the DNA World we live in now? (What two functions does RNA have that we currently see in DNA and proteins)

Early life relied on RNA for both information storage (like DNA) and catalysis (like proteins).

What is a mutation? What can cause a mutation?

Changes in the DNA sequence Environmental factors, viruses, errors in replication, and transcription can cause a mutation.

Define point mutation.

A change in a single nucleotide base pair in the DNA sequence.

Why is an insertion/deletion mutation way worse than a substitution mutation? Use the word "frame-shift" in your explanation.

They cause a frameshift, altering the entire sequence of amino acids after the mutation.

What is the mutation rate in humans?

1:1 million-1 billion.

Why are most point mutations considered neutral? (what percent of the human genome actually codes for proteins, and what often happens when a point mutation occurs on the third nucleotide of a codon).

They do not affect the protein. Only about 1-2% of the human genome codes for proteins.

What is the role of mutations and evolution?

Mutations allow for new variation which may allow you to survive in a new environment.

What did Linus Pauling use the amino acid sequence of hemoglobin of three different animals to figure out? (what does mutation rate tell us)?

Mutation rates are proportional to evolutionary distance.

Why are mitochondrial mutation rates used as evidence for human evolution?

mtDNA is maternally inherited and has a higher mutation rate compared to nuclear DNA.

Does every cell in a multicellular organism transcribe the same genes? Why?

No, cells have different functions.

Give an example of a protein that is produced in the pancreas cells that is not produced in a skin cell.

Insulin.

What is a transcription factor?

A protein that regulates gene transcription.

What is an operon?

A series of genes that are transcribed into a single mRNA molecule.

What is the promoter site in an operon?

Upstream from the genes.

What attaches to the promoter site that will transcribe the genes?

RNA polymerase.

What will block the promoter site?

Repressors.

What will release it from blocking the promoter site?

An inducer.

What is the "on" switch for the lac operon?

The presence of lactose.

How many genes (that code for enzymes) are in the lac operon?

3 genes.

Regulation of DNA in eukaryotes can be done by histones. What molecule attaches to a histone tail that will prevent the gene from being transcribed? (an off switch)

Methyl.

What is the relationship between enhancers and activators?

Enhancers attach to the activators.

What tool do scientists use to transfer small amounts of liquids?

Micropipettes.

What instrument would you use to transfer 5 microliters of a liquid? 120 microliters? 450 microliters?

5 microliters: P20 120 microliters: P200 450 microliters: P1000

What tool do scientists use to separate/identify DNA fragments by size?

Gel electrophoresis.

What is the gel made of?

Agarose.

What is the charge of DNA?

Negative charge.

What pulls the DNA? What goes faster, a small or large fragment of DNA?

Electricity pulls the DNA toward the positive charge, and a small fragment goes faster.

Why do you include a DNA marker (ladder)?

A reference for fragment sizes.

What is a plasmid?

A plasmid is a small, circular DNA molecule.

Humans use plasmids as a tool for what?

Genetic engineering.

What tool (enzyme from bacteria) do scientists use to cut DNA at specific sites to create sticky ends?

Restriction enzymes.

What was the first enzyme that cuts DNA that was discovered in E. coli called?

EcoR1.

What gene do scientists make sure that are on the plasmid so you can isolate them on a Petri Dish of ampicillin?

Ampicillin Resistance gene (ampR).

What gene (for a protein) do scientists attach to make a molecule glow red?

Red fluorescent protein (RFP).

What do we call the process of putting DNA into a bacteria?

Transformation.

What "turns on" the pARA-R operon?

Arabinose sugar.