Molecular Biology Quiz

Transcription

Transcription

• Process ⟹ DNA to RNA

• Template ⟹ DNA

• Enzyme ⟹ RNA polymerase

• Product ⟹ complementary RNA sequence

Translation

• Process ⟹ RNA to Amino Acid

• Template ⟹ RNA

• Organelle involved ⟹ Ribosomes

• Product ⟹ amino acids, and eventually protein

• Proteins monomers ⟹ Amino acids

• Protein function ⟹ ‘doers’ of the cell

Codons

• What are they?

  • Groups of 3 RNA nucleotides

  • Read by ribosomes

  • One codon ⟹ one amino acid.

• Where are they found? mRNA or DNA

DNA

• Structure

  • Double-helix

  • Base pairing rules ⟹ A - T and C - G

  • Sugar-phosphate backbone

  • Anti-parallel

• Monomers ⟹ Nucleotides

• Function ⟹ Store genetic information/genes

  • Location ⟹ Nucleus or cytoplasm

RNA

• Structure

  • Single-stranded

  • Base pairing ⟹ A - U and C - G

• Monomers ⟹ Nucleotides

• Process ⟹ transcription makes RNA

  • Where is RNA made? Nucleus

DNA Polymerase

enzyme that replicates the nucleotides with the appropriate base

Ligase

enzyme that connects two fragments of DNA

Mutation

a change in the DNA-base sequence

Substitution Mutation

a base is substituted for a different base

Insertion Mutation

extra base is inserted into the sequence; causes frameshift

Deletion Mutation

a base is deleted from the sequence; causes frameshift

Silent Mutation

no effect; type of substitution mutation

Missense Mutation

changes the amino acid to be different than the one produced with no mutation; type of substitution mutation

Nonsense Mutation

random stop

What does it mean when a mutation causes a frameshift?

it changes the sequence of the RNA nucleotides, leading to different amino acids being produced

Which one has the most significant impact on the protein’s function in the cell?

Any mutation that causes a frameshift (insertion + deletion) is the most impactful; substitution mutations can sometimes be harmless

Mutation Effects

can lead to different species and can affect the way an organism lives (good or bad)

BLAST

• Purpose ⟹ to find and identify DNA, RNA, or protein sequences

• How to use it:

  • Go to website

  • Enter sequence in the search bar

  • Click on ‘BLAST’ and the program will search the database

  • Analyze the data

Restriction Enzymes

• Purpose ⟹ to cut DNA; to create sticky ends

• How they work:

  • Restriction enzymes find their specific restriction site

  • Restriction enzyme cuts both strands - creating either sticky or blunt ends

Blunt Ends

when the restriction enzyme cuts directly across from each other

Sticky Ends

when the restriction enzyme cuts staggered, leaving one short single-stranded sequence without its complement; *wanted for making recombinant DNA/plasmids*

Restriction Site

location where the restriction enzyme cuts the sequence

Recombinant DNA

• Purpose ⟹ used for genetic engineering

• How to make it:

  • Cut both DNA samples with the same restriction enzyme

  • Mix the samples so that the sticky ends are attracted to each other

  • Ligase will join the sugar-phosphate backbone of the recombinant molecule

Gel Electrophoresis

• Purpose ⟹ to separate molecules based on size and charge

• How does it work:

  • An agarose gel is poured and sets

  • Samples are loaded into the wells

  • The gel is placed in the chamber with a buffer solution

  • An electrical current is supplied and molecules move through the gel

What determines the direction and distance a substance travels on the gel by electrophoresis?

the farther away the band is from the well, the smaller the molecule; molecules with a negative charge would go to the positive electrode and vice versa

CRISPR-Cas9

• Purpose ⟹ to cut DNA at a specific and programmable sequence - we can then insert a gene of interest in that location

• How it works:

  • Cas9 is given a guideRNA

  • Cas9 searches the DNA looking for the complementary sequence to the guide RNA

  • Once it finds the sequence, Cas9 cuts the DNA

  • Fix the gene

DNA Fingerprinting

• Purpose ⟹ to compare DNA samples

• Steps:

  • Cut DNA with restriction enzymes

  • Run DNA samples on a gel (gel electrophoresis)

  • Compare banding patterns on the gel

Polymerase Chain Reaction (PCR)

• Purpose ⟹ to makes copies of DNA

• Steps:

  • Heat to denature

  • Cool and allow primers to recombine

  • DNA polymerase extends the new DNA nucleotide chain

  • Repeat cycle

DNA Sequencing - SANGER

• Purpose ⟹ to determine the sequence of bases in a segment of DNA

• Steps:

  • Replicate DNA in 4 different samples - one for each dideoxynucleotide (chain-ending nucleotide)

  • Separate replicated fragments by electrophoresis

  • Read from shortest fragment to largest to know the order to the bases (shorter closer to the electrode)

Bacterial Transformation

• Purpose ⟹ to use bacteria to make proteins for medicines and other uses

• Steps:

  • Isolate and cut plasmid with restriction enzyme

  • Cut our gene of interest with the same restriction enzyme

  • Mix DNA samples

  • DNA ligase will join the fragments together

  • Mix recombinant plasmids with bacteria and some will take up the recombinant plasmids

  • Select the transformed bacteria

  • They will make the protein of your interest

Plasmid

• What is it ⟹ a small extra ring of DNA in the cytoplasm of bacteria

• Purpose ⟹ transfer foreign genetic materials into a cell

How do our cells make proteins from our genes?

Through transcription and translation (transcription first (ALWAYS!!) and then translation)

tRNA (transfer RNA)

adaptor between the nucleic acid form of genetic info and the protein genetic info

mRNA (messenger RNA)

tells ribosomes how to make proteins

Point Mutation

type of substitution mutation that only affects a few nucleotides

Anneal Primers

the molecule chain to which mRNA connects transcribed DNA code