GENETICS TEST FLASHCARDS

which type of bacterial gene transfer is: plasmid transfer via pilus

Conjugation (the freaky one)

which type of bacterial gene transfer is: uptake of free DNA from environment

Transformation (pickup hooker, life is better for bacteria)

which type of bacterial gene transfer is: bacteriophage transfers DNA

Transduction (letting goth baddie ruin your life)

which type of bacterial gene transfer is: movement of genes between species

general lateral gene transfer (horizontal)

What is the structure of plasmids?

Small, circular, double-stranded DNA molecules independent of the bacterial chromosome

what is the function of plasmids?

They carry nonessential genes (e.g., resistance, fertility) that give survival advantages

F plasmids (fertility) R plasmids (antibiotic resistance)

which media supports phototrophs?

Minimal medium

Complete medium supports what type of bacteria

supports auxotrophs.(Because it provides all nutrients)

what are other media types

• Supplemented minimal medium: Minimal + missing compound.

• Selective medium: Includes antibiotics or alternative sugars.

• Replica plating: Used to test colonies under multiple media conditions.

what are the steps of the Lytic cycle

Attachment → DNA injection → phage DNA replication → transcription/translation of viral proteins → assembly → lysis and release

what are the steps of the lysogenic cycle

Attachment of the phage particle to the host cell.

Injection of the phage DNA into the host, followed by phage-chromosome circularization.

• (These first two steps are the same as the lytic cycle.)

Integration of the phage chromosome into the host chromosome at a specific DNA sequence found in both chromosomes.

• Once integrated, the phage DNA is called the prophage.

Excision of the prophage in response to an environmental signal, through a reversal of the site-specific integration.

Resumption of the lytic cycle, beginning with phage-chromosome replication.

How do the lytic and lysogenic cycles relate to one another?

Both start with phage attachment and DNA injection. In the lysogenic cycle, viral DNA integrates into the host genome as a prophage and is passively replicated until triggered. In the lytic cycle, viral DNA is actively replicated, viral proteins are produced, and the host cell is lysed. Lysogeny can switch to lysis when environmental signals cause prophage excision

What is mRNA and what polymerase is used?

mRNA: encodes proteins, polymerase 2

Which RNA delivers the amino acid chain

tRNA, polymerase 3

what is the function of rRNA

to form ribosomes polymerase 1

what is the function of snRNA, and snoRNA

Splicing & rRNA modification

what is functional RNA for

noncoding but critical for ribosome structure and protein synthesis

Regulatory and processing RNAs produced by eukaryotes (was on study guide)

• miRNA, siRNA, piRNA: Regulate mRNA stability and translation.

• lncRNA: Chromatin modification, X-inactivation.

• SRP RNA: Protein targeting to ER.

• RNaseP RNA: Processes tRNA

What are the three steps for transcription and translation?

Initiation, Elongation, Termination

what are the steps for transcription?

TFII factors bind TATA box → RNA Pol II forms preinitiation complex → elongation 5′→3′ → termination at AAUAAA poly-A signal

what happens in initiation in translation?

Small subunit + eIFs bind 5′ cap → scans for AUG in Kozak sequence → initiator tRNA binds → large subunit joins (80S ribosome

what happens during elongation in translation?

tRNA enters A site, peptide bond in P site, exit via E site; GTP + elongation factors drive process.

what happens during termination in Translation?

Stop codon enters A site → eRF1 binds → polypeptide released → ribosome dissociates.

what is the role of the ribosome in translation?

bind mRNA/start codon, pair codon/anticodon, catalyze peptide bond.

what RNA’s do the polymerases code for?

• Pol I: rRNA (except 5S).

• Pol II: mRNA, snRNA, miRNA, siRNA.

• Pol III: tRNA, 5S rRNA, some snRNAs

which way does the template strand sit?

3’ to 5’

which way does mRNA code?

5’ to 3’

what enzyme caps the 5’ side of mRNA?

Guanylyltransferase adds 7-methylguanosine cap

what is the role of the 5’ cap?

improves stability, transport, splicing, and translation efficiency.

what is the sequence of bases that sends the polydentylation sequence that ends transcription?

AAUAAA polyadenylation signal. Recognized by CPSF; cleavage and poly-A addition follow.

what componets of a splicosome remove the introns from mRNA?

snRNPs+proteins, Splicing requires GU at 5′ site, AG at 3′ site

what is the role of alternative splicing in eukaryotes?

Allows different mRNAs/proteins from one gene (70% of human genes undergo alternative splicing)

where does transcription and translation take place?

transcription in the nucleus, translation in the cytoplasm(ribosomes or rough ER)

what is the structure of a ribosome?

80S ribosome = 40S (small, 18S rRNA + 34 proteins) + 60S (28S, 5.8S, 5S rRNA + 49 proteins).

how do ribosomes work?

Bind mRNA → decode codons with tRNAs → peptide bond catalysis → elongation via A, P, E sites → release at stop codon.

GTP + elongation factors power translocation; ribosome is a "protein synthesis machine

how many possible codons are there? How many stops?

64 codons  3 stops   61 coding

why are codons called redundant?

due to all All amino acids (except Met, Trp) encoded by ≥2 codons

Role of wobble bases in tRNA?

Flexible pairing at 3rd codon position reduces number of required tRNAs.(wobble allows isoaccepting tRNAs to recognize multiple codons.)

what enzyme charges tRNA

aminoacyl-tRNA synthetases

why is charge tRNA important

A tRNA molecule must be “charged” with the correct amino acid before it can participate in translation

how do charged tRNA work

Use the anti-codon to read mRNA, carry the appropriate amino acids, then the aminoacyl-tRNA synthetases make sure it leaves with the right stuff