Genetics Lecture Exam (ch. 7-9)

Transformation of Bacteria

only DNA transforms

Hershe-Chase experiment

only radiolabeled DNA is passed to offspring viruses

Nucleotides

composed of deoxyribose sugar, phosphates, and nitrogenous bases (A,T,G, and C)

Sugar-phosphate backbone

the phosphodiester bonds between nucleotides in a single DNA strand is also known as

DNA double helix

two DNA strands intertwine to form a double helix with base pairing between antiparallel strands

Hydrogen bonding

Base pairing between A-T and G-C (aka bases in complementary DNA) results from?

phosphodiester bonds

What type of bond is the DNA backbone made up of?

RNA

What is the intermediate between DNA and protein?

5’ end to 3’ end

What direction does transcription of RNA polymerase occur in?

DNA polymerase

What catalyzes the synthesis of DNA?

5’ end to 3’ end; creates leading and lagging strands during replication

What direction does DNA synthesize?

RNA polymerase

What synthesizes RNA using DNA as a template?

Initiation, Elongation, and Termination of transcription.

What are the three steps of RNA synthesis?

7-methylguanosine

What molecule caps the 5’ end of mRNA?

removes introns and pastes exons together.

What does splicing do?

poly A tail

What is added to the 3' end of mRNA?

20 different ones

How many amino acids are there?

primary structure

the linear order of amino acids in a protein

secondary structure

the arrangement of amino acids that are near each other in a polypeptide (or protein) in alpha helices and beta pleated sheets

Tertiary Structure

the spatial arrangement of amino acids (and secondary structures) that are far apart in the linear sequence

Quaternary Structure

spatial relationship on different polypeptides (or proteins) that associate with each other to form a multi-subunit molecule

Fals; one gene can only code for one protein.

T or F: In eukaryotes, one gene can code for more that one protein.

codon

three nucleotides in mRNA encode a single amino acid

anti-codon

three nucleotides in tRNA that are complementary to codon in mRNA

AUG

What is the start codon for reading genetic code?

Groups of Three

Codons are read in groups of how many until a stop codon is reached?

some amino acids are specified

degenerate code

UAA, UAG, UGA

What are the three codons that are stop codons?

UUU and UUC both code for phenylalanine

What is an example of a degenerate code?

True

T or F: Genetic code is evolutionarily conserved. (i.e., the same for all life on Earth).

True

T or F: a change in a single nucleotide can change amino acids in a protein or result in a premature stop codon

False; it has dramatic effects

T or F: changes in the primary structure of a protein has little effects on the function of the protein.

Protein Function

Protein Structure determines?

Proteome

refers to all proteins in cell, tissue, or organism

False; they can

T or F: proteins can not interact with each other.

False; they can.

T or F: proteins cannot be modified after translation

Deoxyribose Sugar

What sugar is found in DNA?

Ribose Sugar

What sugar is found in RNA?

Uracil (U)

What is the nitrogenous base found only in RNA?

Thymine (T)

What is the nitrogenous base found only in DNA?

Double-stranded DNA

What do the strands of DNA look like?

Single Stranded RNA

What do the strands of RNA look like?

Initiation of transcription

What phase of RNA synthesis happens at specific DNA sequences called promoters.

Elongation of RNA

What phase of RNA synthesis proceeds in a 5’ to 3’ direction (phosphodiester bonds link to adjacent bases)?

Termination of Transcription

What phase of RNA synthesis occurs at specific sequences in the RNA transcript?

Hairpin Loops

What signals the ribosomes to stop transcription?

rho protein

What actively removes transcript from the ribosome?

Ribsomes

made of ribsomal RNA (rRNA) and ribosomal proteins that together catalyze protein synthesis using mRNA template and tRNAs

tRNAs

carry amino acids and serve as the molecules that “translate” the genetic code in mRNA into the corresponding amino acid.

mRNA

Three nucleotides in what encode a single amino acid?

tRNA synthetases

What enzyme charges tRNAs.

Initiation factor IF3

blocks binding of the large ribosomal subunit to the small ribosomal subunit, thus allowing mRNA to bind to the small subunit.

Initiation of Translation

pairing between Shine-Delgarno sequence in mRNA and complementary sequence in 16S rRNA positions mRNA for intitiation

Elongation factor; EF-Tu

escorts charged tRNA into the A site

Elongation factor EF-Ts

catalyzes the release of EF-Tu and GDP from the ribosome.

Intitiation Factor IF2

binds to GTP and Met-tRNA and brings them into the P site

The large ribosomal subunit

associates with the complex, hydrolyses GTP and releases IF2 and IF3

Peptidyl Transferase

catalyzes the formation of a peptide bond between the amino acids in the P and A sites.

Elongation Factor EF-G

catalyzes the release of the uncharged tRNA and movement of the ribosome one codon further down the mRNA

Termination of Translation

release factors recognize the stop codons in the A site, discharge the polypeptide chain, and dissociate

Cuts and pastes exons together

What does splicing do?

Alternative splicing

During this process, introns are removed from a precursor mRNA, and exons are joined in different combinations.

Effects of Altervative Splicing on Protein Structure

addition or deletion of structural domains; shift in reading frames; disruption of secondary/tertiary folding

Effects of Alternative Splicing on Protein Function

Enzymatic activity, binding specificity, subcellular localization, receptor, and ion channel properties, disease implication

PCR

an indispensable tool for modern genetics

PCR

has multiple uses (genotyping, study of gene expression, site-directed mutagenesis, and genetic testing)

DNA Polymerase

synthesizes new DNA strands by reading an existing template strand and adding matching nucletides

Primase

synthesizes short RNA sequences that provide a necessary starting point for DNA replication

Ligase

joins two large molecules together by forming a new chemical bond

Telomerase

lengthens and maintains telomeres

Helicase

use energy from ATP hydrolysis to separate double-stranded nucleic acids into single strands

Topoisomerase

manage DNA topology by creating temporary single- or double-strand breaks to relieve torsional strain, supercoiling, and tangling during cellular processes like replication and transcription

Meselson-Stahl Experiments

proof that DNA synthesis is semiconservative