Genetics

What does semiconservative DNA replication mean?

Each new DNA molecule contains one original parental strand and one newly synthesized strand.

Who demonstrated that DNA replication is semiconservative?

Meselson and Stahl.

Where does DNA replication begin?

At an origin of replication.

In what direction are new DNA strands synthesized?

5′ → 3′.

What enzyme synthesizes new DNA?

DNA polymerase.

What is the central dogma of molecular biology?

DNA → RNA → Protein.

What is transcription?

The process of using DNA as a template to synthesize RNA.

What is translation?

The process of using mRNA to assemble a protein.

What is mRNA?

RNA that carries genetic information from DNA to the ribosome for translation.

What is rRNA?

RNA that forms part of the ribosome.

What is tRNA?

RNA that carries amino acids to the ribosome during translation.

What is reverse transcription?

The production of DNA from an RNA template using reverse transcriptase.

What enzyme performs transcription?

RNA polymerase.

What is the template strand?

The DNA strand used to make the RNA transcript.

What is the coding strand?

The DNA strand that has the same sequence as the RNA except DNA has T instead of U.

How does RNA compare to the coding DNA strand?

It has the same sequence except RNA contains U instead of T.

What base replaces thymine in RNA?

Uracil (U).

What is a promoter?

A DNA sequence where transcription begins.

What are exons?

Regions of a eukaryotic gene that remain in mature RNA.

What are introns?

Regions removed from RNA before translation.

What is a codon?

A three-nucleotide sequence on mRNA that specifies an amino acid or stop signal.

What is an anticodon?

A three-nucleotide sequence on tRNA that pairs with an mRNA codon.

What is the start codon?

AUG.

In what direction does the ribosome move along mRNA?

5′ → 3′.

What are the three stop codons?

UAA, UAG, and UGA.

How many possible codons are there?

64.

How many codons specify amino acids?

61.

How many stop codons are there?

3.

How many common amino acids are there?

20.

What is gel electrophoresis used for?

Separating DNA, RNA, or proteins based on properties such as size and charge.

What is a Southern blot used to detect?

DNA.

What is a Northern blot used to detect?

RNA/mRNA.

What is a Western blot used to detect?

Protein.

What is genomics?

The study of genomes and their sequences.

What is proteomics?

The study of the complete set of proteins produced or encoded by a genome.

What is a mutation?

A change in DNA sequence that can create genetic variation.

What are the four major processes that change allele frequencies?

Natural selection, migration (gene flow), mutation, and genetic drift.

What is natural selection?

Differential reproductive success caused by differences in heritable traits.

What is genetic drift?

Random changes in allele frequencies caused by chance.

What is migration/gene flow?

The movement of individuals or alleles between populations.

What is a phylogenetic tree?

A diagram representing evolutionary relationships among organisms.

What is a clade?

A group consisting of an ancestor and its descendants that share derived characteristics.

What is the blending theory of inheritance?

The incorrect idea that offspring traits permanently blend the traits of their parents.

What did Mendel's experiments demonstrate?

That hereditary information is passed as discrete units rather than permanently blending.

What is a pure-breeding organism?

An organism that consistently produces the same phenotype when bred.

What is the P generation?

The parental generation.

What is the F1 generation?

The first filial generation produced from the P generation.

What is the F2 generation?

The second filial generation produced from F1 individuals.

What is a dominant phenotype?

The phenotype expressed in a heterozygous individual.

What is a recessive phenotype?

A phenotype masked by a dominant allele in a heterozygote.

What is homozygous?

Having two identical alleles for a gene.

What is heterozygous?

Having two different alleles for a gene.

What is an allele?

An alternative version of a gene.

What is the law of segregation?

The two alleles for a gene separate during gamete formation, so each gamete receives one allele.

What is a Punnett square used for?

Predicting possible offspring genotypes and phenotypes.

What is the typical F2 phenotypic ratio of a Mendelian monohybrid cross?

3 dominant : 1 recessive.

What is the typical F2 genotypic ratio of Aa × Aa?

1 AA : 2 Aa : 1 aa.

What is a test cross?

Crossing an individual with an unknown genotype with a homozygous recessive individual.

What is a dihybrid cross?

A cross examining the inheritance of two genes simultaneously.

What is the law of independent assortment?

Alleles of different genes assort independently during gamete formation when the genes assort independently.

What is the typical F2 phenotypic ratio for a Mendelian dihybrid cross?

9 : 3 : 3 : 1.

What gametes can an RrGg individual produce if the genes assort independently?

RG, Rg, rG, and rg.

What is the product rule?

For independent events, multiply their probabilities when BOTH must occur.

What is the sum rule?

Add probabilities when multiple mutually exclusive outcomes can satisfy the condition.

When should you use the product rule?

When BOTH events or conditions must occur.

When should you use the sum rule?

When EITHER of several mutually exclusive outcomes can satisfy the condition.

What is binomial probability used for?

Calculating the probability of obtaining a particular number of outcomes in repeated trials.

What is a chi-square test used for?

Determining whether observed results differ significantly from expected results.

What does a chi-square test compare?

Observed results with expected results.