DNA Structure and Function Lecture

These flashcards cover key concepts related to DNA structure, function, replication, and the processes of transcription and translation.

Recognize functions of DNA.

DNA performs replication, storage of information, expression of that information, and variety by mutation.

Griffith's experiment stransformation principle.

Demonstrated that a macromolecule from type S bacteria can convert type R bacteria into type S at the genetic level.

Avery-MacLeod-McCarty experiment.

Identified DNA as the 'transforming principle' by purifying DNA from S strain and transferring it to R strain of bacteria.

Hershey-Chase experiment hypothesis.

Supported the idea that DNA is the hereditary molecule by showing only viral DNA enters host bacteria.

Chargaff's observations.

Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C). Purines include A and G; Pyrimidines include C, T, and Uracil (U).

Definition of 'polarity' in DNA.

Refers to the orientation of the DNA strands, with a 5′ end having a phosphate group and a 3′ end having a hydroxyl group.

Types of chemical bonds in DNA.

Include phosphate bonds (covalent), hydrogen bonds (between complementary bases), and van der Waals interactions.

Semiconservative replication model.

Each new DNA molecule is composed of one old strand and one new strand.

Effects of missing key replication enzymes.

If helicase is missing, DNA strands cannot separate; if DNA polymerase is missing, new DNA strands cannot be synthesized.

Function of telomeres.

Protect chromosome ends from degradation during replication; telomerase extends telomeres.

One gene-one polypeptide hypothesis.

Replaced the one gene-one enzyme hypothesis, acknowledging that not all proteins are enzymes.

Differences in transcription/translation in prokaryotes vs eukaryotes.

In prokaryotes, both occur in the cytoplasm, while in eukaryotes, transcription occurs in the nucleus and translation in the cytoplasm.

Degeneracy of the genetic code.

Means multiple codons can code for the same amino acid, which helps to mitigate the effects of mutations.

Reading frame of mRNA.

Refers to how nucleotides are grouped into codons during translation; a frameshift alters all downstream codons.

Universality of the genetic code.

Same codons specify the same amino acids in all organisms, supporting the idea of a common ancestor.

Structure of a ribosome.

Made of ribosomal RNA (rRNA) and proteins, with a small subunit for mRNA binding and a large subunit for peptide bond formation.

Process of transcription.

Involves initiation, elongation, and termination with RNA polymerase synthesizing RNA from the DNA template.

Function of tRNA in translation.

tRNA brings the correct amino acids to the ribosome corresponding to the codon in mRNA.

Effects of point mutations.

Include missense mutations (change amino acid), silent mutations (no change), nonsense mutations (stop codon introduced), and frameshift mutations.