Chapter 7 Lecture 1: Genetics and Molecular Biology

A collection of vocabulary flashcards covering key concepts from Chapter 7 of the lecture notes, particularly focused on genetics and molecular processes.

Bacterial DNA replication

Occurs in a circular manner using a single origin of replication, generally faster than eukaryotic replication.

Eukaryotic DNA replication

Occurs in a linear manner with multiple origins of replication, involves chromatin structure.

Genotype

The genetic constitution of an organism; the specific alleles present.

Phenotype

The observable traits or characteristics of an organism, resulting from the interaction of genotype with the environment.

Central Dogma of Genetics

Describes the flow of genetic information from DNA to RNA to proteins.

Protein synthesis processes

Includes transcription (DNA to RNA) and translation (RNA to protein).

Promoter

A DNA sequence that initiates transcription by binding RNA polymerase.

Operator

A segment of DNA that regulates the activity of the promoter in prokaryotic cells.

Bubble in transcription

The region of unwound DNA where RNA synthesis occurs during transcription.

Sigma factor

A protein that initiates the transcription process in bacteria by helping RNA polymerase to bind to the promoter.

RNA polymerase

The enzyme responsible for synthesizing RNA from the DNA template during transcription.

Steps of transcription

Involves initiation, elongation, and termination.

Energy accommodation in transcription

Transcription requires ATP to provide energy for the RNA polymerase action.

GC-rich terminator

A sequence that signals RNA polymerase to stop transcription by forming a stable hairpin structure.

Rho-dependent terminator

A mechanism that requires the Rho protein to terminate transcription.

Polyribosome

A cluster of ribosomes reading a single mRNA strand, allowing for multiple protein copies to be synthesized simultaneously.

Eukaryotic transcription vs prokaryotic

Eukaryotic transcription occurs in the nucleus, requires splicing, and involves 5’ capping and poly-A tail; prokaryotic transcription is more direct.

5’ capping

The addition of a 7-methylguanylate cap to the 5’ end of mRNA, vital for stability and recognition.

Poly-A tail

A stretch of adenine nucleotides added to the 3’ end of mRNA, important for mRNA stability and export from the nucleus.

Alternative RNA splicing

The process by which different combinations of exons are joined together to produce various proteins from a single gene.

Amino acids encoded in DNA/mRNA

Encoded by sets of three nucleotides called codons in mRNA which match with tRNA's anti-codons.

Triplet nucleotide variations

There are 64 possible triplet combinations from four nucleotides, but only 20 amino acids; excess variations are often redundant codons.

Transfer (t)RNA vs mRNA structure

tRNA has a cloverleaf shape and carries amino acids, whereas mRNA is linear and carries codons.

Role of tRNA

To transport specific amino acids to the ribosome during translation, matching them to the corresponding mRNA codon.

Ribosomes in eukaryotic vs prokaryotic

Eukaryotic ribosomes are larger (80S) and more complex than prokaryotic ribosomes (70S).

Ribosome assembly

Involves ribosomal RNA and proteins coming together to form the ribosomal subunits.

A, P, and E sites

The three sites on a ribosome: A (aminoacyl), P (peptidyl), E (exit); involved in the sequential binding of tRNA and formation of polypeptide chains.

Benefits of polyribosome in prokaryotes

Allows for efficient protein synthesis by enabling multiple ribosomes to translate a single mRNA simultaneously.

Translation initiation and termination

Initiation differs with the start codon (AUG) for eukaryotes and prokaryotes, where they have different contextual recognition elements.