EXAM 2: Microbial Genetics Flashcards
Genetics
Study of inheritance and inheritable traits
Genome
The entire genetic complement of an organism
Ploidy
The number of sets of chromosomes in the nucleus of a biological cell
Genotype
Set of genes in an organism
Phenotype
Physical and function traits of an organism
Transcription
The process by which genetic information represented by a sequence of DNA nucleotides is copied into newly synthesized molecules of RNA, with the DNA serving as a template
Translation
The process by which a sequence of nucleotide triplets in an mRNA molecule gives rise to a specific sequence of amino acids during synthesis of a polypeptide or protein
Polycistronic
A description of mRNA that encodes for multiple polypeptides
Gene
A hereditary unit of information
Compare the structure of prokaryotic and eukaryotic genomes
write out chart!!
Discuss the structure of DNA
- Strands are reverse complementary
- Base pairs: A-T, G-C , NO uracil present
- Double helical
- Runs 5’ to 3’
- DNA grows from the 3’ end (adding nucleotides to the 3’ end)
- Held together by hydrogen bonds between base pairs
- Nucleotides are the monomers that make up NA
Nucleic acid structure:
1. Phosphate
2. Pentose sugar (deoxyribose of ribose)
3. 1 of 5 cyclic nitrogen bases
- Pyrimidines: TCU
- Purines: A&G
Discuss the central dogma of genetics; DNA replication, transcription & translation. Discuss the properties of DNA that facilitate these processes. Describe these processes
Draw out central dogma
DNA replication:
- Starts at the origin of replication (ori)
- DNA polymerase replicates DNA only 5’ to 3’ (nucleotides are added to 3’ end)
- Key to replication is reverse complementary structure of the two strands
- Replication is semiconservative
Transcription:
- Information in DNA is copied as RNA
- Begins at a region of DNA called a promoter (recognized by RNA polymerase) and ends with a sequence called a terminator
- Initiation, Elongation, Termination
Translation:
- RNA → polypeptides, starts AUG
- Ribosomes use genetic information of nucleotide sequences to synthesize polypeptides
- For a new round of peptide chain elongation to occur, the P-site tRNA must move to the E-site and the A-site tRNA must move to the P-site.
Distinguish between genotype and phenotype
Genotype: a set of genes in the genome
Phenotype: physical features and functional traits of the organism
~75% of genes expressed at any given time (allows cells to conserve energy; other genes transcribed and translated when cells need them)
Compare and contrast inducible operons and repressible operons
Inducible operons: must be activated by inducers
- Lactose operon
- Catabolic pathways → presence of substrate
Repressible operons: transcribed continuously until deactivated by repressors
- Tryptophan operon
- Anabolic pathway → presence of product
Describe the different mechanisms of genetic transfer
Horizontal gene transfer among prokaryotes:
- Transfer of genes from one independent, mature organism to another
- Donor cell contributes part of the genome to the recipient cell
- Genes can be transferred to the same or different species
Transformation: Cells that take up DNA are competent
Transduction: - Direct transfer of DNA into a bacteria via viral vector
- Generalized transduction: bacteriophage carries random DNA segment from donor to recipient
- Specialized transduction: Only certain donor DNA sequences are transferred
Bacterial Conjugation: - A conjugation pilus connecting two cells mediates the transfer of DNA between the cells
