EXAM 2: Microbial Genetics Flashcards
(16 cards)
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
Compare the 3 types of horizontal genetic transfer discuss in lecture
Transformation:
- bacteria take up extracellular DNA from the environment. bacteria that do so are deemed competent
Transduction:
- Direct transfer of DNA into a bacteria via viral vector
- Generalized vs Specialized (explain them)
Bacterial Conjugation:
- A conjugation pilus connecting two cells mediates the transfer of DNA between the cells
