Micro EX 2: Microbial Genetics Flashcards
Define Gene
section of DNA that codes proteins
Define Telomeres
ends of a linear chromosomes
When telomeres are frayed and worn what does that mean?
linked with aging and chronic diseases
Describe Purines & name the complementary base
2-ring structure; Adenine & Guanine
Describe Pyrimidines & name the complementary base
1-ring structure; Thymine(DNA), Cytosine, & Uracil(RNA)
Review: Describe the chromosomal structure in Eukaryotes vs Prokaryotes
Eukaryotes: linear chromosomes
Prokaryotes: 1 circular chromosome
Describe Genome
-all genes in an organism
-most associated with chromosomes
-extrachromosomal genes:
~Eukaryote: Mitochondria, Chloroplasts & Plasmids in some one-celled organisms
~Prokaryote: Plasmids
Review: What are plasmids?
drug-resistance genes
What is the complementary base of Guanine?
Cytosine
What is the complementary base of Thymine?
Adenine
What is the complementary base of Cytosine?
Guanine
What is the complementary base of Adenine?
DNA: Thymine; RNA: Uracil
What is another name for DNA Synthesis?
DNA Replication
Describe Genetic Code
-base on triplets of DNA nucleotides
~A/T/C/G
~each triplet codes for an amino acid and/or punctuation
-64 combinations
~to cover the 20 amino acids
*used to make proteins & punctuation
Define mRNA
makes a complementary copy of the template strand of DNA
Where does transcription take place in the Eukaryote & Prokaryote?
Eukaryote: Nucleus
Prokaryote: Cytosol
What happens in transcription?
mRNA copies DNA (replicate before dividing)
Describe translation
- protein synthesis
- mRNA attaches to the ribosome & tRNA brings in raw amino acids
Describe Codon
triplets of nucleotides of mRNA
Describe Anticodon
triplets of nucleotides of tRNA
Name some types of RNA
- mRNA
- tRNA
- rRNA
- RNA Primer
- 5th RNA
Which RNA goes thru both translation & transcription?
mRNA
Which RNA goes thru translation only?
tRNA
What is the triplet for a Start Codon?
AUG (Methionine)
Which karyote has introns & exons?
Eukaryotes
Which karyote does not have introns or exons?
Prokaryotes
Which karyote can have simultaneous transcription & translation?
Prokaryote
Why are translation & transcription separate events? Name the karyote associated with this.
Because the nucleus have nuclear membranes; Eukaryotes
Describe Exons
expressed when needed
Describe Introns
not expressed; cut out “GARBAGE”
Describe 5th RNA
works as an enzyme, cut out introns splices exons together
Define DNA Replication
Precursor for cell division
Describe antiparallel concept
Grows 5’–> 3’
Applies to DNA molecules
In a nucleotide what is attached to 1’?
Nitrogen base
In a nucleotide what is attached to 3’?
Hydroxyl (OH) group
In a nucleotide what is attached to 5’?
Phosphate group
Where does DNA Replication occur in mitosis?
Interphase
What is the process of DNA Replication?
- Helicase- “unzips” DNA breaking hydrogen bonds
- Primase/RNA Polymerase- builds RNA primer
- DNA Polymerase 3- puts DNA nucleotides after RNA Primer
- DNA Polymerase 1- replaces RNA primer with DNA nucleotides
- DNA Ligase- connects Okazaki fragments togerther
- Gyrase- super coils the strands together
Describe the Leading Strand.
grows 5’ –> 3’ towards Helicase
Describe the Lagging Strand
grow 5’ –> 3’ in the opposite direction of the leading strand it grows in fragments called Okazaki fragments
Describe Regulatory Gene
- can be anywhere on the chromosome
- codes for a repressor protein that can fit on the operator gene and block transcription of the structural genes
Describe Operon
- consists of the promoter gene, operator gene, & structural genes
- these genes have to be found together on a chromosome
What is consists of a palindrome of nucleotide bases that signals the beginning of a codon?
promoter gene
What is a palindrome?
a word, that reads the same backwards or forward
What works as a red/green light?
the operator gene
If the operator gene is blocked by the repressor protein what happens?
nothing happens
If the operator gene is not blocked what happens?
the structural genes are transcribed then translated into proteins and cells can now metabolize something
What is the purpose of the structural genes?
codes for specific enzymes that helps in catabolic or anabolic reactions
What are 2 different operons?
inducible operon & repressible operon
What operons are normally on but can turned off, normally by excess product?
repressible operon
What operons are normally off but can be turn on?
inducible operon
What is an example of inducible operon?
the lac operon
What is an example of repressible operon?
the trp operon
What does trp stand for?
tryptophan
Which operon are normally involved in anabolism?
repressible operons
Which operon are normally involved in catabolism?
inducible operons
What binds to lac repressor causes a change in the lac repressor protein,preventing it to bind to the lac operator site?
Allolactose (Lactose inducer)
If there is an excess product of tryptophan what happens?
the trp operon stops
In transcription of the trp operon, mRNA codes multiple polypeptides what happens in translation?
enzymes make tryptophan amino acids
Define SNPS “snips”
single nucleotide polymorphism
What is polymorphism?
many forms
Define Point Mutation
one nucleotide is change
How many base(s) does it take to make 5-6 thousand SNPs to cause a disease?
1 single base
Name the 3 point mutations
- silent mutation
- missense mutation
- nonsense mutation
Point Mutation: changes in codons but doesnt change in amino acids
Silent mutation
Point Mutation: change from an amino acid to stop codon (ends all codings)
Nonsense mutation
Point Mutation: switch out 1 base code for different amino acids
Missense Mutation
Define frameshift mutation
when the whole reading frame shifts due to an addition or deletion
What are the 5 factors that incrases mutations?
- radiation
- heat
- high doses of electricity
- extreme in pH
- some caustic chemicals
Denature of hydrogen bonds break where?
between complementary bases
What are produced from burned products & are frameshift mutagens?
benzopyrenes
Describe Afla Toxins
- Aspergillus mold (white powders mostly found on peanuts)
- frameshift mutagens
What are the 3 chemical factors of a frameshift mutagen?
- Benzopyrenes
- Afla Toxins
- Base Analogs
Describe Base Analogs
imitate nitrogen bases
Describe Conjugation
Is the direct transfer of DNA plasmid from one cell to another
Give examples of genetic transfers
Drug resistance genes & E. coli
Describe transformation
bacteria pick up pieces of DNA or plasmids from the environment and incorporate this into their genome
Name an example of something that is similar to transformation
saprophytes
Define transduction
Injection of foreign DNA by a bacteriophage(virus that attacks bacteria) virus into the host bacterium by recombination
Explain Griffen’s Experiment
- he takes avirulent w/o a capsule and mixes it with a virulent capsule
- injects it in a mouse
- mouse dies
- because all bacteria are dead but genes are more stable & kills the mouse
Explain the process of transduction
- phage injects in DNA
- phage enzyme degrade host DNA
- cell synthesizes new phages that incorporate phage DNA & mistakenly some host DNA
- transduction phage injects donor DNA
- Donor DNA is added into recipient’s chromosome by recombination
Explain the steps of Conjugation
- Donor cell attaches to a recipient cell w/ its pilus. pilus draws cells together
- cells contact one another
- one strand of plasmid DNA transfer to recipient
- recipient synthesizes a complementary strand to become an F+ cell (restoring its complete plasmid
