Chapter 7 Flashcards
Central dogma
Information is encoded in DNA
What did griffiths transformation principle test?
Wether protein or nucleic acid contained the genome
Mouse experiment
DNA encodes for what two types of genes?
Structural genes- sequence of nucleotides that can be decided to produce a functional RNA molecule
DNA control region-sequence of nucleotides that regulates expression of adjacent structural gene
Structural genes
Sequence of nucleotides that can be decoded to produce a functional RNA molecule
DNA control regions
Sequence of nucleotides that regulate expression of an adjacent structural gene
Define conjugation
Horizontal gene transfer that requires cell to cell contact, genes can be transferred sequentially over a period of time
Bacterial chromosome shape
Circular
How do euks have more non coding DNA than proks
Enhancers-sequences needed for transcription of promoters
Promoters-sequences preceding a gene that activated the genes expression
Enhancer
Sequence of nucleotide needed for transcribing a promoter
Promoter
Sequence proceeding a gene that activates the genes expression
Monocistronic
RNA produced from an independent gene encodes for one protein
(One gene, one RNA)
Define operon
Genes next to one another that are all involved in the same metabolic process and controlled by the same regulatory sequence
Define regulon
Collection of genes and operons in different areas of the chromosome that are involved in the same metabolic process and are regulated by the same regulatory proteins
What makes up DNA?
A nitrogenous base
Deoxyribose
Phosphate group
What bases are pyrimidines?
Cystine and thymine (if it has a y, it’s a pyrimidine)
How are individual nucleotides linked?
Covalent bonds
How many hydrogen bonds between A’s and t’s?
2
How many hydrogen bonds between Cs and Gs?
3
How does RNA differ from DNA?
- Contained virus
- Contained uracil
- Usually single-stranded
How are bacterial DNA loops anchored?
Histone like proteins
Nucleoid
Series of DNA loops and domains in bacterial genome
Is the DNA of most organisms negatively supercoiled or positively supercoiled? Why?
Negatively
It’s easier to separate
Topoisomerases
Enzymes that change DNA supercoiling
Positive super coiling vs negative supercoiling
Positive- overwound
Negative- underwound
Type I topoisomerases
Usually single proteins
Cleave one strand of DNA and are used to unwind supercoils
Type II topoisomerases
Multiple subunits Cleave both strands of DNA Used to introduce supercoils Targeted by quinolones Ex DNA gyrase
Stages of DNA replication
Initiation
Elongation
Termination
Initiation (DNA)
Melting of the double helix, loading of DNA polymerase complex
Elongation (DNA)
Addition of deoxyribonucleltides and proof reading
Termination (DNA )
DNA is completely duplicated, super coils are stored, DNA is methylated (if not methylated, it’s destroyed)
What activates and deactivates initiation? (DNA)
DNAA activates, SeqA deactivates
SeqA protein functions
Binds to hemimethylated (newly replicated) origins and prevents another initiation too soon after replication
DnaB
Helicase
DNA primase
Synthesis of RNA primer
DNA pol III
Major replication enzyme
DNA pol I
Replaces DNA primer with DNA
DNA gyrase
Relieves DNA supercoiling
What is DNA-ATPs role in DNA replication?
When DNA A accumulates, DNA-ATP binds upstream of origin and causes DNA to loop in prep for being melted
DNA pol III’s main jobs are…?
It’s the main replication polymerase, proofreads, and has 5’ to 3’ exonuclease that removes improperly paired base
Replisome is made of?
DNA pol III, DNA primate, and helicase
Replisome does what?
Ensures leading and lagging strands are synthesized simultaneously in the proper direction
Fixed miscellaneous location are attached to cell membrane
What removed RNA primers?
Rnase
What fills in gaps in DNA?
DNA pol I
What seals phosphide ester nicks?
DNA ligase
TUS
Terminus utilization substance binds tj terminator sequence and acts as counter helicase
Low copy vs high copy plasmids
Low copy- plasmids segregate equally between daughter cells when cell divides
High copy- plasmids randomly segregate
How are plasmids transferred between cells?
Conjugation- transfer via cell to cell contact (via pilli)
Transformation- plasmids released from dead cells can sometimes be taken up by live cells
Euk chromosome
Bigger than bacterial
Linear, need reverse transcriptase called telomerase that rebuilds telomeres
Pack DNA using histones
Has introns and exons
Archael similarities to bacteria
Operons, asexual reproduction, no nuclear membrane, single circular chromosome
Archael similarities to euks
DNA packing proteins,RNA polymerase
Ribosomal components more closely resemble euks, DNA polymerase
Restriction endonucleoases
Cleave DNA at specific points, usually 4-6 bp palindromes
What is the Sanger dideoxy strategy of DNA sequencing?
Incorporation of a 2’ 3’ dideoxynucleotide
It prevents the growing chain felt elongation. The ending nucleotide is then selected for and read
Meta genomics
Using modern genomic techniques to study microbial communities directly in nature
Whole genome sequencing
Shotgun cloning approach
Genome is broken up and sequenced