LEC EXAM #2 CHP. 10 Flashcards
Biofilm: (3)
- Growth of bacteria/fungi on a surface
- Composed of polysaccharides, nucleic acids, proteins, and lipids
- Allows for formation of water channels to provide shelter, protection, hydration, and nutrients to cells
Bacterial cells secrete:
A gel-like extracellular substance that allows for good attachment to a surface and passage of water channels
Benefit of water channels passing through:
Can send signals to other bacterial cells that nutrients are present
Bacterial growth through binary fission:
Bacteria duplicates DNA->grows->splits into 2 cells
Septum:
Used to build new cell wall off of for the next cell
Gregor Mendel:
- Father of modern genetics
- Bread pea plants
- Observed characteristics of genes being passed from parents to progeny (vertical gene transfer)
Binary fission is:
Asexual reproduction
Chromosomal genes of inheritance:
DNA contains certain segments that contain specific genes
Hammerling’s contribution:
- Importance of how DNA functions
- Indirect
- Mushroom Experiment: Took am a mushroom and cut off the head-> head regenerated DT the nucleus being at the foot of the mushroom
Griffith experiment:
Original belief?
- 1st experiment to determine what genetic info is made of
- Indirect
- Originally they thought amino acids were our DNA because we have 20 amino acids and 4 nucleotides in DNA-> more amino acids than DNA variations
How did Griffith experiment work?
2 strains of pneumoniae:
- virulent strain: causes disease (smooth strain)
- avirulent strain: non-disease causing (rough strain)
Why is virulent strain smooth?
In a capsule for protection against getting engulfed and abx treatment
Griffith exp.
- Smooth inject mouse->
- Rough inject mouse->
- Heat smooth inject mouse->
- Heat smooth + rough inject mouse->
Dies
Lives
Lives
Dies
Why does the mouse die when you heat the smooth and add it to rough then inject the mouse?
Because DNA doesn’t die with heat-> genes for capsule from smooth is passed onto R-> builds a capsule through transcription and translation-> mouse dies-> recovers live S
During his experiments, Griffith only knew:
That R got transformed into S
Avery experiment contribution:
- Practiced extension of Griffith’s experiments
- Indirect
How did Avery’s experiments work? (3)
- Heated S-> adds RNAase (eats RNA)-> adds live R-> injects mouse-> mouse dies + live S
- Heated S-> adds protease (eats protein)-> adds live R-> injects mouse-> mouse dies + live S
- Heated S-> adds DNAase (eats DNA)-> adds live R-> injects mouse-> mouse lives + no live S
In Avery experiments, why did the mouse live when adding DNAase to heated S?
Because when DNAase eats DNA, this gets rid of the gene to make a capsule-> can’t go through transcription or translaton-> R can’t transform into S
Hershey and Chase experiment:
- Directly tests if DNA is genetic info
- Phages infected host cells with DNA and protein-> DNA (Phosphorus-32) found inside cells and protein (Sulfur-35) found outside cell
How was the Beadle and Tatum experiment performed?
Starts with fungal spores that are treated in 2 different ways:
A. 1 left alone
B. 1 with x-ray on it-> causes mutations to spores
Mutation of DNA causes:
Mutation of a gene that’s important for synthesis of a particular protein/amino acid
Significance of Beadle and Tatum’s experiment:
Showed when pieces of DNA are mutated, it caused direct effect on the proteins needed for growth
Structure of deoxyribose nucleotide:
Sugar- deoxyribose (no O2)
Phosphate
Nitrogenous base
Purines
- Double rings
- bigger structure
- adenine + guanine
Pyrimidines
-Single rings
-small structure
-cytosine + thymine
(both have Y’s)
How do we link nucleotides together?
Phosphodiester bond
What is off of your 3’ carbon?
OH
-Attacked by incoming nucleotide’s phosphate-> phosphate creates covalent bond with OH (phosphodiester bond)
You ALWAYS add to:
a free 3’ hydroxyl
Synthesis of DNA goes:
5’ phosphate to 3’ hydroxyl
5’ reacts with 3’ to:
Create a phosphodiester bond
You CANNOT add onto:
a free 5’ phosphate
A -> T have:
2 hydrogen bonds
C -> G have:
3 hydrogen bonds
Twist make bonds:
More stable
Heating causes:
Bonds to break apart but won’t break individual strains apart
How does deoxyribonucleotide differ from a ribonucleotide?
H for DNA
OH for RNA
RNA does not have:
A complementary strand because RNA is single stranded
DNA vs. RNA:
DNA
- deoxyribose
- thymine instead of uracil
- double stranded
RNA
- ribose
- uracil instead of thymine
- single stranded
- complementary strand to template DNA
Process of making mRNA:
Transcription
Process that happens between DNA-> mRNA:
Transcription
Process that happens between mRNA-> protein:
Translation
tRNA used to:
Link together correct amino acids
tRNA structure:
- unique piece of RNA
- only double stranded RNA molecule
- has an amino acid attached to its 3’ hydroxyl end
- at the other end it has 3 bases that are complementary to mRNA strand
Once tRNA hydrogen bonds with mRNA:
The correct amino acid is on the other end
Codon:
3 base pairs on mRNA that codes for an amino acid
Anti-codon:
Complimentary tRNA to codon
Gene:
Segment of DNA that codes for a protein
Non-coding region of DNA is important for:
Chromosomal structure/integrity
Telomerase:
- Enzyme that rebuilds telomere
- Rebuilds the chewed up portion that the DNAase eats
Telomeres:
- on ends of chromosomes
- non-coding (no genes)
- prevents genes from getting eaten
Kineticore:
Group of proteins that binds mitotic spindle + centromere
Centromere:
- Non-coding region
- Important for structural movement of chromosomes
- Middle DNA of chromosome
Genotype vs. phenotype:
- Genotype doesn’t change
- Phenotype changes due to temperature
How do organize our DNA?
- Nucleosome: DNA wraps around 8 histone protein octomer that has tails that have positive charges
- Phosphate on DNA has negative charge so DNA has negative charge
Nucleosome:
-DNA + histone octamer
First level of impaction:
Second level of impaction:
Nucleosome
Solenoid
6 octamer/nucleosomes=
Solenoid
Human DNA structure vs. bacterial DNA:
Humans have linear DNA
Bacteria have circular DNA + plasmids
Quorum sensing:
- Is how biofilm communicate with each other or change gene expression
- Causes upregulation of gene expression
Plasmids:
- Extra pieces of DNA inside bacterial cell
- Can replicate independently
How to transfer plasmids to other bacterial cells?
Pilus
Exponential/log phase:
- Adjusts their gene expression to the nutrients available and grow rapidly until the nutrients are depleted
- 99% of bacteria we use
Lag phase:
- Uptaking gene and changing gene expression
- No increase in bacterial cell growth yet because they are still getting used to/acclimated to the environment
Good biofilm vs. bad biofilm:
Good: on gut and respiratory lining
Bad: formation on teeth, plaque
