Microbial Genetics (8.1-8.3) Flashcards
(41 cards)
Where are the genomes located in bacteria?
Chromosomes or plasmids
Where are the genomes located in viruses?
The nucleocapsid
What are the structural features of DNA? What 3 things makes that structural feature?
Made of Nucleotides
- Phospate
- Deoxyribose (FIVE CARBON SUGAR)
- Nitrogenous base
What are the two groups of Nitrogenous bases?
pyrimidines and purines
What are the pyrimidines?
T (Thymine), C (cytosine) and U (uracil)
What are the Purines?
A (adenine), and G (guanine)
How do nucleotides covalently bond to each other?
Through a sugar- phosphate linkage. The 5’ carbon on the deoxyribose connects to a phosphate group that connects to the 3’ carbon to form a strand.
What are the nitrogenous base pairs and how many Hydrogen bonds do they have?
- Adenine (A) pairs with Thymine (T) = 2 pairs
- Guanine (G) with Cytosine (C) = 3 pairs
DNA is a _____ helix and has an ______ arrangement.
Double ; antiparallel
Overall DNA replication process is called __________ replication. Why?
semiconservative ; because there’s a parent strand that creates a complementary strand. (one original strand and one new strand on both new double helixes)
Break down the process of DNA replication. Include all 3 enzymes.
- Topoisomeras unwinds the DNA helix
- Helicase breaks the hydrogen bonds holding the two strands together, creating two separate strands
- Polymerase (III) Adds the nucleotides that pair with the nucleotides on the leading strand (the one that goes 5’ to 3’) because polymerase can only builds a 5’ to 3’ strand.
The strand that’s originally in the 3’ to 5’ is called the lagging strand because polymerase has to keep moving in order to build a strand in the 5’ to 3’ direction which is where primers help tell them where to stop and start. This creates Okazaki fragments DNA polymerase (I) removes the primers and closed gaps and the fragments are joined together to make a strand by DNA ligase.
At the end of DNA replication you have TWO double helix molecules.
Why are A (Adenine) & T (Thymine)’s bond important in DNA replication?
They only have two hydrogen bonds so it’s easier to split the double helix.
What direction is the leading strand synthesized in?
5’ to 3’
On the ____ strand, DNA polymerase synthesizes a few bases at a time in the direction _____ from the replication fork
lagging ; away
The enzyme that then joins the fragments together to create the strand is called
DNA ligase
True or False
Bacteria replicates DNA at a pace of 750 bases per seconds at each fork (fast) which makes mutations more likely to occur
true
What is transcription?
when DNA is used to create RNA (mRNA)
Explain the process of transcription. when does it stop? Can include the 3 steps.
Initiation: RNA polymerase binds to the template strand that goes (5’ (near the replication fork) to 3’ at the end away from the replication fork
Elongation: and creates an mRNA strand that goes 5’ to 3’ towards the replication fork
Termination: Keeps going until RNA polymerase reaches the TERMINATION REGION
What is a regulatory RNA?
List the 4 examples of one.
They are important regulators of gene expression in bacteria. (They regulate transcription and translation.) Examples: -Micro RNAs - Anti-sense RNAs -Riboswitches - Small interfering RNAs
What is translation?
Making proteins from mRNA directions
What are the STOP CODON nucleotides?
UAA, UGA, UAG
Explain the process of transcription + translation
Transcription: mRNA is made from a DNA strand
Ribosomal subunits (50S + 30S) come together to hold the mRNA and tRNA. The ribosome scans the mRNA inn a 5' to 3' direction.
THEN
tRNA anticodons match the right nucleotides to the mRNA codons and creates the amino acids
What is a codon?
A group of three nucleotides that dictate which amino acid is added to the growing peptide chain
What is a wobble ?
The first two nucleotides that are required to encode the correct amino acid.
permits some variation or mutation without altering the message.
