Microbial Genetics Flashcards
1
Q
Nucleic acids
A
polymers of basic building blocks called nucleotide
2
Q
A nucleoside is what
A
a pentose sugar attached to 5 nitrogenous bases
3
Q
RNA
A
ribonucleic aid
4
Q
DNA
A
deoxyribonucleic acid contains genetic code
5
Q
5 nitrogenous bases
A
- Adenine
- Guanine
- Cytosine
- Thymine
6
Q
base pairing between what two nitrogenous bases are in RNA only
A
adenine and uracil
uracil replaces the thymine
6
Q
What are the base pairs
A
A-T
G-C OR IN RNA U-C
7
Q
DNA of prokaryotic genomes are found in two structures
A
- Chromosomes
- Plasmids
8
Q
Prokaryotic Chromosomes
A
-bacterial cells package the main portion of DNA along with RNA and proteins in chromosome
9
Q
Every cell has “” copy of the genome
A
single copy
haploid
10
Q
A typical chromosome consists of what shape and where
A
circular molecule of DNA in the region of cytoplasm called the nucleiod
11
Q
Is there a membrane surrounding the nucleiod
A
No
12
Q
Archael DNA is what shape and located where
A
haploid
located in nuclei
13
Q
What surrounds the archael chromosome
A
DNA is wrapped around globular proteins called histones
14
Q
Plasmids
A
many cells contain one or more plasmids
small molecules of DNA that will replicate independentlyW
15
Q
What are the shape of plasmids
A
usually circular
16
Q
Each plasmid carries what
A
information required for its own replications
17
Q
There are 4 different types of plasmids
A
- Fertility
- Resistance
- Bacterocin
- Virulence plasmids
18
Q
Fertility Plasmids
A
carry instructions for conjugation : process by which bacterial cells transfer DNA to another bacterial cell
19
Q
Resistance Plasmids
A
carry genes for resistance to one or more antimicrobial drug, certain cells will transfer resistance plasmids to other cells which then acquire resistance to same antimicrobial chemicals
20
Q
Bacteriocin
A
carry genes for toxins called bacteriocins, which will kill bacterial cells of the same or similar species that lack a plasmid, the plasmid will kill its competitors
21
Q
Virulence Plasmids
A
carry instructions for structures, enzymes or toxins that will enable bacteria to become pathogenic
22
Q
Eukaryotic Genomes consist of
A
consist of
Nuclear and Extranuclear, some plasmids
23
Q
What is the structure of Eukaroytic Genomes
A
chromosomes are linear, and within a nucleus
24
Are eukaryotic cells haploid
No, they are often diploid : two chromosome copies
25
Nuclear Chromosomes
have more than 1 nuclear chromosomes
some loose chromosomes as they mature
are all linear with nucleus
there is a nucleus envelop
26
Extranuclear Chromosomes
DNA molecules of mitochondria and chloroplasts
have similar resemblance to prokaryotes
27
DNA is what shape in Eukaryotic Genomes
circular
28
Whats the % coded in the extranuclear space
genes located in the extranuclear code for 5% RNA
nuclear DNA codes for the remaining 95%
29
DNA replication is what type of process
anabolic polymerization process = allowing cells to make copies of its genomes
30
The process of DNA requires what
monomers and energy
dGTP, dCTP, dTTP, dATP = using ribose sugar
31
What is the key to DNA replication
the complementary structure of the 2 strands
32
The process
a cell will separate two original strands and use each template for the synthesis of the new complementary strand
33
Replication is semiconservative
each of the daughter molecules retains on parental strand and has one new strand
each is half new and half old
34
During DNA synthesis what is released and needed
proteins needed
energy is being released
35
DNA replication begins at a specific sequence of nucleotides called
origin
36
What does the enzyme DNA helices do
unzips the DNA molecule by breaking the H bonds between the nucleotide bases and exposes these bases to the replication fork
37
What do protein molecules do at the replication fork
the protein molecules will stabilize the separated single strands so that they do not rejoin while replication proceeds
38
What happens after helices untwists and separates the strands of DNA
polymerase will bind to each strand
catalyze synthesis of DNA by addition of new nucleotide at the 3' end
39
DNA polymerase III
is the enzyme of DNA replication in bacteria
40
How are the strands synthesized in different ways
Leading stand 5-3'
Lagging strand 5-3' but in shorter segments
41
What is the replication fork
the area where the DNA replication takes place
42
What enzymes remove supercoils and cut DNA
gyros and topoisomerase
43
Helicase functions to
unzip and unwind and introduces supercoils in the DNA
44
Methylation
makes DNA replication more complicated
45
What happens in methylation
methylation of daughter strands where a methyl group is added to one or two bases
initiates DNA replication
46
Methylation controls what
methylation is the control of genetic expression, turn off / turn on and transcribe
47
Leading strand
synthesized continuously
48
Lagging strand
synthesized discontinously
49
Promoter of a gene
region of DNA located at beginning of the gene
binding site for RNA polymerase
50
RNA polymerase is the enzyme responsible for
initiating transcription
contain nucleotides
51
RNA coding sequence
region that codes information to produce RNA molecules
series of codons that specific AA
52
Terminator
sequence of 3' nucleotides to @ end of 5'
gene signalling the termination of transcription
53
Cells transcribe 6 main types of RNA from DNA
1. RNA primer
2. messenger RNA
3. Ribosomal RNA
4. Transfer RNA
5. Regulatory RNA
6. Ribozymes
54
RNA primer
molecules for DNA polymerase to use during DNA replciation
55
Messenger RNA
molecules which carry genetic information from chromosomes to ribosomes
56
Ribosomal RNA
molecules that combine ribosomal polypeptides to form ribosomes
57
Transfer RNA
molecules which deliver the correct AA to ribosomes based on the sequences of nucleotides in mRNA
58
Regulatory RNA
molecules that interact with DNA to control gene expression
59
Ribosomes
which are RNA molecules that function as metabolic enzymes in a cell
60
What is transcription
genetic information encoded in DNA and copied into complementary RNA molecule > essential for gene expression
61
What are the 3 steps of transcription
1. Initiation
2. Elongation
3. Termination
62
Initiation of Transcription
occurs when the enzyme RNA polymerase binds to a region called the promoter
signal the DNA to unwind so the enzyme can "read" the bases in one of the DNA strands
the enzyme is now ready to make a strand of mRNA with the complementary sequence of bases
63
Where does transcription occur
in the nucleotide region of the cytoplasm in bacteria
64
What is a promoter
enzymes that synthesize RNA will bind to a specific DNA nucleotide to initiate transcription
65
Whats the difference between a promoter sequence and origin
A promoter is a DNA sequence that signals where to start transcribing a gene into RNA for protein synthesis, while the origin of replication is a sequence where replication of the entire DNA molecule begins during cell division.
66
Elongation of Transcription of RNA
refers to the phase in which RNA polymerase synthesizes an RNA molecule using the DNA template
occurs after initiation
RNA moves along the DNA template strand 3' to 5' synthesizing a complementary RNA molecule in 5' to 3'
it will unwind the DNA double helix
the enzyme will add ribonucleotides to the growing RNA chain
67
Elongation in Transcription will continue until
RNA polymerase encounters a termination signal in the DNA sequence
68
What are the two types of transcription termination
1. rho independent termination
2. rho dependent termination
69
Rho INdependent termination
a specific DNA sequence in C-G known as GC-hairpin forms in the RNA transcript
this structure causes the RNA polymerase to pause and dissociate from the DNA template
70
Rho DEpendent termination
a protein called RHO interacts with RNA transcript and RNA polymerase to facilitate termination
when RHO reaches the polymerase it induces the release of RNA polymerase from the DNA template which will lead to the termination of the transcription
71
Transcriptional Differences in Eukaryotes
-occurs in the nucleus
-while translation occurs in cytoplasm
-have 3 RNA polymerases RNA pol I, II, III
-numerous transcription factors
-mRNA processed before translation
72
Translation
process in which ribosomes use genetic information of nucleotide sequence to synthesize polypeptides
73
In prokaryotic ribosomes are responsible for
protein synthesis, or translation
74
What are the subunits of prokaryotic ribosomes
consist of two subunits
small subunit 30S and the large is 50S
which come together to form 70S
75
When ribosomes are attached to mRNA during translation they provide what
binding sites for mRNA and tRNA molecules
76
How many tRNA binding sites are there
there are three main tRNA binding sites located in the large subunit where tRNA molecules bind during translation
77
A site
aminoacyl site
binding site for incoming aminoacyl tRNA carrying the amino acid corresponding to the next codon in the mRNA sequence
78
P site
peptidyl site
binding site for the tRNA molecule that carries the growing polypeptide chain
where peptide bond formation occurs between adjacent amino acids
79
E site
exit site
binding site for the tRNA molecule that has already delivered its AA to the growing polypeptide chain and is ready to exit the ribosome
80
After a peptide is formed what happens to the sites
the tRNA at the P site moves to the E site before being released from the ribosome and recycled for another round of translation
81
What are the steps of Translation
1. Initiation
2. Elongation
3. Termination
82
Initiation of Translation
beginning of protein synthesis
assembly of ribosome
translation intitation begins with recognition of start codon typically AUG
the start codon proceeds by a ribosome binding site of the small ribosomal subunit
the large ribosomal completes at 70S ribosome
the initiator tRNA is bound to the P-site
83
