Bacterial Genome (Block 1)

?
  • Created by: hkaur25
  • Created on: 26-12-18 17:27
Name three features of the bacterial chromosome
1. Haploid, 2. Double Stranded, 3. Circular
1 of 52
What does the bacterial chromosome look like?
Circular
2 of 52
How many chromosome are there in a bacteria cell?
1
3 of 52
What is a genetic linkage group and how many does the bacterial chromosome have?
A genetic linkage group when all genes in the chromosome are inherited together. There is only one genetic linkage group in a bacterial chromosome as there is only one chromosome which is replicated identically.
4 of 52
What is a nucleoid?
A nuceloid is a non membrane bound organelle which contains the bacterial chromosome
5 of 52
What features do eukaryotic chromosomes contain which bacterial chromosomes do not?
Bacterial chromosomes do not contain histones which are proteins responsible for gene regulation and do not contain chromatin
6 of 52
How is DNA contained in the chromosome?
Loop domains. These contain folded chromosomes which are supercoiled to allow it to fit in the cell.
7 of 52
What is the purpose of DNA Gyrase?
DNA Gyrase is responsible for supercoiling of the chromosome in the cell
8 of 52
What proteins stabilise the supercoiling of the chromosome?
HU and HNS
9 of 52
How much bigger is the chromosome than the cell?
x1000
10 of 52
Name three characteristics of chromosomal replication
1. Semi Conservative, 2. Single unique origin of replication, 3. bi-directional (x2 replichores)
11 of 52
How many genes are there in E-coli? How many of these do we know the function of?
4288 with 62% with a known function
12 of 52
What is the G:C ratio in E-coli?
50%
13 of 52
What does the E-coli gene look like?
It only contains promoter/terminators, RNA and the coding sequence. The coding sequence takes up 87% of the gene, the promoters 10% and RNA 2%
14 of 52
What do eukaryotic genes contain that bacterial genes do not?
Junk DNA (non-coding) and introns.
15 of 52
How is a genetic map created?
Using co-inheritance
16 of 52
What is a plasmid?
Extrachromosomal genetic elements
17 of 52
Are plasmids double or single stranded?
double
18 of 52
what is the size of a plasmid?
1.5 kb - 150 kb
19 of 52
True or False? - Plasmids are found in every bacterial cell
True
20 of 52
What is the function of the plasmid? Is it essential to the viability of the cell?
Plasmids are non-essential to the viability of the cell, however provide benefits such as antibiotic resistance and heavy metal tolerance (eg. mercury) and vectors for genetic engineering. These functions are important for inheritance.
21 of 52
How does the plasmid replicate?
Autonomously, it does not require the chromosome to replicate. It replicates semi conservatively and has a short replication time (6seconds).
22 of 52
What is OriV?
The origin site of plasmid replication. It is a fixed site. It is responsible for copy numbers.
23 of 52
Where are plasmids genes found?
Transposons.
24 of 52
How do plasmids regulate replication if they do not use the chromosome?
They have DNA polymerase and their own initiator proteins. The regulator is responsible for the copy number.
25 of 52
What is incompatibility
More than one plasmid cannot exist in the same cell
26 of 52
What does ColE1 replication produce?
RNAII upstream of the OriV, this creates a DNA-RNA hybrid
27 of 52
What is the purpose of RNaseH in the replication of ColE1?
Cuts the DNA-RNA hybrid at a specific site to form 3'OH which is a primer for DNA synthesis
28 of 52
How is ColE1 replication regulated?
RNAI is complementary to the 5' prime end of RNAII. They form a RNAI-RNAII hybrid with the help on Rom protein. RNAI is responsible for controlling replication.
29 of 52
True or False? - RNaseH does NOT cut RNAI-RNAII hybrid.
True
30 of 52
Why are RNAI and Rom levels important?
The levels of Rom and RNAI interfere with initiation of replication
31 of 52
What is the function of RepA in the replication of R100?
Enables plasmid replication from oriV
32 of 52
What inhibits RepA transcription?
CopB inhibits plasmid entering cell
33 of 52
Without the presence of CopB, what happens when the plasmid enters the cell?
Burst of plasmid replication
34 of 52
What does CopA produce as a second level of control?
antisense RNA
35 of 52
What does the amount of CopA RNA tell you?
plasmid copy number
36 of 52
What happens to the level of CopA RNA after cell division
Decreases
37 of 52
What makes plasmids incompatible?
If they have the same copy control and the same specificity control
38 of 52
What does incompatibility tell you?
How closely related the plasmids are. Incompatible plasmid DNA's are homologous. Incompatibility is used as a measure of classification.
39 of 52
How does incompatibility arise?
1. Experiencing common replication control 2. random choice of plasmid copies for replication
40 of 52
What method do plasmids use to move between cells?
Transmission is caused by conjugation
41 of 52
What is conjugation?
Cell to cell transmission using a 'bridge' like structure.
42 of 52
What is an example of a conjugative plasmid? What features does it have?
Fertility factor F (E-coli), it is large (50 kb), has its own unique origin of transfer replication (oriT), carry genes encoding “transfer functions”. (Tra+) such as the production of pilus on cell surface and has ssDNA transfered by “rolling circle'
43 of 52
What is an example of a non-conjugative plasmid?
ColE1, they are transferred using conjugative plasmids. They are small and carry oriT but no transfer genes. 'relaxation complex'
44 of 52
What is an example of a plasmid that has transferred between kingdoms?
Ti plasmid of Agrobacterium transferred to plant cells.
45 of 52
True or False? - Some plasmids can integrate into chromosome
True
46 of 52
What are transposable elements?
known as "jumping genes" or transposons, are sequences of DNA that move (or jump) from one location in the genome to another.
47 of 52
What are three characteristics of transposable elements?
1. They can be chromosomes, plasmids or just phage. 2. Mutagenic as it causes insertional inactivation (disable expression of a gene). 3. independent of host recombination system
48 of 52
What are IS- elements
Insertion Sequences - short discrete segments of DNA that transpose to new locations in the genome as they carry gene(s) responsible for transposition.
49 of 52
Do IS elements affect the phenotype?
No as they do not carry phenotype determining genes.
50 of 52
What can be found on the ends of IS elements?
Inverted Repeats
51 of 52
How do inverted repeats affect insertion of IS elements?
Insertion of the IS elements at new site causes duplication of target sequence
52 of 52

Other cards in this set

Card 2

Front

What does the bacterial chromosome look like?

Back

Circular

Card 3

Front

How many chromosome are there in a bacteria cell?

Back

Preview of the front of card 3

Card 4

Front

What is a genetic linkage group and how many does the bacterial chromosome have?

Back

Preview of the front of card 4

Card 5

Front

What is a nucleoid?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Genetics resources »