Genetic Recombination

Question 1

Why is variation good

Answer 1

It helps an organism survive because of natural selction

Question 2

Genetic recombination

Answer 2

Cutting and pasting DNA backbones

Question 3

Genetic recombination requires

Answer 3

At the simplest 2 unique DNA strands, something to bring DNA close, and enzymes to cut, exchange, and paste DNA

Question 4

Sugar phosphate backbone

Answer 4

Winds around base pairs connected by weak hydrogen bonds, It is held together by strong covalent bonds

Question 5

Homologues

Answer 5

Similar but not identical, allows for precise recombination

Question 6

Recombination general process

Answer 6

Homologues regions pair,
Enzymes break 4 phosphate bonds
Free ends are exchanged in DNA, then recombined

Question 7

There are x backbones

Answer 7

4/every recombination event

Question 8

Recombination in bacteria

Answer 8

Uses DNA from other cells because it produces asexually

Question 9

How is E.Coli la grown

Answer 9

In a medium containing water, an organic carbon source, and an inorganic salts (1 including a nitrogen base), agar

Question 10

Cultures

Answer 10

Lots of clone bacteria. Made by spreading bacteria on the agar gel so a colony can form

Question 11

Prototrophs

Answer 11

Strains of ecoli that can make amino acids

Question 12

Auxotrophes

Answer 12

Mutant strains that cannot make amino acids. Cannot make arginine

Question 13

ArgA

Answer 13

Gene that governs if a cell can make arginine

Question 14

E. coli study

Answer 14

Proto and auxotroph’s were placed near each other and were observed for DNA mixing

Question 15

2 strains of DNA from x-ray mutating

Answer 15

They were extracted from replica plating. Fount that colonies grew when nothing was present, suggesting the 2 parental types combined to create healthy bio+ met+ leu+ thr+ thi+

Question 16

1st strain

Answer 16

Needed biotin and the amino acid methionine to grow

bio- met- leu+ thr+ thi+

Question 17

2nd strain

Answer 17

Needed the amino acids leucine and threonine and vitamin thiamine. bio+ met+ leu- thr- thi-

Question 18

Mutate back

Answer 18

Didn’t happen when the cells were alone therefore it was unlikely to have occurred when the cells were together

Question 19

How did the cells DNA mix

Answer 19

Conjugation

Question 20

Conjugation

Answer 20

Cells contact each other along the sex pilus and form a cytoplasmic bridge.
Copied part of the DNA flows through and non directional transfer and gene regulation occurs

Question 21

The F factor and conjugation

Answer 21

Initiated by a small bacteria with small circle DNA called plasmids

Question 22

Fertility plamsid (vertical interference)

Answer 22

Carries genes and a replication origin allowing DNA copies to be passed on, proteins that encode for the sex pili

Question 23

Horizontal interference

Answer 23

An F factor is copied and passed on to a recipient cell

Question 24

F+

Answer 24

Donor cell (containing the F factor). Can mate with each other

Question 25

F-

Answer 25

Recipient cell that lacks the F factor

Question 26

Rolling circle

Answer 26

How the F factor replicates DNA

Question 27

Steps to rolling circle DNA replication

Answer 27

1 DNA strand is broken at the replication site The strand is pulled through the cytoplasmic bridge while the other strand rolls DNA synthesis fill in complimentary base pairings

Question 28

Recombination and rolling circle

Answer 28

Does not occur between the 2 cells DNA

Question 29

Hfr cells

Answer 29

Cells that donate DNA and make sex pili and conjugate with F cells

Question 30

F+ DNA combination

Answer 30

2 DNA circles recombine to become 1 large circle

Question 31

In Hfr recombination

Answer 31

DNA is only altered in the one specific cell, the F factor is integrated, but gene expression still occurs

Question 32

Conjugate bridge

Answer 32

Easily breaks-Very rare for a whole chromosome to be transfered

Question 33

F factor in Hfr

Answer 33

1/2 is the leading head of DNA, and the other 1/2 is the end of the DNA strand. If the full strand is transferred the recipient cell becomes Hfr

Question 34

Partial diploid

Answer 34

More common. 2 copies of the genes that came through

Question 35

Enzymes in the recipient cell

Answer 35

Degrade the linear Hfr chromosome after recombination. | Cells produce creating clones of the new DNA

Question 36

Mapping enes by conjugation experiment

Answer 36

Matin Hfr and F cells with different number of alleles | They were broken apart at different stages

Question 37

Mapping genes by conjugation results

Answer 37

The longer they waited the more donor genes that entered the recipient, producing recombinants

Question 38

Mapping genes by conguation application

Answer 38

This is how the genes for E. Coli were mapped

Question 39

Transformation and transduction

Answer 39

Other ways SNA can be transferred, can use living or dead organisms

Question 40

Transformation

Answer 40

Bacteria take up DNA pieces released into the environment by other cells The transfer occurs the same as conjugation

Question 41

Artificial transformation

Answer 41

Because not all cells can do it naturally. Uses chemical or electrical currents

Question 42

Transduction

Answer 42

DNA transfer occurs inside the head of an infecting bacterial virus

Question 43

Bacteriophages

Answer 43

Cycle of viruses that infect bacteria

Question 44

Transduction process

Answer 44

Phages assemble in a cell Viral/hosts DNA is incorporated and the host is killed Phages take over the cell and spread their DNA the same way conjugation does

Question 45

Bacterial DNA from a host cell

Answer 45

May be altered but does not kill the cell it enters

Question 46

2 types of transduction

Answer 46

Arise from different infection cycles. General and specialized transduction

Question 47

General transduction

Answer 47

All donor genes are equally likely to be transferred. Associated with virulent phages Host chromosomes destroyed for building of new chromosomes

Question 48

Virulent phages

Answer 48

Kill the host cell every lytic (infection) cycle

Question 49

If some genes are missed in general treansduction

Answer 49

It becomes a transducing phage, and manually infects cells. | The new recipient cell survives

Question 50

Specialized transduction

Answer 50

A mistake in a different infection cycle. Involves temperate bacteriophage

Question 51

Temperate bacteriophage

Answer 51

Determines if a host will be a host for a long time.

Question 52

If temperate bacteriophage says no

Answer 52

the cell makes new phages and then explodes

Question 53

If temperate bacteriophage says yes

Answer 53

A single recombination event occurs

Question 54

Phphage

Answer 54

A state similar to the integration of an F factor. Is passed on to all daughter cells

Question 55

Specialized transduction mistake

Answer 55

When a prophage is excreted from the chromosome. | It can be imprecise, leaving bacteria DNA behind. The host cell is not killed

Question 56

Conjugation, transformation and transduction similarities

Answer 56

DNA from 2 bacteria cells is brought together, creating diversity