Genetics exam 2

**Arrangements of Alleles on Chromosomes in a Dihybrid:**

\- when **one chromosome carries both mutations** and the **homolog carries both wild-type alleles**

cis- configuration

**Arrangements of Alleles on Chromosomes in a Dihybrid:**

\- when the two mutations are on separate homologs, as are the wild-type alleles

trans-configuration

**Arrangements of Alleles on Chromosomes in a Dihybrid:**

\- What is another name for trans configuration?

repulsion

**Arrangements of Alleles on Chromosomes in a Dihybrid:**

\- What is another name for cis coupling?

coupling

How do you get the recombination frequency (or % recombination)?

add up the recombinant types, divide it by the total, multiply by 100.

Recombination frequency equals map distance in ___ _____(mu) or _________(cm)

map units, centimorgans

another word for crossing over is ....

recombination

crossing over between nonsister chromatids is also known as ...

chiasma

you can actually get the creation of the recombinant types through the crossover of nonsister chromatids known as ....

chiasma

When genes are **not linked** and on **different chromosomes**, we obviously get **independent assortment**. With this, we would expect the even ______ ratio

1:1:1:1

If two genes are **extremely close together** and **on the same chromosome** (right on top of each other) they would never create a recombinant type offspring. This is called ________ linkage

complete

If 2 genes are farther apart but still linked, you will end up with a ______ map distance.

Bigger

Two-Point Mapping:

\- When trying to identify the recombinant and parent offspring, we typically see the parental offspring having the __**(smaller/bigger)**__ number and the recombinant offspring having the **(smaller/bigger)** number

bigger, smaller

True or false...

\- There is recombination in both male & female Drosophila

False

The gene that switches in a single crossover in 3 point mapping is the one on the ___

end

The location of crossover determines the _____ _____ (genotypes) in the four gametes produced

allele combos

are single or double crossovers more likely?

single

In double crossovers the gene that switches is **ALWAYS** in the ______

middle

Genotype created by double crossovers depends on which gene is in the ______

middle

In order to determine which gene is in the middle, you must look at the data given in 3 point mapping problems and see that the numbers are very __**(high/low)**__ for 2 classes

low

**In 3 Point mapping:**

\- What is the first step?

Identifying recombinant and parental types in the F2

Coefficients of coincidence = _____________ / ____________

observed frequency of DCOS/ Expected frequency of DCOS

**Classes of Asci:**

\- ________ _______ are two types of **spores**, identical to the parentals = PD

Parental ditypes

**Classes of Asci:**

\- __________ _______ are two types of spores, **not identical to the parentals**, recombinants = NPD

nonparental ditypes

Classes of Asci:

\- ________ four types of spores, both parentals and recombinants & recombinants = TT

Tetratypes

All three Ascus types are generated whether the Two Loci are _______ or _____ ___________

linked, assort independently

**If the a and b genes are linked:**

____ are a result of no crossover

PD

**If the a and b genes are linked:**

____ are a result of double crossover events involving all four chromatids

NPD

**If the a and b genes are linked:**

\- In summary, ____ are expected to be **significantly more numerous** than _____ for linked loci

PD, NPD

**If the a and b genes are NOT linked:**

\- ____ and _____ are generated through independent assortment

PD, NPD

**If the a and b genes are NOT linked:**

\- Than PD and NPD should occur in _____ _________

equal frequencies

**If the a and b genes are NOT linked:**

\- ____ are generated by one crossover in which only half the tetra type chromatids are recombinant

TT

In haploid mapping problems for Asci, what is the first step?

Identify which are PD,NPD, and TT

In haploid mapping problems for Asci, in the 2nd step, we compared the frequencies of ____ and _____ to determine if the genes are ______

PD, NPD, linked

What is the name for the **2 largest phenotypic categories** in the **F2** that have the **same phenotypes** as the **original parents** from the **P generation?**

Parental or nonrecombinant types

Outside of the parental types in the resulting phenotypes, what are the others called?

\- least amount

recombinant types

In haploid mapping problems, we calculate the **recombination frequency** with the formula:

\[# of NPD + 1/2 # of TT\]/ # total asci

\- Why is the # of tetratypes halved?

because only half the TT chromatids are recombinant

In haploid mapping problems, we calculate the **recombination frequency** with the formula:

\[# of NPD + 1/2 # of TT\]/ # total asci

\- Why isn't the # of nonparental ditypes halved?

because they are all recombinants

With Asci, octads can be either ___ or ___

FDS, SDS

___: first division segregation

has the ratio (__:__)

FDS, 4:4

___: second division segregation

has the ratio (___:___:___:___, and __:__:__)

SDS, 2:2:2:2, 2:4:2

With Asci, the recombination frequency equation is (1/2# of SDS asci/# of total asci), what does this measure?

gene to centromere distance

Crossing over **DOES** rarely occur in mitosis, it is known as mitotic or _____ _______ _____

somatic crossing over

Crossing over occurs between sister chromatids during meiosis known as ...

sister chromatid exchange

___ _______ and _______ _____ cause exceptions to the law of segregation

gene conversion , meiotic drive

True or false...

\- mapping can be done at the microscopic level with DNA sequences

True

Bacteria can increase variation by __________ _____

exchanging genes

Bacteria can increase variation by exchanging genes, what are some other examples?

conjugation, transduction, and transformation

**Gene exchange in Prokaryotes**

\- The uptake of DNA from the environment

Transformation

Gene exchange in Prokaryotes

* With transformation, oftentimes plasmids are the vectors
* Is it vertical or horizontal gene transfer?

horizontal

A big difference between eukaryote and bacteria DNA is that bacteria have ______ DNA whereas Eukaryotes have _______ DNA

Circular, Linear

Microscopic particles that infect living cells are called....

viruses

Viruses consist of a genome (DNA or RNA) wrapped in a protein coat called a ____

capsid

Some viruses are wrapped in a capsid while some are enclosed by an _______

envelope

What gives viruses their bizarre structures?

spikes and other accessory structures

True or false...

\- Viruses' genome may be DNA or RNA, single or double stranded, linear or circular, haploid or diploid

True

What do bacteriophages do to a cell?

attach and inject genetic material

What are the two life cycle types of bacteriophages?

Virulent and temperate phages

**Which bacteriophage life cycle is this...**

\- immediate production of new phages and cell lysis

Virulent phages

**Which bacteriophage life cycle is this...**

\- integration into host genome (**prophage**) or plasmid

temperate phage

Temperate phages can participate in 2 different life history types, what are they?

Lysogenic and lytic cycle

**Lysogenic or lytic cycle?**

\- Bacterial cell harbors a prophage, replicating it in all daughter cells

lysogenic

**Lysogenic or lytic cycle?**

\- Eventually lead to by other cycle, phage gene expression, cell lysis, release of new phages

Lytic cycle

Virulent bacteriophages only do which cycle?

Lytic cycle

Gaps in the bacterial lawn that occur due to phage infection

plaques

Prototrophs vs Auxotrophs:

* Wild type, can grow on minimal medium
* Notation has +

Prototrophs

Prototrophs vs Auxotrophs:

* Mutants that cannot grow on minimal medium unless it is supplemented
* Notation has -

Auxotrophs

The more frequently genes are incorporated into the recipient cell together, the closer those loci are to each other

Cotransformation mapping

cotransformation frequency is __**(inversely/proportionally)**__ related to distance

inversely

If cotransformation frequency is **inversely** related to distance, than a large number must mean a _____ distance

small

Cotransformation: Data Analysis

* Calculating r = the cotransformation frequency
* r = _______________ for both loci / total transformants

cotransformants

For bacteria in 3 point cotransformation, how do we determine which gene is in the middle?

the gene that wasn't incorporated after quadruple crossover

In bacteria 3 point cotransformation, is the middle gene the **least or most** frequent?

least

When mapping with cotransformation, what is another method that can be used?

Use recomb frequency to get distance

What is it called when a bacterial DNA is transferred from one cell to another via a direct connection?

conjugation

another word for a direct connection is ....

Pilus

What does the F in F factor stand for?

fertility

another word for bacterial mating is called __________

conjugation

**Transfer of Genomic DNA:**

\- F plasmid can sometimes recombine into host chromosome to become _________

integrated

**Transfer of Genomic DNA:**

\- When an integrated F plasmid starts to transfer genes, it can include linked _______ ___

genomic DNA

When F plasmid recombines into Genomic DNA it forms a ___ ____

Hfr cell

Hfr conjugation transfers DNA about how much faster than F+?

one thousand times

In Hfr conjugation, transferred DNA is called ________

exogenote

In Hfr conjugation, host genome is called ________

endogenote

In Hfr conjugation, E.coli cell with two copies of a DNA sequence is called a ________ or partial diploid

merozygote

Transfer can be interrupted by shaking culture called ___________ _______

Interrupted mating

Interrupted mating allows to start and then interrupted at ________ ______

different times

Interrupted mating can determine gene order by looking at timing of _____ ______

allele transfer

__________: gene transfer by Phages

Transduction

Bacterial DNA sometimes gets incorporated into _____ _____

phage head

_________ ___________: bacterial genome joined to phage DNA

specialized transduction

_____________ ___________: random parts of bacterial genome separate from phage DNA

generalized transduction

When bacterial DNA is transferred from one cell to another via a virus is known as ___________

Transduction

When mapping with cotransduction, we must determine what genes cotransduce with each other, these must be _____ together

close

Determining rarest class of cotransductants: the gene that isn't _________ is in the middle

transduced

true or false...

the skills for getting map distance in cotransduction is the exact same as cotransformation

True

______ genetic mapping undergo recombination when multiple phages infect the same cell

phage

With phage genetic mapping, map distance is _________ just as in eukaryotes

inferred

There are _______ _______ when there are more than two alleles for a single gene

multiple alleles

________: more than two genes affect a single trait

Polygenic