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Question 33

Answer 33

Crossing over between linked genes produces nonrecombinant and recombinant offspring. See example in answers of a diagram.

Question 34

Coupling (or cis) configuration is an arrangement where wild type alleles are found on one chromosome and mutant alleles are found on the other chromosome.

Repulsion (or trans) configuration is when each chromosome contains one wild type and one mutant allele.

Answer 34

Explain coupling and repulsion configuration and how they differ. Also what is another name for both configurations.

Question 35

the sorting of alleles into new combinations

Answer 35

Recombination is?

Question 36

sorting of alleles on different chromosomes (independent assortment) or random segregation of chromosomes in anaphas I of meiosis and is the kind of recombination that Mendel discovered while studying dihybrid crosses.

Produces 50% nonrecombinant gametes and 50% recombinant gametes.

Answer 36

Interchromosomal recombination is?

Question 37

the sorting of alleles on the same chromosome (crossing over), the exchange of genetic material in prophase I of meiosis.

Often produces less than 50% recombinant gametes, however, if genes are far apart on same chromosome then intrachromosomal recombination also produces 50% recombinant gametes.

Answer 37

Intrachromosomal recombination is?

Question 38

Answer 38

Physical evidence of recombination as presented by Creighton and McClintock in 1931.

Question 39

determining the proportions of the types of offspring.

Answer 39

The recombination frequency is?

Question 40

a testcross for three genes

Answer 40

What is a three point testcross?

Question 41

Answer 41

Three types of crossover can take place among three linked loci

Question 42

1. relative
2. not

Answer 42

1. Recombination provides the order of genes and _____ distances
2. double cross overs will ____ be counted and underestimate distances

Question 43

different, mapping

Answer 43

Recombination between _____ genes can be used for gene ______

Question 44

First, determine order of loci

Then, determine cross overs

Answer 44

To determine the gene order you do what first then what second?

Question 45

information abou the location and number of crossovers in the gametes that produced the progeny of a cross is needed.

An efficient way to obtain this information is to use a three point cross test in which an individual heterozygous at three linked loci is crossed with an individual that is homozygous recessive at the three loci.

Answer 45

To map genes what is needed? What is an efficient way to obtain this information?

Question 46

underestimates

Answer 46

Recombination between different genes can be used for gene mapping but it ________ frequencies

Question 47

pedigree analysis
Example: linkage of nail-patella syndrome and ABO blood group system.

nail-patella syndrome is a rare autosomal dominant disorder characterised by abnormal fingernails and absent or rudimentary kneecaps.

Answer 47

Gene mapping in humans uses? Give an example.

Question 48

gene mapping

Answer 48

Molecular markers can be used for?

Question 49

RFLPs - restriction fragment length polymorphisms which are variations in DNA sequence detected by cutting the DNA with restriction enzymes.

Answer 49

What was one of the earliest molecular markers? Explain a bit about it.

Question 50

Molecular markers which is detecting variable numbers of short DNA sequences repeated in tandem.

Answer 50

What are microsatellites?

Question 51

Sequencing

Answer 51

What is the ultimate mapping tool?

Question 52

chromosomal location

Answer 52

Recombination established linkage groups but gives no information on ______ ________.

Question 53

1. chromosomal location of genes
2. No

Answer 53

1. Physical chromosome methods were developed to determine?
2. Is this dependant on crossing over?

Question 54

is based on the observation that genes that reside physically close on a chromosome remain linked during meiosis. Genetic linkage analysis is a powerful tool to detect the chromosomal location of disease genes. It is a more traditional approach

Answer 54

Linkage analysis is?

Question 55

looks at traits in combination with suites of alleles, or looking for nonrandom associations between the presence of a trait and alleles at many different loci scattered across the genome.

It looks for associations between traits and particular suites of alleles in a population.

For instance (see below) a gene involved with bipolar diseases is linked to a certain haplotype.
Crossing over reduces this link
Fast reduction means not close together

Answer 55

What is genome wide association

Question 56

wikipedia: is a combination of alleles (DNA sequences) at adjacent locations (loci) on a chromosome that are transmitted together.

free dictionary: a combination of alleles (for different genes) that are located closely together on the same chromosome and that tend to be inherited together

Answer 56

What is haplotype?

Question 57

**text**: the nonrandom association between alleles in a haplotype. **slides**: Non random association of the trait with a certain haplotype **wikipedia**: is the non-random association of alleles at two or more loci, that may or may not be on the same chromosome.

Answer 57

What is linkage disequilibrium?

Question 58

absence of one or more of the bands that are normally on a chromosome reveals a chromosome deletion, a mutation in which part of the chromosome is missing. Genes can be assigned to regions of chromosomes by studying the association between a gene's phenotype or product and particular chromosomal deletions.

Answer 58

What is deletion mapping?

Question 59

is the fusion of different types of cells. to do this cells that will divide indefinitely are used (from tumours or altered by viruses) and are cultured in laboratory to create a **cell line**. Human and mouse cell lines can fuse to create cells with two nuclei which is called a **heterokaryon**. The two nuclei gradually fuse then as cell divides then all but a few human chromosomes are lost. The presence of extra human chromosomes in the mouse genome makes it possible to assign human genes to specific chromosomes.

Answer 59

Explain somatic cell hybridization

Question 60

In cell line 1 the gene product is present when chromosome 4 is intact. The gene product is absent in cell line 2 when the entire chromosome 4 is absent. The gene product is absent in cell line 3 when the short arm is missing.

Answer 60

Genes can be localised to a specific part of a chromosome by using somatic-cell hydrisation. See diagram on next page.

Question 61

where researchers actually see genes through a radioactive probe that fluoresces under ultraviolet light so that it can be visualised.

Answer 61

What is **in situ hybridization**?

Question 62

extensively

Answer 62

Recombination rates vary ________ between species and between chromosomes in one species

Question 63

2

Answer 63

There are __ times more recombination in humans than in mice and rats

Question 64

21 and 22 2 and 4

Answer 64

Human chromosomes \_\_\_\_ and _____ have highest recombination level, ___ and ___ the lowest

Question 65

Yes

Answer 65

Might recombination hotspots be species specific?